Michigan Administrative Code › Department - Environmental Quality › Drinking Water And Municipal Assistance Division › Supplying Water to the Public › Part 7 - SURVEILLANCE, INSPECTION, AND MONITORING › Section R. 325.10707 - Repeat monitoring for coliform bacteria

Current through Vol. 24-12, July 15, 2024
Rule 707.
(1) If a
				  routine sample is total coliform-positive, a supplier of water shall collect a
				  set of repeat samples within 24 hours of being notified of the positive result.
				  If a supplier of water is required to collect more than 1 routine sample per
				  month, the supplier shall collect not less than 3 repeat samples for each total
				  coliform-positive sample found. If a supplier of water is required to collect
				  not more than 1 routine sample per month, the supplier shall collect not less
				  than 4 repeat samples for each total coliform-positive sample found. The
				  department may extend for a specified time the 24-hour limit on a case-by-case
				  basis if the system has a logistical problem beyond its control in collecting
				  the repeat samples within 24 hours. The requirements for a supplier of water to
				  collect repeat samples shall not be waived.
(2) A supplier of water shall collect at
				  least 1 repeat sample from the sampling tap where the original total
				  coliform-positive sample was taken and at least 1 repeat sample at a tap within
				  5 service connections upstream and at least 1 repeat sample at a tap within 5
				  service connections downstream of the original sampling site.
(3) If a supplier of water collects a routine
				  sample from within 5 adjacent service connections of a previous
				  coliform-positive sample before being notified of this result, the most recent
				  sample may be considered a repeat sample instead of a routine sample.
(4) A supplier of water shall collect all
				  repeat samples on the same day, except that for a water supply with a
				  single-service connection, a supplier of water may collect the required repeat
				  samples once a day over a 4-day period or collect a large volume repeat sample
				  or samples in 1 or more sample containers of any size if the total volume
				  collected is not less than 400 milliliters or not less than 300 milliliters for
				  suppliers of systems who collect more than 1 routine sample per
				  month.
(5) If 1 or more repeat
				  samples in the set is total coliform-positive, the public water supplier shall
				  collect an additional set of repeat samples, as set forth in this subrule and
				  subrules (1), (2), and (4) of this rule, and the owner of the public water
				  supply shall notify the department not later than 24 hours or the next business
				  day after learning of the results. The additional samples shall be collected
				  within 24 hours of notification of the positive result, unless the department
				  extends the limit as provided in subrule (1) of this rule. A supplier of water
				  shall repeat this process until either total coliforms are not detected in 1
				  complete set of repeat samples or the supplier of water determines that the MCL
				  for total coliforms has been exceeded and notifies the department.
(6) When it is determined that an MCL
				  violation for coliform bacteria has occurred, a supplier of water shall do all
				  of the following:
(a) Initiate an
				  investigation to determine the extent of the problem, which may include the
				  collection of additional samples.
(b) Initiate precautionary measures and
				  appropriate corrective actions as required by the department until it is
				  determined by the department that the problem has been resolved.
(c) Conduct additional sampling at a
				  frequency approved by the department until such time that it is determined the
				  problem has been resolved.