R 325.10704c Total coliform; general monitoring.

Rule 704c. (1) Sample siting plan requirements for compliance with the total coliform rules in R 325.10704a are all of the following: (a) Supplies shall develop a written sample siting plan that identifies sampling sites and a sample collection schedule that are representative of water throughout the distribution system not later than March 31, 2016. These plans are subject to department review and revision. Supplies shall collect total coliform samples according to the written sample siting plan. Monitoring required by R 325.10704d to R 325.10704h may take place at a customer’s premise, dedicated sampling station, or other designated compliance sampling location. Routine and repeat sample sites and the sampling points necessary to meet the requirements of the groundwater rules of R 325.10739 to R 325.10739b shall be reflected in the sampling plan. (b) Supplies shall collect samples at regular time intervals throughout the month, except that supplies that use only ground water and serve 4,900 or fewer people may collect all required samples on a single day if they are taken from different sites. (c) Supplies shall take at least the minimum number of required samples even if the supply has had an E. coli MCL violation or has exceeded the coliform treatment technique triggers in R 325.10704i(1). (d) A supply may conduct more compliance monitoring than is required by these total coliform rules R 325.10704a to R 325.10704k to investigate potential problems in the distribution system and use monitoring as a tool to assist in uncovering problems. A supply may take more than the minimum number of required routine samples and shall include the results in calculating whether the coliform treatment technique trigger in R 325.10704i(1)(a)(i) and (ii) has been exceeded only if the samples are taken in accordance with the existing sample siting plan and are representative of water throughout the distribution system. (e) Supplies shall identify repeat monitoring locations in the sample siting plan. All of the following apply to repeat monitoring locations: (i) Unless the provisions of paragraph (iii) of this subdivision are met, the supply 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. If a total coliform-positive sample is at the end of the distribution system, or 1 service connection away from the end of the distribution system, the supply shall still take all required repeat samples. However, the department may allow an alternative sampling location instead of the requirement to collect at least 1 repeat sample upstream or downstream of the original sampling site. (ii) Supplies required to conduct triggered source water monitoring under R 325.10739(1)(a) shall take ground water source sample or samples in addition to repeat samples required under these total coliform rules R 325.10704a to R 325.10704k. (iii) Supplies may propose repeat monitoring locations to the department that the supply believes to be representative of a pathway for contamination of the distribution system. A supply may elect to specify either alternative fixed locations or criteria for selecting repeat sampling sites on a situational basis in a standard operating procedure (SOP) in its sample siting plan. The supply shall design its SOP to focus the repeat samples at locations that best verify and determine the extent of potential contamination of the distribution system area based on specific situations. The department may modify the SOP or require alternative monitoring locations as needed. (f) The department may review, revise, and approve, as appropriate, repeat sampling proposed by supplies under subdivision (e)(iii) of this subrule. The supply shall demonstrate that the sample siting plan remains representative of the water quality in the distribution system. The department may determine that monitoring at the entry point to the distribution system (especially for undisinfected ground water supplies) is effective to differentiate between potential source water and distribution system problems. (2) Special purpose samples, such as those taken to determine whether disinfection practices are sufficient following pipe placement, replacement, or repair, shall not be used to determine whether the coliform treatment technique trigger has been exceeded. Repeat samples taken under R 325.10704h are not considered special purpose samples, and shall be used to determine whether the coliform treatment technique trigger has been exceeded. (3) A total coliform-positive sample invalidated under this subrule does not count toward meeting the minimum monitoring requirements of these total coliform rules R 325.10704a to R 325.10704k. A sample is invalidated under either of the following: (a) The department may invalidate a total coliform-positive sample only if 1 or more of the following conditions are met: (i) The laboratory establishes that improper sample analysis caused the total coliform- positive result. (ii) The department, on the basis of the results of repeat samples collected as required under R 325.10704h(1), determines that the total coliform-positive sample resulted from a domestic or other non-distribution system plumbing problem. For example, the department determines that the total coliform-positive sample result, which is from a sample tap that is approved in the sample siting plan, is isolated to that specific sample location. The department shall not invalidate a sample on the basis of repeat sample results unless both of the following occur: (A) All repeat sample or samples collected at the same tap as the original total coliform- positive sample are also total coliform-positive. (B) All repeat samples collected at a location other than the original tap are total coliform-negative. Note to subdivision (ii) of this subrule: For example, the department shall not invalidate a total coliform-positive sample on the basis of repeat samples if all the repeat samples are total coliform-negative, or if the supply has only 1 service connection. (iii) The department has substantial grounds to believe that a total coliform-positive result is due to a circumstance or condition that does not reflect water quality in the distribution system, such as use of an unapproved sample location or documented gross deviation from accepted sample collection procedures that clearly could be expected to contaminate the sample itself. In this case, the supply shall still collect all repeat samples required under R 325.10704h(1), and use them to determine whether a coliform treatment technique trigger in R 325.10704i has been exceeded. To invalidate a total coliform- positive sample under this subdivision, the decision and supporting rationale shall be documented in writing, and approved and signed by the supervisor of the department official who recommended the decision. The department shall make this document available to the EPA and the public. The written documentation shall state the specific cause of the total coliform-positive sample, and what action the supply has taken, or will take, to correct this problem. The department shall not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative. (b) Both of the following apply to laboratory invalidation of a sample: (i) A laboratory shall invalidate a total coliform sample, unless total coliforms are detected, if 1 or more of the following occur: (A) The sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined, for example, the multiple-tube fermentation technique. (B) The sample produces a turbid culture in the absence of an acid reaction in the presence-absence (p-a) coliform test. (C) The sample exhibits confluent growth or produces colonies too numerous to count with an analytical method using a membrane filter, for example, membrane filter technique. (ii) If a laboratory invalidates a sample because of the interference, the supply shall collect another sample from the same location as the original sample within 24 hours of being notified of the interference problem, and have it analyzed for the presence of total coliforms. The supply shall continue to resample within 24 hours and have the samples analyzed until it obtains a valid result. The department may waive the 24-hour time limit on a case-by-case basis.