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Quick Reference Guide for the Ground Water Rule
What is the Ground Water Rule?
The U.S. Environmental Protection Agency (EPA) published the Ground
Water Rule (GWR) on November 8, 2006. One goal of the GWR is to
provide increased protection against microbial pathogens, specifically
bacterial and viral pathogens, in public water systems (PWSs) that use
ground water. One of the key elements to the GWR is monitoring.
There are two types of monitoring that are a part of the GWR:
- Source Water Monitoring: Triggered source water monitoring is
required for any GWS that has a routine, positive total coliform
result under the Total Coliform Rule (TCR) and does not provide and
monitor for 4-log treatment of viruses.
- Compliance Monitoring: GWSs that provide at least 99.99
percent (4-log) treatment of viruses of all of their ground water
can conduct compliance monitoring to show they are providing
consistent and sufficient treatment of their ground water. Systems
that choose to do compliance monitoring are not subject to triggered
source water monitoring.
Requirements of Source Water Monitoring for GWSs with Their
Own Source
When a GWS has a routine, positive total coliform result under the
TCR that system must collect at least one ground water source sample
before treatment from each source in use when the positive total
coliform result was collected. This source sample is called a
triggered source water sample.
If the triggered source water sample
is positive for E. coli, the Department will require the GWS to take
five follow-up triggered source water samples from that same source.
If any one of the follow-up triggered source water samples is
E. coli
positive, the system must take corrective action.
Requirements of Source Water Monitoring for GWSs that
Purchase Their Source Water
Per the Ground Water Rule, a consecutive system with a routine,
positive total coliform result under the TCR must notify its wholesale
system(s) within 24 hours of being notified of the positive sample.
However, to ensure notification is being consistent, the Department is
notifying the wholesaler on behalf of the consecutive system.
Requirements of Source Water Monitoring for GWSs that Sell
Their Water
A wholesale system that receives notice from the Department of a
routine, positive total coliform result under the TCR must collect a
triggered source water sample before treatment from each source in use
when the positive total coliform result was collected. If the
triggered source water sample is positive for
E. coli, the wholesale
system must notify, by public notice, their consumers and all
consecutive systems served by that source within 24 hours of being
notified. Any consecutive systems served by that source must
notify, by public notice, their consumers within 24 hours of being
notified of the result. The wholesale system must collect five
follow-up triggered source water samples from that same source. If
any one of the follow-up triggered source water samples is
E. coli
positive, the wholesale system must take corrective action.
Requirements of Compliance Monitoring
GWSs that choose to perform compliance monitoring are not subject to
triggered source water monitoring; however, those systems must report
monthly chlorine disinfectant residuals to the Department. GWSs
that decide to do compliance monitoring must work with the Department to
determine if that system meets 4-log removal/inactivation of viruses and
to determine the minimum chlorine disinfectant level. GWSs using
chloramines for disinfection would not qualify for this monitoring.
Compliance monitoring is based on a system's population.
- GWSs serving ≤ 3300 must take a daily grab sample during peak
flow and record that chlorine disinfectant residual. These results
are reported monthly to the Department.
- GWSs serving > 3300 must monitor continuously and record the
lowest, daily chlorine disinfectant residual. These results are
reported monthly to the Department.
If there are any questions regarding the Ground Water Rule, please
contact Gary Stefanovsky at 701-328-5287.
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