Section R. 325.10707 - Repeat monitoring for coliform bacteriaRule 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.(7) If a supplier of water who collects less than 5 routine samples per month has 1 or more total coliform-positive samples and the department does not invalidate the sample or samples pursuant to the provisions of R 325.10707a, the supplier shall collect not less than 5 routine samples during the next month that the supply provides water to the public.(8) The department may waive the requirement to collect 5 routine samples during the next month that the supplier provides water to the public if the department performs a site visit before the end of the next month that the supplier provides water to the public. The site visit shall be sufficiently detailed to allow the department to determine whether additional monitoring or corrective action, or both, is needed. An employee of the supplier is not eligible to perform this site visit.(9) The department may waive the requirement to collect 5 routine samples during the next month that the supplier provides water to the public if the department has determined why the sample was total coliform-positive and establishes that the supplier of water has corrected the problem or will correct the problem before the end of the next month that the supplier provides water to the public. The department's decision to waive the following month's additional monitoring requirement shall be in writing and shall be available to the EPA and the public. The requirement to collect 5 routine samples during the next month that the supplier provides water to the public shall not be waived solely because all repeat samples are total coliform-negative. A supplier of water shall collect and have analyzed at least 1 routine sample before the end of the next month the supplier serves water to the public and use it to determine compliance with the MCL for total coliform, unless the department has determined that the supplier of water has corrected the contamination problem before the supplier of water took the set of repeat samples and all repeat samples were total coliform-negative.Mich. Admin. Code R. 325.10707