Dear Valued Client:
As of November 30, 2009, new ground water sources put in place after this date must meet triggered source water monitoring requirements or conduct compliance monitoring. As of December 1, 2009, GWSs that do not provide at least 4-log virus inactivation (demonstrated through various treatment technologies) and have an approved 4-log application, must conduct triggered source water monitoring for positive total coliform samples within 24 hours of being notified of a total coliform positive sample. GWSs must collect at least one ground water (raw water) sample from each source in use at the time the total coliform sample was collected and submit it to a certified laboratory for analysis using one of the approved methods. The sample(s) from the well must be unchlorinated (well pumped until no chlorine residual detected).
If the triggered monitoring is positive for fecal indicators (either E. coli, Coliphage or Enterococci), the GWS must then either take corrective action directed by the state or conduct additional source water sampling. Additional source water sampling requires five additional samples be collected from any well that had a fecal indicator positive from the triggered source water monitoring sample within 24 hours of notification of the fecal indicator positive.
Due to the 24-hour requirement and for ease of resampling, it is advisable for systems to submit compliance total coliform samples to the laboratory Monday through Wednesday.
The EPA has approved multiple methods for monitoring of fecal indicators (e.g. E. coli, Enterococci and Coliphage) in source water. Most water systems will likely collect samples for both total coliform and E. coli by Standard Method 9223B (Colilert/Colisure).
In addition to the Total Coliform/Fecal Indicator source water monitoring requirement, systems must simultaneously collect chlorine residual samples (taken at the wellhead, not in the distribution system) in a 250 mL amber bottle, or equivalent, for any samples collected for compliance with the Ground Water Rule.
Results for all analyses must be reported on the approved Arizona Department of Environmental Quality (ADEQ) forms:
- Routine Total Coliform Monitoring for Total Coliform Rule: Form DWAR-1
- Triggered Source Water Monitoring for Ground Water Rule: Form DWAR-1G
Complimentary copies of these forms are available from LEGEND through your assigned Project Manager or online at: Click Here
For specific information on how the Ground Water Rule revisions affect your drinking water system, please contact the ADEQ Drinking Water Division at (602) 771-4641 for clarification. For instructions on submission of samples under this rule or to obtain pre-printed forms, please contact your LEGEND Project Manager at (602) 324-6100.
LEGEND TECHNICAL SERVICES OF ARIZONA, INC.
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