NR 809.327(4)(a)1. 1. All water suppliers for community water systems shall continuously monitor the residual disinfectant concentration using analytical methods and requirements specified in s. NR 809.563 at a location approved by the department and shall record the lowest residual disinfectant concentration each day that water from the groundwater source is served to the public, unless the department allows less frequent monitoring as outlined in subd. 2.

NR 809.327(4)(a)1.a. a. The groundwater system shall maintain the department determined residual disinfectant concentration every day the public water system serves water from the groundwater source to the public.

NR 809.327(4)(a)1.b. b. If there is a failure in the continuous monitoring equipment, the water supplier shall conduct grab sampling every four hours until the continuous monitoring equipment is returned to service.

NR 809.327(4)(a)1.c. c. The water supplier for the public water system shall resume continuous residual disinfectant monitoring, as soon as possible, but no later than 14 days after the failure.

NR 809.327(4)(a)2. 2. The water supplier for a community water systems serving 3,300 or fewer people shall be allowed to monitor the residual disinfectant concentration less than continuously, if the water supplier receives approval under s. NR 811.48 (3) (b) to monitor less than continuously. The monitoring shall be done using analytical methods and requirements specified in s. NR 809.563 at a location approved by the department and the residual disinfection concentration shall be recorded from that water every day the groundwater source is served to the public.

NR 809.327(4)(a)2.a. a. The groundwater system shall maintain the department determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source to the public. The water supplier for a groundwater system shall take a daily grab sample during the hour of peak flow or at another time specified by the department.

NR 809.327(4)(a)2.b. b. If any daily grab sample measurement falls below the department determined residual disinfectant concentration, the water supplier shall take follow-up samples at the frequency determined by the department under s. NR 811.48 (3) (b) but no less than four hours until the residual disinfectant concentration is restored to the department determined level.

NR 809.327(4)(a)3. 3. Water suppliers for non-community systems serving 3,300 or fewer people, unless otherwise required by the department under s. NR 812.37, shall monitor the residual disinfectant concentration using analytical methods and requirements specified in s. NR 809.563 at a location approved by the department and record the residual disinfection concentration once each day that water from the groundwater source is served to the public.

NR 809.327(4)(a)3.a. a. The water supplier for a groundwater system shall maintain the department determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source to the public. The water supplier for a groundwater system shall take a daily grab sample during the hour of peak flow or at another time specified by the department.

NR 809.327(4)(a)3.b. b. If any daily grab sample measurement falls below the department determined residual disinfectant concentration, the water supplier shall take follow-up samples every four hours until the residual disinfectant concentration is restored to the department determined level.

NR 809.327(4)(a)3.c. c. Alternatively, water suppliers for non-community groundwater systems that serve 3,300 or fewer people may monitor continuously in order to meet the requirements of subd. 1.

NR 809.327(4)(b) (b) Membrane filtration. A water supplier for a groundwater system that uses membrane filtration to meet the requirements of sub. (2) shall monitor the membrane filtration process in accordance with all department specified monitoring requirements and shall operate the membrane filtration in accordance with all department specified compliance requirements. To be in compliance with the requirement to achieve at least 4-log treatment of viruses when a public water system uses membrane filtration exclusively, the public water system shall meet all of the following:

NR 809.327(4)(b)1. 1. The membrane shall have an absolute molecular weight cut-off (MWCO), or an alternate parameter that describes the exclusion characteristics of the membrane, that can reliably achieve at least 4-log removal of viruses.

NR 809.327(4)(b)2. 2. The membrane process shall be operated in accordance with department-specified compliance requirements.

NR 809.327(4)(b)3. 3. The integrity of the membrane is intact.

NR 809.327(4)(b)4. 4. The public water system shall be provided with at least 2 log of additional treatment of viruses using a chemical disinfectant.

NR 809.327(4)(c) (c) Alternative treatment. A water supplier for a groundwater system that uses a department-approved alternative treatment to meet the requirements of sub. (2) (d) for providing at least 4-log treatment of viruses before or at the first customer shall do all of the following:

NR 809.327(4)(c)1. 1. Monitor the alternative treatment in accordance with all department specified monitoring requirements.

NR 809.327(4)(c)2. 2. Operate the alternative treatment in accordance with all compliance requirements that the department determines to be necessary to achieve at least 4-log treatment of viruses.

NR 809.327(5) (5) Discontinuing treatment. A water supplier for a groundwater system may discontinue 4-log treatment of viruses before or at the first customer for a groundwater source if the department determines and documents in writing that 4-log treatment of viruses is no longer necessary for that water source. A public water system where 4-log treatment of viruses is discontinued is subject to the source water monitoring requirements of s. NR 809.325.

NR 809.327(6) (6) Failure to meet monitoring requirements. If a water supplier fails to meet any of the monitoring requirements of sub. (4), the public water system is in violation and the water supplier shall complete public notification requirements under s. NR 809.953.

NR 809.327 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; correction in (4) (a) 2. b. made under s. 13.92 (4) (b) 7., Stats., Register November 2010 No. 659; CR 15-049: am. (1) (a), (c) (intro.), (3) (a) 2., (4) (a) 3., (6) Register March 2016 No. 723, eff. 4-1-16.

NR 809.328 NR 809.328 Treatment technique compliance for groundwater source microbiological contaminants.

NR 809.328(1) (1) Treatment technique violations for groundwater systems.

NR 809.328(1)(a) (a) A groundwater system with a significant deficiency is in violation of the treatment technique requirement if, within 120 days of the water supplier receiving written notice from the department of the significant deficiency or earlier if directed by the department, subd. 1. or 2. are not met.

NR 809.328(1)(a)1. 1. The water supplier has not completed a corrective action in accordance with any applicable department plan approval processes under chs. NR 811 and 812, including any department specified interim actions.

NR 809.328(1)(a)2. 2. The public water system is not in compliance with a department-approved corrective action plan and schedule.

NR 809.328(1)(b) (b) Unless the department invalidates an E. coli-positive groundwater source sample collected under s. NR 809.325, a public water system is in violation of the treatment technique requirement under s. NR 809.327 if within 120 days or earlier if directed by the department, the conditions of subd. 1. or 2 are not met.

NR 809.328(1)(b)1. 1. The water supplier does not complete corrective action in accordance with any applicable department plan review processes under chs. NR 811 and 812, including department specified interim measures.