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Virginia Administrative Code (Last Updated: January 10, 2017) |
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Title 12. Health |
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Agency 5. Department of Health |
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Chapter 590. Waterworks Regulations |
Section 425. Raw water monitoring requirements for groundwater sources
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A. The owner of any groundwater source utilizing chlorine disinfection or any other treatment or chemical addition that may alter or affect the bacteriological quality of the raw water shall collect source samples for bacteriological analysis in accordance with this section.
B. All bacteriological samples under this section shall be collected from the raw water prior to any treatment or chemical addition.
1. The owner shall provide a suitable raw water sample tap at each groundwater source.
2. If conditions are such that it is not possible to install a raw water sample tap, an alternate sample location acceptable to the commissioner may be utilized for this monitoring.
C. All samples shall be analyzed in accordance with 12VAC5-590-440 by the DCLS or by a laboratory certified by DCLS for drinking water samples and by a test method that will yield a Most Probable Number (MPN) result for both total coliforms and E. coli.
D. Number of samples.
1. The number of routine raw water samples to be collected and the frequency of sampling shall be determined by the district engineer. The district engineer will notify the waterworks owner of the raw water sampling requirements.
2. As a minimum, the owner shall collect raw water samples in accordance with the following table:
Source Type
Minimum Routine Raw 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
3. When a single sample result from any groundwater source that requires a routine raw water monitoring frequency of less than monthly indicates total coliforms in excess of 50 colonies per 100 mL or the presence of E. coli, the owner shall collect one confirmation sample within 10 calendar days of notification of the results. The district engineer may require that additional samples be collected and will establish the specific number of samples and the monitoring frequency.
E. If the results of the raw water monitoring required by this section indicate total coliforms in excess of 50 colonies per 100 ml in two 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, the waterworks owner shall provide all necessary information required in 12VAC5-590-430 to the district engineer and the commissioner will make a GUDI determination for the groundwater source.
F. If the results of the raw water monitoring required by this section indicate the presence of E. coli in two or more samples collected during any running six-month period, the waterworks owner shall:
1. Issue a Tier 1 public notice in accordance with 12VAC5-590-540 A 1.
2. Provide disinfection treatment to achieve a 4-log virus inactivation as specified in 12VAC5-590-421 A 1 d.
3. Conduct compliance monitoring as specified in 12VAC5-590-421 C 1.
Historical Notes
Derived from Volume 28, Issue 05, eff. December 7, 2011.