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Virginia Administrative Code
Title 12. Health
Agency 5. Department of Health
Chapter 590. Waterworks Regulations
12/5/2022

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.

TABLE 379.1

Monitoring Requirements for Source Water Samples

SOURCE TYPE

MINIMUM ROUTINE SOURCE WATER MONITORING FREQUENCY

PARAMETERS

Well located in non-karst geology

One sample per year

Total coliforms MPN
and E coli MPN

Well located in karst geology

One sample per calendar quarter

Total coliforms MPN
and E coli MPN

Spring

One sample per month

Total coliforms MPN
and E coli MPN

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.

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