Virginia Law

Article 2. General Information [Repealed]

12VAC5-590-370. Monitoring requirements.

A. Bacteriological monitoring.

1. The owner shall collect total coliform samples at specific sites and according to a schedule that is representative of water quality throughout the distribution system, which shall be documented in a written BSSP. The BSSP shall be established or approved by the department after investigation of the source water, method of treatment and storage, and the final delivery of the drinking water through the distribution system. The BSSP shall include the following:

a. Specific routine, repeat, and triggered source water monitoring sites, identified by address or location.

b. Distribution maps showing the location where specific sampling sites will be selected with all monitoring sites identified.

c. A minimum of three routine sample sites identified for each required routine sample for waterworks serving 3,300 or fewer people.

d. A sample collection schedule with the number of routine samples required per monitoring period in accordance with Table 370.1 and subdivision A 4 of this section.

e. Repeat sample sites for each routine sample site that shall include the original routine location, at least one tap within five service connections upstream, and at least one tap within five service connections downstream with the following exceptions:

(1) Alternative repeat sample sites may be allowed when a routine site is one connection away from or at the end of a distribution system main or as approved by the department;

(2) A groundwater system serving 1,000 or fewer people may propose repeat sample sites, such as an entry point to the distribution system, that differentiate potential source water and distribution system contamination; or

(3) A groundwater system serving 1,000 or fewer people with a single well source and no treatment may propose that one repeat sample be collected at the triggered source water monitoring site, provided that representative sampling of the distribution system is still achieved.

f. A repeat sampling site shall not be eliminated from future collections solely based on a history of questionable water quality unless the sampling point is unacceptable as determined by the department.

g. A seasonal waterworks may collect special samples in accordance with an approved start-up procedure pursuant to subdivision A 12 a of this section.

2. The minimum number of bacteriological samples for total coliform evaluation to be collected and analyzed monthly from the distribution system of a community waterworks, or a NTNC shall be in accordance with Table 370.1. The owner of a (i) TNC that uses a surface water source or a groundwater source under the direct influence of surface water or (ii) a large TNC (serving 1,000 or more persons per day) shall collect and submit samples monthly for analysis in accordance with Table 370.1. For all other TNCs, the owner shall collect and submit samples for analysis each calendar quarter in accordance with Table 370.1. The minimum number of samples must be collected and submitted even if the waterworks has exceeded the E. coli PMCL or the total coliform treatment technique triggers.

3. The samples shall be collected at evenly spaced time intervals as practical throughout the month, except that a waterworks that uses only groundwater and serves 4,900 or fewer people may have the required samples collected on a single day if the samples are collected from different sites.

4. If the results of a sanitary survey or other factors determine that some other frequency is more appropriate than that stated in subdivisions A 2 and A 3 of this section, then a modified BSSP may be required. The altered frequency shall be confirmed or changed on the basis of subsequent sanitary surveys or as otherwise determined by the department.

5. The owner may conduct more compliance monitoring than is required by this section to investigate potential problems in the distribution system and to assist in uncovering problems. The owner may collect more than the minimum number of required routine samples. If the samples are collected in accordance with the existing BSSP and are representative of water quality throughout the distribution system, then all of the results shall be included in determining whether a coliform treatment technique has been triggered.

6. The owner may propose repeat monitoring locations believed to be representative of a pathway for contamination of the distribution system. The owner may elect to specify either alternative fixed locations or criteria for selecting repeat sampling sites on a situational basis in a SOP in its BSSP. The owner shall design the SOP to focus on the collection of repeat samples at locations that best verify and determine the extent of potential contamination of the distribution system based on specific situations. The department shall require modifications to the SOP or require alternative monitoring locations as needed.

7. All bacteriological analyses shall be performed in accordance with 12VAC5-590-440 by the DCLS or by a laboratory certified by the DCLS for drinking water samples.

8. Annual monitoring. The department may reduce the bacteriological monitoring frequency at a well-operated TNC from a quarterly sample to one annual sample, and the waterworks may remain at the annual monitoring frequency provided that all of the following conditions are continuously met:

a. The waterworks serves 1,000 or fewer people per day.

b. The waterworks uses groundwater only and is not under the influence of surface water.

c. The waterworks has a clean compliance history for a minimum of 12 consecutive months.

d. The most recent sanitary survey shows that the waterworks is free of sanitary defects or has corrected all identified sanitary defects.

e. The waterworks has a protected water source.

f. The waterworks meets existing approved construction standards.

g. The department has conducted an annual site visit within the last 12 months, and all identified sanitary defects have been corrected. For the purposes of this section, an annual site visit is equivalent to a voluntary Level 2 assessment that meets the criteria in 12VAC5-590-392 C. A sanitary survey may meet the requirement for an annual site visit in the year in which the sanitary survey is completed if all identified sanitary defects have been corrected.

9. Increased monitoring.

a. A TNC on quarterly or annual monitoring shall begin monthly monitoring in the month following an event if any of the following occurs: (i) the waterworks triggers a Level 2 assessment or two Level 1 assessments under the provisions of 12VAC5-590-392 in a rolling 12-month period, (ii) the waterworks has an E. coli PMCL violation, (iii) the waterworks has a coliform treatment technique violation, (iv) the owner has two monitoring violations under 12VAC5-590-370 A 2, or (v) the owner has one monitoring violation under 12VAC5-590-370 A 2 and one Level 1 assessment under 12VAC5-590-392 in a rolling 12-month period. The owner shall continue monthly monitoring until the requirements in subdivisions A 10 a and A 10 b of this section are met. A waterworks on monthly monitoring for other reasons is not considered to be on increased monitoring for the purpose of this subdivision.

b. A TNC on annual monitoring that experiences one monitoring violation of 12VAC5-590-370 must begin quarterly monitoring in the quarter following the event. The owner shall continue quarterly monitoring until the conditions in subdivision A 11 of this section are continuously met and the department reduces the monitoring frequency.

10. Returning to quarterly routine monitoring. The department may return the monitoring frequency of a TNC subject to subdivision A 9 a of this section and using groundwater not under the influence of surface water to quarterly monitoring if:

a. The department has completed a sanitary survey or a site visit within the last 12 months, and the TNC is free of sanitary defects and has a protected water source; and

b. The waterworks has maintained a clean compliance history for a minimum of 12 consecutive months following the event.

11. Returning to annual routine monitoring. The department may reduce the monitoring frequency of a TNC subject to subdivision A 9 of this section and using groundwater not under the influence of surface water to annual monitoring if:

a. An annual site visit or sanitary survey is conducted by the department, and all identified sanitary defects are corrected. The waterworks may substitute a voluntary Level 2 assessment for the annual site visit.

b. The waterworks has a protected water source and maintained a clean compliance history for a minimum of 12 consecutive months following the event.

c. The waterworks has in place or has adopted one or more of the following additional barriers to contamination: (i) an approved cross-connection control program, (ii) a licensed operator, (iii) continuous disinfection and maintenance of a residual in the distribution system in accordance with criteria specified by the department, (iv) demonstration of maintenance of at least a 4-log removal or inactivation of viruses in accordance with 12VAC5-590-379 A, or (v) other equivalent enhancements approved by the department.

12. Seasonal waterworks monitoring.

a. A seasonal waterworks shall demonstrate completion of an approved start-up procedure that may include start-up sampling before serving water.

b. A seasonal waterworks shall monitor every month that it is in operation.

c. The department may waive any seasonal waterworks from some or all of the requirements for seasonal waterworks if the entire distribution system remains pressurized during the entire period that the waterworks is not operating.

d. Failure to complete an approved start-up procedure before serving water is a treatment technique violation and requires the owner to provide public notification under Tier 2 conditions in 12VAC5-590-540 A 2.

e. Failure to submit certification of completion to the department after the owner completes an approved start-up procedure is a reporting violation and requires the owner to provide public notification under Tier 3 conditions in 12VAC5-590-540 A 3.

13. Additional routine monitoring in the month following a total coliform-positive sample.

a. The owner collecting samples on a quarterly or annual frequency shall collect at least three additional routine samples during the month following one or more total coliform-positive samples, with or without a Level 1 treatment trigger. The owner shall use the results of additional routine samples in coliform treatment technique trigger calculations under 12VAC5-590-392 B.

b. The requirements specified in subdivision A 13 a of this section may be waived by the department if:

(1) The department conducts a site visit before the end of the next month in which the waterworks provides water and has determined whether additional monitoring or corrective action is needed;

(2) The department has determined why the sample was total coliform positive and has established that the owner corrected the problem or will correct the problem before the end of the next month in which the waterworks serves water. In this case, the decision and the rationale for the decision shall be documented and approved in writing by the department. The department shall make this document available to EPA and the public. The documentation shall describe the specific cause of the total coliform-positive sample and what action the owner has taken or will take to correct this problem; or

(3) The department determines that the owner has corrected the contamination problem before collecting the set of repeat samples required in 12VAC5-590-380 D 3, and all repeat samples are total coliform negative. The department may waive the requirement for additional routine monitoring the next month.

c. The requirements specified in subdivision A 13 a of this section may not be waived by the department solely on the grounds that all repeat samples are total coliform negative.

14. Any one of the following is a monitoring violation: (i) failure to collect every required routine or additional routine sample in a compliance period, and (ii) failure to analyze for E. coli following a total coliform-positive sample. For each violation, the owner is required to provide public notification under Tier 3 conditions in 12VAC5-590-540 A 3.

15. Any one of the following is a reporting violation: (i) failure to submit monitoring results after the owner properly conducts monitoring, (ii) failure to submit a completed assessment form, and (iii) failure to notify the department following an E. coli-positive sample. The reporting requirements in 12VAC5-590-530 are applicable to this subdivision. For each violation, the owner is required to provide public notification under Tier 3 conditions in 12VAC5-590-540 A 3.

B. Chemical monitoring. The location of sampling points, the chemicals measured, the frequency, and the timing of sampling within each compliance period shall be established or approved by the department at the time of issuance of a waterworks operation permit because of changes in this chapter or conditions at the waterworks.

1. The department may increase required monitoring where necessary to detect variations within the waterworks and to provide quality control for any treatment processes that are employed.

2. Analysis of field composite samples shall not be allowed.

3. Samples for contaminants that may exhibit seasonal variations shall be collected during the period of the year when contamination is most likely to occur.

4. Failure to comply with the sampling schedules in this section, which includes the collection of confirmation samples cited in 12VAC5-590-382 A for inorganic chemicals, 12VAC5-590-382 B for nitrate and nitrite, and 12VAC5-590-383 A for organic chemicals, is a monitoring violation and shall require public notification pursuant to 12VAC5-590-540 A 3.

C. The department may allow a consecutive waterworks that obtains potable water from another waterworks to limit monitoring to bacteriological, residual disinfectant, DBPs, and lead and copper.

D. Monitoring requirements for a waterworks developing new sources of source water are provided in 12VAC5-590-820, 12VAC5-590-830, and 12VAC5-590-840.

E. The department may require an owner to collect additional samples to provide quality control for any treatment processes that are employed.

F. Surface water sampling requirements specified in 12VAC5-590-372 through 12VAC5-590-378 apply to GUDI sources.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from VR355-18-004.04 § 2.4, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 12, Issue 2, eff. November 15, 1995; Volume 16, Issue 21, eff. August 3, 2000; Errata, 18:22 VA.R. 2953 July 15, 2002; amended, Virginia Register Volume 18, Issue 19, eff. July 3, 2002; Volume 19, Issue 17, eff. June 4, 2003; Volume 19, Issue 24, eff. September 10, 2003; Volume 21, Issue 13, eff. April 6, 2005; Volume 22, Issue 15, eff. May 3, 2006; Volume 22, Issue 24, eff. September 6, 2006; Volume 25, Issue 5, eff. December 10, 2008; Volume 27, Issue 1, eff. October 13, 2010; Volume 28, Issue 5, eff. December 7, 2011; Volume 33, Issue 3, eff. November 2, 2016; Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-372. Inorganic chemicals monitoring.

A. The owner of a community waterworks or a NTNC shall conduct monitoring to determine compliance with the PMCLs and SMCLs listed in Table 340.1 in accordance with this section. The owner of a TNC shall conduct monitoring to determine compliance with the nitrate, nitrite, and nitrate-nitrite PMCLs listed in Table 340.1 in accordance with this section.

B. If a waterworks draws water from more than one source and the sources are combined before distribution, then the owner shall sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water is representative of all sources being used).

C. When the results of sampling for antimony, arsenic, asbestos, barium, beryllium, cadmium, cyanide (as free cyanide), chromium, fluoride, mercury, nickel, selenium, or thallium exceed the applicable PMCL, the owner shall collect a confirmation sample, at the same sampling site, within two weeks of notification of the analytical results of the first sample.

D. Monitoring frequency.

1. Asbestos. The department has granted a statewide waiver for asbestos. If the statewide waiver is removed or if site-specific waterworks conditions warrant monitoring for asbestos, then monitoring to determine compliance with the PMCL for asbestos specified in Table 340.1 shall be conducted as follows:

a. The owner of a community waterworks or a NTNC shall monitor for asbestos during the first three-year compliance period of each nine-year compliance cycle.

b. If the statewide waiver is removed, and the owner believes the waterworks is not vulnerable to asbestos contamination from either its source water or due to corrosion of its asbestos-cement pipe, then the owner may apply to the department for a monitoring waiver for asbestos. If the department grants the monitoring waiver, then the owner is not required to monitor.

c. The department may grant a waiver based on a consideration of the following factors:

(1) Potential asbestos contamination of the source water; and

(2) The use of asbestos-cement pipe for finished water distribution and the corrosive nature of the water.

d. A waiver remains in effect until the completion of the compliance period (i.e., three years).

e. The owner of a waterworks vulnerable to asbestos contamination due solely to corrosion of its asbestos-cement pipe shall collect one sample at a tap served by the asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

f. The owner of a waterworks vulnerable to asbestos contamination due to its source water shall monitor at the entry points.

g. The owner of a waterworks vulnerable to asbestos contamination due both to its source water and corrosion of its asbestos-cement pipe shall collect one sample at a tap served by the asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

h. The owner of a waterworks that exceeds the PMCL as determined in 12VAC5-590-382 A shall monitor quarterly beginning in the next quarter after the exceedance occurred.

i. The department may decrease the quarterly monitoring requirement to the frequency specified in subdivision D 1 a of this section provided the department has determined that the waterworks is reliably and consistently below the PMCL. In no case shall the department make this determination unless the owner of a groundwater system collects a minimum of two quarterly samples or the owner of a waterworks that uses a surface water source, in whole or in part, collects a minimum of four quarterly samples.

2. Antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide (as free cyanide), fluoride, mercury, nickel, selenium, and thallium. Monitoring to determine compliance with the PMCL for these contaminants specified in Table 340.1 shall be conducted as follows:

a. The owner shall collect one sample at each groundwater source entry point during each compliance period.

b. The owner shall collect one sample annually at each surface water source entry point, in whole or in part.

c. The owner may apply to the department for a waiver from the monitoring frequencies specified in subdivisions D 2 a and D 2 b of this section.

(1) A condition of the waiver shall require that the owner collect a minimum of one sample while the waiver is effective. The waiver remains in effect for one compliance cycle (i.e., nine years).

(2) The department may grant a waiver provided the owner has monitored surface water source entry points, in whole or in part, annually for at least three years and has conducted a minimum of three rounds of monitoring at groundwater source entry points. At least one sample shall have been collected since January 1, 1990. The owner shall demonstrate that all previous analytical results were less than the PMCL. A waterworks that uses a new groundwater or surface water source is not eligible for a waiver until three rounds of monitoring from the new source have been completed.

(3) In determining the appropriate reduced monitoring frequency, the department shall consider:

(a) The reported concentrations from all previous monitoring;

(b) The degree of variation in reported concentrations; and

(c) Other factors that may affect contaminant concentrations such as changes in groundwater pumping rates, changes in the waterworks configuration, changes in the waterworks operating procedures, or changes in stream flows or characteristics.

(4) A decision by the department to grant a waiver shall be made in writing and shall set forth the basis for the determination. The request for a waiver may be initiated by the department or upon an application by the owner. The owner shall specify the basis for the request. The department shall evaluate and, where appropriate, revise the determination of the appropriate monitoring frequency when the owner submits new monitoring data or when other data relevant to the appropriate monitoring frequency become available.

(5) No arsenic waivers shall be granted by the department.

d. The owner of a waterworks that exceed the PMCLs as calculated in 12VAC5-590-382 shall monitor quarterly beginning in the next quarter after the exceedance occurred. The department may decrease the quarterly monitoring requirement to the frequencies specified in subdivision D 2 a, D 2 b, or D 2 c of this section provided a determination has been made that the analytical results are reliably and consistently below the PMCL. In no case may the department make this determination unless the owner collects a minimum of two quarterly samples from each groundwater source entry point and a minimum of four quarterly samples from each surface water source entry point, in whole or in part.

3. Nitrate and combined nitrate-nitrite as nitrogen. Monitoring to determine compliance with the PMCL for nitrate and combined nitrate-nitrite as nitrogen specified in Table 340.1 shall be conducted as follows:

a. The owner shall collect one sample annually at each groundwater source entry point.

b. The owner shall collect one sample quarterly at each surface water source entry point, in whole or in part.

c. For groundwater source entry points at community and NTNCs, the repeat monitoring frequency shall be quarterly for at least one year following any one sample in which the concentration is greater than 50% of the PMCL. After four consecutive quarters of monitoring, the department may allow the owner to reduce the sampling frequency to annually after determining the results are reliably and consistently less than the PMCL.

d. For surface water source entry points, in whole or in part, the department may allow the owner to reduce the sampling frequency to annually if all analytical results from four consecutive quarters are less than 50% of the PMCL. The waterworks shall return to quarterly monitoring if the concentration found in any one sample is greater than or equal to 50% of the PMCL.

e. After any round of quarterly sampling is completed as required by subdivisions D 3 c and D 3 d of this section, the owner who is monitoring annually shall collect subsequent samples during the quarter that previously resulted in the highest analytical result.

f. No monitoring waivers shall be issued for nitrate or combined nitrate-nitrite as nitrogen.

4. Nitrite. Monitoring to determine compliance with the PMCL for nitrite specified in Table 340.1 shall be conducted as follows:

a. The owner shall collect one sample at each entry point during the initial compliance period.

b. After the initial sample, the owner of a waterworks where an analytical result for nitrite is less than 50% of the PMCL shall monitor at the frequency specified by the department.

c. The repeat monitoring frequency for an owner shall be quarterly for at least one year following any one sample in which the concentration is greater than 50% of the PMCL. The department may allow an owner to reduce the sampling frequency to annually after determining the analysis results are reliably and consistently less than the PMCL.

d. The owner of a waterworks that is monitoring annually shall collect each subsequent sample during the quarter that previously resulted in the highest analytical result.

e. No monitoring waivers shall be issued for nitrite.

5. Aluminum, chloride, copper, corrosivity, fluoride, foaming agents (surfactants), iron, manganese, silver, sulfate, and zinc. Monitoring to determine compliance with the SMCL for these contaminants specified in Table 340.1 shall be conducted as follows:

a. The owner shall collect one sample at each groundwater source entry point during each compliance period.

b. The owner shall collect one sample annually at each surface water source entry point, in whole or in part.

6. Sodium. All community waterworks shall monitor for sodium as follows:

a. The number of samples to be collected shall be determined by the department based on the waterworks infrastructure and occurrence concentrations where applicable.

(1) The owner shall collect at least one sample annually at each surface water source entry point, in whole or in part.

(2) The owner shall collect one sample at each groundwater source entry point at least every three years.

(3) The department may require the owner to collect and analyze water samples for sodium more frequently where sodium content is variable.

b. Sodium shall be analyzed in accordance with methods and laboratory requirements identified in 12VAC5-590-440.

c. Sample results shall be submitted to the department in accordance with 12VAC5-590-530.

d. The department shall notify local and state health officials of the sodium levels.

e. The results of the special monitoring for sodium shall be included in the Consumer Confidence Report in accordance with 12VAC5-590-545 C 5 f.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-373. Organic chemicals monitoring.

A. The owner of a community waterworks or a NTNC shall conduct monitoring to determine compliance with PMCLs listed in Table 340.2 in accordance with this section. Where two or more sources are combined before distribution, the owner shall sample at the entry point for the combined sources during periods of normal operation conditions.

1. The owner of a waterworks that uses groundwater shall collect a minimum of one sample at each entry point.

2. The owner of a waterworks that uses surface water, in whole or in part, shall collect a minimum of one sample at each entry point.

B. During the initial compliance period and each subsequent compliance period, the owner shall monitor during four consecutive calendar quarters for each contaminant listed in Table 340.2. A minimum of one sample at each entry point shall be collected during each calendar quarter.

C. Reduced monitoring.

1. Volatile organic chemicals (VOCs).

a. The requirement for four quarterly samples during initial monitoring as specified in subsection B of this section may not be reduced.

b. The department may decrease the requirement for quarterly monitoring during subsequent compliance periods provided it has been determined that the analytical results are reliably and consistently below the PMCL. In no case shall the department make this determination unless:

(1) The owner collects a minimum of two quarterly samples at each groundwater source entry point; or

(2) The owner collects a minimum of four quarterly samples at each surface water source entry point, in whole or in part.

c. If the department determines that the waterworks is reliably and consistently below the PMCL, then the department may allow the owner to monitor annually. The owner who monitors annually shall monitor during the quarter that previously yielded the highest analytical result.

d. For a groundwater system only. After a minimum of three years of annual sampling, the department may allow the owner with no previous detection of any VOCs listed in Table 340.2 to collect one sample during each compliance period.

e. The owner of a groundwater system that has three consecutive annual samples with no detection of a contaminant may apply to the department for a waiver, in accordance with 12VAC5-590-373 F.

2. Synthetic organic chemicals (SOCs).

a. The owner of a waterworks serving more than 3,300 persons that does not detect any SOCs listed in Table 340.2 in the initial compliance period may reduce the sampling frequency to a minimum of two quarterly samples in one year during each repeat compliance period.

b. The owner of a waterworks serving fewer than or equal to 3,300 persons that does not detect any SOCs listed in Table 340.2 in the initial compliance period may reduce the sampling frequency to a minimum of one sample during each repeat compliance period.

c. The department may reduce the quarterly monitoring required by subdivision B or D of this section provided the department has determined that the analytical results are reliably and consistently below the PMCL. In no case shall the department make this latter determination unless:

(1) The owner collects a minimum of two quarterly samples at each groundwater source entry point.

(2) The owner collects a minimum of four quarterly samples at each surface water source entry point, in whole or in part.

d. If the department determines that the analytical results are reliably and consistently below the PMCL, the department may allow the owner to monitor annually. The owner of a waterworks that monitors annually shall monitor during the quarter that previously yielded the highest analytical result.

e. The owner of a waterworks that has three consecutive annual samples with no detection of a contaminant may apply to the department for a waiver for SOC monitoring by submitting a waiver application as specified in subdivisions F 1 b and F 2 b of this section. The waiver remains in effect for one compliance period (i.e., three years).

D. Increased monitoring.

1. If the owner of a waterworks that is on reduced monitoring detects a contaminant listed in Table 340.2 (see 12VAC5-590-383 A regarding confirmation samples), then the owner shall monitor quarterly at each sampling point where the contaminant was detected unless:

a. That contaminant was previously detected and the department determined it was reliably and consistently below the PMCL according to subdivisions C 1 b and C 2 c of this section;

b. The historical sampling data do not indicate a meaningful increase in the contaminant concentration; and

c. The contaminant concentration does not exceed the PMCL.

2. The owner of a waterworks that exceeds the PMCLs listed in Table 340.2 for VOCs or SOCs, as determined by 12VAC5-590-383, shall monitor quarterly.

a. If, after a minimum of four consecutive quarterly samples that show the waterworks is in compliance as specified in 12VAC5-590-383; and

b. The department determines that the analytical results are reliably and consistently below the PMCL; then

c. The owner may monitor at the frequency and time specified in subdivisions C 1 c and C 2 d of this section.

E. Other monitoring requirements.

1. Vinyl chloride.

a. The owner of a groundwater system that has detected one or more of the following two-carbon organic compounds: trichloroethylene, tetrachloroethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, or 1,1-dichloroethylene, shall monitor quarterly for vinyl chloride. A vinyl chloride sample shall be collected at each sampling point at which one or more of the two-carbon organic compounds were detected. If the results of the first analysis do not detect vinyl chloride, then the department may reduce the quarterly monitoring frequency of vinyl chloride monitoring to one sample during each compliance period.

b. The owner of a waterworks that uses surface water in whole or in part is required to monitor for vinyl chloride as specified by the department.

2. If monitoring detects one or more of certain related contaminants (heptachlor and heptachlor epoxide), then subsequent monitoring shall analyze for all related contaminants.

3. For entry points sampled and analyzed for contaminants listed in Table 340.2, the following detection limits apply:

a. A VOC is detected at a level equal to or greater than 0.0005 mg/L; and

b. A SOC is detected at a level equal to or greater than defined by EPA under 40 CFR 141.24(h)(18) or by the department.

F. Monitoring waivers.

1. Groundwater source entry points.

a. The owner of a waterworks that does not detect a VOC contaminant listed in Table 340.2 may apply to the department for a waiver from the subsequent compliance period requirements of subsection B and subdivision C 1 c of this section after completing the initial monitoring. A waiver shall be effective for no more two compliance periods (i.e., six years).

b. The owner of a waterworks may apply to the department for a SOC monitoring waiver from the requirements of subsection B and subdivision C 2 of this section. The owner must reapply for a waiver for each subsequent compliance period (i.e., three years).

2. Surface water source entry points, in whole or in part.

a. No VOC monitoring waivers shall be issued.

b. The owner of a waterworks that does not detect a SOC contaminant listed in Table 340.2 may apply to the department for a SOC monitoring waiver from the requirements of subsection B and subdivision C 2 of this section. The owner must reapply for a waiver for each subsequent compliance period (i.e., three years).

3. Monitoring waiver applications. The owner shall submit a monitoring waiver application for evaluation on a form approved by the department. The department may grant a waiver after an evaluation of the use, transport, storage, or disposal of any organic contaminant within the watershed or zone of influence of the source.

a. If an evaluation by the department reveals no previous use of the contaminants within the watershed or zone of influence, then a waiver may be granted.

b. If an evaluation by the department reveals either previous use of the contaminants or that use is unknown, then the following factors shall be used to determine whether a waiver is granted:

(1) Previous analytical results.

(2) The proximity of the source water to land use activities that are potential point or nonpoint sources of organic contamination and to potential conduits to groundwater. Point sources include spills and leaks of chemicals at or near a waterworks or at manufacturing, distribution, or storage facilities or from hazardous or municipal waste landfills and other waste handling or treatment facilities. Nonpoint sources for SOCs include the use of pesticides to control insects and weed pests on agricultural areas, forest lands, home and gardens, and other land application uses.

(3) The environmental persistence and transport of the contaminants listed in Table 340.2.

(4) The implementation of a watershed protection program for surface water systems and wellhead protection measures for groundwater systems by the owner.

(5) For groundwater well sources: well construction, well depth, soil type, geological conditions, and well structure integrity.

(6) Special factors, as follows:

(a) For VOCs, the number of persons served by the waterworks and the proximity of a smaller waterworks to a larger waterworks.

(b) For SOCs, elevated nitrate levels at the waterworks' source water.

(c) For SOCs, use of PCBs in equipment used in the production, storage, or distribution of water (i.e., PCBs used in pumps, transformers, and other equipment).

c. An entry point at which treatment has been installed to remove VOCs or SOCs is not eligible for a monitoring waiver for the VOCs or SOCs for which treatment has been installed.

d. All waterworks are granted a waiver from monitoring dioxin, endothall, and glyphosate unless the department determines that there is a source of these contaminants that poses a threat to the source water.

4. Condition for waivers.

a. Groundwater source entry points.

(1) As a condition of the VOC waiver, the owner shall collect one sample at each entry point during the time the waiver is effective (i.e., one sample during two compliance periods or six years) and update the waterworks vulnerability assessment. Based on this data, the department may reconfirm that the source is nonvulnerable. If the department does not make this reconfirmation within three years of the initial determination, then the waiver is invalidated and the owner is required to sample annually.

(2) There are no conditions to SOC waivers.

b. Surface water source entry points, in whole or in part. There are no conditions to VOC and SOC waivers for waterworks in regard to these entry points.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-374. Residual disinfectant, disinfection byproducts, and disinfection byproduct precursors monitoring.

A. Unless otherwise noted, an owner of a waterworks that uses a chemical disinfectant shall comply with the requirements of this section as follows:

1. The owner of a community waterworks or a NTNC shall comply with this section.

2. The owner of a TNC that uses any combination of a surface water source, a GUDI source, or a groundwater source and uses chlorine dioxide as a disinfectant or oxidant shall comply with all the requirements for chlorine dioxide in this section.

B. The owner shall collect all samples during normal operating conditions.

1. Analysis under this section for DBPs (TTHM, HAA5, chlorite, and bromate) shall be conducted by laboratories that have received certification by EPA or DCLS as specified in 12VAC5-590-440, except as noted in subdivisions B 2 and B 3 of this section.

2. Measurement under this section of daily chlorite samples at the entry point to the distribution system, residual disinfectant (free chlorine, combined chlorine, total chlorine, and chlorine dioxide), alkalinity, bromide, TOC, SUVA (DOC and UV₂₅₄), pH, and magnesium shall be made by a party approved by the department.

3. Residual disinfectant concentrations for free chlorine, combined chlorine, total chlorine, and chlorine dioxide shall be made using equipment deemed satisfactory by the department.

C. Monitoring plan. The owner required to monitor under this section shall develop and implement a monitoring plan. The owner shall maintain the plan and make it available for inspection by the department and the general public. The owner of a community waterworks or a NTNC that uses a surface water source, a GUDI source, or both and serves more than 3,300 people shall submit a copy of the monitoring plan to the department no later than the date of the first report required under 12VAC5-590-531 A. The department may also require the plan to be submitted by any other owner. After evaluation, the department may require changes in any of the plan elements. The plan shall include at least the following:

1. Specific locations and schedules with monitoring dates for collecting samples for any parameters included in this section.

2. How the owner will calculate compliance with PMCLs, MRDLs, and treatment techniques.

3. The sampling plan for a consecutive waterworks shall reflect the entire consecutive distribution system.

4. All new waterworks shall comply with the monitoring location requirements of 40 CFR 141 Subpart U, Initial distribution system evaluations, in the development of the waterworks monitoring plan.

D. Failure to monitor in accordance with the monitoring plan required under subsection C of this section is a monitoring violation. Failure to monitor shall be treated as a violation for the entire period covered by the annual average where compliance is based on an RAA of monthly or quarterly samples or averages, and the owner's failure to monitor makes it impossible to determine compliance with PMCLs or MRDLs.

E. The owner may use only data collected under the provisions of this section to qualify for reduced monitoring.

F. TTHM and HAA5 monitoring. The owner of a community waterworks or a NTNC shall conduct the LRAA monitoring for TTHM and HAA5 at the frequency given below, unless otherwise indicated.

1. This subdivision establishes monitoring and other requirements for achieving compliance with PMCLs based on the LRAA for TTHM and HAA5, and for achieving compliance with MRDLs for chlorine and chloramines for certain consecutive waterworks.

2. This subdivision applies to a community waterworks or a NTNC that uses a primary or secondary disinfectant other than UV light or delivers water that has been treated with a primary or secondary disinfectant other than UV light.

3. Routine monitoring.

a. If the waterworks is a NTNC serving fewer than 10,000 people, then the owner shall monitor at the location or locations and dates identified in the monitoring plan in subsection C of this section, updated as required by subdivision F 3 e of this section.

b. The owner shall monitor at no fewer than the number of locations identified in Table 374.1:

c. The owner of a waterworks not using disinfection that then begins using a disinfectant other than UV light shall consult with the department to identify compliance monitoring locations. The owner shall develop a monitoring plan under subdivision F 3 e of this section to include those monitoring locations.

d. The owner shall use an approved method listed in 12VAC5-590-440 for TTHM and HAA5 analyses. Analyses shall be conducted by laboratories that have received certification by EPA or DCLS as specified in 12VAC5-590-440.

e. The owner may revise the monitoring plan to reflect changes in treatment, distribution system operations and layout (including new service areas), or other factors that may affect TTHM or HAA5 formation, or for reasons approved by the department after consultation with the department regarding the need for changes and the appropriateness of the changes. If the owner changes monitoring locations, then the owner shall replace existing compliance monitoring locations with the lowest LRAA with new locations that reflect the current distribution system locations with expected high TTHM or HAA5 levels. The department may also require modifications in the monitoring plan. The owner of a waterworks using a surface water source, a GUDI source, or both and serving more than 3,300 people shall submit a copy of the modified monitoring plan to the department before the date the owner is required to comply with the revised monitoring plan.

4. Reduced monitoring.

a. The owner may reduce monitoring to the level specified in Table 374.2 any time the LRAA is less than or equal to 0.040 mg/L for TTHM and less than or equal to 0.030 mg/L for HAA5 at all monitoring locations. The owner may only use data collected under the provisions of this section to qualify for reduced monitoring. In addition, the source water annual average TOC level, before any treatment, shall be less than or equal to 4.0 mg/L at each water treatment plant treating a surface water source, a GUDI source, or both based on monitoring conducted under subsection J of this section.

b. The owner may remain on reduced monitoring as long as the TTHM LRAA is less than or equal to 0.040 mg/L and the HAA5 LRAA is less than or equal to 0.030 mg/L at each monitoring location (for waterworks with quarterly reduced monitoring) or each TTHM sample is less than or equal to 0.060 mg/L and each HAA5 sample is less than or equal to 0.045 mg/L (for waterworks with annual or less frequent monitoring). In addition, the source water annual average TOC level, before any treatment, shall be less than or equal to 4.0 mg/L at each water treatment plant treating a surface water source or a GUDI source, based on monitoring conducted under subsection J of this section.

c. If the LRAA based on quarterly monitoring at any monitoring location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or if the annual (or less frequent) sample at any location exceeds either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source water annual average TOC level, before any treatment, is greater than 4.0 mg/L at any water treatment plant treating a surface water source, a GUDI source, or both then the owner shall resume routine monitoring under subdivision F 3 of this section or begin increased monitoring if subdivision F 5 of this section applies.

d. A waterworks may return to routine monitoring at the department's discretion.

5. Increased monitoring.

a. The owner of a waterworks required to monitor at a particular location annually or less frequently than annually under subdivision F 3 or F 4 of this section, shall increase monitoring to dual sample sets once per quarter (collected every 90 days) at all locations if a TTHM sample is greater than 0.080 mg/L or a HAA5 sample is greater than 0.060 mg/L at any location.

b. The owner may return to routine monitoring once the waterworks has conducted increased monitoring for at least four consecutive quarters and the LRAA for every monitoring location is less than or equal to 0.060 mg/L for TTHM and less than or equal to 0.045 mg/L for HAA5.

G. Chlorite. The owner of a community waterworks or a NTNC using chlorine dioxide, for disinfection or oxidation, shall conduct monitoring for chlorite.

1. Routine monitoring.

a. The owner shall collect daily samples at the entry point to the distribution system. For any daily sample that exceeds the chlorite PMCL listed in Table 340.6, the owner shall collect additional samples in the distribution system the following day at the locations required by subdivision G 1 c of this section, in addition to the sample required at the entrance to the distribution system.

b. The owner shall collect a three-sample set each month in the distribution system. The owner shall collect one sample at each of the following locations: near the first customer, at a location representative of average residence time, and at a location reflecting maximum residence time in the distribution system. Any additional routine sampling shall be conducted in the same manner (as three-sample sets, at the specified locations). The owner may use the results of additional monitoring conducted under subdivision G 1 c of this section to meet the requirement for monitoring in this subdivision G 1 b.

c. On each day following a routine sample monitoring result that exceeds the chlorite PMCL listed in Table 340.6 at the entrance to the distribution system, the owner is required to collect three chlorite distribution system samples at the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the end of the distribution system as possible (reflecting maximum residence time in the distribution system).

2. Reduced monitoring.

a. Chlorite monitoring at the entrance to the distribution system required by subdivision G 1 a of this subsection may not be reduced.

b. Chlorite monitoring in the distribution system required by subdivision G 1 b of this section may be reduced to one three-sample set per quarter after one year of monitoring where no individual chlorite sample collected in the distribution system under subdivision G 1 b of this section has exceeded the chlorite PMCL listed in Table 340.6 and the owner has not been required to conduct monitoring under subdivision G 1 c of this section. The owner may remain on the reduced monitoring schedule until either any of the three individual chlorite samples collected quarterly in the distribution system under subdivision G 1 b of this section exceeds the chlorite PMCL or the owner is required to conduct monitoring under subdivision G 1 c of this section, at which time the owner shall revert to routine monitoring.

H. Bromate.

1. The owner of a community waterworks or a NTNC water treatment plant using ozone for disinfection or oxidation shall collect one sample per month and analyze it for bromate. The owner shall collect samples monthly at the entrance to the distribution system while the ozonation system is operating under normal conditions.

2. The owner required to analyze for bromate may reduce monitoring from monthly to quarterly if the waterworks RAA bromate concentration is less than or equal to 0.0025 mg/L based on monthly bromate measurements under subdivision H 1 of this section for the most recent four quarters. If a waterworks has qualified for reduced bromate monitoring under this subdivision, then the owner may remain on reduced monitoring as long as the RAA of quarterly bromate samples is equal to or less than 0.0025 mg/L. If the RAA bromate concentration is greater than 0.0025 mg/L, then the owner shall resume routine monitoring required by subdivision H 1 of this section.

I. Monitoring requirements for the residual disinfectant.

1. Chlorine and chloramines.

a. The owner of a waterworks that uses chlorine or chloramines shall measure the residual disinfectant level in the distribution system at the same point in the distribution system and at the same time as total coliform bacteria are sampled, as specified in 12VAC5-590-370 A and 12VAC5-590-380 D. The owner of a waterworks using a surface water source, a GUDI source, or both may use the results of the residual disinfectant concentration sampling found in 12VAC5-590-376 D instead of collecting separate samples.

b. Residual disinfectant level monitoring may not be reduced.

2. Chlorine dioxide.

a. The owner of a waterworks that uses chlorine dioxide for disinfection or oxidation shall collect daily samples at the entrance to the distribution system. For any daily sample that exceeds the MRDL listed in Table 340.7, the owner shall collect samples in the distribution system the following day at the locations required by subdivision I 2 b of this section, in addition to the sample required at the entrance to the distribution system.

b. On each day following a routine sample monitoring result that exceeds the MRDL listed in Table 340.7, the owner is required to collect three chlorine dioxide distribution system samples. If chlorine dioxide or chloramines are used to maintain a residual disinfectant in the distribution system, or if chlorine is used to maintain a residual disinfectant in the distribution system and there is no rechlorination after the entry point, then the owner shall collect three samples as close to the first customer as possible, at intervals of at least six hours. If chlorine is used to maintain a residual disinfectant in the distribution system and there are one or more rechlorination points after the entry point, then the owner shall collect one sample at each of the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the end of the distribution system as possible (reflecting maximum residence time in the distribution system).

c. Chlorine dioxide monitoring may not be reduced.

3. Ozone. Ozone residual levels shall be monitored continuously and recorded. A portable ozone meter is recommended as a backup.

4. Additional monitoring and reporting requirements are specified in 12VAC5-590-500 to demonstrate log inactivation or removal of Giardia lamblia, virus, and Cryptosporidium.

J. Monitoring requirements for DBPPs.

1. The owner of a community waterworks or a NTNC using a surface water source, a GUDI source, or both and using conventional filtration treatment, as defined in 12VAC5-590-10, shall monitor each water treatment plant for TOC no later than the point of CFE turbidity monitoring and representative of the treated water. The owner shall also monitor for TOC in the source water before any treatment at the same time as monitoring for TOC in the treated water. These samples (source water and treated water) are referred to as paired samples. At the same time as the source water sample is collected, the owner shall monitor for alkalinity in the source water before any treatment. The owner shall collect one paired sample and one source water alkalinity sample per month per water treatment plant at a time representative of normal operating conditions and influent water quality.

2. The owner of a community waterworks or a NTNC that uses a surface water source, a GUDI source, or both with an average treated water TOC of less than 2.0 mg/L for two consecutive years, or less than 1.0 mg/L for one year, may reduce monitoring for both TOC and alkalinity to one paired sample and one source water alkalinity sample per water treatment plant per quarter. The owner shall revert to routine monitoring in the month following the quarter when the annual average treated water TOC is equal to or greater than 2.0 mg/L.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-375. Lead and copper monitoring.

A. The owner of a community waterworks or a NTNC shall monitor for lead and copper in tap water (subsection B of this section), water quality (corrosion) parameters in the distribution system and at entry points (subsection C of this section), and lead and copper in water supplies (subsection D of this section).

B. Monitoring requirements for lead and copper in tap water.

1. Sample site location.

a. By the date determined by the department for commencement of monitoring under subdivision B 4 a of this section, the owner shall complete a materials evaluation of the distribution system to identify a pool of targeted sampling sites that meets the requirements of this subdivision, and that is sufficiently large to ensure that the owner can collect the number of lead and copper tap samples required in subdivision B 3 of this section. All sites from which first-draw samples are collected shall be selected from this pool of targeted sampling sites. Sampling sites may not include faucets that have POU devices or POE devices designed to remove inorganic contaminants.

b. When the distribution system evaluation required in subdivision B 1 a of this section is insufficient to locate the requisite number of lead and copper sampling sites that meet the targeting criteria of this section, the owner shall review the sources of information listed in subdivisions B 1 b (1), B 1 b (2), and B 1 b (3) of this section to identify a sufficient number of sampling sites. In addition, the owner shall seek to collect such information where possible in the course of its normal operations (e.g., checking service line materials when reading water meters or performing maintenance activities):

(1) All plumbing codes, permits, and records in the files of the building department that indicate the plumbing materials that are installed within publicly and privately owned structures connected to the distribution system;

(2) All inspections and records of the distribution system that indicate the material composition of the service connections that connect a structure to the distribution system; and

(3) All existing water quality information, which includes the results of all prior analyses of the waterworks or individual structures connected to the waterworks, indicating locations that may be particularly susceptible to high lead or copper concentrations.

c. The sampling sites selected for a community waterworks' sampling pool (Tier 1 sampling sites) shall consist of single-family structures that:

(1) Contain copper pipes with lead solder installed between January 1983 and April 1986 or contain lead pipes; or

(2) Are served by a lead service line.

When multiple-family residences comprise at least 20% of the structures served by a waterworks, the owner may include these types of structures in the sampling pool.

d. The owner of a community waterworks with insufficient Tier 1 sampling sites shall complete the sampling pool with Tier 2 sampling sites consisting of buildings, including multiple-family residences that:

(1) Contain copper pipes with lead solder installed between January 1983 and April 1986 or contain lead pipes; or

(2) Are served by a lead service line.

e. The owner of a community waterworks with insufficient Tier 1 and Tier 2 sampling sites shall complete the sampling pool with Tier 3 sampling sites, consisting of single family structures that contain copper pipes with lead solder installed before 1983. The owner of a community waterworks with insufficient Tier 1, Tier 2, and Tier 3 sampling sites shall complete the sampling pool with representative sites throughout the distribution system. For the purpose of this subdivision, a representative site is a site in which the plumbing materials used at that site would be commonly found at other sites served by the waterworks.

f. The sampling sites selected for a NTNC (Tier 1 sampling sites) shall consist of buildings that:

(1) Contain copper pipes with lead solder installed between January 1983 and April 1986 or contain lead pipes; or

(2) Are served by a lead service line.

g. The owner of a NTNC with insufficient Tier 1 sites that meet the targeting criteria in subdivision B 1 f of this section shall complete the sampling pool with sampling sites that contain copper pipes with lead solder installed before 1983. If additional sites are needed to complete the sampling pool, the owner of a NTNC shall use representative sites throughout the distribution system. For the purpose of this subdivision, a representative site is a site in which the plumbing materials used at that site would be commonly found at other sites served by the waterworks.

h. The owner of a waterworks whose distribution system contains lead service lines shall draw 50% of the samples the owner collects during each monitoring period from sites that contain lead pipes, or copper pipes with lead solder, and 50% of the samples the owner collects from sites served by a lead service line. The owner who cannot identify a sufficient number of sampling sites served by a lead service line shall collect first-draw tap samples from all of the sites identified as being served by these lines.

2. Sample collection methods.

a. All tap samples for lead and copper, with the exception of lead service line samples collected under 12VAC5-590-405 C 4 and samples collected under subdivision B 2 e of this section, shall be first-draw samples.

b. Each first-draw tap sample for lead and copper shall be one liter in volume, have stood motionless in the plumbing system of each sampling site for at least six hours, and have been collected without flushing the tap. First-draw samples from residential housing shall be collected from the cold-water kitchen tap or from a bathroom sink tap. First-draw samples from a nonresidential building shall be one liter in volume and shall be collected at an interior tap from which water is typically drawn for consumption. Non-first-draw samples collected instead of first-draw samples pursuant to subdivision B 2 e of this section shall be one liter in volume and shall be collected at an interior tap from which water is typically drawn for consumption. First-draw samples may be collected by the owner or the owner may allow residents to collect first-draw samples after instructing the residents of the sampling procedures specified in this subdivision. To avoid problems of residents handling nitric acid, acidification of first-draw samples may be done up to 14 days after the sample is collected. After acidification to resolubilize the metals, the sample must stand in the original container for the time specified in the approved EPA method before the sample can be analyzed. If an owner allows residents to perform sampling, then the owner may not challenge, based on alleged errors in sample collection, the accuracy of sampling results.

c. Each lead service line sample collected pursuant to 12VAC5-590-405 C 4 for the purpose of avoiding replacement shall be one liter in volume and have stood motionless in the lead service line for at least six hours. Lead service line samples shall be collected in one of the following three ways:

(1) At the tap after flushing the volume of water between the tap and the lead service line. The volume of water shall be calculated based on the interior diameter and length of the pipe between the tap and the lead service line;

(2) Tapping directly into the lead service line; or

(3) If the sampling site is a building constructed as a single-family residence, then allowing the water to run until there is a significant change in temperature that would be indicative of water that has been standing in the lead service line.

d. The owner shall collect each first-draw tap sample from the same sampling site from which the owner collected a previous sample. If, for any reason, the owner cannot gain entry to a sampling site to collect a follow-up tap sample, then the owner may collect the follow-up tap sample from another sampling site in the sampling pool as long as the new site meets the same targeting criteria and is within reasonable proximity of the original site.

e. The owner of a NTNC, or a community waterworks that meets the criteria of 12VAC5-590-405 D 2 e (2) that does not have enough taps that can supply first-draw samples, as defined in subdivision B 2 b of this section, may apply to the department in writing to substitute non-first-draw samples. If approved by the department, then an owner shall collect as many first-draw samples from appropriate taps as possible and identify sampling times and locations that would likely result in the longest standing time for the remaining sites.

3. Number of samples.

a. The owner shall collect at least one sample during each monitoring period specified in subdivision B 4 of this section from the number of sites listed in the first column (standard monitoring) of Table 375.1. The owner of a waterworks conducting reduced monitoring under subdivision B 4 d of this section shall collect at least one sample from the number of sites specified in the second column (reduced monitoring) of Table 375.1 during each monitoring period specified in subdivision B 4 d of this section. Reduced monitoring sites shall be representative of the sites required for standard monitoring. The department may specify sampling locations when an owner is conducting reduced monitoring.

b. The owner of a waterworks that has fewer than five drinking water taps that are normally used for human consumption meeting the sample site criteria of subdivision B 1 of this section to reach the required number of sample sites listed in Table 375.1 shall collect at least one sample from each tap and then shall collect additional samples from those taps on different days during the monitoring period to meet the required number of sites. Alternatively, the department may allow the owner to collect a number of samples less than the number of sites specified in Table 375.1, provided that 100% of all taps that are normally used for human consumption are sampled. The department shall approve this reduction of the minimum number of samples in writing based on a request from the owner or onsite verification by the designated department representative.

c. The lead and copper tap sample table is as follows:

4. Timing of monitoring.

a. Initial tap sampling. The first six-month monitoring period for small (serving less than 3,300 population), medium (serving 3,301 to 50,000 population), and large waterworks (serving greater than 50,000 population) shall be established by the department.

(1) The owner of a large waterworks shall monitor during two consecutive six-month periods.

(2) The owner of a small or a medium waterworks shall monitor during each six-month monitoring period until the waterworks exceeds the lead or copper AL and is therefore required to implement the corrosion control treatment requirements under 12VAC5-590-405 A 2, in which case the owner shall continue monitoring in accordance with subdivision B 4 b of this section, or the waterworks meets the lead and copper ALs during two consecutive six-month monitoring periods, in which case the owner may reduce monitoring in accordance with subdivision B 4 d of this section.

b. Monitoring after installation of corrosion control and source water treatment.

(1) The owner of a large waterworks that installs optimal corrosion control treatment pursuant to 12VAC5-590-405 A 2 d (4) shall monitor during two consecutive six-month monitoring periods by the date specified in 12VAC5-590-405 A 2 d (5).

(2) The owner of a small or a medium waterworks that installs optimal corrosion control treatment pursuant to 12VAC5-590-405 A 2 e (5) shall monitor during two consecutive six-month monitoring periods by the date specified in 12VAC5-590-405 A 2 e (6).

(3) The owner of a waterworks that installs source water treatment pursuant to 12VAC5-590-405 B 1 c shall monitor during two consecutive six-month monitoring periods by the date specified in 12VAC5-590-405 B 1 d.

c. Monitoring after the department specifies water quality parameter values for optimal corrosion control. After the department specifies the values for water quality control parameters under 12VAC5-590-405 A 1 f, the owner shall monitor during each subsequent six-month monitoring period, with the first monitoring period to begin on the date the department specifies the optimal values.

d. Reduced monitoring.

(1) The owner of a small or a medium waterworks that meets the lead and copper ALs during each of two consecutive six-month monitoring periods may reduce the number of samples in accordance with subdivision B 3 of this section, and reduce the frequency of sampling to once per year. The owner of a small or a medium waterworks collecting fewer than five samples, as specified in subdivision B 3 b of this section, that meets the lead and copper ALs during each of two consecutive six-month monitoring periods may reduce the frequency of sampling to once per year. In no case may the owner reduce the number of samples required below the minimum of one sample per available tap. This sampling shall begin during the calendar year immediately following the end of the second consecutive six-month monitoring period.

(2) The owner of a waterworks that meets the lead AL and maintains the range of values for the water quality control parameters reflecting optimal corrosion control treatment specified by the department under 12VAC5-590-405 A 1 f during each of two consecutive six-month monitoring periods may reduce the frequency of monitoring to once per year and to reduce the number of lead and copper samples in accordance with subdivision B 3 of this section if the owner receives written approval from the department. This sampling shall begin during the calendar year immediately following the end of the second consecutive six-month monitoring period. The department shall evaluate monitoring, treatment, and other relevant information submitted by the owner in accordance with 12VAC5-590-532 and shall notify the owner in writing when a determination is made that the owner is eligible to commence reduced monitoring pursuant to this subdivision. The department shall evaluate and, where appropriate, revise the determination when the owner submits new monitoring or treatment data or when other data relevant to the number and frequency of tap sampling becomes available.

(3) The owner of a small or a medium waterworks that meets the lead and copper ALs during three consecutive years of monitoring may reduce the frequency of monitoring for lead and copper from annually to once every three years. The owner of a waterworks that meets the lead AL and maintains the range of values for the water quality control parameters reflecting optimal corrosion control treatment specified by the department under 12VAC5-590-405 A 1 f during three consecutive years of monitoring may reduce the frequency of monitoring from annually to once every three years if the owner receives written approval from the department. Samples collected once every three years shall be collected no later than every third calendar year. The department shall evaluate monitoring, treatment, and other relevant information submitted by the owner in accordance with 12VAC5-590-532 and shall notify the owner in writing when a determination is made that the owner is eligible to commence reduced monitoring pursuant to this subdivision. The department shall evaluate and where appropriate, revise the determination when the owner submits new monitoring or treatment data, or when other data relevant to the number and frequency of tap sampling becomes available.

(4) The owner of a waterworks that reduces the number and frequency of sampling shall collect these samples from representative sites included in the pool of targeted sampling sites identified in subdivision B 1 of this section. The owner sampling annually or less frequently shall conduct the lead and copper tap sampling during the months of June, July, August, or September. For a NTNC that does not operate during the months of June through September, the department shall designate an alternate monitoring period that represents a time of normal operation for the waterworks. This sampling shall begin in the calendar year immediately following the end of the second consecutive six-month monitoring period for the owner initiating annual monitoring, and during the three-year period following the end of the third consecutive calendar year of annual monitoring for the owner initiating triennial monitoring.

(5) The owner of a waterworks that demonstrates for two consecutive six-month monitoring periods that the tap water lead level computed under 12VAC5-590-385 C is less than or equal to 0.005 mg/L and the tap water copper level computed under 12VAC5-590-385 C is less than or equal to 0.65 mg/L may reduce the number of samples in accordance with subdivision B 3 of this section and reduce the frequency of sampling to once every three calendar years.

(6) The owner of a small or a medium waterworks subject to reduced monitoring that exceeds the lead or copper AL shall resume sampling in accordance with subdivision B 4 c of this section and collect the number of samples specified for standard monitoring under subdivision B 3 of this section. The owner shall also conduct water quality parameter monitoring in accordance with subdivisions C 2, C 3, and C 4 of this section (as appropriate) during the monitoring period in which the AL is exceeded. The owner of a waterworks may resume annual monitoring for lead and copper at the tap at the reduced number of sites specified in subdivision B 3 of this section after it has completed two subsequent consecutive six-month rounds of monitoring that meet the criteria of subdivision B 4 d (1) of this section or may resume triennial monitoring for lead and copper at the reduced number of sites after it demonstrates through subsequent rounds of monitoring that it meets the criteria of either subdivision B 4 d (3) or B 4 d (5) of this section.

(7) The owner of a waterworks subject to the reduced monitoring frequency that fails to meet the lead ALs during any four-month monitoring period or that fails to operate at or above the minimum value or within the range of values for the water quality parameters specified by the department under 12VAC5-590-405 A 1 f for more than nine days in any six-month period specified in subdivision C 4 of this section shall conduct tap water sampling for lead and copper at the frequency specified in subdivision B 4 c of this section, collect the number of samples specified for standard monitoring under subdivision B 3 of this section, and resume monitoring for water quality parameters within the distribution system in accordance with subdivision C 4 of this section. This standard tap water sampling shall begin no later than the six-month period beginning January 1 of the calendar year following the lead AL exceedance or water quality parameter excursion. The owner of such a waterworks may resume reduced monitoring for lead and copper at the tap and for water quality parameters within the distribution system under the following conditions:

(a) The owner may resume annual monitoring for lead and copper at the tap at the reduced number of sites specified in subdivision B 3 of this section after completion of two subsequent six-month rounds of monitoring that meet the criteria of subdivision B 4 d (2) of this section and the owner has received written approval from the department that it is appropriate to resume reduced monitoring on an annual frequency. This sampling shall begin during the calendar year immediately following the end of the second consecutive six-month monitoring period.

(b) The owner may resume triennial monitoring for lead and copper at the tap at the reduced number of sites after demonstration through subsequent rounds of monitoring that it meets the criteria of either subdivision B 4 d (3) or B 4 d (5) of this section and the owner has received written approval from the department that it is appropriate to resume triennial monitoring.

(c) The owner may reduce the number of water quality parameter tap water samples required in accordance with subdivision C 5 a of this section and the frequency with which it collects these samples in accordance with subdivision C 5 b of this section. The owner of such a waterworks may not resume triennial monitoring for water quality parameters at the tap until it demonstrates, in accordance with the requirements of subdivision C 5 b of this section, that it has requalified for triennial monitoring.

(8) The owner of a waterworks subject to a reduced monitoring frequency under subdivision B 4 d of this section shall notify the department in writing in accordance with 12VAC5-590-530 and 12VAC5-590-532 of any upcoming long-term change in the treatment or addition of a new source water as described in this section. The department shall evaluate and approve the addition of a new source water or long-term change in the water treatment before it is implemented by the owner. The department may require the owner to resume sampling in accordance with subdivision B 4 c of this section and collect the number of samples specified for standard monitoring under subdivision B 3 of this section or take other appropriate steps such as increased water quality parameter monitoring or re-evaluation of its corrosion control treatment given the potentially different water quality considerations.

5. Additional monitoring by owner. The results of monitoring conducted in addition to the minimum requirements of this section shall be considered by the owner and the department in making determinations (i.e., calculating the 90th percentile lead or copper level) under 12VAC5-590-385 C.

6. Invalidation of lead or copper tap water samples. A sample invalidated under this subdivision does not count toward determining lead or copper 90th percentile levels under 12VAC5-590-385 C or toward meeting the minimum monitoring requirements of subdivision B 3 of this section.

a. The department may invalidate a lead or copper tap water sample if at least one of the following conditions is met:

(1) The laboratory establishes that improper sample analysis caused erroneous results.

(2) The department determines that the sample was collected from a site that did not meet the site selection criteria of this section.

(3) The sample container was damaged in transit.

(4) There is substantial reason to believe that the sample was subject to tampering.

b. The owner shall report the results of all samples to the department and all supporting documentation for samples the owner believes should be invalidated.

c. To invalidate a sample under subdivision B 6 a of this section, the decision and the rationale for the decision shall be documented in writing. The department may not invalidate a sample solely on the grounds that a follow-up sample result is higher or lower than that of the original sample.

d. The owner shall collect a replacement sample for a sample invalidated under this section if after the invalidation of one or more samples, the owner has too few samples to meet the minimum requirements of subdivision B 3 of this section. A replacement sample shall be collected as soon as possible, but no later than 20 days after the date the department invalidates the sample or by the end of the applicable monitoring period, whichever occurs later. Replacement samples collected after the end of the applicable monitoring period shall not also be used to meet the monitoring requirements of a subsequent monitoring period. The replacement samples shall be collected at the same locations as the invalidated samples or, if that is not possible, at locations other than those already used for sampling during the monitoring period.

7. Monitoring waivers for small waterworks. The owner of a small waterworks that meets the criteria of this subdivision may apply to the department to reduce the frequency of monitoring for lead and copper to once every nine years (i.e., a full waiver) if the owner meets all of the materials criteria specified in subdivision B 7 a of this section and all of the monitoring criteria specified in subdivision B 7 b of this section. The owner of a small waterworks that meets the criteria in subdivisions B 7 a and B 7 b of this section only for lead, or only for copper, may apply to the department for a waiver to reduce the frequency of tap water monitoring to once every nine years for that contaminant only (i.e., a partial waiver).

a. Materials criteria. The owner shall demonstrate that the distribution system service lines and plumbing connected to the waterworks, including plumbing conveying drinking water within all residences and buildings connected to the waterworks, are free of lead-containing materials or copper-containing materials, as those terms are defined in this subdivision, as follows:

(1) Lead. To qualify for a full waiver, or a waiver of the tap water monitoring requirements for lead (i.e., a lead waiver), the owner shall provide certification and supporting documentation to the department that the waterworks is free of all lead-containing materials, as follows:

(a) It contains no plastic pipes that contain lead plasticizers, or plastic service lines that contain lead plasticizers;

(b) Solders and flux contain no more than 0.2% lead; and

(c) The weighted average of wetted surface of pipes, pipe fittings, plumbing fittings, and plumbing fixtures contain no more than 0.25% lead.

(2) Copper. To qualify for a full waiver, or a waiver of the tap water monitoring requirements for copper (i.e., a copper waiver), the owner shall provide certification and supporting documentation to the department that the waterworks contains no copper pipes or copper service lines.

b. Monitoring criteria for waiver issuance. The owner shall have completed at least one six-month round of standard tap water monitoring for lead and copper at sites approved by the department and from the number of sites required by subdivision B 3 of this section and demonstrate that the 90th percentile levels for any and all rounds of monitoring conducted since the owner became free of all lead-containing or copper-containing materials, as appropriate, meet the following criteria:

(1) Lead levels. To qualify for a full waiver, or a lead waiver, the owner shall demonstrate that the 90th percentile lead level does not exceed 0.005 mg/L.

(2) Copper levels. To qualify for a full waiver, or a copper waiver, the owner shall demonstrate that the 90th percentile copper level does not exceed 0.65 mg/L.

c. Department approval of waiver application. The department shall notify the owner of the waiver determination, in writing, setting forth the basis of the decision and any condition of the waiver. As a condition of the waiver, the department may require the owner to perform specific activities (e.g., limited monitoring, periodic outreach to customers to remind them to avoid installation of materials that might void the waiver) to avoid the risk of lead or copper concentration of concern in tap water. The owner of a small waterworks shall continue monitoring for lead and copper at the tap as required by subdivisions B 4 a through B 4 d of this section, as appropriate, until it receives written notification from the department that the waiver has been approved.

d. Monitoring frequency for owners with waivers.

(1) The owner with a full waiver shall conduct tap water monitoring for lead and copper in accordance with subdivision B 4 d (4) of this section at the reduced number of sampling sites identified in subdivision B 3 of this section at least once every nine years and provide the materials certification specified in subdivision B 7 a of this section for both lead and copper to the department along with the monitoring results. Samples collected every nine years shall be collected no later than every ninth calendar year.

(2) The owner with a partial waiver shall conduct tap water monitoring for the waived contaminant in accordance with subdivision B 4 d (4) of this section at the reduced number of sampling sites specified in subdivision B 3 of this section at least once every nine years and provide the materials certification specified in subdivision B 7 a of this section pertaining to the waived contaminant along with the monitoring results. The owner also shall continue to monitor for the nonwaived contaminant in accordance with requirements of subdivisions B 4 a through B 4 d of this section, as appropriate.

(3) The owner with a full or partial waiver shall notify the department in writing in accordance with 12VAC5-590-532 B 3 of any upcoming long-term change in the treatment or addition of a new source water, as described in 12VAC5-590-532. The department shall evaluate and approve the addition of a new source water or a long-term change in water treatment before it is implemented by the owner. The department has the authority to require the owner to add or modify waiver conditions (e.g., require recertification that the waterworks is free of lead-containing or copper-containing materials; require additional round or rounds of monitoring), if it deems these modifications are necessary to address treatment or source water changes at the waterworks.

(4) If an owner with a full or partial waiver becomes aware that it is no longer free of lead-containing or copper-containing materials, as appropriate (e.g., as a result of new construction or repairs), then the owner shall notify the department in writing no later than 60 days after becoming aware of the change.

e. Continued eligibility. If the owner continues to satisfy the requirements of subdivision B 7 d of this section, then the waiver will be renewed automatically, unless any of the conditions listed in subdivision B 7 e (1), B 7 e (2), or B 7 e (3) of this section occurs. The owner whose waiver has been revoked may reapply for a waiver when the owner again meets the appropriate materials and monitoring criteria of subdivisions B 7 a and B 7 b of this section.

(1) A waterworks with a full waiver or a lead waiver no longer satisfies the materials criteria of subdivision B 7 a (1) of this section or has a 90th percentile lead level greater than 0.005 mg/L.

(2) A waterworks with a full waiver or a copper waiver no longer satisfies the materials criteria of subdivision B 7 a (2) of this section or has a 90th percentile copper level greater than 0.65 mg/L.

(3) The department notifies the owner, in writing, that the waiver has been revoked, setting forth the basis of the decision.

f. Requirements following waiver revocation. A waterworks whose full or partial waiver has been revoked by the department is subject to the corrosion control treatment and lead and copper tap water monitoring requirements, as follows:

(1) If the waterworks exceeds the lead or copper AL, then the owner shall implement corrosion control treatment in accordance with the deadlines specified in 12VAC5-590-405 A 2 e and any other applicable requirements of this section.

(2) If the waterworks meets both the lead and the copper ALs, then the owner shall monitor for lead and copper at the tap no less frequently than once every three years using the reduced number of sample sites specified in subdivision B 3 of this section.

g. Pre-existing waivers. Waivers for small waterworks approved by the department in writing before April 11, 2000, shall remain in effect under the following conditions:

(1) If the waterworks has demonstrated that it is both free of lead-containing and copper-containing materials, as required by subdivision B 7 a of this section and that its 90th percentile lead levels and 90th percentile copper levels meet the criteria of subdivision B 7 b of this section, then the waiver will remain in effect so long as the owner continues to meet the waiver eligibility criteria of subdivision B 7 e of this section. The first round of tap water monitoring conducted pursuant to subdivision B 7 d of this section shall be completed no later than nine years after the last time the owner has monitored for lead and copper at the tap.

(2) If the waterworks has met the materials criteria of subdivision B 7 a of this section but has not met the monitoring criteria of subdivision B 7 b of this section, then the owner shall conduct one six-month round of standard tap water monitoring for lead and copper at sites approved by the department demonstrating that it meets the criteria of subdivision B 7 b of this section. Thereafter, the waiver shall remain in effect as long as the owner meets the continued eligibility criteria of subdivision B 7 e of this section. The first round of tap water monitoring conducted pursuant to subdivision B 7 d of this section shall be completed no later than nine years after the round of monitoring conducted pursuant to subdivision B 7 b of this section.

C. Monitoring requirements for water quality parameters. The owners of all large waterworks and all small and medium waterworks that exceed the lead or copper AL shall monitor for water quality parameters in addition to lead and copper in accordance with this section.

1. General requirements.

a. Sample collection methods.

(1) Tap samples shall be representative of water quality throughout the distribution system taking into account the number of persons served, the different sources of water, the different treatment methods employed by the waterworks, and seasonal variability. Tap sampling under this section is not required to be conducted at taps targeted for lead and copper sampling under subdivision B 1 of this section. The owner may find it convenient to conduct tap sampling for water quality parameters at sites approved for coliform sampling.

(2) Samples collected at the entry point or points to the distribution system shall be from locations representative of each source water after treatment. If a waterworks draws water from more than one source water and the source waters are combined before distribution, then the owner shall sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water is representative of all source waters being used).

b. Number of samples.

(1) The owner shall collect two tap samples from the standard monitoring number of sites given in Table 375.2 for applicable water quality parameters during each monitoring period specified under subdivisions C 2 through C 5 of this section.

(2) Except as provided in subdivision C 3 c of this section, the owner shall collect two samples for each applicable water quality parameter at each entry point to the distribution system during each monitoring period specified in subdivision C 2 of this section. During each monitoring period specified in subdivisions C 3, C 4, and C 5 of this section, the owner shall collect one sample for each applicable water quality parameter at each entry point to the distribution system.

2. Initial sampling. The owner of a large waterworks shall measure the applicable water quality parameters as specified below at taps and at each entry point to the distribution system during each six-month monitoring period specified in subdivision B 4 a of this section. The owner of a small or a medium waterworks shall measure the applicable water quality parameters at the locations specified below during each six-month monitoring period specified in subdivision B 4 a of this section during which the waterworks exceeds the lead or copper AL.

a. At taps:

(1) pH;

(2) Alkalinity;

(3) Orthophosphate, when an inhibitor containing a phosphate compound is used;

(4) Silica, when an inhibitor containing a silicate compound is used;

(5) Calcium;

(6) Conductivity; and

(7) Water temperature.

b. At each entry point to the distribution system: all of the applicable parameters listed in subdivision C 2 a of this section.

3. Monitoring after installation of corrosion control. The owner of a large waterworks that installs optimal corrosion control treatment pursuant to 12VAC5-590-405 A 2 d (4) shall measure the water quality parameters at the locations and frequencies specified below during each six-month monitoring period specified in subdivision B 4 b (1) of this section. The owner of a small or a medium waterworks that installs optimal corrosion control treatment shall conduct monitoring during each six-month monitoring period specified in subdivision B 4 b (2) of this section in which the waterworks exceeds the lead or copper AL.

a. At taps, two samples for:

(1) pH;

(2) Alkalinity;

(3) Orthophosphate, when an inhibitor containing a phosphate compound is used;

(4) Silica, when an inhibitor containing a silicate compound is used; and

(5) Calcium, when calcium carbonate stabilization is used as part of corrosion control.

b. Except as provided in subdivision C 3 c of this section, at each entry point to the distribution system, at least one sample no less frequently than every two weeks (biweekly) for:

(1) pH;

(2) When alkalinity is adjusted as part of optimal corrosion control, a reading of the dosage rate of the chemical used to adjust the alkalinity and the alkalinity concentration; and

(3) When a corrosion inhibitor is used as part of optimal corrosion control, a reading of the dosage rate of the inhibitor used and the concentration of orthophosphate or silica (whichever is applicable).

c. The owner of a groundwater system may limit entry point sampling described in subdivision C 3 b of this section to those entry points that are representative of water quality and treatment conditions throughout the waterworks. If water from untreated groundwater sources mixes with water from treated groundwater sources, then the owner shall monitor for water quality parameters both at representative entry points receiving treatment and representative entry points receiving no treatment. Before the start of any monitoring under this subdivision, the owner shall provide to the department written information identifying the selected entry points and documentation, including information on seasonal variability, sufficient to demonstrate that the sites are representative of water quality and treatment conditions throughout the waterworks.

4. Monitoring after the department specifies water quality parameter values for optimal corrosion control. After the department specifies the values for applicable water quality control parameters reflecting optimal corrosion control treatment under 12VAC5-590-405 A 1 f, the owner of a large waterworks shall measure the applicable water quality parameters in accordance with subdivision C 3 of this section and determine compliance with the requirements of 12VAC5-590-405 A 1 g every six months with the first six-month period to begin on either January 1 or July 1, whichever comes first, after the department specifies the optimal values under 12VAC5-590-405 A 1 f. The owner of a small or a medium waterworks shall conduct monitoring during each six-month monitoring period specified in this subdivision in which the waterworks exceeds the lead or copper AL. For the owner of a small or a medium waterworks that is subject to a reduced monitoring frequency pursuant to subdivision B 4 d of this section at the time of the AL exceedance, the start of the applicable six-month period under this subdivision shall coincide with the start of the applicable monitoring period under subdivision B 4 d of this section. Compliance with the department-designated optimal water quality parameter values shall be determined as specified under 12VAC5-590-405 A 1 g.

5. Reduced monitoring.

a. The owner of a waterworks that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment during each of two consecutive six-month monitoring periods under subdivision C 4 of this section shall continue monitoring at the entry point or points to the distribution system as specified in subdivision C 3 b of this section. The owner of the waterworks may collect two tap samples for applicable water quality parameters from the reduced number of sites during each six-month monitoring period shown in Table 375.2.

b. The owner of a waterworks that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under 12VAC5-590-405 A 1 f during three consecutive years of monitoring may reduce the frequency with which the owner collects the number of tap samples for applicable water quality parameters specified in subdivision C 5 of this section from every six months to annually. This sampling begins during the calendar year immediately following the end of the monitoring period in which the third consecutive year of six-month monitoring occurs. The owner of a waterworks that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under 12VAC5-590-405 A 1 f during three consecutive years of annual monitoring under this subdivision may reduce the frequency with which it collects the number of tap samples for applicable water quality parameters specified in subdivision C 5 a of this section from annually to every three years. This sampling begins during the calendar year immediately following the end of the monitoring period in which the third consecutive year of six-month monitoring occurs.

c. The owner of a waterworks may reduce the frequency with which tap samples are collected for applicable water quality parameters specified in subdivision C 5 a of this section to every three years if the owner demonstrates during two consecutive monitoring periods that the tap water lead level at the 90th percentile is less than or equal to the PQL for lead (0.005 mg/L), that the tap water copper level at the 90th percentile is less than or equal to 0.65 mg/L for copper, and that the owner also has maintained the range of values for water quality parameters reflecting optimal corrosion control treatment specified by the department under 12VAC5-590-405 A 1 f. Monitoring conducted every three years shall be done no later than every third calendar year.

d. The owner of a waterworks that conducts sampling annually shall collect these samples evenly throughout the year so as to reflect seasonal variability.

e. The owner of a waterworks subject to the reduced monitoring frequency that fails to operate at or above the minimum value or within the range of values for the water quality parameters specified by the department under 12VAC5-590-405 A 1 f for more than nine days in any six-month period specified in 12VAC5-590-405 A 1 g shall resume distribution system tap water sampling in accordance with the number and frequency requirements in subdivision C 4 of this section. The owner may resume annual monitoring for water quality parameters at the tap at the reduced number of sites specified in subdivision C 5 of this section after completion of two subsequent consecutive six-month rounds of monitoring that meet the criteria of that subdivision or may resume triennial monitoring for water quality parameters at the tap at the reduced number of sites after demonstration through subsequent rounds of monitoring that the criteria of either subdivision C 5 b or C 5 c of this section has been met.

6. Additional monitoring by owners. The results of any monitoring conducted in addition to the minimum requirements of this section shall be considered by the owner and the department in making any determinations under this section or 12VAC5-590-405 A 1.

D. Monitoring requirements for lead and copper in water supplies (source water).

1. Sample location, collection methods, and number of samples.

a. The owner of a waterworks that fails to meet the lead or copper AL on the basis of tap samples collected in accordance with subsection A of this section shall collect lead and copper source water samples in accordance with the following requirements regarding sample location, number of samples, and collection methods:

(1) The owner of a waterworks served by groundwater sources shall collect a minimum of one sample at every entry point to the distribution system. The owner shall collect one sample at the same sampling point unless conditions make another sampling point more representative of each source water or water treatment plant.

(2) The owner of a waterworks served by surface water sources shall collect a minimum of one sample at every entry point to the distribution system. The owner shall collect each sample at the same sampling point unless conditions make another sampling point more representative of each source water or water treatment plant. Note that for the purpose of this subdivision, a waterworks served by a surface water source includes waterworks served by a combination of surface water and groundwater sources.

(3) If a waterworks draws water from more than one source water and the source waters are combined before distribution, then the owner shall collect samples at an entry point to the distribution system during periods of normal operating conditions (i.e., when water is representative of all source waters being used).

(4) The department may reduce the total number of samples that must be analyzed by allowing the use of compositing. Compositing of samples shall be done by certified laboratory personnel. Composite samples from a maximum of five samples are allowed, provided that if the lead concentration in the composite sample is greater than or equal to 0.001 mg/L or the copper concentration is greater than or equal to 0.160 mg/L, then either a follow-up sample shall be collected and analyzed within 14 days at each sampling point included in the composite; or if duplicates or sufficient quantities from the original samples from each sampling point used in the composite are available, then the owner may use these instead of resampling.

b. Where the results of sampling indicate an exceedance of maximum permissible source water levels established under 12VAC5-590-405 B 4, the department may require that one additional sample be collected as soon as possible after the initial sample was collected (but not to exceed two weeks) at the same sampling point. If a confirmation sample required by the department is collected for lead or copper, then the results of the initial and confirmation sample shall be averaged in determining compliance with the department-specified maximum permissible levels. A sample value below the MDL shall be considered to be zero. A value above the MDL but below the PQL shall either be considered as the measured value or be considered one-half the PQL. The PQL for lead is equal to 0.005 mg/L, and the PQL for copper is equal to 0.050 mg/L.

2. Monitoring frequency after a waterworks exceeds a tap AL. The owner of a waterworks that exceeds the lead or copper AL at the tap shall collect one source water sample from each entry point to the distribution system no later than six months after the end of the monitoring period during which the lead or copper AL was exceeded. For monitoring periods that are annual or less frequent, the end of the monitoring period is September 30 of the calendar year in which the sampling occurs, or if the department has established an alternate monitoring period, the last day of that period.

3. Monitoring frequency after installation of source water treatment. The owner of a waterworks that installs source water treatment pursuant to 12VAC5-590-405 B 1 c shall collect an additional source water sample from each entry point to the distribution system during two consecutive six-month monitoring periods by the deadline specified in 12VAC5-590-405 B 1 d.

4. Monitoring frequency after the department specifies maximum permissible source water lead and copper levels or determines that source water treatment is not needed.

a. The owner shall monitor at the frequency specified in subdivisions D 4 a (1) and D 4 a (2) of this section in cases where the department specifies maximum permissible source water lead and copper levels under 12VAC5-590-405 B 1 e or determines that the owner is not required to install source water treatment under 12VAC5-590-405 B 2 b.

(1) The owner of a waterworks using only groundwater shall collect samples once during the three-year compliance period in effect when the applicable department determination under subdivision D 4 a of this section is made. The owner shall collect samples once during each subsequent compliance period. Triennial samples shall be collected every third calendar year.

(2) The owner of a waterworks using surface water (or a combination of surface water and groundwater) shall collect samples once during each year, the first annual monitoring period to begin during the year in which the applicable department determination is made under subdivision D 4 a of this section.

b. The owner is not required to conduct source water sampling for lead or copper if the waterworks meets the AL for the specific contaminant in tap water samples during the entire source water sampling period applicable to the waterworks under subdivision D 4 a (1) or D 4 a (2) of this section.

5. Reduced monitoring frequency.

a. The owner of a waterworks using only groundwater may reduce the monitoring frequency for lead and copper in source waters to once during each nine-year compliance cycle provided that the samples are collected no later than every ninth calendar year and if the owner meets one of the following criteria:

(1) The owner demonstrates that the finished water entering the distribution system has been maintained below the maximum permissible lead and copper concentrations specified by the department under 12VAC5-590-405 B 1 e during at least three consecutive compliance periods under subdivision D 4 a of this section; or

(2) The department has determined that source water treatment is not needed and the owner demonstrates that, during the last three consecutive compliance periods in which sampling was conducted under subdivision D 4 a of this section, the concentration of lead in the source water was less than or equal to 0.005 mg/L and the concentration of copper in the source water was less than or equal to 0.65 mg/L.

b. The owner of a waterworks using surface water (or a combination of surface water and groundwater sources) may reduce the monitoring frequency for lead and copper in source waters to once during each nine-year compliance cycle provided that the samples are collected no later than every ninth calendar year and if the owner meets one of the following criteria:

(1) The owner demonstrates that finished water entering the distribution system has been maintained below the maximum permissible lead and copper concentrations specified by the department under 12VAC5-590-405 B 1 e for at least three consecutive years; or

(2) The department has determined that source water treatment is not needed and the owner demonstrates that, during the last three consecutive years, the concentration of lead in the source water was less than or equal to 0.005 mg/L and the concentration of copper in the source water was less than or equal to 0.65 mg/L.

c. The owner of a waterworks that uses a new source water is not eligible for reduced monitoring for lead or copper until concentrations in samples collected from the new source water during three consecutive monitoring periods are below the maximum permissible lead and copper concentrations specified in 12VAC5-590-405 B 1 e.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 27, Issue 1, eff. October 13, 2010; amended, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-376. Surface water and GUDI sources treatment monitoring.

A. The owner of a waterworks that uses a surface water source, a GUDI source, or both and provides filtration treatment shall monitor in accordance with this section.

B. Turbidity measurements shall be performed on representative samples of the filtered water every four hours (or more frequently) that the waterworks serves water to the public. The owner may substitute continuous turbidity monitoring for grab sample monitoring if the owner validates the continuous measurement for accuracy on a regular basis using a protocol approved by the department. For a waterworks using slow sand filtration or filtration treatment other than conventional treatment, direct filtration, or diatomaceous earth filtration, the department may reduce the sampling frequency to once per day if the department determines that less frequent monitoring is sufficient to indicate effective filtration performance. For a waterworks serving 500 or fewer persons, the department may reduce the turbidity sampling frequency to once per day, regardless of the type of filtration treatment used, if the department determines that less frequent monitoring is sufficient to indicate effective filtration performance.

1. The owner of a waterworks supplied by a surface water source, a GUDI source, or both using conventional filtration treatment or direct filtration shall conduct continuous monitoring of turbidity for each individual filter. The turbidimeter shall be calibrated using the procedure specified by the turbidimeter manufacturer. The owner shall record the results of individual filter turbidity monitoring a minimum of every 15 minutes.

2. If there is a failure in the continuous turbidity monitoring equipment, then the owner shall conduct grab sampling every four hours instead of continuous monitoring but for no more than five working days (for a waterworks serving 10,000 or more persons) or 14 days (for a waterworks serving fewer than 10,000 persons) following the failure of the equipment.

3. If a waterworks serving fewer than 10,000 persons consists of two or fewer filters, continuous monitoring of the CFE may be used instead of individual filter monitoring.

C. The residual disinfectant concentration of the water entering the distribution system shall be monitored continuously, and the lowest and highest values shall be recorded each day. If there is a failure in the continuous monitoring equipment, then grab sampling every four hours shall be conducted instead of continuous monitoring, but such grab sampling shall be conducted for no more than five working days following the failure of the equipment. The owner of a waterworks serving 3,300 or fewer persons may collect grab samples instead of continuous monitoring on an ongoing basis at the frequencies prescribed in Table 376.1.

1. The day's samples cannot be collected at the same time.

2. The sampling intervals are subject to department's evaluation and approval.

3. If at any time the residual disinfectant concentration falls below 0.2 mg/L in a waterworks using grab sampling instead of continuous monitoring, then the owner shall collect a grab sample every four hours until the residual disinfectant concentration is equal to or greater than 0.2 mg/L.

D. The residual disinfectant concentration shall be measured at least at the same points in the distribution system and at the same time as total coliform bacteria are sampled, as specified in 12VAC5-590-370 A and 12VAC5-590-380 D, except that the department may allow the owner of a waterworks that uses a groundwater source along with a surface water source, a GUDI source, or both to collect residual disinfectant samples at points other than the total coliform sampling points if the department determines that these points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria, measured as HPC as specified in 12VAC5-590-395 A 2 a (3), may be measured instead of residual disinfectant concentration.

E. The following information on the samples collected in the distribution system in conjunction with total coliform monitoring pursuant to 12VAC5-590-395 A 2 shall be reported monthly to the department by the owner:

1. Number of instances where the residual disinfectant concentration is measured;

2. Number of instances where the residual disinfectant concentration is not measured but heterotropic plate count (HPC) is measured;

3. Number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;

4. Number of instances where no residual disinfectant concentration is detected and where the HPC is greater than 500/mL;

5. Number of instances where the residual disinfectant concentration is not measured and HPC is greater than 500/mL; and

6. For the current and previous month the waterworks serves water to the public, the value of "V," in percent, in the following formula:

V = [(c + d + e) / (a + b)] X 100

where

a = the value in subdivision E 1 of this section;

b = the value in subdivision E 2 of this section;

c = the value in subdivision E 3 of this section;

d = the value in subdivision E 4 of this section;

e = the value in subdivision E 5 of this section.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-377. Physical constituent monitoring.

A. Monitoring to determine compliance with the SMCLs for color, odor, pH, and total dissolved solids as specified in Table 340.3 shall be conducted as follows:

1. The owner shall collect one sample at each groundwater source entry point during each compliance period.

2. The owner shall collect one sample annually at each surface water source entry point, in whole or in part.

B. Onsite daily turbidity measurements may be required to be performed on representative samples collected at each entry point for groundwater sources not required to filter, to determine compliance set forth in 12VAC5-590-379 B. The turbidity monitoring requirements for a waterworks required to filter are specified in 12VAC5-590-376 B.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-378. Radiological monitoring.

A. The location of sampling points, the radionuclides measured in community waterworks, the frequency, and the timing of sampling within each compliance period shall be established or approved by the department. The department may increase required monitoring where necessary to detect variations within the waterworks. Failure to comply with the sampling schedules in this section will require public notification pursuant to 12VAC5-590-540 A 3.

B. The owner of a community waterworks shall conduct monitoring to determine compliance with the PMCLs listed in Table 340.4 and 12VAC5-590-388 in accordance with this section.

1. Monitoring requirements for gross alpha particle activity, radium-226, radium-228, and uranium.

a. The owner shall conduct initial monitoring to determine compliance with the PMCLs listed in Table 340.4 for gross alpha particle activity, radium-226, radium-228, and uranium. For the purposes of monitoring for gross alpha particle activity, radium-226, radium-228, uranium, and beta particle and photon radioactivity in drinking water, "detection limit" is defined as specified in Table 378.1.

(1) Applicability and sampling location for an existing community waterworks or its sources. The owner using groundwater, surface water, or both groundwater and surface water shall sample at every entry point to the distribution system that is representative of all sources being used under normal operating conditions. The owner shall collect each sample at the same entry point unless conditions make another sampling point more representative of each source.

(2) Applicability and sampling location for a new community waterworks or its sources. A new community waterworks or a community waterworks that uses a new source water shall begin to conduct initial monitoring for the new source water within the first quarter after initiating use. The owner shall conduct more frequent monitoring when directed by the department in the event of possible contamination or when changes in the distribution system or treatment processes occur that may increase the concentration of radioactivity in the finished water.

b. Initial monitoring. The owner shall conduct initial monitoring for gross alpha particle activity, radium-226, radium-228, and uranium as follows:

(1) The owner shall collect four consecutive quarterly samples at all entry points.

(2) For gross alpha particle activity, uranium, radium-226, and radium-228 monitoring, the department may waive the final two quarters of initial monitoring for an entry point if the results of the samples from the previous two quarters are below the detection limit as defined by and as specified in Table 378.1.

(3) If the average of the initial monitoring results for an entry point is above the PMCL, then the owner shall collect and analyze quarterly samples at that entry point until the owner has results from four consecutive quarters that are at or below the PMCL, unless the owner enters into another schedule as part of a formal compliance agreement with the department.

c. Reduced monitoring. The department may allow the owner to reduce the future frequency of monitoring from once every three years to once every six or nine years at each entry point, based on the following criteria:

(1) If the average of the initial monitoring results for each contaminant (i.e., gross alpha particle activity, uranium, radium-226, or radium-228) is below the detection limit as specified in Table 378.1, then the owner shall collect and analyze for that contaminant using at least one sample at that entry point every nine years.

(2) For gross alpha particle activity, combined radium, and uranium, if the average of the initial monitoring results for each contaminant is at or above the detection limit as specified in Table 378.1, but at or below half of the PMCL, then the owner shall collect and analyze for that contaminant using at least one sample at that entry point every six years.

(3) For gross alpha particle activity, combined radium, and uranium, if the average of the initial monitoring results for each contaminant is above half the PMCL but at or below the PMCL, then the owner shall collect and analyze at least one sample at that entry point every three years.

(4) The owner shall use the samples collected during the reduced monitoring period to determine the monitoring frequency for subsequent monitoring periods (e.g., if a waterworks entry point is on a nine-year monitoring period, and the sample result is above half the PMCL, then the next monitoring period for that entry point is three years).

(5) If the owner has a monitoring result that exceeds the PMCL while on reduced monitoring, then the owner shall collect and analyze quarterly samples at that entry point until the results from four consecutive quarters are below the PMCL, unless the waterworks enters into another schedule as part of a formal compliance agreement with the department.

d. Compositing. To fulfill quarterly monitoring requirements for gross alpha particle activity, radium-226, radium-228, or uranium, the owner may composite up to four consecutive quarterly samples from a single entry point if analysis is done within a year of the first sample. The department will treat analytical results from the composited sample as the average analytical result to determine compliance with the PMCLs and the future monitoring frequency. If the analytical result from the composited sample is greater than half the PMCL, then the department may direct the owner to collect additional quarterly samples before allowing the owner to sample under a reduced monitoring schedule.

e. A gross alpha particle activity measurement may be substituted for the required radium-226 measurement provided that the measured gross alpha particle activity does not exceed 5 pCi/L. A gross alpha particle activity measurement may be substituted for the required uranium measurement provided that the measured gross alpha particle activity does not exceed 15 pCi/L. The gross alpha measurement shall have a confidence interval of 95% (1.65 σ, where σ is the standard deviation of the net counting rate of the sample) for radium-226 and uranium. When an owner uses a gross alpha particle activity measurement instead of a radium-226 or uranium measurement, the gross alpha particle activity analytical result will be used to determine the future monitoring frequency for radium-226 or uranium. If the gross alpha particle activity result is less than the detection limit as specified in Table 378.1, then half the detection limit will be used to determine compliance and the future monitoring frequency.

2. Monitoring requirements for beta particle and photon radioactivity. To determine compliance with the PMCL in Table 340.4 for beta particle and photon radioactivity, an owner shall monitor at a frequency as follows:

a. The owner (using surface water or groundwater sources) designated by the department as vulnerable shall sample for beta particle and photon radioactivity. The owner shall collect quarterly samples for beta emitters and annual samples for tritium and strontium-90 at each entry point to the distribution system, beginning within one quarter after being notified by the department. A waterworks already designated by the department shall continue to sample until the department evaluates and either reaffirms or removes the designation.

(1) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at an entry point has an RAA (computed quarterly) less than or equal to 50 pCi/L (screening level), then the department may reduce the frequency of monitoring at that entry point to once every three years. The owner shall collect all samples required in subdivision B 2 a of this section during the reduced monitoring period.

(2) For a waterworks in the vicinity of a nuclear facility, the department may allow the owner to utilize environmental surveillance data collected by the nuclear facility instead of monitoring at the waterworks entry point, where the department determines the data is applicable to a particular waterworks. In the event that there is a release from a nuclear facility, the owner who is using surveillance data shall begin monitoring at the waterworks entry point in accordance with subdivision B 2 a of this section.

b. The owner (using a surface water, a groundwater source, or both) designated by the department as utilizing waters contaminated by effluents from nuclear facilities shall sample for beta particle and photon radioactivity. The owner shall collect quarterly samples for beta emitters and iodine-131 and annual samples for tritium and strontium-90 at each entry point to the distribution system, beginning within one quarter after being notified by the department. The owner of a waterworks already designated by the department as using waters contaminated by effluents from nuclear facilities shall continue to sample until the department evaluates and either reaffirms or removes the designation.

(1) Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples or the analysis of a composite of three monthly samples. The former procedure, analysis of monthly samples, is recommended.

(2) For iodine-131, a composite of five consecutive daily samples shall be analyzed once each quarter. As directed by the department, more frequent monitoring shall be conducted when iodine-131 is identified in the finished water.

(3) Annual monitoring for strontium-90 and tritium shall be conducted by means of the analysis of a composite of four consecutive quarterly samples or analysis of four quarterly samples. The latter procedure, analysis of monthly samples, is recommended.

(4) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at a sampling point has an RAA (computed quarterly) less than or equal to 15 pCi/L (screening level), then the department may reduce the frequency of monitoring at that sampling point to every three years. The owner shall collect all samples required in subdivision B 2 b of this section during the reduced monitoring period.

(5) For a waterworks in the vicinity of a nuclear facility, the department may allow the owner to utilize environmental surveillance data collected by the nuclear facility instead of the monitoring at the waterworks entry point, where the department determines the data is applicable to a particular waterworks. In the event that there is a release from a nuclear facility, the owner who is using surveillance data shall begin monitoring at the waterworks entry point in accordance with subdivision B 2 b of this section.

c. The owner of a waterworks designated by the department to monitor for beta particle and photon radioactivity cannot apply to the department for a waiver from the monitoring frequencies specified in subdivision B 2 a or B 2 b of this section.

d. The owner may analyze for naturally occurring potassium-40 beta particle activity from the same or equivalent sample used for the gross beta particle activity analysis. The owner is allowed to subtract the potassium-40 beta particle activity value from the total gross beta particle activity value to determine if the screening level is exceeded. The potassium-40 beta particle activity shall be calculated by multiplying elemental potassium concentrations (in mg/L) by a factor of 0.82.

e. If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity exceeds the appropriate screening level, then an analysis of the sample shall be performed to identify the major radioactive constituents present in the sample and the appropriate doses shall be calculated and summed to determine compliance with the PMCL for beta particles and photon radioactivity. Doses shall also be calculated and combined for measured levels of tritium and strontium to determine compliance.

f. The owner shall monitor monthly at each entry point that exceeds the PMCLs listed in Table 340.4 beginning the month after the exceedance occurs. The owner shall continue monthly monitoring until the waterworks has established, by a rolling average of three monthly samples, that the PMCL is being met. The owner who establishes that the PMCL is being met shall return to quarterly monitoring until the requirements set forth in subdivision B 2 a (1) or B 2 b (4) of this section are met.

3. General monitoring requirements for radionuclides.

a. The department may require more frequent monitoring than specified in subdivisions B 1 and B 2 of this section or may require confirmation samples at the department's discretion. The results of the initial and confirmation samples shall be averaged for use in compliance determinations.

b. The owner shall monitor at the time designated by the department during each compliance period.

c. The department has the discretion to delete results of obvious sampling or analytic errors.

d. Table 378.1 provides the minimum detection limits for radiological analyses.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-379. Groundwater system monitoring.

A. General monitoring requirements.

1. The owner of a groundwater system, including consecutive and wholesale waterworks, shall conduct monitoring in accordance with this section, except that requirements do not apply to waterworks that combine all of their groundwater sources with surface water sources or with GUDI sources before treatment in accordance with 12VAC5-590-395.

2. Source water monitoring by the owner of a groundwater system that does not provide 4-log treatment of viruses for their groundwater sources before or at the first customer is described in subsection B of this section.

3. The owner of a groundwater system that provides at least 4-log treatment of viruses before or at the first customer is required to conduct compliance monitoring in accordance with 12VAC5-590-421 C.

4. The owner of a groundwater system that has confirmed E. coli contamination, as determined by source water monitoring conducted under subsection B of this section or has been notified of a significant deficiency as described in 12VAC5-590-350 D shall implement one or more of the corrective actions outlined in 12VAC5-590-421 A 1, as prescribed by the department.

5. The owner of a groundwater system that does not provide 4-log treatment of viruses before or at the first customer and is not performing compliance monitoring shall provide a triggered source water monitoring plan to the department.

6. Any source water sample collected in accordance with this section shall be analyzed for E. coli using one of the analytical methods in 40 CFR 141.402(c).

B. Groundwater source microbial monitoring.

1. Triggered source water monitoring.

a. General requirements. The groundwater system owner shall conduct triggered source water monitoring if both the conditions identified in subdivisions B 1 a (1) and B 1 a (2) of this section exist.

(1) The groundwater system owner does not provide at least 4-log treatment of viruses before or at the first customer for each groundwater source; and

(2) The groundwater system owner is notified that a sample collected under 12VAC5-590-370 A is total coliform positive and the sample is not invalidated under 12VAC5-590-380 E.

b. Sampling requirements. The groundwater system owner shall collect, within 24 hours of notification of the total coliform-positive sample, one source water sample from each groundwater source in use at the time the total coliform-positive sample was collected under 12VAC5-590-370 A, except as provided in this subdivision B 1 b.

(1) The department may extend the 24-hour time limit on a case-by-case basis if the owner cannot collect the source water sample within 24 hours due to circumstances beyond his control. In the case of an extension, the department shall specify how much time the owner has to collect the sample.

(2) If approved by the department, the owner of a waterworks with more than one groundwater source may meet the requirements of this subdivision B 1 by sampling representative groundwater sources. The owner shall submit for the department's approval a triggered source water monitoring plan that identifies one or more groundwater sources that are representative of each monitoring site in the waterworks' bacteriological sample siting report or that identifies groundwater sources that are hydrogeologically similar and clearly identifies which sources will be sampled.

(3) A groundwater system serving 1,000 people or fewer may use a triggered source water sample collected from a groundwater source to meet both the requirements of 12VAC5-590-380 and to satisfy the monitoring requirements of this subdivision B 1 for a groundwater source.

c. Additional requirements.

(1) If an E. coli-positive triggered source water sample collected under this subdivision B 1 is not invalidated under subdivision B 2 of this section, then the groundwater system owner shall provide public notification and collect five additional source water samples from the same source within 24 hours of being notified of the E. coli-positive sample.

(a) If the E. coli-positive triggered source water sample is also used as a repeat sample, then an E. coli PMCL violation is incurred under 12VAC5-590-380 B 1 a.

(b) If a waterworks collects more than one repeat sample at the monitoring location required for triggered source water monitoring, then the number of additional source water samples required under subdivision B 1 c (1) of this section may be reduced by the number of repeat samples collected at that location that were not E. coli positive.

(2) If any of the five additional samples are E. coli positive, the groundwater system owner shall comply with the treatment technique requirements of 12VAC5-590-421.

d. Consecutive and wholesale waterworks.

(1) A consecutive groundwater system owner that has a total coliform-positive sample collected in accordance with 12VAC5-590-370 A shall notify the wholesale waterworks owner and the department within 24 hours of being notified of the total coliform-positive sample.

(2) The wholesale groundwater system owner shall comply with the following:

(a) The wholesale groundwater system owner that receives notice from a consecutive waterworks it serves that a sample collected in accordance with 12VAC5-590-370 A is total coliform positive shall, within 24 hours of being notified, collect a sample from each groundwater source as described in subdivision B 1 of this section.

(b) If the sample collected under this subdivision B 1 is E. coli positive, then the wholesale groundwater system owner shall within 24 hours notify all consecutive waterworks served by that groundwater source of the E. coli-positive source water sample as described in 12VAC5-590-540 and shall meet the requirements of subdivision B 1 c of this section.

e. Exception to the triggered source water monitoring requirements. A groundwater system owner is not required to comply with the source water monitoring requirements of this subdivision B 1 if the department determines and documents in writing that:

(1) The total coliform-positive sample collected in accordance with 12VAC5-590-370 A is invalidated under 12VAC5-590-380 E.

(2) The total coliform-positive sample collected in accordance with 12VAC5-590-370 A is caused by a distribution system deficiency (sanitary defect).

(3) The total coliform-positive sample collected in accordance with 12VAC5-590-370 A was caused by distribution system conditions that will cause total coliform-positive samples.

2. Invalidation of an E. coli-positive groundwater source sample.

a. The groundwater system owner may obtain the department's invalidation of an E. coli-positive groundwater source sample collected under subdivision B 1 of this section only under the following conditions:

(1) The groundwater system owner provides the department with written notice from the laboratory that improper sample analysis occurred; or

(2) The department determines and documents in writing that there is substantial evidence that the E. coli-positive groundwater source sample is not related to source water quality.

b. If the department invalidates an E. coli-positive groundwater source sample, then the groundwater system owner shall collect another source water sample under subdivision B 1 of this section within 24 hours of being notified by the department of the invalidation decision and have the source water sample analyzed for E. coli.

3. Sampling location. All groundwater source samples required under subdivision B 1 of this section shall be collected at a location before any treatment of the groundwater source unless otherwise approved by the department.

4. Public notification. The owner of a groundwater system with a source water sample collected under this subsection that is E. coli positive and that is not invalidated under subdivision B 2 of this section, including consecutive waterworks served by the groundwater source, shall conduct public notification as required in 12VAC5-590-540 A 1.

5. Monitoring violations. Failure to meet the monitoring requirements of subdivision B 1 of this section is a violation and requires the groundwater system owner to provide public notification as required in 12VAC5-590-540 A 3.

C. Monitoring requirements for source water.

1. The owner of a groundwater source utilizing chlorine disinfection or any other treatment or chemical addition that may alter or affect the bacteriological quality of the source water shall collect source water samples for bacteriological analysis in accordance with this section.

2. All bacteriological samples under this section shall be collected from the source water before any treatment or chemical addition.

a. The owner shall provide a suitable source water sample tap at each groundwater source.

b. If conditions indicate that it is not possible to install a source water sample tap, then an alternate sample location acceptable to the department may be utilized for this monitoring.

3. All samples shall be analyzed by a test method that will yield a most probable number (MPN) result for both total coliforms and E. coli.

4. Number of samples.

a. The number of routine source water samples to be collected and the frequency of sampling shall be determined by the department. The department will notify the owner of the source water sampling requirements.

b. As a minimum, the owner shall collect source water samples in accordance with Table 379.1.

c. When a single sample result from a groundwater source that requires a routine source water monitoring frequency of less than monthly indicates total coliforms in excess of 50 colonies/100 mL or the presence of E. coli, the owner shall collect one confirmation sample within seven calendar days after notification of the results.

d. The department may require that additional source water samples be collected and will establish the specific number of samples and the monitoring frequency.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 28, Issue 5, eff. December 7, 2011; amended, Virginia Register Volume 33, Issue 3, eff. November 2, 2016; Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-380. Bacteriological compliance.

A. The owner needs only to determine the presence or absence of total coliforms and E. coli for routine bacteriological monitoring at entry points or distribution system locations.

B. PMCLs for microbial contaminants.

1. A waterworks is in compliance with the PMCL for E. coli unless any of the conditions identified in this subdivision occur. A violation may pose an acute risk to public health and is a Tier 1 condition requiring public notification as described in 12VAC5-590-540 A 1 when:

a. A repeat sample following a total coliform-positive routine sample is E. coli positive;

b. A repeat sample following an E. coli-positive routine sample is total coliform positive;

c. The owner fails to collect all required repeat samples following an E. coli-positive routine sample; or

d. The owner fails to test for E. coli when any repeat sample tests positive for total coliform.

2. Compliance shall be determined with the PMCL for E. coli for each monitoring period for which monitoring for total coliforms is required.

C. The best available technology (BAT), treatment techniques, or other means available for achieving compliance with the PMCL for E. coli shall be:

1. Protection of wells from contamination by coliforms by appropriate placement, construction, and maintenance of the wells;

2. Maintenance of a detectable residual disinfectant throughout the distribution system;

3. Proper maintenance of the distribution system including appropriate pipe replacement and repair procedures, water main flushing programs, proper operation and maintenance of storage tanks and reservoirs, continual maintenance of positive water pressure in all parts of the distribution system, and an approved cross-connection control program;

4. Filtration and disinfection of a surface water source, a GUDI source, or both; and

5. Disinfection of groundwater using strong oxidants such as chlorine, chlorine dioxide, or ozone.

D. A total coliform-positive result is indicative of a breakdown in the protective barriers and shall be cause for repeat monitoring and special follow-up action to locate and eliminate the cause of contamination.

1. For each routine sample found to be total coliform positive, the owner shall collect a set of three repeat samples within 24 hours of being notified of the positive result. The department may extend the 24-hour limit on a case-by-case basis. For groundwater systems, the requirements of 12VAC5-590-379 shall also apply, and all repeat samples must be analyzed for E. coli using one of the analytical methods in 40 CFR 141.402(c).

a. The owner shall collect at least one repeat sample from the sampling tap where the original total coliform-positive sample was collected, and at least one repeat sample at a tap within five service connections upstream and at least one repeat sample at a tap within five service connections downstream of the original sampling site. If a total coliform-positive sample is at the end of the distribution system or one service connection away from the end of the distribution system, the owner must still collect all required repeat samples.

b. The owner shall collect an additional set of repeat samples if one or more repeat samples in the current set of repeat samples is total coliform positive. The owner shall collect the additional set of repeat samples within 24 hours of being notified of the positive results, unless the department extends the limit as provided in this section. The owner shall continue to collect additional sets of repeat samples until either total coliforms are not detected in one complete set of repeat samples or the owner determines that a coliform treatment technique trigger specified in 12VAC5-590-392 B has been exceeded as a result of a repeat sample being total coliform positive and notifies the department. If a trigger identified in 12VAC5-590-392 B is exceeded as a result of a routine sample being total coliform positive, then the owner is required to conduct only one round of repeat monitoring for each total coliform-positive routine sample.

c. If the owner collects a routine sample before learning the results of the previous routine sample, and the sample is collected within five service connections of the initial routine sample, then the owner may count the subsequent sample as a repeat sample when the initial sample results are found to be total coliform positive.

d. If one or more repeat samples collected at the monitoring location required for triggered source water monitoring are E. coli positive, then the owner has exceeded the E. coli PMCL and must comply with the groundwater system treatment technique requirements specified in 12VAC5-590-421.

e. If all repeat samples collected at the monitoring location required for triggered source water monitoring are E. coli negative, and a repeat sample collected at a monitoring location other than the one required for triggered source water monitoring is E. coli positive, then the owner has exceeded the E. coli PMCL. However, the owner is not required to collect five additional source water samples from the same source within 24 hours of learning the E. coli-positive result.

f. The owner shall collect all repeat samples on the same day, except the department may allow the owner of a waterworks with a single service connection to collect the required set of repeat samples over a three-day period or to collect a larger volume repeat sample in one or more sample containers of any size as long as the total volume collected is at least 300 ml.

g. If a repeat sample collected at the monitoring location required for triggered source water monitoring is E. coli-positive, then the owner has exceeded the E. coli PMCL and must collect five additional source water samples from the same source within 24 hours of learning the E. coli-positive result.

2. Results of all routine and repeat samples not invalidated by the department shall be used to determine compliance with the PMCL for E. coli and whether a treatment technique trigger specified in 12VAC5-590-392 B has been exceeded.

3. Special-purpose samples, such as those collected to determine whether disinfection practices are sufficient following pipe placement, replacement, or repair, and samples collected before start-up of a seasonal waterworks, shall not be used to determine compliance. Repeat samples are not considered special-purpose samples.

E. A total coliform-positive sample invalidated under this subsection does not count toward meeting the minimum monitoring requirements of this section. To invalidate a total coliform-positive sample under this subsection, the written decision and rationale shall be evaluated, approved, and signed by the department. The department shall make this document available to EPA and the public. The written documentation shall state the specific cause of the total coliform-positive sample and what action the owner has taken, or will take, to correct this problem. The department shall not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform negative.

1. The department may invalidate a total coliform positive sample if any of the following conditions are met:

a. The laboratory establishes that improper sample analysis caused the total coliform-positive result;

b. The department, on the basis of the results of repeat samples collected as required by subdivision D 1 of this section, determines that the total coliform-positive sample resulted from a domestic or other nondistribution system plumbing problem. The department cannot invalidate a sample on the basis of repeat sample results unless all repeat samples collected at the same tap as the original total coliform-positive sample are also total coliform positive, and all repeat samples collected at a location other than the original tap are total coliform negative (e.g., the department cannot invalidate a total coliform-positive sample on the basis of repeat samples if all the repeat samples are total coliform negative or if the waterworks has only one service connection); or

c. The department has substantial grounds to believe that a total coliform-positive result is due to a circumstance or condition that does not reflect water quality in the distribution system. In this case, the owner shall still collect all repeat samples required under subdivision D 1 of this section, and use them to determine whether a coliform treatment technique trigger in 12VAC5-590-392 B has been exceeded.

2. A laboratory must invalidate a sample because of sampling interference (i.e., turbid culture in absence of (i) gas production, or (ii) acid reaction; exhibition of confluent growth; or production of colonies too numerous to count). The owner shall collect a replacement sample from the same location within 24 hours, and have it analyzed for the presence of total coliforms. The owner must continue to resample within 24 hours and have the samples analyzed until a valid result is obtained. The department may waive the 24-hour time limit on a case-by-case basis.

F. Escherichia coli (E. coli).

1. If a routine, repeat, or replacement sample is total coliform positive, then the owner shall analyze the total coliform-positive culture medium to determine if E. coli are present. If E. coli are present, then the owner shall notify the department by the end of the day when the owner is notified of the test result, unless the department is closed, in which case the department must be notified before the end of the next business day.

2. The department has the discretion to allow an owner, on a case-by-case basis, to forgo E. coli testing on a total coliform-positive sample if the owner assumes that the total coliform-positive sample is E. coli positive. Accordingly, the owner must notify the department as specified in subdivision F 1 of this subsection and the provisions of subdivision B 1 of this section apply.

G. Groundwater sources.

1. Groundwater sources shall be disinfected in accordance with 12VAC5-590-421 A 1 d when the results of the source water monitoring samples specified in 12VAC5-590-430 B 2 or 12VAC5-590-840 K 1 a indicate a total coliform concentration (geometric mean) of the 20 samples to be greater than 3 colonies/100 mL but less than 100 colonies/100 mL. The value 1.0 shall be used to represent a zero coliform result in the calculation of the geometric mean.

2. Groundwater source monitoring results conducted in accordance with 12VAC5-590-430 B 2 or 12VAC5-590-840 K 1 a that indicate a total coliform concentration equal to or greater than 100 colonies/100 ml constitutes contamination that is not treatable by single-barrier disinfection treatment alone.

3. Groundwater sources shall be disinfected in accordance the requirements of 12VAC5-590-421 A 1 d when the source water quality contributes to the waterworks' failure to meet the bacteriological PMCL specified in subsection B of this section.

4. If the results of the source water monitoring required by 12VAC5-590-379 C or 12VAC5-590-430 B 2 indicate the presence of E. coli in two or more samples collected during any running six-month period, then the owner shall:

a. Issue a Tier 1 public notice in accordance with 12VAC5-590-540 A 1.

b. Provide disinfection treatment to achieve a 4-log virus inactivation and removal as specified in 12VAC5-590-421 A 1 d.

c. Conduct compliance monitoring as specified in 12VAC5-590-421 B and 12VAC5-590-421 C.

5. If the results of the source water monitoring required in 12VAC5-590-379 C indicate total coliform concentration in excess of 50 colonies/100 mL in three or more samples collected during any running six-month period or the presence of E. coli in two or more samples collected during any running six-month period, then the source water shall be reevaluated for GUDI determination in accordance with 12VAC5-590-430.

6. The department may require that any groundwater source be disinfected in accordance with the requirements of 12VAC5-590-421 A 1 d.

H. All samples shall be analyzed by laboratories that have received certification by EPA or DCLS as specified in 12VAC5-590-440 for drinking water analyses.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from VR355-18-004.05 § 2.5, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 19, Issue 24, eff. September 10, 2003; Volume 28, Issue 5, eff. December 7, 2011; Volume 33, Issue 3, eff. November 2, 2016; Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-382. Inorganic chemicals compliance.

A. When the results of sampling for antimony, arsenic, asbestos, barium, beryllium, cadmium, cyanide (as free cyanide), chromium, fluoride, mercury, nickel, selenium, or thallium exceed the applicable PMCL, the owner shall collect a confirmation sample at the same sampling point within two weeks of notification of the analytical results of the first sample. The fluoride PMCL applies only to community waterworks.

1. The results of the initial and confirmation samples shall be averaged to determine compliance with subsection A of this section. The department has the discretion to delete results of obvious sampling errors.

2. Compliance with the PMCLs for antimony, arsenic, asbestos, barium, beryllium, cadmium, cyanide (as free cyanide), chromium, fluoride, mercury, nickel, selenium, and thallium listed in Table 340.1 shall be determined based on the analytical results obtained at each sampling point.

a. For the owner of a waterworks that conducts monitoring more frequently than annually, compliance with the PMCL for antimony, arsenic, asbestos, barium, beryllium, cadmium, cyanide (as free cyanide), chromium, fluoride, mercury, nickel, selenium, or thallium is determined by an RAA at each sampling point. If the average at any sampling point is greater than the PMCL, then the waterworks is out of compliance. If any single sample would cause the annual average to be exceeded, then the waterworks is out of compliance immediately. A sample result below the MDL shall be calculated as zero for the purpose of determining the annual average. If the owner fails to collect the required number of samples, compliance (average concentration) shall be based on the total number of samples collected.

b. For the owner of a waterworks that monitors annually or less frequently, the waterworks is not out of compliance with the PMCL for antimony, arsenic, asbestos, barium, beryllium, cadmium, cyanide (as free cyanide), chromium, fluoride, mercury, nickel, selenium, or thallium if the average of the original sample and a confirmation sample of a contaminant at any sampling point is greater than the PMCL. If sample results for the owner monitoring annually or less frequently exceed the PMCL, the owner shall begin quarterly sampling. The owner shall not be considered in violation of the PMCL until one year of quarterly sampling has been completed and the RAA is exceeded. However, if the confirmation sample is not collected, the owner is in violation of the PMCL for antimony, arsenic, asbestos, barium, beryllium, cadmium, cyanide (as free cyanide), chromium, fluoride, mercury, nickel, selenium, or thallium. If the owner fails to collect the required number of samples, then compliance (average concentration) shall be based on the total number of samples collected.

B. Compliance with the PMCLs for nitrate and nitrite shall be determined based on the analytical results obtained at each sampling point. The waterworks is not out of compliance with the PMCL if the concentrations of these contaminants are equal to or below the PMCLs. Where nitrate or nitrite sample results exceed the PMCL, the owner shall collect a confirmation sample, from the same sampling point that exceeded the PMCL within 24 hours of the owner's receipt of the analytical results of the first sample. The results of the initial and confirmation sample shall be averaged to determine compliance. The owner unable to comply with the 24-hour sampling requirement shall immediately notify the consumers in the area served by the waterworks in accordance with 12VAC5-590-540 A 1. The owner exercising this option shall collect and analyze a confirmation sample within two weeks of notification of the analytical results of the first sample. The department may require more frequent monitoring. The department has the discretion to delete results of obvious sampling errors.

1. Nitrate nitrogen (NO₃-N) levels not exceeding 20 mg/L may be allowed in a noncommunity waterworks if the owner:

a. Demonstrates to the satisfaction of the department that this water will not be available to children under six months of age;

b. Provides continuous posting of the fact that NO₃-N levels exceed 10 mg/L and the potential health effects of exposure;

c. Notifies health officials annually of NO₃-N levels that exceed 10 mg/L; and

d. The department shall determine that no adverse health effects will result.

2. Nitrite in water poses a significant health hazard. Water with nitrite-nitrogen concentrations over 1 mg/L should not be used for infant feedings.

C. Compliance with the SMCLs for aluminum, chloride, copper, corrosivity, fluoride, foaming agents, iron, manganese, silver, sulfate, or zinc shall be determined based on the analytical results obtained at each sampling point. When the result of a sample exceeds the applicable SMCL, the owner shall collect a confirmation sample at the same sampling point within two weeks of notification of the analytical results of the first sample. The results of the initial and confirmation samples shall be averaged to determine compliance. If the average concentration level of any of these constituents exceeds the SMCL, then the department shall determine whether treatment for the constituents can be accomplished or more suitable source waters are, or can be made, available. This determination shall be made as quickly as possible. If either of these alternatives is feasible, then corrective action shall be promptly implemented by the owner if deemed necessary by the department. Exceeding the fluoride SMCL requires annual public notice in accordance with 12VAC5-590-540 G.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-383. Organic chemicals compliance.

A. When the results of sampling indicate positive results for contaminants listed in Table 340.2, the owner shall collect a confirmation sample at the same sampling point within two weeks of notification of the analytical results of the first sample.

B. The results of the initial and confirmation samples shall be averaged to determine waterworks compliance in accordance with subsection C of this section. The department has the discretion to delete results of obvious sampling errors.

C. Compliance with Table 340.2 shall be determined based on the analytical results obtained at each sampling point. A sample result below the detection limit shall be calculated as zero for the purposes of determining the annual average. If the owner fails to collect the required number of samples, then compliance (average concentration) shall be based on the total number of samples collected.

1. For the owner of a waterworks that conducts monitoring more frequently than annually, compliance is determined by an RAA of all samples collected at each sampling point. If the annual average of any sampling point is greater than the PMCL, then the waterworks is out of compliance. If the initial sample or a subsequent sample would cause the annual average to be exceeded, then the waterworks is out of compliance immediately. A sample result below the detection limit shall be calculated as zero for purposes of determining the annual average.

2. If the owner is conducting monitoring annually or less frequently, then the owner is not in violation if the average of the initial and confirmation samples is greater than the PMCL for that contaminant; however, the owner shall begin quarterly sampling. The owner will not be considered in violation of the PMCL until one year of quarterly sampling has been completed and the RAA is exceeded. If any sample will cause the RAA to exceed the PMCL at any sampling point, then the waterworks is immediately out of compliance with the PMCL.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-384. Residual disinfectant, DBPs, and DBPPs compliance.

A. General requirements.

1. Where compliance is based on an RAA of monthly or quarterly samples or averages and the owner fails to monitor for TTHM, HAA5, or bromate, this failure to monitor shall be treated as a monitoring violation for the entire period covered by the annual average. Where compliance is based on an RAA of monthly or quarterly samples or averages and the owner's failure to monitor makes it impossible to determine compliance with MRDLs for chlorine and chloramines, this failure to monitor shall be treated as a monitoring violation for the entire period covered by the annual average.

2. All samples collected and analyzed under the provisions of this section shall be included in determining compliance, even if that number is greater than the minimum required.

3. The owner is in violation of the PMCL when the LRAA exceeds the PMCLs listed in Table 340.6 calculated based on four consecutive quarters of monitoring, or the LRAA calculated based on fewer than four quarters of data if the PMCL would be exceeded regardless of the monitoring results of subsequent quarters. The owner is in violation of the monitoring requirements for each quarter that a monitoring result would be used in calculating the LRAA if the owner fails to monitor.

B. Disinfection byproducts.

1. TTHM and HAA5.

a. The owner of a waterworks required to monitor quarterly shall calculate the LRAAs for TTHM and HAA5 using monitoring results collected under 12VAC5-590-374 F and determine that each LRAA does not exceed the PMCL in order to comply with the PMCLs listed in Table 340.6. If the owner fails to complete four consecutive quarters of monitoring, then the owner shall calculate compliance with the PMCL based on the average of the available data from the most recent four quarters. If the owner collects more than one sample per quarter at a monitoring location, then the owner shall average all samples collected in the quarter at that location to determine a quarterly average to be used in the LRAA calculation.

b. The owner of a waterworks required to monitor annually or less frequently shall determine that each sample collected is less than the PMCL in order to determine compliance with the PMCLs listed in Table 340.6. If any sample result exceeds the PMCL, then the owner shall comply with the requirements of 12VAC5–590-374 F 5. If no sample result exceeds the PMCL, then the sample result for each monitoring location is considered the LRAA for that monitoring location.

c. The owner is in violation of the monitoring requirements for each quarter that a monitoring result would be used in calculating an LRAA if the owner fails to monitor.

d. A waterworks has exceeded the operational evaluation level at any monitoring location where the sum of the two previous quarters' TTHM results plus twice the current quarter's TTHM result, divided by four to determine an average, exceeds 0.080 mg/L, or where the sum of the two previous quarters' HAA5 results plus twice the current quarter's HAA5 result, divided by four to determine an average, exceeds 0.060 mg/L.

(1) The owner of a waterworks that exceeds the operational evaluation level shall conduct an operational evaluation and submit a written report of the evaluation to the department on a form approved by the department no later than 90 days after being notified of the analytical result that caused the waterworks to exceed the operational evaluation level. The written report shall be made available to the public upon request.

(2) The operational evaluation report shall include an examination of the waterworks treatment and distribution operational practices, including source water conditions, storage tank operations, excess storage capacity, distribution system flushing, changes in source water or source water quality, and treatment changes or problems that may contribute to TTHM and HAA5 formation and what steps could be considered to minimize future exceedances.

(3) The owner may request and the department may allow the owner to limit the scope of the evaluation if the owner is able to identify the cause of the operational evaluation level exceedance. The request to limit the scope of the evaluation does not extend the schedule in subdivision B 1 d (1) of this section for submitting the written report. The department shall approve this limited scope of evaluation in writing, and the owner shall keep that approval with the completed report.

2. Bromate. Compliance shall be based on a running annual arithmetic average, computed quarterly, of monthly samples collected by the owner as prescribed by 12VAC5-590-374 H. For months in which the owner collects more than one sample, compliance is based on the average of all samples collected during the month. If the average result of the samples covering any consecutive four-quarter period exceeds the PMCL listed in Table 340.6, then the owner is in violation of the PMCL and shall notify the public pursuant to 12VAC5-590-540 A 2, in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531. If the owner fails to complete 12 consecutive months of monitoring, then compliance with the PMCL for the last four-quarter compliance period shall be based on the average of the available data.

3. Chlorite. Compliance shall be based on an arithmetic average of each three-sample set collected in the distribution system as prescribed by 12VAC5-590-374 G. If the arithmetic average of any three-sample set exceeds the PMCL listed in Table 340.6, then the owner is in violation of the PMCL and shall notify the public pursuant to 12VAC5-590-540 A 2, in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531.

C. Residual disinfectant.

1. Chlorine and chloramines.

a. Compliance shall be based on a running annual arithmetic average, computed quarterly, of monthly averages of all samples collected by the owner under 12VAC5-590-374 I 1 a. If the average covering any consecutive four-quarter period exceeds the MRDL listed in Table 340.7, then the owner is in violation of the MRDL and shall notify the public pursuant to 12VAC5-590-540 A 2, in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531.

b. In cases where the owner switches between the use of chlorine and chloramines for residual disinfection during the year, compliance shall be determined by including together all monitoring results of both chlorine and chloramines in calculating compliance. Reports submitted pursuant to 12VAC5-590-530 and 12VAC5-590-531 shall clearly indicate which residual disinfectant was analyzed for each sample.

c. Notwithstanding the MRDLs listed in Table 340.7, operators may increase the residual disinfectant levels of chlorine or chloramines in the distribution system to a level and for a time necessary to protect public health to address specific microbiological contamination problems caused by circumstances such as water main breaks in the distribution system, storm runoff events, source water contamination, or cross-connections.

2. Chlorine dioxide.

a. Acute violations. Compliance shall be based on consecutive daily samples collected by the owner under 12VAC5-590-374 I 2 a. If any daily sample collected at the entrance to the distribution system exceeds the MRDL listed in Table 340.7, and on the following day one or more of the three samples collected in the distribution system exceed the MRDL, then the owner is in violation of the MRDL and shall take immediate corrective action to lower the level of chlorine dioxide below the MRDL and shall notify the public pursuant to the procedures for Tier 1 conditions in 12VAC5-590-540 A 1 in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531. Failure to collect samples in the distribution system the day following an exceedance of the chlorine dioxide MRDL at the entrance to the distribution system shall also be considered an MRDL violation, and the owner shall notify the public of the violation in accordance with the provisions for Tier 1 conditions in 12VAC5-590-540 A 1 in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531.

b. Nonacute violations. Compliance shall be based on consecutive daily samples collected by the owner under 12VAC5-590-374 I 2 a. If any two consecutive daily samples collected at the entrance to the distribution system exceed the MRDL listed in Table 340.7 and all distribution system samples collected are below the MRDL, then the owner is in violation of the MRDL and shall take corrective action to lower the level of chlorine dioxide below the MRDL at the point of sampling and shall notify the public pursuant to the procedures for Tier 2 conditions in 12VAC5-590-540 A 2 in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531. Failure to monitor at the entrance to the distribution system the day following an exceedance of the chlorine dioxide MRDL at the entrance to the distribution system is also an MRDL violation, and the owner shall notify the public of the violation in accordance with the provisions for Tier 2 conditions in 12VAC5-590-540 A 2 in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531.

D. Disinfection byproduct precursors (DBPPs).

1. Compliance shall be determined as specified by 12VAC5-590-411 A 3.

2. For the owner required to meet Step 1 TOC removals, if the value calculated under 12VAC5-590-411 A 3 a (4) is less than 1.00, then the owner is in violation of the treatment technique requirements and shall notify the public pursuant to 12VAC5-590-540 A 2 in addition to reporting to the department pursuant to 12VAC5-590-530 and 12VAC5-590-531.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-385. Lead and copper AL compliance.

A. The lead AL is exceeded if the concentration of lead in more than 10% of tap water samples collected during any monitoring period conducted in accordance with 12VAC5-590-375 B is greater than 0.015 mg/L (i.e., if the 90th percentile lead level is greater than 0.015 mg/L).

B. The copper AL is exceeded if the concentration of copper in more than 10% of tap water samples collected during any monitoring period conducted in accordance with 12VAC5-590-375 B is greater than 1.3 mg/L (i.e., if the 90th percentile copper level is greater than 1.3 mg/L).

C. The 90th percentile lead and copper levels shall be computed as follows:

1. The results of all lead or copper samples taken during a monitoring period shall be placed in ascending order from the sample with the lowest concentration to the sample with the highest concentration. Each sampling result shall be assigned a number, ascending by single integers beginning with the number 1 for the sample with the lowest contaminant level. The number assigned to the sample with the highest contaminant level shall be equal to the total number of samples taken.

2. The number of samples taken during the monitoring period shall be multiplied by 0.9.

3. The contaminant concentration in the numbered sample yielded by the calculation in subdivision C 2 of this section is the 90th percentile contaminant level.

4. For a waterworks serving fewer than 100 people, and the owner collects five samples per monitoring period, the 90th percentile is computed by taking the average of the highest and second highest concentrations.

5. For the owner that has been allowed by the department to collect fewer than five samples in accordance with 12VAC5-590-375 B 3, the sample result with the highest concentration is considered the 90th percentile value.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 27, Issue 1, eff. October 13, 2010; amended, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-388. Radiological compliance.

A. MCLGs for radionuclides are listed in Table 546.1 of 12VAC5-590-546 B.

B. PMCLs for radionuclides are applicable to community waterworks only and are listed in Table 340.4. Compliance with PMCLs will be determined based on the analytical results obtained at each entry point. If the sample result at one entry point exceeds the PMCL, then the owner is in violation of the PMCL.

1. For the owner that is monitoring more than once per year, compliance with the PMCL is determined by an RAA of the analytical results at each entry point. If the average result at any entry point is greater than the PMCL, then the waterworks is out of compliance with the PMCL.

2. For the owner of a waterworks that monitors more than once per year, if any sample result will cause the RAA to exceed the PMCL at any entry point, then the waterworks is out of compliance with the PMCL immediately.

3. All samples collected and analyzed under the provisions 12VAC5-590-378 shall be included in determining compliance, even if that number is greater than the minimum required.

4. If the owner does not collect all required samples when compliance is based on an RAA result of quarterly samples, then compliance will be based on the RAA result of the samples collected.

5. If a sample result is less than the detection limit as specified in Table 378.1, then zero will be used to calculate the RAA unless a gross alpha particle activity result is being used instead of radium-226 or uranium. If the gross alpha particle activity result is less than the detection limit as specified in Table 378.1, then one half the detection limit will be used to calculate the RAA.

C. Radiological (gross alpha, combined radium-226 and radium-228, uranium, and man-made radioactivity).

1. Compliance with the radiological PMCLs shall be based on the RAA results. PMCLs are indicated in Table 340.4. Sampling for radiological analysis shall be in compliance with 12VAC5-590-378.

2. Compliance shall be determined by rounding off results to the same number of significant figures as the PMCL for the radionuclide in question.

D. If a PMCL for radioactivity listed in Table 340.4 is exceeded, then the owner shall give notice to the department pursuant to 12VAC5-590-530 and to the public as required by 12VAC5-590-540 A 2.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-390. Physical constituent compliance.

A. Color, odor, pH, and total dissolved solids.

1. When the sampling results for color, odor, pH, or total dissolved solids exceed the applicable SMCL, the owner shall collect a confirmation sample at the same sampling site within two weeks of notification of the analytical results of the first sample.

2. The results of the initial and confirmation samples shall be averaged to determine compliance with 12VAC5-590-340 C. The department has the discretion to void results of obvious sampling errors.

3. If the average concentration level of any contaminant of color, odor, pH, or total dissolved solids is greater than the SMCL listed in Table 340.3, then the department shall determine whether treatment to remove that contaminant can be accomplished or more suitable supplies of source water are, or can be made, available.

B. Turbidity in groundwater sources not required to filter shall not:

1. Interfere with disinfection throughout the distribution system;

2. Cause taste and odors upon disinfection; or

3. Cause consumers to question the safety of their drinking water.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from VR355-18-004.06 § 2.6, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 12, Issue 2, eff. November 15, 1995; Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-391. Treatment technique requirements.

A. When it is not technically or economically feasible to monitor for a particular PMCL or a contaminant, one or more specific treatment techniques that lead to a reduction in the concentration level of that contaminant shall be required. The application of that treatment technique reduces the contaminant in question to a concentration level that achieves compliance with this chapter.

B. Failure to continuously maintain the treatment technique is a violation of this chapter and public notification in accordance with 12VAC5-590-540 A 2 is required.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-392. Coliform treatment technique triggers and assessment requirements.

A. Assessments shall be conducted in accordance with subsections C, D, and E of this section after exceeding treatment technique triggers.

B. Treatment technique triggers.

1. Level 1 treatment technique triggers:

a. For the owner required to collect 40 or more samples per month, the number of total coliform-positive samples exceeds 5.0% of the number of samples collected for the month.

b. For the owner required to collect fewer than 40 samples per month, when there are two or more total coliform-positive samples in the same month.

c. The owner fails to collect every required repeat sample after any single total coliform-positive sample.

2. Level 2 treatment technique triggers:

a. An E. coli PMCL violation, as specified in 12VAC5-590-380 B 2.

b. A second Level 1 trigger occurs within a rolling 12-month period, unless the department has determined a likely reason for the first Level 1 treatment technique trigger and that the owner has corrected the problem.

C. Assessment requirements.

1. Level 1 and 2 assessments shall be conducted to identify the possible presence of sanitary defects and defects in the distribution system coliform monitoring practices. The owner shall be responsible for conducting Level 1 assessments. Level 2 assessments shall be conducted by the department.

2. When conducting Level 1 and Level 2 assessments, the assessor shall include:

a. An evaluation and identification of inadequacies in sample sites, sampling protocol, and sample processing;

b. An evaluation of atypical events that could affect distributed water quality or indicate that distributed water quality was impaired;

c. An evaluation of changes in distribution system maintenance and operation that could affect distributed water quality, including water storage;

d. An evaluation of source and treatment considerations that impact distributed water quality; and

e. An evaluation of existing water quality monitoring data.

3. Level 1 assessment.

a. The owner shall complete the assessment and document the assessment on a form approved by the department. The owner shall submit the assessment form, as soon as practical, but within 30 days after the owner learns that a trigger in subdivision B 1 of this section has been exceeded.

b. If the department evaluates the completed Level 1 assessment and determines that the assessment is not sufficient, including any proposed timetable for any corrective actions, then the department shall consult with the owner. If the department requires revisions after the consultation, then the owner shall submit a revised assessment form to the department on an agreed upon schedule not to exceed 30 days from the date of consultation.

c. Upon completion and submission of the assessment form by the owner, the department shall determine if the owner has identified a likely cause for the Level 1 trigger and, if so, confirm that the owner has corrected the problem or has included a schedule acceptable to the department for correcting the problem.

4. Level 2 assessment.

a. The department will complete the assessment and document the assessment on a form approved by the department. The department will consult with the owner during the assessment and complete the assessment within 30 days upon learning that the waterworks has exceeded any trigger in subdivision B 2 of this section.

b. The department will send to the owner the completed assessment form, which will describe any detected sanitary defects, corrective actions completed or needed and, if needed, a timetable to complete the corrective actions. The owner will return the form within seven days with a signature that indicates concurrence with the listed actions needed and timetable to complete the corrective actions. If the owner does not concur with either an action or timetable to complete a corrective action, then the owner shall notify the department, complete consultation with the department, and develop a revised corrective action schedule. The owner shall submit the revised schedule to the department for evaluation and approval within 30 days of the date of the consultation.

D. Corrective actions.

1. The owner shall correct sanitary defects found through either the Level 1 or the Level 2 assessment conducted under subsection C of this section.

2. The owner shall complete the corrective actions in compliance with the timetable approved by the department in consultation with the owner. The owner shall notify the department no later than seven days after each scheduled corrective action is completed.

E. Consultation.

1. At any time during the assessment or corrective action phase, either the owner or the department may request a consultation with the other party to determine the appropriate actions to be taken.

2. The owner may consult with the department on all relevant information that may impact the ability to comply with subsection D of this section.

F. Violations. Failure to conduct the required assessment or corrective actions in accordance with subsections C and D of this section, after exceeding a treatment technique trigger specified in subsection B of this section, is a treatment technique violation. The owner shall provide public notification as required under Tier 2 conditions specified in 12VAC5-590-540 A 2.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 33, Issue 3, eff. November 2, 2016; amended, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-395. Surface water and GUDI sources, polymers, and recycle treatment techniques.

A. Surface water and GUDI source treatment techniques.

1. The filtration and disinfection provisions of this section are required treatment techniques for a waterworks supplied by a surface water source, a GUDI source, or both. These treatment technique requirements are in place of a PMCL for the following contaminants: Giardia lamblia, viruses, heterotrophic bacteria, Cryptosporidium, Legionella, and turbidity. A waterworks that uses a surface water source, a GUDI source, or both shall provide treatment of that source water that complies with these treatment technique requirements. See 12VAC5-590-401 for filtration log removal credits and required log inactivation for Cryptosporidium. See 12VAC5-590-500 for log removal credits and required log inactivation for Giardia lamblia and viruses. These treatment technique requirements consist of installing and properly operating water treatment processes that reliably achieve:

a. At least 99.9% (3-log) removal or inactivation of Giardia lamblia between a point where the source water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer;

b. At least 99.99% (4-log) removal or inactivation of viruses between a point where the source water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer; and

c. At least 99% (2-log) removal of Cryptosporidium between a point where the source water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer.

2. A waterworks that uses a surface water source, a GUDI source, or both is considered to be in compliance with the requirements of subdivision A 1 of this section if it meets the following disinfection and filtration requirements:

a. Disinfection requirements.

(1) The disinfection treatment shall be sufficient to ensure that the total treatment processes of that waterworks achieve at least 99.9% (3-log) inactivation or removal of Giardia lamblia and at least 99.99% (4-log) inactivation or removal of viruses. If any physical process can achieve at least a 3-log removal of Giardia lamblia but cannot adequately remove pathogens, then the disinfection treatment shall provide a second treatment barrier for Giardia lamblia, Legionella, heterotrophic bacteria, and viruses. The disinfection treatment shall be sufficient to assure at least a 0.5 log inactivation of Giardia lamblia.

(2) The residual disinfectant concentration in the water entering the distribution system shall not be less than 0.2 mg/L for more than four hours.

(3) The residual disinfectant concentration in the distribution system, measured as total chlorine, free chlorine, combined chlorine, or chlorine dioxide, shall not be undetectable in more than 5% of the samples each month, for any two consecutive months that the waterworks serves water to the public. If the department determines that a waterworks is experiencing excessive coliform occurrences in its distribution system, then the department may require the owner to maintain minimum chlorine residual levels of 0.2 mg/L or monochloramine levels of 0.5 mg/L throughout the distribution system. Water in the distribution system with a heterotrophic bacteria concentration less than or equal to 500/mL, measured as HPC, is deemed to have a detectable residual disinfectant for the purposes of determining compliance with this requirement. Thus, the value "V," in percent, in the following formula shall not exceed 5% in one month, for any two consecutive months.

V = [(c + d + e) / (a + b)] X 100

where

a = number of instances where the residual disinfectant concentration is measured;

b = number of instances where the residual disinfectant concentration is not measured but HPC is measured;

c = number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;

d = number of instances where no residual disinfectant concentration is detected and where the HPC is greater than 500/mL; and

e = number of instances where the residual disinfectant concentration is not measured and HPC is greater than 500/mL.

(4) The department may determine that the HPC compliance requirements of subdivision A 2 a (3) of this section do not apply based on site-specific considerations or if an owner has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions and the waterworks is providing adequate disinfection in the distribution system.

b. Filtration requirements. A waterworks that uses a surface water source, a GUDI source, or both shall provide filtration treatment by using one of the following methods:

(1) Conventional filtration.

(a) Achieve a filtered water turbidity of less than or equal to 0.3 NTU in at least 95% of the measurements taken each month. Samples shall be representative of the waterworks' filtered water.

(b) The turbidity level of representative samples of a waterworks' filtered water shall at no time exceed one NTU, measured as specified in 12VAC5-590-440.

(c) A waterworks that uses lime softening may acidify representative samples before analysis using a protocol approved by the department.

(d) Water treatment plants utilizing conventional or direct filtration with gravity flow granular media filters are capable of producing filtered water with turbidity consistently less than 0.10 NTU. Therefore, for these types of water treatment plants, the operational goal for filter effluent turbidity for each filter, before any post-filtration chemical addition, shall be 0.10 NTU.

(2) Diatomaceous earth filtration.

(a) The turbidity level of representative samples of a waterworks' filtered water shall be less than or equal to one NTU in at least 95% of the measurements taken each month.

(b) The turbidity level of representative samples of a waterworks' filtered water shall at no time exceed five NTU.

(3) Slow sand filtration.

(a) The turbidity level of representative samples of a waterworks' filtered water shall be less than or equal to one NTU in at least 95% of the measurements taken each month, except that if the department determines there is no significant interference with disinfection at a higher turbidity level, then the department may substitute this higher turbidity limit for that waterworks.

(b) The turbidity level of representative samples of a waterworks' filtered water shall at no time exceed five NTU.

(4) Membrane filters, bag filters, and cartridge filters.

(a) The turbidity level of representative samples of a waterworks' filtered water shall be less than or equal to 0.3 NTU in at least 95% of the measurements taken each month, except that if the department determines there is no significant interference with disinfection at a higher turbidity level, then the department may substitute this higher turbidity limit for that waterworks.

(b) Water treatment plants utilizing membrane filtration are capable of producing filtered water with turbidity consistently less than 0.05 NTU. Therefore, for these types of water treatment plants, the operational goal for filter effluent turbidity for each filter, before any post-filtration chemical addition, is 0.05 NTU.

(c) The turbidity level of representative samples of a waterworks' filtered water shall at no time exceed one NTU.

(5) The owner may use a filtration technology not listed in this section if the owner demonstrates to the satisfaction of the department by full-scale, pilot plant, or challenge studies, or by other approved means that the alternative filtration technology, in combination with disinfection, will meet the requirements of this section.

3. Once the department has determined that a waterworks utilizes a surface water source, a GUDI source, or both (see 12VAC5-590-430), then filtration and disinfection treatments are required. The owner shall install and have in operation treatment units that meet the requirements described in subdivisions A 1 and A 2 of this section no later than 18 months following the department's determination. During the interim period, and until filtration and disinfection treatments are installed and in operation, the owner shall discontinue use of the surface water source, GUDI source, or both unless the source must remain in service because discontinuing the source is not a viable option, at which point the owner shall:

a. Issue a continuous boil water notice through the public notification procedure in 12VAC5-590-540 A 1 until the required filtration and disinfection treatments are installed and are in operation;

b. Provide disinfection treatment to achieve a 4-log inactivation of virus during the interim period before the filtration treatment is installed. Monitoring equipment shall be installed that will ensure compliance with this requirement; and

c. Increase bacteriological sampling frequency in the distribution system. For the owner required to collect routine distribution system bacteriological samples at a monthly frequency, the owner shall collect twice the number of samples required for that population each month. For the owner required to collect routine bacteriological samples at a quarterly frequency, the owner shall increase the sampling frequency to monthly.

B. Polymer treatment techniques.

1. The owner shall certify annually in writing to the department (using third-party or manufacturer's certification) that, when polymers containing acrylamide or epichlorohydrin are used by the waterworks, the combination (or product) of dose and monomer level does not exceed the following specified levels:

a. Acrylamide = 0.05% dosed at one ppm (or equivalent) of polymer.

b. Epichlorohydrin = 0.01% dosed at 20 ppm (or equivalent) of polymer.

2. Certifications may rely on the manufacturers or third parties as approved by the department.

C. Recycle treatment techniques.

1. If spent filter backwash water, thickener supernatant, or liquids from dewatering processes are recycled, in a waterworks supplied by a surface water source, a GUDI source, or both that employ conventional filtration or direct filtration treatment, then the waterworks is subject to the treatment technique requirement described in subsection A of this section.

2. Under this requirement, recycle flows shall be returned through all the processes of the treatment system or an alternative location approved by the department.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-400. (Repealed.)

Historical Notes

Derived from VR355-18-004.07 § 2.7, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 12, Issue 2, eff. November 15, 1995; Volume 19, Issue 24, eff. September 10, 2003; Volume 22, Issue 15, eff. May 3, 2006; repealed, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-401. Enhanced filtration and disinfection for Cryptosporidium treatment techniques.

A. A waterworks using a surface water source, a GUDI source, or both shall comply with the requirements of this section based on their population or if the waterworks is a wholesaler, based on the population of the largest waterworks in the combined distribution system.

B. The owner shall conduct an initial and a second round of source water monitoring for each water treatment plant that treats a surface water source, a GUDI source, or both. This monitoring may include sampling for Cryptosporidium, E. coli, and turbidity to determine what level, if any, of additional Cryptosporidium treatment is required.

1. Initial round of source water monitoring. The owner shall conduct the following monitoring on the schedule in subdivision B 3 of this section unless the monitoring avoidance criteria in subdivision B 4 of this section are met.

a. The owner of a waterworks serving at least 10,000 people shall sample the source water for Cryptosporidium, E. coli, and turbidity at least monthly for 24 months.

b. The owner of a waterworks serving fewer than 10,000 people:

(1) Shall sample the source water for E. coli at least once every two weeks for 12 months, or

(2) May avoid E. coli monitoring if the owner notifies the department that the owner will monitor for Cryptosporidium as described in subdivision B 1 c of this section. The owner shall notify the department no later than three months before the date at which the owner is otherwise required to start E. coli monitoring.

c. The owner of a waterworks serving fewer than 10,000 people shall sample the source water for Cryptosporidium at least twice per month for 12 months or at least monthly for 24 months if the owner meets one of the following, based on monitoring conducted under subdivision B 1 b of this section:

(1) For a waterworks using source water from a lake or reservoir, the annual mean E. coli concentration is greater than 10 E. coli/100 mL.

(2) For a waterworks using source water from flowing stream, the annual mean E. coli concentration is greater than 50 E. coli/100 mL.

(3) The waterworks does not conduct E. coli monitoring as described in subdivision B 1 b of this section.

(4) The waterworks using a GUDI source shall comply with the requirements of this subdivision B 1 c based on the E. coli level that applies to the nearest surface water body. If no surface water body is nearby, the waterworks shall comply based on the requirements that apply to a waterworks using source water from a lake or reservoir.

d. For the waterworks serving fewer than 10,000 people, the department may approve monitoring for an indicator other than E. coli under subdivision B 1 b (1) of this section. The department also may approve an alternative to the E. coli concentration in subdivision B 1 c (1), B 1 c (2), or B 1 c (4) of this section to trigger Cryptosporidium monitoring. This approval by the department shall be provided to the owner in writing and shall include the basis for the department's determination that the alternative indicator or trigger level will provide a more accurate identification of whether a waterworks will exceed the Bin 1 Cryptosporidium level in subdivision B 1 a of this section.

e. The waterworks may sample more frequently than required under this section if the sampling frequency is evenly spaced throughout the monitoring period.

2. Second round of source water monitoring. The owner shall conduct a second round of source water monitoring that meets the requirements for monitoring parameters, frequency, and duration described in subdivision B 1 of this section, unless the monitoring exemption criteria in subdivision B 4 of this section are met. The owner shall conduct this monitoring on the schedule in subdivision B 3 of this section.

3. Monitoring schedule. The owner shall begin the monitoring required in subdivisions B 1 and B 2 of this section no later than the month beginning with the date listed in Table 401.1:

4. Monitoring avoidance.

a. The owner is not required to conduct source water monitoring if the waterworks will provide a total of at least 5.5-log of treatment for Cryptosporidium, equivalent to meeting the treatment requirements of Bin 4 in subdivision D 2 of this section.

b. If the owner chooses to provide the level of treatment in subdivision B 4 a of this section, rather than start source water monitoring, then the owner shall notify the department in writing no later than the date the owner is otherwise required to submit a sampling schedule for monitoring under subdivision B 5 of this section. Alternatively, the owner may choose to stop sampling at any point after initiating monitoring if the owner notifies the department in writing that he will provide this level of treatment. The owner shall install and operate technologies to provide this level of treatment by the applicable treatment compliance date in subdivision D 3 of this section.

5. Sampling schedules.

a. The owner of a waterworks required to conduct source water monitoring in accordance with subsection B of this section shall submit a sampling schedule that specifies the calendar dates when the owner shall collect each required sample.

(1) The owner shall submit a sampling schedule to the department no later than three months before the applicable date listed in subdivision B 3 of this section for each round of required monitoring.

(2) If the department does not respond to the owner regarding the sampling schedule, then the owner shall sample at the reported schedule.

b. The owner shall collect samples within two days before or two days after the dates indicated in the sampling schedule (i.e., within a five-day period around the schedule date) unless one of the conditions of this subdivision b applies:

(1) If an extreme condition or situation exists that may pose danger to the sample collector or that cannot be avoided and causes the owner to be unable to sample in the scheduled five-day period, then the owner shall sample as close to the scheduled date as is feasible unless the department approves an alternative sampling date. The owner shall submit an explanation for the delayed sampling date to the department concurrent with the shipment of the sample to the laboratory.

(2) If the owner is unable to report a valid analytical result for a scheduled sampling date due to equipment failure, loss of or damage to the sample, failure to comply with the analytical method requirements, including the quality control requirements of 12VAC5-590-440, or the failure of an approved laboratory to analyze the sample, then the owner shall collect a replacement sample. The owner shall collect the replacement sample not later than 21 days after receiving information that an analytical result cannot be reported for the scheduled date unless the owner demonstrates that collecting a replacement sample within this timeframe is not feasible or the department approves an alternative resampling date. The owner shall submit an explanation for the delayed sampling date to the department concurrent with the shipment of the sample to the laboratory.

c. The owner of a waterworks that fails to meet the criteria of subdivision B 5 b of this section for any source water sample required under subsection B of this section shall revise the sampling schedule to add dates for collecting all missed samples. The owner shall submit the revised schedule to the department for approval before the owner begins collecting the missed samples.

6. Sampling locations.

a. The owner of a waterworks required to conduct source water monitoring under subsection B of this section shall collect samples for each water treatment plant that treats a surface water source, a GUDI source, or both. Where multiple water treatment plants draw source water from the same influent, such as the same pipe or intake, the department may approve one set of monitoring results to be used to satisfy the requirements of subsection B of this section for all water treatment plants.

b. The owner shall collect source water samples before chemical treatment, such as coagulants, oxidants, and disinfectants. However, the department may approve the collection of a source water sample after chemical treatment. To grant this approval, the department shall determine that collecting a sample before chemical treatment is not feasible for the owner and that the chemical treatment is unlikely to have a significant adverse effect on the analysis of the sample.

c. The owner of a waterworks that recycles filter backwash water shall collect source water samples before the point of filter backwash water addition.

d. Bank filtration.

(1) The owner that receives Cryptosporidium treatment credit for bank filtration under 12VAC5-590-395 A 2 b (1) shall collect source water samples from the surface water before bank filtration.

(2) The owner that uses bank filtration as pretreatment to a water treatment plant shall collect source water samples from the well (i.e., after bank filtration). The use of bank filtration during monitoring shall be consistent with routine operational practice. The owner collecting samples after a bank filtration process may not receive treatment credit for the bank filtration under subdivision E 4 c of this section.

e. Multiple sources. The owner of a waterworks that uses multiple source waters, including multiple surface water sources and blended surface water and groundwater sources, shall collect samples as specified in subdivision B 6 e (1) or B 6 e (2) of this section. The use of multiple source waters during monitoring shall be consistent with routine operational practice.

(1) If a sampling tap is available where the source waters are combined before treatment, then the owner shall collect samples from the tap.

(2) If a sampling tap is not available where the source waters are combined before treatment, then the owner shall collect samples at each source near the intake on the same day and shall follow either subdivision B 6 e (2) (a) or B 6 e (2) (b) of this section for sample analysis.

(a) The owner may composite samples from each source into one sample before analysis. The volume of sample from each source shall be weighted according to the proportion of the source water in the total water treatment plant flow at the time the sample is collected.

(b) The owner may choose to have samples analyzed from each source separately and calculate a weighted average of the analysis results for each sampling date. The weighted average shall be calculated by multiplying the analysis result for each source water by the fraction the source water contributed to the total water treatment plant flow at the time the sample was collected and then summing these values.

f. Additional requirements. The owner shall submit a description of each sampling location to the department at the same time as the sampling schedule required in subdivision B 3 of this section. This description shall address the position of the sampling location in relation to the waterworks' source waters and treatment processes, including pretreatment, points of chemical treatment, and filter backwash recycle. If the department does not respond to an owner regarding sampling location, then the owner shall sample at each reported location.

7. Analytical methods. All analytical methods shall be conducted in accordance with 12VAC5-590-440.

8. Approved laboratories.

a. Cryptosporidium. The owner shall have Cryptosporidium samples analyzed by a laboratory that has received reciprocal certification approved under the DCLS Laboratory Certification Program for Analysis of Cryptosporidium in Water.

b. E. coli. A laboratory certified by the DCLS for total coliform analysis under 12VAC5-590-440 is approved for E. coli analysis when the laboratory uses the same technique for E. coli that the laboratory uses under 12VAC5-590-440. Laboratories shall use methods for enumeration of E. coli in source water approved in 12VAC5-590-440.

c. Turbidity. Measurements of turbidity shall be made by a party approved by the department.

9. Reporting of the source water results shall be in accordance with 12VAC5-590-531.

10. The owner of a waterworks treating a surface water source, a GUDI source, or both, that operates for only part of the year shall conduct source water monitoring in accordance with this section, but with the following modifications:

a. The owner shall sample the source water only during the months that the waterworks operates unless the department specifies another monitoring period based on waterworks operating practices.

b. The owner of a waterworks that operates less than six months per year and that monitors for Cryptosporidium shall collect at least six Cryptosporidium samples per year during each of two years of monitoring. Samples shall be evenly spaced throughout the period the waterworks operates.

11. New sources.

a. The owner of a waterworks that begins using a surface water source, a GUDI source, or both, is required to begin monitoring under subdivision B 3 of this section and shall monitor the new source on a schedule approved by the department. Source water monitoring shall meet the requirements of this section. The owner shall also meet the bin classification and Cryptosporidium treatment requirements of subdivisions D 1 and D 2 of this section, for the new source on a schedule approved by the department.

b. The requirements of this section apply to a waterworks using a surface water source, a GUDI source, or both, that begins operation after the monitoring start date applicable to the size of the waterworks under subdivision B 3 of this section.

c. The owner shall begin a second round of source water monitoring no later than six years following the initial bin classification under subdivision D 1 of this section.

12. Failure to collect any source water sample required under this section in accordance with the sampling schedule, sampling location, analytical method, approved laboratory, and reporting requirements of subdivisions B 5 through B 9 of this section is a monitoring violation.

13. Grandparenting monitoring data. The owner may use monitoring data collected before the applicable monitoring start date in subdivision B 3 of this section (grandparented data) to meet the initial source water monitoring requirements in subdivision B 1 of this section. Grandparented data may be substituted for an equivalent number of months at the end of the monitoring period. All data submitted under this subdivision B 13 shall meet the requirements in subdivisions B 13 a through B 13 h of this section and be approved by the department:

a. The owner may grandparent Cryptosporidium samples to meet the requirements of this section when the owner does not have corresponding E. coli and turbidity samples. The owner who grandparents Cryptosporidium samples without E. coli and turbidity samples is not required to collect E. coli and turbidity samples when the owner completes the requirements for Cryptosporidium monitoring under this section.

b. The analysis of E. coli samples shall meet the analytical method and approved laboratory requirements of subdivisions B 7 and B 8 of this section.

c. The analysis of Cryptosporidium samples shall meet the requirements of subdivision B 8 of this section.

d. The sampling location shall meet the conditions in subdivision B 6 of this section.

e. Cryptosporidium sample collection intervals may vary for the conditions specified in subdivisions B 5 b (1) and B 5 b (2) of this section if the owner provides documentation of the condition when reporting monitoring results.

(1) The department may approve grandparenting of previously collected data where there are time gaps in the sampling frequency if the owner conducts additional monitoring the department specifies to ensure that the data used to comply with the initial source water monitoring requirements of subsection B of this section are seasonally representative and unbiased.

(2) The owner may grandparent previously collected data where the sampling frequency within each month varied. If the Cryptosporidium sampling frequency varied, then the owner shall follow the monthly averaging procedure in subdivision D 1 a (5) of this section when calculating the bin classification for a filtered waterworks.

f. The owner of a waterworks that requests to grandparent previously collected monitoring results shall report the following information by the applicable dates listed in the following subdivisions. The owner shall report this information to the department.

(1) The owner shall report the intent to submit previously collected monitoring results for grandparenting. This report shall specify the number of previously collected results the owner shall submit, the dates of the first and last sample, and whether an owner shall conduct additional source water monitoring to meet the requirements in subsection B of this section. The owner shall report this information no later than the date the sampling schedule listed in subdivision B 3 of this section is required.

(2) The owner shall report previously collected monitoring results for grandparenting no later than two months after the applicable date listed in subdivision B 3 of this section.

(a) For each sample result, the owner shall report the applicable data elements in 12VAC5-590-531 A 5.

(b) The owner shall certify that the reported monitoring results include all results the waterworks generated during the time period beginning with the first reported result and ending with the final reported result. This applies to samples that were collected from the sampling location specified for source water monitoring under subdivision B 1 of this section, not spiked, and analyzed using the laboratory's routine process for the analytical methods listed in this section.

(c) The owner shall certify that the samples were representative of a waterworks' source waters and the source waters have not changed. The owner shall report a description of each sampling location, which shall address the position of the sampling location in relation to the waterworks' source waters and treatment processes, including points of chemical addition and filter backwash recycle.

(d) For Cryptosporidium samples, the laboratory that analyzed the samples shall provide a letter certifying that the quality control criteria specified in the methods listed in subdivision B 8 of this section were met for each sample batch associated with the reported results. Alternatively, the laboratory may provide bench sheets and sample examination report forms for each field, matrix spike, initial precision and recovery (IPR), ongoing precision and recovery (OPR), and method blank sample associated with the reported results.

g. If the department determines that a previously collected data set submitted for grandparenting was generated during source water conditions that were not normal for the waterworks, such as a drought, the department may disapprove the data. Alternatively, the department may approve the previously collected data if the owner reports additional source water monitoring data, as determined by the department, to ensure that the data set used under subdivision D 1 of this section represents average source water conditions for the waterworks.

h. If the owner submits previously collected data that fully meets the number of samples required for initial source water monitoring under subdivision B 1 of this section and some of the data are rejected due to not meeting the requirements of this section, then the owner shall conduct additional monitoring to replace rejected data on a schedule approved by the department. The owner is not required to begin this additional monitoring until two months after notification that data have been rejected and additional monitoring is necessary.

C. The owner of a waterworks that plans to make a significant change to the disinfection practice shall develop disinfection profiles and calculate disinfection benchmarks as described in 12VAC5-590-500.

1. The owner shall notify the department before changing the disinfection practice and shall include in this notice the following information:

a. A completed disinfection profile and disinfection benchmark for Giardia lamblia and viruses;

b. A description of the proposed change in disinfection practice; and

c. An analysis of how the proposed change will affect the current level of disinfection.

2. Significant changes to the disinfection practice are defined as follows:

a. Changes to the point of disinfection;

b. Changes to any disinfectant used in the water treatment plant;

c. Changes to the disinfection process; or

d. Any other modification identified by the department as a significant change to disinfection practice.

D. The owner shall determine the Cryptosporidium treatment bin classification as described in subdivision D 1 of this section and provide additional treatment for Cryptosporidium, if required, as described in subdivision D 2 of this section. The owner shall implement Cryptosporidium treatment according to the schedule in subdivision D 3 of this section.

1. Bin classification for waterworks.

a. Following completion of the initial round of source water monitoring required under subdivision B 1 of this section, the owner shall calculate an initial Cryptosporidium bin concentration for each water treatment plant for which monitoring was required. Calculation of the bin concentration shall use the Cryptosporidium results reported under subdivision B 1 of this section and shall follow these procedures:

(1) For the owner who collects a total of at least 48 samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.

(2) For the owner who collects a total of at least 24 samples, but not more than 47 samples, the bin concentration is equal to the highest arithmetic mean of all sample concentrations in any 12 consecutive months during which Cryptosporidium samples were collected.

(3) For the owner of a waterworks that serves fewer than 10,000 people and monitors for Cryptosporidium for only one year (i.e., collect 24 samples in 12 months), the bin concentration is equal to the arithmetic mean of all sample concentrations.

(4) For water treatment plants that operate only part of the year and that monitor fewer than 12 months per year under subdivision B 1 of this section, the bin concentration is equal to the highest arithmetic mean of all sample concentrations during any year of Cryptosporidium monitoring.

(5) If the monthly Cryptosporidium sampling frequency varies, then the owner shall first calculate a monthly average for each month of monitoring. The owner shall then use these monthly average concentrations, rather than individual sample concentrations, in the applicable calculation for bin classification in subdivisions D 1 a (1) through D 1 a (4) of this section.

b. The owner shall determine the initial bin classification from Table 401.2 using the Cryptosporidium bin concentration calculated under subdivision D 1 a of this section:

c. Following completion of the second round of source water monitoring required under subdivision B 2 of this section, the owner shall recalculate the Cryptosporidium bin concentration using the Cryptosporidium results reported under subdivision B 2 of this section and following the procedures in subdivisions D 1 a (1) through D 1 a (4) of this section. The owner shall then redetermine the bin classification using this bin concentration and Table 401.3.

d. Reporting of bin classifications.

(1) The owner shall report the initial bin classification under subdivision D 1 b of this section to the department for approval no later than six months after the waterworks is required to complete the initial source water monitoring based on the schedule in subdivision B 3 of this section.

(2) The owner shall report the bin classification under subdivision D 1 c of this section to the department for approval no later than six months after the owner is required to complete the second round of source water monitoring based on the schedule in subdivision D 1 a (3) of this section.

(3) The bin classification report to the department shall include a summary of source water monitoring data and the calculation procedure used to determine bin classification.

e. Failure to comply with the conditions of subdivision D 1 d of this section is a violation of the treatment technique requirement.

2. Waterworks additional Cryptosporidium treatment requirements.

a. A waterworks shall provide the level of additional treatment for Cryptosporidium specified in this subdivision based on the bin classification as determined under subdivision D 1 of this section and according to the schedule in subdivision D 3 b of this section.

b. Additional treatment.

(1) The owner shall use one or more of the treatment and management options listed in subsection E of this section, termed the microbial toolbox, to comply with the additional Cryptosporidium treatment required in subdivision D 2 a of this section.

(2) A waterworks classified in Bin 3 and Bin 4 shall achieve at least 1-log of the additional Cryptosporidium treatment required under subdivision D 2 a of this section using either one or a combination of the following: (i) bag filters, (ii) bank filtration, (iii) cartridge filters, (iv) chlorine dioxide, (v) membranes, (vi) ozone, or (vii) UV as described in subdivisions E 3 through E 7 of this section.

c. Failure by a waterworks in any month to achieve treatment credit by meeting criteria in subdivisions E 3 through E 7 of this section for microbial toolbox options that is at least equal to the level of treatment required in subdivision D 2 a of this section is a violation of the treatment technique requirement.

d. If the department determines during a sanitary survey or an equivalent source water assessment that after an owner completed the monitoring conducted under subdivision B 1 or B 2 of this section, significant changes occurred in the waterworks watershed that could lead to increased contamination of the source water by Cryptosporidium, then the owner shall take actions specified by the department to address the contamination. These actions may include additional source water monitoring or implementing microbial toolbox options listed in subdivision E 2 of this section.

3. Schedule for compliance with Cryptosporidium treatment requirements.

a. Following the initial bin classification in accordance with subdivision D 1 b of this section, the owner shall provide the level of treatment for Cryptosporidium required under subdivision D 2 of this section according to the schedule in subdivision D 3 b of this section.

b. If the bin classification for a filtered waterworks changes following the second round of source water monitoring, as determined under subdivision D 1 c of this section, then the owner shall provide the level of treatment for Cryptosporidium required under subdivision D 2 of this section on a schedule approved by the department.

E. The owner of a waterworks required to provide additional treatment for Cryptosporidium shall implement microbial toolbox options that are designed and operated as described in subdivisions E 1 through E 7 of this section.

1. The owner receives the treatment credits listed in Table 401.4 by meeting the conditions for microbial toolbox options described in subdivisions E 3 through E 7 of this section. The owner shall apply these treatment credits to meet the treatment requirements in subdivision D 2 of this section.

2. Microbial Toolbox Summary Table: Options, Treatment Credits and Criteria.

3. Source toolbox components.

a. Reserved.

b. Alternative source.

(1) The owner may conduct source water monitoring that reflects a different intake location (either in the same source or for an alternate source) or a different procedure for the timing or level of withdrawal from the source (alternative source water monitoring). If the department approves, then the owner may determine the bin classification under subdivision D 1 of this section based on the alternative source water monitoring results.

(2) If the owner conducts alternative source water monitoring under subdivision E 3 b (1) of this section, then the owner shall also monitor the current water treatment plant intake concurrently as described in subsection B of this section. "Plant intake" means the works or structures at the head of a conduit through which source water is diverted (e.g., river or lake) into the water treatment plant.

(3) Alternative source water monitoring under subdivision E 3 b (1) of this section shall meet the requirements for source water monitoring to determine bin classification, as described in subdivisions B 1 through B 13 of this section. The owner shall report the alternative source water monitoring results to the department, along with supporting information documenting the operating conditions under which the samples were collected.

(4) If the owner determines the bin classification under subdivision D 1 of this section using alternative source water monitoring results that reflect a different intake location or a different procedure for managing the timing or level of withdrawal from the source, then the owner shall relocate the intake or permanently adopt the withdrawal procedure, as applicable, no later than the applicable treatment compliance date in subdivision D 3 of this section.

4. Prefiltration treatment toolbox components.

a. Presedimentation. The owner receives 0.5-log Cryptosporidium treatment credit for a presedimentation basin during any month the process meets the following criteria:

(1) The presedimentation basin shall be in continuous operation and shall treat the entire water treatment plant flow at a waterworks using a surface water source, a GUDI source, or both.

(2) A coagulant shall be continuously added to the presedimentation basin.

(3) The presedimentation basin shall achieve the performance criteria in either of the following:

(a) Demonstrates at least 0.5-log mean reduction of influent turbidity. This reduction shall be determined using daily turbidity measurements in the presedimentation process influent and effluent and shall be calculated as follows: log10 (monthly mean of daily influent turbidity) - log10 (monthly mean of daily effluent turbidity).

(b) Complies with the performance criteria approved by the department that demonstrate at least 0.5-log mean removal of micron-sized particulate material through the presedimentation process.

b. Two-stage lime softening. The owner receives an additional 0.5-log Cryptosporidium treatment credit for a two-stage lime softening plant if chemical addition and hardness precipitation occur in two separate and sequential softening stages before filtration. Both softening stages shall treat the entire plant flow taken from a surface water source, a GUDI source, or both.

c. Bank filtration. The owner receives Cryptosporidium treatment credit for bank filtration that serves as pretreatment to a water filtration plant by meeting the criteria in this subdivision. The owner using bank filtration upon beginning source water monitoring under subdivision B 1 of this section shall collect samples as described in subdivision B 6 d of this section and is not eligible for this credit.

(1) Wells with a groundwater flow path of at least 25 feet receive 0.5-log treatment credit; and wells with a groundwater flow path of at least 50 feet receive 1.0-log treatment credit. The groundwater flow path shall be determined as specified in subdivision E 4 c (4) of this section.

(2) Only wells in granular aquifers are eligible for treatment credit. Granular aquifers are those comprised of sand, clay, silt, rock fragments, pebbles or larger particles, and minor cement. The owner shall characterize the aquifer at the well site to determine aquifer properties. The owner shall extract a core from the aquifer and demonstrate that in at least 90% of the core length, grains less than 1.0 mm in diameter constitute at least 10% of the core material.

(3) Only horizontal and vertical wells are eligible for treatment credit.

(4) For vertical wells, the groundwater flow path is the measured distance from the edge of the surface water body under high flow conditions (determined by the 100-year flood elevation boundary or by the floodway, as defined in Federal Emergency Management Agency flood hazard maps) to the well screen. For horizontal wells, the groundwater flow path is the measured distance from the bed of the river under normal flow conditions to the closest horizontal well lateral screen.

(5) The owner shall monitor each wellhead for turbidity at least once every four hours while the bank filtration process is in operation. If monthly average turbidity levels, based on daily maximum values in the well, exceed 1 NTU, the owner shall report this result to the department and conduct an assessment within 30 days to determine the cause of the high turbidity levels in the well. If the department determines that microbial removal has been compromised, the department may revoke treatment credit until the owner implements corrective actions approved by the department to remediate the problem.

(6) Springs and infiltration galleries are not eligible for treatment credit under this section.

(7) Bank filtration demonstration of performance. The department may approve Cryptosporidium treatment credit for bank filtration based on a demonstration-of-performance study that meets the criteria in this subdivision. This treatment credit may be greater than 1.0-log and may be awarded to bank filtration that does not meet the criteria in subdivisions E 4 c (1) through E 4 c (5) of this section.

(a) The study shall follow a protocol approved by the department and shall involve the collection of data on the removal of Cryptosporidium or a surrogate for Cryptosporidium and related hydrogeologic and water quality parameters during the full range of operating conditions.

(b) The study shall include sampling both from any production well and from monitoring wells that are screened and located along the shortest flow path between the surface water source and the production well.

5. Treatment performance toolbox components.

a. Combined filter performance. The owner using conventional filtration treatment or direct filtration treatment receives an additional 0.5-log Cryptosporidium treatment credit during any month the waterworks meets the criteria in this subdivision. Combined filter effluent (CFE) turbidity shall be less than or equal to 0.15 NTU in at least 95% of the measurements. Turbidity shall be measured as described in 12VAC5-590-376 B.

b. Individual filter performance. The owner using conventional filtration treatment or direct filtration treatment receives 0.5-log Cryptosporidium treatment credit, which can be in addition to the 0.5-log credit under subdivision E 5 a of this section, during any month the waterworks meets the criteria in this subdivision. Compliance with these criteria shall be based on individual filter turbidity monitoring as described in 12VAC5-590-376 B.

(1) The filtered water turbidity for each individual filter shall be less than or equal to 0.15 NTU in at least 95% of the measurements recorded each month.

(2) No individual filter may have a measured turbidity greater than 0.3 NTU in two consecutive measurements collected 15 minutes apart.

(3) The owner that has received treatment credit for individual filter performance and fails to meet the requirements of subdivision E 5 b (1) or E 5 b (2) of this section during any month does not receive a treatment technique violation under subdivision D 2 c of this section if the department determines the following:

(a) The failure was due to unusual and short-term circumstances that could not reasonably be prevented through optimizing water treatment plant design, operation, and maintenance.

(b) The waterworks has experienced no more than two failures in any calendar year.

6. Additional filtration toolbox components.

a. Bag and cartridge filters. The owner receives Cryptosporidium treatment credit of up to 2.0-log for individual bag or cartridge filters and up to 2.5-log for bag or cartridge filters operated in series by meeting the criteria in subdivisions E 6 a (1) through E 6 a (10) of this section. To be eligible for this credit, the owner shall report the results of challenge testing that meets the requirements of subdivisions E 6 a (2) through E 6 a (9) of this section to the department. The filters shall treat the entire water treatment plant flow taken from a surface water source, a GUDI source, or both.

(1) The Cryptosporidium treatment credit awarded to bag or cartridge filters shall be based on the removal efficiency demonstrated during challenge testing that is conducted according to the criteria in subdivisions E 6 a (2) through E 6 a (9) of this section. A factor of safety equal to 1-log for individual bag or cartridge filters and 0.5-log for bag or cartridge filters in series shall be applied to challenge testing results to determine removal credit. The owner may use the results from challenge testing conducted before January 5, 2006, if the prior testing was consistent with the criteria specified in subdivisions E 6 a (2) through E 6 a (9) of this section.

(2) Challenge testing shall be performed on full-scale bag or cartridge filters, and the associated filter housing or pressure vessel, that are identical in material and construction to the filters and housings the waterworks will use for removal of Cryptosporidium. Bag or cartridge filters shall be challenge tested in the same configuration that the waterworks will use, either as individual filters or as a series configuration of filters.

(3) Challenge testing shall be conducted using Cryptosporidium or a surrogate that is removed no more efficiently than Cryptosporidium. The microorganism or surrogate used during challenge testing is referred to as the challenge particulate. The concentration of the challenge particulate shall be determined using a method capable of discreetly quantifying the specific microorganism or surrogate used in the test; gross measurements such as turbidity shall not be used.

(4) The maximum feed water concentration that can be used during a challenge test shall be based on the detection limit of the challenge particulate in the filtrate (i.e., filtrate detection limit) and shall be calculated using the following equation:

Maximum Feed Concentration = 1 x 10⁴ x (Filtrate Detection Limit)

(5) Challenge testing shall be conducted at the maximum design flow rate for the filter as specified by the manufacturer.

(6) Each filter evaluated shall be tested for a duration sufficient to reach 100% of the terminal pressure drop that establishes the maximum pressure drop under which the filter may be used to comply with the requirements of this subdivision E 6.

(7) Removal efficiency of a filter shall be determined from the results of the challenge test and expressed in terms of log removal values using the following equation:

LRV = LOG₁₀(C_f) - LOG₁₀(C_p),

where LRV = log removal value demonstrated during challenge testing;

C_f = the feed concentration measured during the challenge test; and

C_p = the filtrate concentration measured during the challenge test.

In applying this equation, the same units shall be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, then the term C_p shall be set equal to the detection limit.

(8) Each filter tested shall be challenged with the challenge particulate during three periods over the filtration cycle: within two hours of start-up of a new filter; when the pressure drop is between 45% and 55% of the terminal pressure drop; and at the end of the cycle after the pressure drop has reached 100% of the terminal pressure drop. An LRV shall be calculated for each of these challenge periods for each filter tested. The LRV for the filter (LRV filter) shall be assigned the value of the minimum LRV observed during the three challenge periods for that filter.

(9) If fewer than 20 filters are tested, then the overall removal efficiency for the filter product line shall be set equal to the lowest LRV filter among the filters tested. If 20 or more filters are tested, then the overall removal efficiency for the filter product line shall be set equal to the 10th percentile of the set of LRV filter values for the various filters tested. The percentile is defined by (i/(n+1)), where i is the rank of n individual data points ordered lowest to highest. If necessary, the 10th percentile may be calculated using linear interpolation.

(10) If a previously tested filter is modified in a manner that could change the removal efficiency of the filter product line, then challenge testing to demonstrate the removal efficiency of the modified filter shall be conducted and submitted to the department.

b. Membrane filtration.

(1) The owner receives Cryptosporidium treatment credit for membrane filtration that meets the criteria of this subdivision E 6 b. Membrane cartridge filters that meet the definition of membrane filtration in 12VAC5-590-10 are eligible for this credit. The level of treatment credit the owner receives is equal to the lower of the values determined as follows:

(a) The removal efficiency demonstrated during challenge testing conducted under the conditions in subdivision E 6 b (2) of this section.

(b) The maximum removal efficiency that can be verified through direct integrity testing used with the membrane filtration process under the conditions in subdivision E 6 b (3) of this section.

(2) Challenge Testing. The membrane used by the waterworks shall undergo challenge testing to evaluate removal efficiency and the owner shall report the results of the challenge testing to the department. Challenge testing shall be conducted according to the criteria in subdivisions E 6 b (2) (a) through E 6 b (2) (g) of this section. The owner may use data from challenge testing conducted before January 5, 2006, if the prior testing was consistent with the following criteria:

(a) Challenge testing shall be conducted on either a full-scale membrane module, identical in material and construction to the membrane modules used in the waterworks treatment facility, or a smaller-scale membrane module, identical in material and similar in construction to the full-scale module. A module is defined as the smallest component of a membrane unit in which a specific membrane surface area is housed in a device with a filtrate outlet structure.

(b) Challenge testing shall be conducted using Cryptosporidium or a surrogate that is removed no more efficiently than Cryptosporidium. The organism or surrogate used during challenge testing is referred to as the challenge particulate. The concentration of the challenge particulate, in both the feed and filtrate water, shall be determined using a method capable of discretely quantifying the specific challenge particulate used in the test; gross measurements such as turbidity shall not be used.

(c) The maximum feed water concentration that can be used during a challenge test is based on the detection limit of the challenge particulate in the filtrate and shall be determined according to the following equation:

Maximum Feed Concentration = 3.16 x 10⁶ x (Filtrate Detection Limit)

(d) Challenge testing shall be conducted under representative hydraulic conditions at the maximum design flux and maximum design process recovery specified by the manufacturer for the membrane module. Flux is defined as the throughput of a pressure-driven membrane process expressed as flow per unit of membrane area. Recovery is defined as the volumetric percent of feed water that is converted to filtrate over the course of an operating cycle uninterrupted by events such as chemical cleaning or a solids removal process (i.e., backwashing).

(e) Removal efficiency of a membrane module shall be calculated from the challenge test results and expressed as a log removal value according to the following equation:

LRV = LOG₁₀(C_f) - LOG₁₀(C_p),

where LRV = log removal value demonstrated during the challenge test;

C_f = the feed concentration measured during the challenge test; and

C_p = the filtrate concentration measured during the challenge test.

Equivalent units shall be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, then the term C_p is set equal to the detection limit for the purpose of calculating the LRV. An LRV shall be calculated for each membrane module evaluated during the challenge test.

(f) The removal efficiency of a membrane filtration process demonstrated during challenge testing shall be expressed as a log removal value (LRV_C-Test). If fewer than 20 modules are tested, then LRV_C-Test is equal to the lowest of the representative LRVs among the modules tested. If 20 or more modules are tested, then LRV_C-Test is equal to the 10th percentile of the representative LRVs among the modules tested. The percentile is defined by (i/(n+1)), where i is the rank of n individual data points ordered lowest to highest. If necessary, the 10th percentile may be calculated using linear interpolation.

(g) The challenge test shall establish a QCRV for a nondestructive performance test that demonstrates the Cryptosporidium removal capability of the membrane filtration module. This performance test shall be applied to each production membrane module used by the waterworks that was not directly challenge tested to verify Cryptosporidium removal capability. Production modules that do not meet the established QCRV are not eligible for the treatment credit demonstrated during the challenge test.

(h) If a previously tested membrane is modified in a manner that could change the removal efficiency of the membrane or the applicability of the nondestructive performance test and associated QCRV, then additional challenge testing to demonstrate the removal efficiency of, and determine a new QCRV for, the modified membrane shall be conducted and submitted to the department.

(3) Direct integrity testing. The owner shall conduct direct integrity testing in a manner that demonstrates a removal efficiency equal to or greater than the removal credit awarded to the membrane filtration process and meets the requirements described in subdivisions E 6 b (3) (a) through E 6 b (3) (f) of this section. A direct integrity test is defined as a physical test applied to a membrane unit to identify and isolate integrity breaches (i.e., one or more leaks that could result in contamination of the filtrate).

(a) The direct integrity test shall be independently applied to each membrane unit in service. A membrane unit is defined as a group of membrane modules that share common valving that allows the unit to be isolated from the rest of the waterworks for the purpose of integrity testing or other maintenance.

(b) The direct integrity method shall have a resolution of three micrometers or less, where resolution is defined as the size of the smallest integrity breach that contributes to a response from the direct integrity test.

(c) The direct integrity test shall have a sensitivity sufficient to verify the log treatment credit awarded to the membrane filtration process by the department, where sensitivity is defined as the maximum log removal value that can be reliably verified by a direct integrity test. Sensitivity shall be determined using the approach in either of the following as applicable to the type of direct integrity test the waterworks uses:

(i) For direct integrity tests that use an applied pressure or vacuum, the direct integrity test sensitivity shall be calculated according to the following equation:

LRV_DIT = LOG₁₀(Q_p /(VCF x Q_breach)),

where LRV_DIT = the sensitivity of the direct integrity test;

Q_p = total design filtrate flow from the membrane unit;

Q_breach = flow of water from an integrity breach associated with the smallest integrity test response that can be reliably measured; and

VCF = volumetric concentration factor.

The volumetric concentration factor is the ratio of the suspended solids concentration on the high-pressure side of the membrane relative to that in the feed water.

(ii) For direct integrity tests that use a particulate or molecular marker, the direct integrity test sensitivity shall be calculated according to the following equation:

LRV_DIT = LOG₁₀(C_f) - LOG₁₀(C_p),

where LRV_DIT = the sensitivity of the direct integrity test;

C_f = the typical feed concentration of the marker used in the test; and

C_p = the filtrate concentration of the marker from an integral membrane unit.

(d) The owner shall establish a control limit within the sensitivity limits of the direct integrity test that is indicative of an integral membrane unit capable of meeting the removal credit awarded by the department.

(e) If the result of a direct integrity test exceeds the control limit established under subdivision E 6 b (3) (d) of this section, then the owner shall remove the membrane unit from service. The owner shall conduct a direct integrity test to verify any repairs, and may return the membrane unit to service only if the direct integrity test is within the established control limit.

(f) The owner shall conduct direct integrity testing on each membrane unit at a frequency of not less than once each day that the membrane unit is in operation. The department may approve less frequent testing based on demonstrated process reliability, the use of multiple barriers effective for Cryptosporidium, or reliable process safeguards.

(4) Indirect integrity monitoring. The owner shall conduct continuous indirect integrity monitoring on each membrane unit according to the criteria in subdivisions E 6 b (4) (a) through E 6 b (4) (e). Indirect integrity monitoring is defined as monitoring some aspect of filtrate water quality that is indicative of the removal of particulate matter. The owner that implements continuous direct integrity testing of membrane units in accordance with the criteria in subdivisions E 6 b (3) (a) through E 6 b (3) (f) of this section is not subject to the requirements for continuous indirect integrity monitoring. The owner shall submit a monthly report to the department summarizing all continuous indirect integrity monitoring results triggering direct integrity testing and the corrective action that was taken in each case.

(a) Unless the department approves an alternative parameter, continuous indirect integrity monitoring shall include continuous filtrate turbidity monitoring.

(b) Continuous monitoring shall be conducted at a frequency of no less than once every 15 minutes.

(c) Continuous monitoring shall be separately conducted on each membrane unit.

(d) If indirect integrity monitoring includes turbidity and if the filtrate turbidity readings are above 0.15 NTU for a period greater than 15 minutes (i.e., two consecutive 15-minute readings above 0.15 NTU), direct integrity testing shall immediately be performed on the associated membrane unit as specified in subdivisions E 6 b (3) (a) through E 6 b (3) (f) of this section.

(e) If indirect integrity monitoring includes an alternative parameter approved by the department and if the alternative parameter exceeds a control limit approved by the department for a period greater than 15 minutes, then direct integrity testing shall immediately be performed on the associated membrane units as specified in subdivisions E 6 b (3) (a) through E 6 b (3) (f) of this section.

c. Second stage filtration. The owner receives 0.5-log Cryptosporidium treatment credit for a separate second stage of filtration that consists of sand, dual media, GAC, or other fine grain media following granular media filtration if approved by the department. To be eligible for this credit, the first stage of filtration shall be preceded by a coagulation step and both filtration stages shall treat the entire water treatment treatment plant flow taken from a surface water source, a GUDI source, or both. A cap, such as GAC, on a single stage of filtration is not eligible for this credit. The department shall approve the treatment credit based on an assessment of the design characteristics of the filtration process.

d. Slow sand filtration as secondary filter. The owner is eligible to receive 2.5-log Cryptosporidium treatment credit for a slow sand filtration process that follows a separate stage of filtration if both filtration stages treat the entire water treatment plant flow taken from a surface water source, a GUDI source, or both and no residual disinfectant is present in the influent water to the slow sand filtration process. The department shall approve the treatment credit based on an assessment of the design characteristics of the filtration process. This subdivision does not apply to treatment credit awarded to slow sand filtration used as a primary filtration process.

7. Inactivation toolbox components.

a. Calculation of CT values.

(1) CT is the product of the disinfectant contact time (T, in minutes) and disinfectant concentration (C, in milligrams per liter). The owner of a waterworks with treatment credit for chlorine dioxide or ozone under subdivision E 7 b of this section shall calculate CT at least once each day, with both C and T measured during peak hourly flow in accordance with the procedure listed in 12VAC5-590-500.

(2) A waterworks with several disinfection segments in sequence may calculate CT for each segment, where a disinfection segment is defined as a treatment unit process with a measurable residual disinfectant level and a liquid volume. Under this approach, the owner shall add the Cryptosporidium CT values in each segment to determine the total CT for the treatment plant.

b. CT values for chlorine dioxide and ozone.

(1) The owner receives the Cryptosporidium treatment credit listed in Table 401.5 by meeting the corresponding chlorine dioxide CT value for the applicable water temperature, as described in subdivision E 7 a of this section.

(2) The owner receives the Cryptosporidium treatment credit listed in Table 401.6 by meeting the corresponding ozone CT values for the applicable water temperature, as described in subdivision E 7 a of this section.

c. UV light. The owner receives Cryptosporidium, Giardia lamblia, and virus treatment credits for UV light reactors by achieving the corresponding UV dose values shown in subdivision E 7 c (1) of this section. The owner shall validate and monitor UV reactors as described in subdivisions E 7 c (2) and E 7 c (3) of this section to demonstrate that they are achieving a particular UV dose value for treatment credit.

(1) UV dose table. The treatment credits listed in Table 401.7 are for UV light at a wavelength of 254 nm as produced by a low-pressure mercury vapor lamp. To receive treatment credit for other lamp types, the owner shall demonstrate an equivalent germicidal dose through reactor validation testing as described in subdivision E 7 c (2) of this section. The UV dose values listed in Table 401.7 are applicable only to post-filter applications of UV in filtered waterworks.

(2) Reactor validation testing. The owner shall use UV reactors that have undergone validation testing to determine the operating conditions under which the reactor delivers the UV dose required in subdivision E 7 c (1) of this section (i.e., validated operating conditions). These operating conditions shall include flow rate, UV intensity as measured by a UV sensor, and UV lamp status.

(a) When determining validated operating conditions, the owner shall account for the following factors: (i) UV absorbance of the water; (ii) lamp fouling and aging; (iii) measurement uncertainty of online sensors; (iv) UV dose distributions arising from the velocity profiles through the reactor; (v) failure of UV lamps or other critical waterworks components; and (vi) inlet and outlet piping or channel configurations of the UV reactor.

(b) Validation testing shall include the following: full-scale testing of a reactor that conforms uniformly to the UV reactors used by the waterworks and inactivation of a test microorganism whose dose-response characteristics have been quantified with a low-pressure mercury vapor lamp.

(c) UV reactor validation testing shall be in accordance with EPA's recommended validation protocol for UV reactors, as described in EPA's "Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced Surface Water Treatment Rule," November 2006, EPA Office of Water. Alternative protocols may be considered for approval by the department on a case-by-case basis.

(d) Validation testing, whether onsite or offsite, shall be performed by a third party independent of the UV reactor manufacturer and the owner to ensure that validation testing and data analysis are conducted in a technically sound manner without bias.

(e) To receive credit for lamp types other than low-pressure types, the owner shall demonstrate an equivalent germicidal dose through reactor validation testing.

(f) A validation report shall be submitted and approved by the department to receive disinfection credit.

(3) UV reactor monitoring.

(a) The owner shall monitor the UV reactors to determine if the reactors are operating within validated conditions as determined under subdivision E 7 c (2) of this section. This monitoring shall include UV intensity as measured by a UV sensor, flow rate, lamp status, and other parameters the department designates based on UV reactor operation. The owner shall verify the calibration of UV sensors and shall recalibrate sensors in accordance with a protocol approved by the department.

(b) To receive treatment credit for UV light, the owner shall treat at least 95% of the water delivered to the public during each month by the UV reactors operating within validated conditions for the required UV dose as described in subdivisions E 7 c (1) and E 7 c (2) of this section. The owner shall demonstrate compliance with this condition by the monitoring required under subdivision E 7 c (3) (a) of this section.

F. The owner shall comply with the applicable recordkeeping and reporting requirements described in 12VAC5-590-530, 12VAC5-590-531, 12VAC5-590-550, and 12VAC5-590-570.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-405. Lead and copper treatment techniques.

A. Lead and copper corrosion control techniques.

1. Corrosion control treatment requirements. The owner of a community waterworks or a NTNC shall install and operate optimum corrosion control treatment by completing the corrosion control treatment requirements described below which are applicable to these waterworks under subdivision A 2 of this section.

a. Owner's proposal regarding corrosion control treatment. Based upon the results of lead and copper tap monitoring and water quality parameter monitoring, the owner of a small or a medium waterworks exceeding the lead or copper AL shall propose installation of one or more of the corrosion control treatments listed in subdivision A 1 c (1) of this section that the owner believes constitutes optimal corrosion control for that waterworks. The department may require the owner to conduct additional water quality parameter monitoring in accordance with 12VAC5-590-375 C 2 to assist the department in evaluating the proposal.

b. Applicability of studies of corrosion control treatment (applicable to small and medium waterworks). The department may require the owner of a small or a medium waterworks that exceeds the lead or copper AL to perform corrosion control studies under subdivision A 1 c of this section to identify optimal corrosion control treatment for the waterworks.

c. Corrosion control studies.

(1) The owner of a waterworks required by the department to perform corrosion control studies shall evaluate the effectiveness of each of the following treatments, and, if appropriate, combinations of the following treatments to identify the optimal corrosion control treatment for that waterworks:

(a) Alkalinity and pH adjustment;

(b) Calcium hardness adjustment; and

(c) The addition of a phosphate-based or silicate-based corrosion inhibitor at a concentration sufficient to maintain an effective corrosion inhibitor residual concentration in all test tap samples, such that a passivating film is formed on the interior walls of the pipe.

(2) The owner shall evaluate each of the corrosion control treatments using either pipe rig or loop tests, metal coupon tests, partial-system tests, or analyses based on documented analogous treatments with other waterworks of similar size, water chemistry, and distribution system configuration.

(3) The owner shall measure the following water quality parameters in any tests conducted under subdivision A 1 c of this section before and after evaluating the corrosion control treatments listed in subdivision A 1 c (1) of this section:

(a) Lead;

(b) Copper;

(c) pH;

(d) Alkalinity;

(e) Calcium;

(f) Conductivity;

(g) Orthophosphate (when an inhibitor containing a phosphate compound is used);

(h) Silicate (when an inhibitor containing a silicate compound is used); and

(i) Water temperature.

(4) The owner shall identify all chemical or physical constraints that limit or prohibit the use of a particular corrosion control treatment and document such constraints with at least one of the following:

(a) Data and documentation showing that a particular corrosion control treatment has adversely affected other water treatment processes when used by another waterworks with comparable water quality characteristics; or

(b) Data and documentation demonstrating that the owner has previously attempted to evaluate a particular corrosion control treatment and has found that the treatment is ineffective or adversely affects other water quality treatment processes.

(5) The owner shall evaluate the effect of the chemicals used for corrosion control treatment on other water quality treatment processes.

(6) On the basis of an analysis of the data generated during each evaluation, the owner shall propose in writing to the department that the treatment option resulting from the corrosion control studies constitutes optimal corrosion control treatment for that waterworks. The owner shall provide a rationale for the recommendation along with all supporting documentation specified in subdivisions A 1 c (1) through A 1 c (5) of this section.

d. Approval of optimal corrosion control treatment.

(1) Based upon consideration of available information including, where applicable, studies performed under subdivision A 1 c of this section and the owner's proposed treatment alternative, the department shall either approve the corrosion control treatment option recommended by the owner, or designate alternative corrosion control treatment from among those listed in subdivision A 1 c (1) of this section. When approving optimal treatment, the department shall consider the effects that additional corrosion control treatment will have on water quality parameters and on other water quality treatment processes.

(2) The department shall notify the owner of the determination on optimal corrosion control treatment in writing and explain the basis for this determination. If the department requests additional information to aid an evaluation, then the owner shall provide the information.

e. Installation of optimal corrosion control. The owner shall properly install and operate throughout the waterworks the optimal corrosion control treatment approved by the department under subdivision A 1 d of this section. A construction permit is required before installation of any treatment in accordance with 12VAC5-590-200.

f. The department's evaluation of treatment and specification of the optimal water quality control parameters shall consist of the following:

(1) The department shall evaluate the results of all lead and copper tap samples and water quality parameter samples submitted by the owner and determine whether the owner has properly installed and operated the optimal corrosion control treatment approved by the department under subdivision A 1 d of this section. Upon evaluating the results of tap water and water quality parameter monitoring by the owner, both before and after the owner installs optimal corrosion control treatment, the department shall designate:

(a) A minimum value or a range of values for pH measured at each entry point to the distribution system;

(b) A minimum pH value, measured in all tap samples. The value shall be equal to or greater than 7.0, unless the department determines that meeting a pH level of 7.0 is not technologically feasible or is not necessary for the owner to optimize corrosion control;

(c) If a corrosion inhibitor is used, then a minimum concentration or a range of concentrations for the inhibitor, measured at each entry point to the distribution system and in all tap samples, that the department determines is necessary to form a passivating film on the interior walls of the pipes of the distribution system;

(d) If alkalinity is adjusted as part of the optimal corrosion control treatment, then a minimum concentration or a range of concentrations for alkalinity, measured at each entry point to the distribution system and in all tap samples; or

(e) If calcium carbonate stabilization is used as part of the corrosion control, then a minimum concentration or a range of concentrations for calcium, measured in all tap samples.

(2) The values for the applicable water quality control parameters listed in subdivision A 1 c (3) of this section shall be those that the department determines to reflect optimal corrosion control treatment for the waterworks. The department may designate values for additional water quality control parameters determined by the department to reflect optimal corrosion control for the waterworks. The department shall notify the owner in writing of these determinations and explain the basis for the decisions.

g. Continued operation and monitoring. The owner of a waterworks optimizing corrosion control shall continue to operate and maintain optimal corrosion control treatment, including maintaining water quality parameters at or above minimum values or within ranges designated by the department under subdivision A 1 f of this section as verified by all samples collected under 12VAC5-590-375 C 4,12VAC5-590-375 C 5, and 12VAC5-590-375 C 6. Compliance with the requirements of this subdivision shall be determined every six months, as specified under 12VAC5-590-375 C 4. The waterworks is out of compliance with the requirements of this subdivision for a six-month period if excursions occur for any department-specified parameter on more than nine days during the period. An excursion occurs whenever the daily value for one or more of the water quality parameters measured at a sampling location is below the minimum value or outside the range designated by the department. The department has discretion to delete results of obvious sampling errors from this calculation. Daily values shall be calculated as follows:

(1) On days when more than one measurement for the water quality parameter is collected at the sampling location, the daily value shall be the average of all results collected during the day regardless of whether they are collected through continuous monitoring, grab sampling, or a combination of both.

(2) On days when only one measurement for the water quality parameter is collected at the sampling location, the daily value shall be the result of that measurement.

(3) On days when no measurement is collected for the water quality parameter at the sampling location, the daily value shall be the daily value calculated on the most recent day on which the water quality parameter was measured at the sample site.

h. Modification of the department's treatment decisions. Upon the department's initiative or in response to a request by an owner or other interested party, the department may modify the determination of the optimal corrosion control treatment under subdivision A 1 d of this section or optimal water quality control parameters under subdivision A 1 f of this section. A request for modification by an owner or other interested party shall be in writing, explain why the modification is appropriate, and provide supporting documentation. The department may modify the determination where it is concluded that the change is necessary to ensure that the waterworks continues to optimize corrosion control treatment. A revised determination shall be made in writing, set forth the new treatment requirements, explain the basis for the department's decision, and provide an implementation schedule for completing the treatment modifications.

2. Corrosion control treatment steps.

a. The owner shall complete the applicable corrosion control treatment requirements described in subdivision A 1 of this section by the deadlines established in this subdivision.

(1) The owner of a large waterworks (serving greater than 50,000 persons) shall complete the corrosion control treatment steps specified in subdivision A 2 d of this section, unless the owner is deemed to have optimized corrosion control under subdivision A 2 b (2) or A 2 b (3) of this section.

(2) The owner of a small waterworks (serving fewer than or equal to 3300 persons) or a medium waterworks (serving greater than 3,300 and fewer than or equal to 50,000 persons) shall complete the corrosion control treatment steps specified in subdivision A 2 e of this section, unless the owner is deemed to have optimized corrosion control under subdivisions A 2 b (1) through A 2 b (3) of this section.

b. The owner is deemed to have optimized corrosion control and is not required to complete the applicable corrosion control treatment steps identified in this subdivision if the waterworks satisfies one of the criteria specified in subdivisions A 2 b (1) through A 2 b (3) of this section. The owner deemed to have optimized corrosion control under this subdivision and to have treatment in place shall continue to operate and maintain optimal corrosion control treatment and meet any requirements that the department determines appropriate to ensure optimal corrosion control treatment is maintained.

(1) The owner of a small or a medium waterworks is deemed to have optimized corrosion control if the waterworks meets the lead and copper ALs during each of two consecutive six-month monitoring periods conducted in accordance with 12VAC5-590-375.

(2) The owner may be deemed by the department to have optimized corrosion control treatment if the owner demonstrates to the satisfaction of the department that the owner has conducted activities equivalent to the corrosion control steps applicable to the waterworks under this section. If the department makes this determination, then the owner shall be provided with a written notice explaining the basis for the decision and the notice shall specify the water quality control parameters representing optimal corrosion control in accordance with subdivision A 1 f of this section. The owner deemed to have optimized corrosion control under this subdivision shall operate in compliance with the department designated optimal water quality control parameters in accordance with subdivision A 1 g and continue to conduct lead and copper tap and water quality parameter sampling in accordance with 12VAC5-590-375 B 4 c and 12VAC5-590-375 C 4, respectively. The owner shall provide the department with the following information to support a determination under this subdivision:

(a) The results of all test samples collected for each of the water quality parameters in subdivision A 1 c (3) of this section;

(b) A report explaining the test methods used by the owner to evaluate the corrosion control treatments listed in subdivision A 1 c (1) of this section, the results of all tests conducted, and the basis for the owner's selection of optimal corrosion control treatment;

(c) A report explaining how corrosion control has been installed and how it is being maintained to insure minimal lead and copper concentrations at consumers' taps; and

(d) The results of tap water samples collected in accordance with 12VAC5-590-375 B at least once every six months for one year after corrosion control treatment has been installed.

(3) A waterworks is deemed to have optimized corrosion control if the owner submits results of tap water monitoring conducted in accordance with 12VAC5-590-375 B and source water monitoring conducted in accordance with 12VAC5-590-375 D that demonstrates for two consecutive six-month monitoring periods that the difference between the 90th percentile tap water lead level, computed under 12VAC5-590-385 C, and the highest source water lead concentration is less than the PQL for lead (0.005 mg/L).

(a) The owner that submits monitoring results indicating that the highest source water lead level is below the MDL may also be deemed to have optimized corrosion control under this subdivision if the 90th percentile tap water lead level is less than or equal to the PQL for lead (0.005 mg/L) for two consecutive six-month monitoring periods.

(b) The owner deemed to have optimized corrosion control under this subdivision shall continue monitoring for lead and copper at the tap no less frequently than once every three calendar years using the reduced number of sites specified in 12VAC5-590-375 B 3 and collecting the samples at times and locations specified in 12VAC5-590-375 B 4 d (4).

(c) The owner deemed to have optimized corrosion control pursuant to this subdivision shall notify the department in writing pursuant to 12VAC5-590-532 B 3 of any upcoming long-term change in treatment or addition of a new source water as described in 12VAC5-590-532 B 3. The department shall evaluate and approve the addition of a new source water or long-term change in water treatment before it is implemented by the owner. The department may require the owner of a waterworks to conduct additional monitoring or to take other actions the department deems appropriate to ensure that minimum levels of corrosion control are being maintained in the distribution system.

(d) The owner is not deemed to have optimized corrosion control under this subdivision, and shall implement corrosion control treatment specified in subdivision A 2 b (3) (e) of this section, unless the copper AL is met.

(e) The owner of a waterworks triggered into corrosion control because the waterworks is no longer deemed to have optimized corrosion control under this subsection shall implement corrosion control treatment in accordance with the deadlines in subdivision A 2 e of this section. The owner of a large waterworks shall adhere to the schedule specified in subdivision A 2 e of this section for a medium waterworks, with the time period for completing each step being triggered by the date the owner is no longer deemed to have optimized corrosion control treatment under this subsection.

c. The owner of a small or a medium waterworks that is required to complete the corrosion control steps due to the exceedance of the lead or copper AL may cease completing the treatment steps whenever the waterworks meets both ALs during each of two consecutive six-month monitoring periods conducted pursuant to 12VAC5-590-375 B 4 a and submits the results to the department. If a waterworks thereafter exceeds the lead or copper AL during any monitoring period, the owner shall recommence completion of the applicable treatment steps, beginning with the first treatment step that was not previously completed in its entirety. The department may require the owner to repeat treatment steps previously completed where the department determines that this is necessary to properly implement the treatment requirements of this section. The department shall notify the owner in writing of the determination and explain the basis for the decision. The requirement for the owner of a small or a medium waterworks to implement corrosion control treatment steps in accordance with subdivision A 2 e of this section (including waterworks deemed to have optimized corrosion control under subdivision A 2 b (1) of this section) is triggered whenever a small or a medium waterworks exceeds the lead or copper AL.

d. Treatment steps and deadlines for large waterworks. Except as provided in subdivisions A 2 b (2) and A 2 b (3) of this section, the owner of a large waterworks shall complete the following corrosion control treatment steps (described in the referenced portions of subdivision A 1 of this section, 12VAC5-590-375 B, and 12VAC5-590-375 C).

(1) Step 1: The owner shall conduct initial monitoring (12VAC5-590-375 B 4 a and 12VAC5-590-375 C 2) during two consecutive six-month monitoring periods by a date specified by the department.

(2) Step 2: The owner shall complete corrosion control studies (subdivision A 1 c of this section) and submit the study and recommendations to the department no later than 18 months after the date that initial monitoring is completed as specified in Step 1.

(3) Step 3: The department shall approve optimal corrosion control treatment (subdivision A 1 d of this section) no later than 12 months following receipt of the corrosion control study required in Step 2.

(4) Step 4: The owner shall install optimal corrosion control treatment (subdivision A 1 e of this section) no later than 24 months following the department's approval of optimal corrosion control treatment specified in Step 3.

(5) Step 5: The owner shall complete follow-up sampling (12VAC5-590-375 B 4 b and 12VAC5-590-375 C 3) no later than 12 months following the installation of optimal corrosion control treatment specified in Step 4.

(6) Step 6: The department shall evaluate the installation of treatment and designate optimal water quality control parameters (subdivision A 1 f of this section) no later than six months following completion of follow-up sampling specified in Step 5.

(7) Step 7: The owner shall operate the waterworks in compliance with the department-specified optimal water quality control parameters (subdivision A 1 g of this section) and continue to conduct tap sampling (12VAC5-590-375 B 4 c and 12VAC5-590-375 C 4).

e. Treatment steps and deadlines for small and medium waterworks. Except as provided in subdivision A 2 b of this section, the owner of a small or a medium waterworks shall complete the following corrosion control treatment steps (described in the referenced portions of subdivision A 1 of this section, 12VAC5-590-375 B, and 12VAC5-590-375 C):

(1) The owner shall conduct initial tap sampling (12VAC5-590-375 B 4 a and 12VAC5-590-375 C 2) until the waterworks either exceeds the lead or copper AL or becomes eligible for reduced monitoring under 12VAC5-590-375 B 4 d. The owner of a waterworks exceeding the lead or copper AL shall propose optimal corrosion control treatment (subdivision A 1 a of this section) within six months after the end of the monitoring period during which it exceeds one of the ALs.

(2) Within 12 months after the end of the monitoring period during which a waterworks exceeds the lead or copper AL, the department may require the owner to perform corrosion control studies (subdivision A 1 b of this section). If the department does not require the owner to perform these studies, the department shall specify optimal corrosion control treatment (subdivision A 1 d of this section) within the following timeframes:

(a) For a medium waterworks, within 18 months after the end of the monitoring period during which the waterworks exceeds the lead or copper AL.

(b) For a small waterworks, within 24 months after the end of the monitoring period during which the waterworks exceeds the lead or copper AL.

(3) If the department requires the owner to perform corrosion control studies under subdivision A 2 e (2) of this section, then the owner shall complete the studies (subdivision A 1 c of this section) and submit the study and recommendations to the department within 18 months after the department requires that the studies be conducted.

(4) If the owner has performed corrosion control studies under subdivision A 2 e (2) of this section, then the department shall designate optimal corrosion control treatment (subdivision A 1 d of this section) within six months after completion of the provisions of subdivision A 2 e (3) of this section.

(5) The owner shall install optimal corrosion control treatment (subdivision A 1 e of this section) within 24 months after the department designates such treatment. A construction permit is required before installation of any treatment, in accordance with 12VAC5-590-200.

(6) The owner shall complete follow-up sampling (12VAC5-590-375 B 4 b and 12VAC5-590-375 C 3) within 36 months after the department designates optimal corrosion control treatment.

(7) The department shall evaluate the owner's installation of treatment and designate optimal water quality control parameters (subdivision A 1 f of this section) within six months after completion of the provisions of subdivision A 2 e (6) of this section.

(8) The owner shall operate the waterworks in compliance with the department-designated optimal water quality control parameters (subdivision A 1 g of this section) and continue to conduct tap sampling (12VAC5-590-375 B 4 c and 12VAC5-590-375 C 4).

B. Source water treatment technique requirements for lead and copper. The owner of a waterworks exceeding the lead or copper AL shall complete the applicable source water monitoring and treatment requirements (described in the referenced portions of subdivision B 2 of this section, and in 12VAC5-590-375 B and 12VAC5-590-375 D) by the following deadlines:

1. Deadlines for completing source water treatment steps.

a. The owner of a waterworks exceeding the lead or copper AL shall complete lead and copper source water monitoring (12VAC5-590-375 D 2) and submit a treatment proposal to the department (subdivision B 2 a of this section) no later than 180 days after the end of the monitoring period during which the lead or copper AL was exceeded.

b. The department shall make a determination regarding the need for source water treatment (subdivision B 2 b of this section) within six months after submission of monitoring results under subdivision B 1 a of this section.

c. If the department requires installation of source water treatment, then the owner shall install the treatment (subdivision B 3 of this section) within 24 months after completion of subdivision B 1 b of this section.

d. The owner shall complete follow-up tap water monitoring (12VAC5-590-375 B 4 b) and source water lead and copper monitoring (12VAC5-590-375 D 3) within 36 months after completion of subdivision B 1 b.

e. The department shall evaluate the owner's installation and operation of the source water treatment and specify maximum permissible source water lead and copper levels (subdivision B 4 of this section) within six months after completion of subdivision B 1 d of this section.

f. The owner shall operate the waterworks in compliance with the department-specified maximum permissible source water lead and copper levels (subdivision B 4 of this section) and continue source water monitoring (12VAC5-590-375 D 4).

2. Description of source water treatment requirements.

a. Waterworks treatment recommendation. The owner of a waterworks that exceeds the lead or copper AL shall propose in writing to the department the installation and operation of one of the source water treatments listed in subdivision B 2 b of this section. The owner may propose that no treatment be installed based upon a demonstration that source water treatment is not necessary to minimize lead and copper levels at consumer taps.

b. Department's determination regarding source water treatment. The department shall complete an evaluation of the results of all source water samples submitted by the owner to determine whether source water treatment is necessary to minimize lead or copper levels in water delivered to consumer taps. If the department determines that treatment is needed, then the department shall either require installation and operation of the source water treatment recommended by the owner or require the installation and operation of another source water treatment from among the following: (i) ion exchange, (ii) RO, (iii) lime softening, or (iv) coagulation or filtration. If the department requests additional information to aid in the evaluation, then the owner shall provide the information by the date specified by the department in the request. The department shall notify the owner in writing of the determination and set forth the basis for the decision.

3. Installation of source water treatment. The owner shall properly install and operate the source water treatment designated by the department under subdivision B 2 b of this section.

4. The department's evaluation of source water treatment and specification of maximum permissible source water lead and copper levels. The department shall evaluate the source water samples collected by the owner both before and after the owner installs source water treatment, and determine whether the owner has properly installed and operated the source water treatment designated by the department. Based upon the evaluation, the department shall designate the maximum permissible lead and copper concentrations for finished water entering the distribution system. The levels shall reflect the contaminant removal capability of the treatment properly operated and maintained. The department shall notify the owner in writing and explain the basis for the decision.

5. Continued operation and maintenance. The waterworks shall be operated to maintain lead and copper levels below the maximum permissible concentrations designated by the department at each sampling point monitored in accordance with 12VAC5-590-375 D. The waterworks is out of compliance with this subdivision B 5 if the level of lead or copper at any sampling point is greater than the maximum permissible concentration designated by the department.

6. Modification of the department's treatment decisions. Upon the department's initiative or in response to a request by an owner or other interested party, the department may modify the determination of the source water treatment under subdivision B 2 b of this section, or may modify the maximum permissible lead and copper concentrations for finished water entering the distribution system under subdivision B 4 of this section. A request for modification by an owner or other interested party shall be in writing, explain why the modification is appropriate, and provide supporting documentation. The department may modify the determination where the conclusion is made that the change is necessary to ensure that the waterworks continues to minimize lead and copper concentrations in source waters. A revised determination shall be made in writing, set forth the new treatment requirements, explain the basis for the department's decision, and provide an implementation schedule for completing the treatment modifications.

C. Lead service line replacement treatment technique requirements:

1. The owner of a waterworks that fails to meet the lead AL in tap samples collected pursuant to 12VAC5-590-375 B 4 b, after installing corrosion control or source water treatment (whichever sampling occurs later), shall replace lead service lines in accordance with the requirements of this section. If the owner is in violation of subdivision A 2 of this section or subsection B of this section for failure to install source water or corrosion control treatment, then the department may require the owner to commence lead service line replacement under this section after the date by which the owner was required to conduct monitoring under 12VAC5-590-375 B 4 b has passed.

2. The owner shall replace annually at least 7.0% of the initial number of lead service lines in its distribution system. The initial number of lead service lines is the number of lead lines in place at the time the replacement program begins. The owner shall identify the initial number of lead service lines in its distribution system based upon a materials evaluation, including the evaluation required under 12VAC5-590-375 B 1. The first year of lead service line replacement shall begin on the first day following the end of the monitoring period in which the lead AL was exceeded under subdivision C 1 of this section. If monitoring is required annually or less frequently, then the end of the monitoring period is September 30 of the calendar year in which the sampling occurs. If the department has established an alternate monitoring period, then the end of the monitoring period will be the last day of that period.

3. The owner of a waterworks resuming a lead service line replacement program after the cessation of the lead service line replacement program as allowed by subdivision C 7 of this section shall update the inventory of lead service lines to include those sites that were previously determined not to require replacement through the sampling provision under subdivision C 4 of this section. The owner shall then divide the updated number of remaining lead service lines by the number of remaining years in the program to determine the number of lines that must be replaced per year (7.0% lead service line replacement is based on a 15-year replacement program; so, for example, the owner resuming lead service line replacement after previously conducting two years of replacement would divide the updated inventory by 13). For the owner that has completed a 15-year lead service line replacement program, the department will determine a schedule for replacing or retesting lines that were previously tested out under the replacement program when the waterworks re-exceeds the lead AL.

4. The owner is not required to replace an individual lead service line if the lead concentration in all service line samples from that line, collected pursuant to 12VAC5-590-375 B 2 c, is less than or equal to 0.015 mg/L.

5. The owner shall replace that portion of the lead service line that is owned by the waterworks. In cases where the owner does not own the entire lead service line, the owner shall notify the building owner, or the building owner's authorized agent, that the owner will replace that portion of the service line that is owned by the waterworks and shall offer to replace the building owner's portion of the line. The owner is not required to bear the cost of replacing the building owner's portion of the service line, nor is the owner required to replace the building owner's portion where the owner chooses not to pay the cost of replacing the building owner's portion of the line, or where replacing the building owner's portion would be precluded by state, local, or common law. The owner that does not replace the entire length of the service line also shall complete the following tasks:

a. At least 45 days before commencing with the partial replacement of a lead service line, the owner shall provide notice to the resident or residents of all buildings served by the line explaining that they may experience a temporary increase of lead levels in the drinking water, along with guidance on measures consumers can take to minimize their exposure to lead. The department may allow the owner to provide notice under the previous sentence less than 45 days before commencing partial lead service line replacement where the replacement is in conjunction with emergency repairs. In addition, the owner shall inform each resident served by the lead service line that the owner will, at the owner's expense, collect a sample from each partially replaced lead service line that is representative of the water in the service line for analysis of lead content, as prescribed in 12VAC5-590-375 B 2 c, within 72 hours after the completion of the partial replacement of the lead service line. The owner shall collect the sample and report the results of the analysis to the building owner and each resident served by the service line within three business days of receiving the results. Mailed notices post-marked within three business days of receiving the results shall be considered on time.

b. The owner shall provide the information required by subdivision C 5 a of this section to the residents of individual dwellings by mail or by other methods approved by the department. In instances where multi-family dwellings are served by the service line, the owner shall have the option to post the information at a conspicuous location.

6. The department shall require the owner to replace lead service lines on a shorter schedule than that required by this subsection, taking into account the number of lead service lines in the waterworks, where a shorter replacement schedule is feasible. The department shall make this determination in writing and notify the owner of the findings within six months after the waterworks is triggered into lead service line replacement based on monitoring referenced in subdivision C 1 of this section.

7. The owner may cease replacing lead service lines whenever first-draw tap samples collected pursuant to 12VAC5-590-375 B 2 b meet the lead AL during each of two consecutive six-month monitoring periods and the owner submits the results to the department. If the first-draw tap samples collected in a waterworks thereafter exceed the lead AL, then the owner shall recommence replacing lead service lines, pursuant to subdivision C 3 of this section.

8. To demonstrate compliance with subdivisions C 1 through C 5 of this section, an owner shall report to the department the information specified in 12VAC5-590-532.

D. Lead public education requirements. The owner shall deliver a consumer notice of lead tap water monitoring results to all persons served by the waterworks at sites that are tested in accordance with subdivision D 4 of this section. The owner of a waterworks that exceeds the lead AL based on tap water samples collected in accordance with 12VAC5-590-375 B shall deliver the public education materials contained in subdivision D 1 of this section in accordance with the requirements in subdivision D 2 of this section. The owner of a waterworks that exceeds the lead AL shall sample the tap water of any customer who requests it in accordance with subdivision D 3 of this section.

1. Content of written materials. The owner shall include the following text in all of the printed materials distributed through the lead public education program:

a. Community waterworks and NTNCs. The owner of community waterworks or a NTNC shall include the following elements in printed materials (e.g., brochures and pamphlets) in the same order as listed in this subdivision D 1 a. In addition, the language specified in subdivisions D 1 a (1) and D 1 a (2) and in subdivision D 1 a (6) of this section shall be included in materials, exactly as written, except for the text in brackets for which the owner shall include system-specific information. Any additional information presented by the owner shall be consistent with the information in this subdivision D 1 a and be in plain language that can be understood by the general public. The department may require the owner to obtain approval of the content of written material before delivery.

(1) IMPORTANT INFORMATION ABOUT LEAD IN YOUR DRINKING WATER. "(Insert name of waterworks) found elevated levels of lead in drinking water in some homes or buildings. Lead can cause serious health problems, especially for pregnant women and young children. Please read this information closely to see what you can do to reduce lead in your drinking water."

(2) Health effects of lead. "Lead can cause serious health problems if too much enters your body from drinking water or other sources. It can cause damage to the brain and kidneys, and can interfere with the production of red blood cells that carry oxygen to all parts of your body. The greatest risk of lead exposure is to infants, young children, and pregnant women. Scientists have linked the effects of lead on the brain with lowered IQ in children. Adults with kidney problems and high blood pressure can be affected by low levels of lead more than healthy adults. Lead is stored in the bones, and it can be released later in life. During pregnancy, the child receives lead from the mother's bones, which may affect brain development."

(3) Sources of lead.

(a) Explain what lead is.

(b) Explain possible sources of lead in drinking water and how lead enters drinking water. Include information on home or building materials and services lines that may contain lead.

(c) Discuss other important sources of lead exposure in addition to drinking water (e.g., paint).

(4) Discuss the steps the consumer can take to reduce their exposure to lead in drinking water.

(a) Encourage running the water to flush out the lead.

(b) Explain concerns with using hot water from the tap and specifically caution against the use of hot water for preparing baby formula.

(c) Explain that boiling water does not reduce lead levels.

(d) Discuss other options consumers can take to reduce exposure to lead in drinking water, such as alternative sources or treatment of water.

(e) Suggest that parents have their child's blood tested for lead.

(5) Explain why there are elevated levels of lead in the waterworks' drinking water (if known) and what the owner is doing to reduce the lead levels in homes and buildings.

(6) "For more information call us at (Insert owner's contact phone number), or if applicable, visit our website at (Insert waterworks' website URL here). For more information on reducing lead exposure around your home or building and the health effects of lead, visit EPA's website at http://www.epa.gov/lead or contact your health care provider."

b. In addition to including the elements specified in subdivision D 1 a of this section, the owner of a community waterworks shall:

(1) Tell consumers how to get their water tested.

(2) Discuss lead in plumbing components and the difference between low lead and lead free. "Lead free" means (i) when used with respect to solders and flux refers to solders and flux containing not more than 0.2% lead, and (ii) when used with respect to pipes, pipe fittings, plumbing fittings, and plumbing fixtures refers to the weighted average of wetted surfaces of pipes, pipe fittings, plumbing fittings, and plumbing fixtures containing not more than 0.25% lead.

2. Delivery of public education materials.

a. The owner of a waterworks serving a large proportion of non-English speaking consumers, as determined by the department, shall include in all public education materials information in the appropriate languages regarding the importance of the notice or contain a telephone number or address where persons served may contact the waterworks to obtain a translated copy of the public education materials or to request assistance in the appropriate language.

b. The owner of a community waterworks that exceeds the lead AL on the basis of tap water samples collected in accordance with 12VAC5-590-375 B, and that is not already conducting public education tasks, shall conduct the public education tasks under this subdivision within 60 days after the end of the monitoring period in which the exceedance occurred. For a waterworks that is required to conduct monitoring annually or less frequently, the end of the monitoring period is September 30 of the calendar year in which the sampling occurs, or, if the department has established an alternate monitoring period, the last day of that period. These public education tasks include:

(1) Delivering printed materials meeting the content requirements of subdivision D 1 of this section to all bill paying customers.

(2) Contacting customers who are most at risk by delivering education materials that meet the content requirements of subdivision D 1 of this section to the local health department even if they are not located within the waterworks service area, along with an informational notice that encourages distribution to all the organization's potentially affected customers or community waterworks consumers. The owner shall contact the local health department directly by phone or in person. The local health department may provide a specific list of additional community based organizations serving target populations, which may include organizations outside the service area of the waterworks. If these lists are provided, then the owner shall deliver education materials that meet the content requirements of subdivision D 1 of this section to all organizations on the provided lists.

(3) Contacting customers who are most at risk by delivering materials that meet the content requirements of subdivision D 1 of this section to the following organizations that are located within the waterworks service area, along with an informational notice that encourages distribution to all the organization's potentially affected customers or community waterworks users: (i) public and private schools or school boards; (ii) Women, Infants and Children (WIC) and Head Start programs; (iii) public and private hospitals and medical clinics; (iv) pediatricians; (v) family planning clinics; and (vi) local welfare agencies.

(4) Make a good faith effort to locate the following organizations within the service area and deliver materials that meet the content requirements of subdivision D 1 of this section to them, along with an informational notice that encourages distribution to all potentially affected customers or consumers. The good faith effort to contact at-risk customers may include requesting a specific contact list of these organizations from the local health department, even if the agencies are not located within the waterworks service area: (i) licensed childcare centers, (ii) public and private preschools, and (iii) obstetricians-gynecologists and midwives.

(5) No less often than quarterly, providing information on or in each water bill as long as the waterworks exceeds the AL for lead. The message on the water bill shall include the following statement exactly as written except for the text in brackets for which the owner shall include system-specific information: "(Insert name of waterworks) found high levels of lead in drinking water in some homes. Lead can cause serious health problems. For more information please call (insert name of waterworks) or (if applicable) visit our website at (insert waterworks website URL here)". The message or delivery mechanism can be modified in consultation with the department; specifically, the department may allow a separate mailing of public education materials to customers if the owner cannot place the information on water bills.

(6) Posting materials meeting the content requirements of subdivision D 1 of this section on the waterworks website if the waterworks serves a population greater than 100,000 persons.

(7) Submitting a press release to newspapers, television, and radio stations.

(8) In addition to the delivery requirements contained in subdivisions D 2 b (1) through D 2 b (7) of this section, the owner of a waterworks exceeding the lead AL shall implement at least three activities from one or more of the following categories: (i) public service announcements, (ii) paid advertisements, (iii) public area informational displays, (iv) emails to customers, (v) public meetings, (vi) household deliveries, (vii) targeted individual customer contact, (viii) direct material distribution to all multi-family homes and institutions, and (ix) other methods approved by the department. The educational content and selection of these activities shall be determined in consultation with the department.

(9) As long as a community waterworks exceeds the lead AL, the owner shall repeat the following public education activities:

(a) The owner of a community waterworks shall repeat the tasks contained in subdivisions D 2 b (1), D 2 b (2), D 2 b (3), and D 2 b (8) of this section every 12 months.

(b) The owner of a community waterworks shall repeat tasks contained in subdivision D 2 b (5) of this section with each billing cycle.

(c) The owner of a community waterworks serving a population greater than 100,000 shall post and retain the material on a publicly accessible website pursuant to subdivision D 2 b (6) of this section.

(d) The owner of a community waterworks shall repeat the task in subdivision D 2 b (7) of this section twice every 12 months on a schedule agreed upon with the department.

(10) The department may allow the public education activities described in subdivision D 2 b of this section to extend beyond the 60-day requirement if needed for implementation purposes on a case-by-case basis; however, this extension must be approved in writing by the department in advance of the 60-day deadline.

c. The owner of a NTNC that exceeds the lead AL on the basis of tap water samples collected in accordance with 12VAC5-590-375 B, and that is not already conducting public education tasks, shall conduct the public education tasks under this subdivision within 60 days after the end of the monitoring period in which the exceedance occurred. For a waterworks that is required to conduct monitoring annually or less frequently, the end of the monitoring period is September 30 of the calendar year in which the sampling occurs, or, if the department has established an alternate monitoring period, the last day of that period. These public education tasks include:

(1) Posting informational posters containing all of the public education elements contained in subdivision D 1 of this section in a public place or common area in each of the buildings served by the waterworks; and

(2) Distributing informational pamphlets or brochures on lead in drinking water containing all of the public education elements in subdivision D 1 of this section to each person served by the NTNC. The department may allow the owner to utilize electronic transmission instead of or combined with printed materials as long as it achieves at least the same coverage.

(3) The owner of a NTNC shall repeat the tasks contained in subdivisions D 2 c (1) and D 2 c (2) of this section at least once during each calendar year in which the waterworks exceeds the lead AL.

(4) The department may allow the public education activities described in subdivision D 2 c of this section to extend beyond the 60-day requirement if needed for implementation purposes on a case-by-case basis; however, this extension must be approved in writing by the department in advance of the 60-day deadline.

d. The owner may discontinue delivery of public education materials if the waterworks has met the lead AL during the most recent six-month monitoring period conducted pursuant to 12VAC5-590-375 B. The owner shall recommence public education in accordance with this subsection if the waterworks subsequently exceeds the lead AL during any monitoring period.

e. The owner of a community waterworks may apply to the department, in writing, (unless the department has waived the requirement for prior approval) to use only the text specified in subdivision D 1 a of this section instead of the text in subdivisions D 1 a and D 1 b of this section and to perform the tasks listed in subdivisions D 2 c (1) and D 2 c (2) of this section instead of the tasks in subdivisions D 2 b (1) through D 2 b (9) of this section if:

(1) The waterworks serves a facility, such as a prison or a hospital, where the population served is not capable of or is prevented from making improvements to plumbing or installing POU treatment devices; and

(2) The owner provides water as part of the cost of services provided and does not separately charge for water consumption.

f. The owner of a community waterworks serving 3,300 or fewer people may limit certain aspects of the public education programs as follows:

(1) With respect to the requirements of subdivision D 2 b (8) of this section, the owner of a waterworks serving 3,300 or fewer people shall implement at least one of the activities listed in that subdivision.

(2) With respect to the requirements of subdivision D 2 b (2) of this section, the owner of a waterworks serving 3,300 or fewer people may limit the distribution of the public education materials required under that subdivision to facilities and organizations served by the waterworks that are most likely to be visited regularly by pregnant women and children.

(3) With respect to the requirements of subdivision D 2 b (7) of this section, the department may waive this requirement for waterworks serving 3,300 or fewer persons as long as the owner distributes notices to every household served by the waterworks.

3. Supplemental monitoring and notification of results. The owner of a waterworks that fails to meet the lead AL on the basis of tap samples collected in accordance with 12VAC5-590-375 B shall offer to sample the tap water of any customer who requests it. The owner is not required to pay for collecting or analyzing the sample, nor is the owner required to collect and analyze the sample itself.

4. Notification of results. The owner of a community waterworks or a NTNC shall provide a notice of the individual tap results from lead tap water monitoring carried out under the requirements of 12VAC5-590-375 B to the persons served by the waterworks at the specific sampling site from which the sample was collected (e.g., the occupants of the residence or buildings where the tap was tested).

a. Timing of notification. The owner shall provide this consumer notice as soon as practical, but no later than 30 days after the owner learns of the tap monitoring results.

b. Content. The consumer notice shall include the results of lead tap water monitoring for the tap that was tested, an explanation of the health effects of lead, list steps consumers can take to reduce exposure to lead in drinking water, and contact information for the waterworks. The notice shall also provide the MCLG and the AL for lead and the definitions for these two terms from 12VAC5-590-10.

c. Delivery. The consumer notice shall be provided to persons served at the tap that was tested, either by postal mail or by another method approved by the department. For example, the owner of a NTNC may post the results on a bulletin board in the facility to allow consumers to review the information. The owner shall provide the notice to customers at sample taps tested, including consumers who do not receive water bills.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 27, Issue 1, eff. October 13, 2010; amended, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-410. (Repealed.)

Historical Notes

Derived from VR355-18-004.08 § 2.8, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 12, Issue 2, eff. November 15, 1995; Volume 18, Issue 19, eff. July 3, 2002; Volume 19, Issue 24, eff. September 10, 2003; Volume 21, Issue 13, eff. April 6, 2005; Volume 22, Issue 15, eff. May 3, 2006; Volume 22, Issue 24, eff. September 6, 2006; Volume 25, Issue 5, eff. December 10, 2008; Volume 27, Issue 1, eff. October 13, 2010; Volume 28, Issue 5, eff. December 7, 2011; repealed, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-411. Disinfection byproduct precursors, disinfection byproducts, and maximum residual disinfection level treatment techniques.

A. Treatment technique for control of DBPPs.

1. Applicability.

a. The owner of a community waterworks or a NTNC shall comply with treatment techniques for the control of DBPPs.

b. A waterworks that uses a surface water source, a GUDI source, or both using conventional filtration treatment shall operate with enhanced coagulation or enhanced softening to achieve the TOC percentage removal levels specified in subdivision A 2 of this section unless the waterworks meets at least one of the alternative compliance criteria listed in subdivision A 1 c or A 1 d of this section.

c. Alternative compliance criteria for enhanced coagulation and enhanced softening waterworks. A waterworks that uses a surface water source, a GUDI source, or both provided with conventional filtration treatment may use the alternative compliance criteria in subdivisions A 1 c (1) through A 1 c (6) of this section to comply with this section instead of complying with subdivision A 2 of this section. The owner shall comply with monitoring requirements in 12VAC5-590-374 I.

(1) The waterworks' source water TOC level is less than 2.0 mg/L, calculated quarterly as an RAA.

(2) The waterworks' treated water TOC level is less than 2.0 mg/L, calculated quarterly as an RAA.

(3) The waterworks' source water TOC level is less than 4.0 mg/L, calculated quarterly as an RAA; the source water alkalinity is greater than 60 mg/L (as CaCO₃), calculated quarterly as an RAA; and no TTHM and HAA5 LRAAs are greater than 0.040 mg/L and 0.030 mg/L, respectively.

(4) No TTHM and HAA5 LRAAs are greater than 0.040 mg/L and 0.030 mg/L, respectively, and the waterworks uses only chlorine for primary disinfection and maintains a residual in the distribution system.

(5) The waterworks' source water SUVA, before any treatment and measured monthly, is less than or equal to 2.0 liters per milligram-meter (L/mg-m), calculated quarterly as an RAA.

(6) The waterworks' finished water SUVA, measured monthly, is less than or equal to 2.0 L/mg-m, calculated quarterly as an RAA.

d. Additional alternative compliance criteria for softening waterworks. A waterworks practicing enhanced softening that cannot achieve the TOC removals required by subdivision A 2 b of this section may use the alternative compliance criteria in subdivisions A 1 c (1) and A 1 c (2) instead of complying with subdivision A 2 of this section. A waterworks shall comply with monitoring requirements in 12VAC5-590-374 J.

(1) Softening that results in lowering the treated water alkalinity to less than 60 mg/L (as CaCO3), measured monthly and calculated quarterly as an RAA.

(2) Softening that results in removing at least 10 mg/L of magnesium hardness (as CaCO3), measured monthly and calculated quarterly as an RAA.

2. Enhanced coagulation and enhanced softening performance requirements.

a. A waterworks shall achieve the percentage reduction of TOC specified in subdivision A 2 b of this section between the source water and the CFE, unless the department approves an owner's request for alternate minimum TOC removal (Step 2) requirements under subdivision A 2 c of this section.

Required Step 1 TOC reductions, indicated in Table 411.1, are based upon specified source water parameters. A waterworks practicing softening is required to meet the Step 1 TOC reductions in the far-right column (source water alkalinity greater than 120 mg/L) for the specified source water TOC.

b. Required Step 1 TOC reductions are indicated in Table 411.1, Required Percentage Removals of TOC.

c. A waterworks that uses a surface water source, a GUDI source, or both with conventional treatment that cannot achieve the Step 1 TOC removals required by subdivision A 2 b due to water quality parameters or operational constraints shall apply to the department within three months of failure to achieve the TOC removals required by subdivision A 2 b of this section for approval of alternative minimum TOC (Step 2) removal requirements submitted by the owner. If the department approves the alternative minimum TOC removal (Step 2) requirements, then the department may make those requirements retroactive for the purposes of determining compliance. Until the department approves the alternate minimum TOC removal (Step 2) requirements, the waterworks shall meet the Step 1 TOC removals contained in subdivision A 2 b of this section.

d. Alternate minimum TOC removal (Step 2) requirements. Applications made to the department by the owner of a waterworks using enhanced coagulation for approval of alternative minimum TOC removal (Step 2) requirements under subdivision A 2 c of this section shall include, at a minimum, results of bench-scale or pilot-scale testing conducted under subdivision A 2 d (1) of this section. The submitted bench-scale or pilot-scale testing shall be used to determine the alternate enhanced coagulation level.

(1) Alternate enhanced coagulation level is defined as coagulation at a coagulant dose and pH as determined by the method described in subdivisions A 2 d (1) through A 2 d (5) of this section so that an incremental addition of 10 mg/L of alum (or equivalent amount of ferric salt) results in a TOC removal of equal to or less than 0.3 mg/L. The percentage removal of TOC at this point on the "TOC removal versus coagulant dose" curve is then defined as the minimum TOC removal required for the waterworks. Once approved by the department, this minimum requirement supersedes the minimum TOC removal requirements listed in Table 411.1. This requirement shall be effective until the department approves a new value based on the results of a new bench-scale and pilot-scale test. Failure to achieve the alternative minimum TOC removal levels set by the department is a violation of this section.

(2) Bench-scale or pilot-scale testing of enhanced coagulation shall be conducted by using representative water samples and adding 10 mg/L increments of alum (or equivalent amounts of ferric salt) until the pH is reduced to a level less than or equal to the enhanced coagulation Step 2 target pH shown in Table 411.2.

(3) For source waters with alkalinities of less than 60 mg/L for which addition of small amounts of alum or equivalent addition of iron coagulant drives the pH below 5.5 before significant TOC removal occurs, the waterworks shall add necessary chemicals to maintain the pH between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/L per 10 mg/L alum added (or equivalent addition of iron coagulant) is reached.

(4) The waterworks may operate at any coagulant dose or pH necessary (consistent with other sections of this chapter) to achieve the minimum TOC percentage removal approved under subdivision A 2 c of this section.

(5) If the TOC removal is consistently less than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose at all dosages of alum (or equivalent addition of iron coagulant), then the water is deemed to contain TOC not amenable to enhanced coagulation. The owner may then apply to the department for a waiver of enhanced coagulation requirements.

3. Compliance calculations.

a. A waterworks that uses a surface water source, a GUDI source, or both other than those identified in subdivision A 1 b or A 1 c of this section shall comply with requirements contained in subdivision A 2 b or A 2 c of this section. The owner shall calculate compliance quarterly, beginning after the waterworks has collected 12 months of data, by determining an annual average using the following method:

(1) Determine actual monthly TOC percentage removal, equal to:

[1-(treated water TOC/source water TOC)] X 100.

(2) Determine the required monthly TOC percentage removal (from either Table 411.1 or from subdivision A 2 c of this section).

(3) Divide the value in subdivision A 3 a (1) of this section by the value in subdivision A 3 a (2) of this section.

(4) Add together the results of subdivision A 3 a (3) of this section for the last 12 months and divide by 12.

(5) If the value calculated in subdivision A 3 a (4) of this section is less than 1.00, then the waterworks is not in compliance with the TOC percentage removal requirements.

b. The owner may use the provisions in subdivisions A 3 b (1) through A 3 b (5) of this section instead of the calculations in subdivisions A 3 a (1) through A 3 a (5) of this section to determine compliance with TOC percentage removal requirements.

(1) In any month that the waterworks' treated or source water TOC level is less than 2.0 mg/L, the waterworks may assign a monthly value of 1.0 (instead of the value calculated in subdivision A 3 a (3) of this section) when calculating compliance under the provisions of subdivision A 3 a of this section.

(2) In any month that a waterworks practicing softening removes at least 10 mg/L of magnesium hardness (as CaCO3), the waterworks may assign a monthly value of 1.0 (instead of the value calculated in subdivision A 3 a (3) of this section) when calculating compliance under the provisions of subdivision A 3 a of this section.

(3) In any month that the waterworks source water SUVA before any treatment is equal to or less than 2.0 L/mg-m, the waterworks may assign a monthly value of 1.0 (instead of the value calculated in subdivision A 3 a (3) of this section) when calculating compliance under the provisions of subdivision A 3 a of this section.

(4) In any month that the waterworks finished water SUVA is equal to or less than 2.0 L/mg-m, the waterworks may assign a monthly value of 1.0 (instead of the value calculated in subdivision A 3 a (3) of this section) when calculating compliance under the provisions of subdivision A 3 a of this section.

(5) In any month that the waterworks practicing enhanced softening lowers the alkalinity below 60 mg/L (as CaCO₃), the waterworks may assign a monthly value of 1.0 (instead of the value calculated in subdivision A 3 a (3) of this section) when calculating compliance under the provisions of subdivision A 3 a of this section.

c. A waterworks that uses a surface water source, a GUDI source, or both and uses conventional treatment may also comply with the requirements of this section by meeting the criteria in subdivision A 1 b or A 1 c of this section.

4. Enhanced coagulation or enhanced softening is the treatment technique required to control the level of DBP precursors in water treatment and distribution system for a waterworks using a surface water source, a GUDI source, or both and using conventional treatment.

B. The BAT, treatment techniques, or other means available for achieving compliance with the PMCLs for DBPs shown in Table 340.6 are listed in this subsection:

1. The BAT, treatment techniques, or other means available for achieving compliance with the PMCLs for bromate and chlorite:

2. The BAT, treatment techniques, or other means available for achieving compliance with the RAA PMCLs for TTHM and HAA5:

3. The BAT, treatment techniques, or other means available for achieving compliance with the LRAA PMCLs for TTHM and HAA5 for a waterworks that disinfects its source water:

4. The BAT, treatment techniques, or other means available for achieving compliance with the LRAA MCLs for TTHM and HAA5 for a a consecutive waterworks and applies only to the disinfected water that a consecutive waterworks buys or otherwise receives:

C. The BAT, treatment techniques, or other means available for achieving compliance with the MRDLs identified in Table 340.7 are the controls of treatment processes to reduce disinfectant demand and controls of disinfection treatment processes to reduce disinfectant levels.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-415. Uncovered finished water storage.

A. A waterworks with uncovered finished water storage facilities shall comply with the requirements to cover the facility as described in this section.

B. The owner shall immediately notify the department of the use of each uncovered finished water storage facility.

C. All uncovered finished water storage facilities shall be covered in compliance with a schedule approved by the department.

D. Failure to comply with the requirements of this section is a violation of the treatment technique requirement.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-420. (Repealed.)

Historical Notes

Derived from VR355-18-004.09 § 2.9, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 12, Issue 2, eff. November, 15, 1995; Volume 18, Issue 19, eff. July 3, 2002; Volume 19, Issue 17, eff. June 4, 2003; Volume 19, Issue 20, eff. July 16, 2003; Volume 21, Issue 13, eff. April 6, 2005; Volume 25, Issue 5, eff. December 10, 2008; Volume 27, Issue 1, eff. October 13, 2010; Volume 28, Issue 5, eff. December 7, 2011; repealed, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-421. Groundwater system treatment techniques.

A. The owner of a groundwater system that (i) has a confirmed E. coli contamination as described in 12VAC5-590-379 B or (ii) has been notified in writing of a significant deficiency as described in 12VAC5-590-350 D shall meet the requirements of this section. Failure to meet any requirement of this section after the applicable time period specified is a treatment technique violation.

1. The owner shall implement one or more of the following corrective actions:

a. Correct all significant deficiencies;

b. Provide an alternate source of water;

c. Eliminate the source of contamination; or

d. Provide treatment of the groundwater source that reliably achieves at least 4-log treatment of viruses before or at the first customer.

2. Unless the department directs the owner to implement a specific corrective action, the owner shall consult with the department regarding the appropriate corrective action within 30 days of receiving written notification from the department or the laboratory. This consultation may take the form of a telephone conversation, email, meeting, or other mechanism agreed to by the department.

3. Within 45 days of receiving this notification, the owner shall submit a written corrective action plan (CAP) to the department that satisfactorily addresses the deficiency. The CAP shall include a schedule for completing individual actions, and it shall include one or more of the corrective actions in subdivision A 1 of this section. Approval of the CAP by the department constitutes an approved CAP.

4. Within 120 days of receiving written notification from the department or the laboratory, the owner shall either:

a. Have completed corrective actions in accordance with the department approved CAP including department specified interim measures; or

b. Be in compliance with a department approved CAP and schedule.

(1) Any subsequent modifications to a department approved CAP and schedule shall also be approved by the department.

(2) If the department specifies interim measures for protection of the public health pending the department's approval of the CAP and schedule or pending completion of the CAP, then the owner shall comply with these interim measures as well as with any schedule specified by the department.

5. When a significant deficiency is identified at a waterworks that uses both a groundwater and a surface water or a GUDI source, the owner shall comply with this section unless the department has determined that the significant deficiency is in a portion of the distribution system that is served solely by the surface water or the GUDI source.

B. The owner of a groundwater system that provides at least 4-log treatment of viruses before or at the first customer shall conduct compliance monitoring to demonstrate treatment effectiveness in accordance with subsection C of this section. The owner shall also conduct source water monitoring in accordance with 12VAC5-590-379 C.

The owner shall provide engineering, operational, or other information as required by the department to complete a determination of virus treatment effectiveness.

C. The owner of a groundwater system that provides at least 4-log treatment of viruses shall monitor the effectiveness and reliability of treatment for that groundwater source before or at the first customer as follows:

1. Chemical disinfection.

a. The owner of a groundwater system that serves greater than 3,300 people shall continuously monitor and record the residual disinfectant concentration using analytical methods specified in 12VAC5-590-440 at a location approved by the department and shall record the lowest residual disinfectant concentration each day that water from the groundwater source is served to the public. The owner shall maintain at least the department-determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source to the public. If there is a failure in the continuous monitoring equipment, the owner shall conduct grab sampling every four hours until the continuous monitoring equipment is returned to service. The system shall resume continuous residual disinfectant monitoring within 14 days.

b. The owner of a groundwater system that serves 3,300 or fewer people shall monitor the residual disinfectant concentration using analytical methods specified in 12VAC5-590-440 at a location approved by the department and record the residual disinfection concentration each day that water from the groundwater source is served to the public. The owner shall maintain the department-determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source to the public. The owner shall collect a daily grab sample during the hour of peak flow or at another time specified by the department. If any daily grab sample measurement falls below the department-determined residual disinfectant concentration, the owner shall collect follow-up samples every four hours until the residual disinfectant concentration is restored to the department-determined level. The owner of a groundwater system that serves 3,300 or fewer people may monitor continuously to meet the requirements of this subsection.

c. When the disinfection treatment is required based on confirmed E. coli contamination in the source water, the requirements in this section apply. When the disinfection treatment is required for any other reason or provided voluntarily by the owner, the department will determine the frequency of residual disinfectant monitoring.

d. Failure to maintain the department-specified minimum residual disinfectant concentration for a period of more than four hours is a violation of the treatment technique requirement.

2. The owner of a groundwater system that uses a department-approved alternative treatment to meet the requirements of this section by providing at least 4-log treatment of viruses before or at the first customer shall:

a. Monitor the alternative treatment in accordance with all department-specified monitoring requirements; and

b. Operate the alternative treatment in accordance with all department-specified compliance requirements necessary to achieve at least 4-log treatment of viruses.

3. Failure to meet the monitoring requirements of subsection C of this section is a violation and requires the owner to provide public notification as required in 12VAC5-590-540 A 3.

D. Discontinuing compliance monitoring or treatment.

1. The owner may discontinue compliance monitoring if the department determines and documents in writing that compliance monitoring is no longer necessary for that groundwater source. The owner of a groundwater systems that has department approval to discontinue compliance monitoring shall be subject to the triggered source water monitoring requirements of 12VAC5-590-379 B 1.

2. The owner of a groundwater system that is discontinuing compliance monitoring is still subject to the requirements of 12VAC5-590-380 G.

3. The owner that has been required by the department to provide at least 4-log treatment of viruses shall not discontinue treatment or monitoring.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 28, Issue 5, eff. December 7, 2011; amended, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-425. (Repealed.)

Historical Notes

Derived from Virginia Register Volume 28, Issue 5, eff. December 7, 2011; repealed, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-430. Determination of surface water influence of groundwater sources.

A. A groundwater source utilized by a waterworks, including wells, springs, and infiltration galleries, shall be evaluated by the department and a determination of surface water influence shall be made by the department. The owner shall provide to the department all necessary information to make this determination in accordance with the three-step procedure described in subsection B of this section.

B. The groundwater source shall be evaluated and subjected to the criteria in a stepwise fashion. Once the department has made a determination with regard to surface water influence, it is not necessary to continue to the next step:

1. Step 1. Evaluation of source history, construction, and location.

a. The source is under the direct influence of surface water if it has been directly associated with a biological waterborne disease outbreak.

b. The source is under the direct influence of surface water if there are any demonstrated or known direct connections between the source to surface water via surface water bodies, sinkholes, troughs, drainage ways, or other geologic features.

c. The source is under the direct influence of surface water if a sanitary survey reveals, or there is other evidence to indicate, that surface water is directly entering the source.

d. If the department has not determined that the source is influenced by surface water based upon the criteria in subdivisions B 1 a, B 1 b, and B 1 c of this section, then the source evaluation proceeds to Step 2.

2. Step 2. Microbiological water quality.

a. The owner shall collect a series of bacteriological samples directly from the source before any treatment. The specific number of samples to be collected, the sampling frequency, and the duration of sampling shall be determined by the department.

(1) At a minimum, a series of 20 samples collected on a weekly frequency is required. Sample collection may be adjusted within the week to collect samples immediately following rainfall events, whenever possible.

(2) All bacteriological analyses shall be performed by laboratories that have received certification by EPA or DCLS as specified in 12VAC5-590-440 for drinking water samples and by a test method that will yield both total coliform concentration and E. coli concentration.

(3) The department may utilize bacteriological results from source water samples collected in accordance with 12VAC5-590-379 C if the sample results cover at least a 20-week period that includes multiple significant rainfall events for this Step 2 evaluation.

b. The total coliform concentration sample results shall be evaluated as follows:

(1) If the results of the total coliform concentration samples indicate three or more samples with total coliform greater than 100 colonies/100 ml, then the source evaluation proceeds to Step 3.

(2) If the results of the total coliform concentration samples indicate a geometric mean equal to or greater than 100 colonies/100 ml, then the requirements of 12VAC5-590-380 G 2 will apply.

c. The E. coli concentration samples shall be evaluated as follows:

(1) If the results of the E. coli concentration samples indicate greater than or equal to five E. coli per 100 ml in three or more samples, then the source evaluation proceeds to Step 3.

(2) If the results of the E. coli concentration samples indicate the presence of E. coli in five or more samples, then the source evaluation proceeds to Step 3.

3. Step 3. Additional water quality monitoring.

a. The owner shall prepare and submit a written source water monitoring plan to the department for approval detailing additional water quality samples to be collected directly from the source before any treatment and if applicable from a nearby surface water source. The monitoring plan shall include the following:

(1) The specific parameters to be monitored.

(2) The monitoring frequency for each parameter.

(3) The duration of monitoring.

b. The source water monitoring plan shall include microscopic particulate analysis (MPA).

(1) A minimum of four source water MPA tests is required, two to be conducted during a wet period and two to be conducted during a dry period. All MPA tests shall be collected at least 60 days apart.

(2) All MPA tests shall be performed by a laboratory approved by the department and shall include both Giardia lamblia and Cryptosporidium.

(3) All MPA testing and reporting of results shall be in accordance with EPA "Consensus Method for Determining Groundwaters Under the Direct Influence of Surface Water Using Microscopic Particulate Analysis (MPA)," dated October 1992, Environmental Services Division.

c. The source water monitoring plan shall include monitoring of the physical parameters such as temperature, pH, turbidity, conductivity, and other parameters.

(1) If a surface water source is located near the groundwater source being evaluated, then monitoring of the nearby surface water source is required using the same physical parameters and frequency as the groundwater source.

(2) Records of rainfall and other climatological events shall be maintained and reported with the physical parameter results.

d. The owner shall provide the department with all of the monitoring results required in the approved monitoring plan. Results of all MPA tests shall be reported within 10 days of receipt by the owner. If any MPA result indicates the presence of Giardia lamblia or Cryptosporidium, then the owner shall notify the department within 24 hours of receipt. The results of the physical parameter monitoring shall be provided along with applicable rainfall or climatological data to the department in a summary report.

e. The additional water quality monitoring results shall be evaluated as follows:

(1) The source is under the direct influence of surface water if any single MPA test result indicates a score of equal to or greater than 20.

(2) The source is under the direct influence of surface water if any two MPA test results indicate a score of equal to or greater than 15.

(3) The source is under the direct influence of surface water if the results of physical parameter monitoring indicate a correlation between fluctuations in the groundwater source in direct response to a rainfall or other climatological event.

(4) The source is under the direct influence of surface water if the results of physical parameter monitoring indicate a direct correlation between the groundwater source being evaluated and the physical parameters of a nearby surface water source.

(5) The source is a groundwater source and is not under the direct influence of surface water if (i) all MPA test results indicate a score of equal to or less than 9, (ii) there are no fluctuations in source water monitored physical parameters in direct response to a rainfall or other climatological event, and (iii) there is no direct correlation in the monitored physical parameters between the groundwater source being evaluated and a nearby surface water source.

f. If the department has not determined that the source is under the direct influence of surface water based upon the criteria in subdivisions B 3 e (1) through B 3 e (4) of this section, and if at least one of the MPA test results indicate a score of greater than 9 but less than 15, then the department shall evaluate all available water quality monitoring data, source construction, location, geology, and any other relevant factors, and to determine that either:

(1) The source is a groundwater source and is not under the direct influence of surface water; or

(2) The source is at risk and requires continued source water monitoring as prescribed by the department.

C. If the source is subject to the requirements of subdivision B 3 of this section, then the owner shall perform the following interim measures until the department has made a final GUDI determination:

1. Provide disinfection treatment to achieve a 4-log inactivation of virus in accordance with 12VAC5-590-421 A 1 d;

2. Conduct compliance monitoring in accordance with 12VAC5-590-421 C 1;

3. If the disinfection treatment required in subdivision C 1 of this section has to be installed, then the owner shall issue a public notice in accordance with 12VAC5-590-540 A 1 advising consumers to boil the water before using it for human consumption. The boil water notice shall remain in effect until the disinfection treatment is installed and in operation; and

4. The department may require that the owner perform additional interim measures if deemed necessary to protect public health.

D. If the total coliform concentration criteria in subdivision B 2 b of this section or the E. coli concentration criteria in subdivision B 2 c of this section are exceeded or if the department has declared the source to be GUDI, then the owner may propose mitigation measures, a plan to correct deficiencies, or both.

1. Any proposed mitigation measures or corrective actions must be detailed in a report submitted to the department for approval. The report shall be prepared by a professional engineer licensed in Virginia, a professional geologist licensed in Virginia, or other licensed professional approved by the department. The report shall include:

a. A description of the proposed mitigation or corrective action activities such as the repair of structural defects, elimination of sources of contamination in proximity to the source, implementation of source water protection measures, or other mitigation or corrective action activities.

b. Specific milestones and milestone completion dates.

c. A follow-up source water monitoring plan to be implemented upon completion of the mitigation measures or of the corrective actions.

2. If the source must remain in operation during the period of time that the mitigation or corrective action activities are implemented and evaluated, then the department may require that the owner implement the interim measures described in 12VAC5-590-395 A 3 or subdivisions C 1 through C 4 of this section.

3. A final summary report detailing the mitigation measures, the corrective actions, or both that are completed; the results of the follow-up monitoring; conclusions; recommendations; and all other supporting data shall be submitted to the department for approval.

a. The final summary report shall be prepared by a professional engineer licensed in Virginia, a professional geologist licensed in Virginia, or other licensed professional approved by the department.

b. Upon evaluation of the final report and supporting data, the department will make a GUDI determination.

E. For any source previously determined to be a groundwater source and not under the direct influence of surface water, the department may:

1. Require that the source be reevaluated in accordance with procedures contained in this section; or

2. Waive any additional reevaluation under this section.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from VR355-18-004.10 § 2.10, eff. June 23, 1993; amended, Virginia Register Volume 37, Issue 20, eff. June 23, 2021.

12VAC5-590-440. Analytical methods.

A. All drinking water analyses for compliance purposes shall be performed by analytical methods that are consistent with current EPA regulations found at 40 CFR Part 141 and 40 CFR Part 143. Standards for laboratories seeking certification to perform drinking water analyses are found in the Regulation for the Certification of Laboratories Analyzing Drinking Water (1VAC30-41) and regulations for the Accreditation for Commercial Environmental Laboratories (1VAC30-46) promulgated by the Department of General Services, DCLS.

B. For the purposes of determining compliance, the department will only accept results from samples that have been collected, handled, processed, and documented in accordance with the Regulation for the Certification of Laboratories Analyzing Drinking Water (1VAC30-41) and regulations for the Accreditation for Commercial Environmental Laboratories (1VAC30-46).

C. Testing for alkalinity, calcium, conductivity, residual disinfectant, orthophosphate, pH, silica, temperature, bromide, turbidity, TOC, DOC, SUVA, and UV₂₅₄ for compliance may be performed by any person or party acceptable to the department in accordance with methods specified in 40 CFR Part 141.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from VR355-18-004.11 § 2.11, eff. June 23, 1993; amended, Virginia Register Volume 12, Issue 2, eff. November 15, 1995; Volume 18, Issue 19, eff. July 3, 2002; Volume 19, Issue 17, eff. June 4, 2003; Volume 19, Issue 24, eff. September 10, 2003; Volume 22, Issue 15, eff. May 3, 2006; Volume 22, Issue 24, eff. September 6, 2006; Volume 25, Issue 5, eff. December 10, 2008; Volume 28, Issue 5, eff. December 7, 2011; Volume 33, Issue 3, eff. November 2, 2016; Volume 37, Issue 20, eff. June 23, 2021.