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.
TABLE 370.1 Bacteriological Monitoring | |
POPULATION SERVED PER DAY | MINIMUM NUMBER OF SAMPLESa |
25 to 1,000b | 1 |
1,001 to 2,500 | 2 |
2,501 to 3,300 | 3 |
3,301 to 4,100 | 4 |
4,101 to 4,900 | 5 |
4,901 to 5,800 | 6 |
5,801 to 6,700 | 7 |
6,701 to 7,600 | 8 |
7,601 to 8,500 | 9 |
8,501 to 12,900 | 10 |
12,901 to 17,200 | 15 |
17,201 to 21,500 | 20 |
21,501 to 25,000 | 25 |
25,001 to 33,000 | 30 |
33,001 to 41,000 | 40 |
41,001 to 50,000 | 50 |
50,001 to 59,000 | 60 |
59,001 to 70,000 | 70 |
70,001 to 83,000 | 80 |
83,001 to 96,000 | 90 |
96,001 to 130,000 | 100 |
130,001 to 220,000 | 120 |
220,001 to 320,000 | 150 |
320,001 to 450,000 | 180 |
450,001 to 600,000 | 210 |
600,001 to 780,000 | 240 |
780,001 to 970,000 | 270 |
970,001 to 1,230,000 | 300 |
1,230,001 to 1,520,000 | 330 |
1,520,001 to 1,850,000 | 360 |
1,850,001 to 2,270,000 2,270,001 to 3,020,000 3,020,001 to 3,960,000 3,960,001 or more | 390 420 450 480 |
aMonthly monitoring is required for the following waterworks: (i) community, (ii) nontransient noncommunity, (iii) all noncommunity waterworks that use a surface water source, a GUDI source, or both, (iv) all seasonal waterworks, and (v) large noncommunity (serving more than 1,000 people per day). Quarterly monitoring is required for noncommuntity waterworks not specifically identified in the monthly requirements. Annual monitoring may be allowed at a TNC that meets the criteria specified in subdivision A 8 of this section. bIncludes a waterworks that have at least 15 service connections, but serve fewer than 25 persons. | |
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.