Chapter NR 810

Percent inactivation = 100 - (100/10), where

z = 3 x summation of (CTcalc/CT99.9)

NR 810.38(1)(f) (f) The residual disinfectant concentration of the water entering the distribution system shall be monitored continuously, and the lowest value shall be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every 4 hours may be conducted in lieu of continuous monitoring, but for no more than 5 working days following the failure of the equipment, and systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the following prescribed frequencies:

NR 810.38(1)(g) (g) The day’s samples to meet par. (f) cannot be taken at the same time. The sampling intervals are subject to department review and approval. If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the water supplier for the system shall take a grab sample every 4 hours until the residual concentration is equal to or greater than 0.2 mg/l.

NR 810.38(1)(h) (h) The residual disinfectant concentration of the water in the distribution system shall be measured as follows:

NR 810.38(1)(h)1. 1. The residual disinfectant concentration shall be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, except that the department may allow the water supplier for a public water system which uses a groundwater source, to take disinfectant residual samples at points other than the total coliform sampling points if the department determines that the points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in s. NR 809.311 (1), Table F, may be measured in lieu of residual disinfectant concentration, when approved by the department.

NR 810.38(1)(h)2. 2. If the department determines, based on site specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified by s. NR 809.311, Table F, and that the system is providing adequate disinfection in the distribution system, the requirements of subd. 1. do not apply to that system.

NR 810.38(2) (2) Monitoring requirements for systems using filtration treatment. Water suppliers for a public water system that uses a surface water source or a groundwater source under the direct influence of surface water and provides filtration treatment shall monitor in accordance with all of the following:

NR 810.38(2)(a) (a) Turbidity measurements as specified in s. NR 810.29 shall be performed on representative samples of the system’s combined filter effluent water every 4 hours, or more frequently, that the system serves water to the public. A water supplier may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the department. For any systems using slow sand filtration or filtration treatment other than conventional filtration treatment, direct filtration or diatomaceous earth filtration, the department may reduce the sampling frequency to once per day if it determines that less frequent monitoring is sufficient to indicate effective filtration performance. For systems serving 500 or fewer persons, the department may reduce the turbidity sampling frequency to once per day, regardless of the type of filtration treatment used, if the department determines that less frequent monitoring is sufficient to indicate effective filtration performance.

NR 810.38(2)(b) (b) Water suppliers for systems using conventional filtration treatment or direct filtration shall conduct continuous monitoring of turbidity for each individual filter using a method approved in s. NR 809.113 (1), Tables A and B and shall calibrate turbidimeters using the procedure specified by the manufacturer. Water suppliers shall record the results of individual filter monitoring every 15 minutes. If there is a failure in the continuous monitoring equipment, the water supplier shall conduct grab sampling every 4 hours in lieu of continuous monitoring, until the turbidimeter is repaired and back on-line. The water supplier shall repair the equipment no later than 5 working days after the failure or the system is in violation.

NR 810.38(2)(c) (c) The residual disinfectant concentration of the water entering the distribution system shall be monitored continuously, and the lowest value shall be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every 4 hours may be conducted in lieu of continuous monitoring, but for no more than 5 working days following the failure of the equipment. Water suppliers for systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies each day prescribed as follows:

1The day’s samples cannot be taken at the same time. The sampling intervals are subject to department review and approval.

If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the water supplier shall take a grab sample every 4 hours until the residual disinfectant concentration is equal to or greater than 0.2 mg/l.

NR 810.38(2)(d) (d) The residual disinfectant concentration in the distribution system shall be measured as follows:

NR 810.38(2)(d)1. 1. The residual disinfectant concentration shall be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled. The department may allow a public water system which uses both a surface water source or a groundwater source under direct influence of surface water, and a groundwater source to take disinfectant residual samples at points other than the total coliform sampling points if the department determines that the points are more representative of treated or disinfected water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in s. NR 809.311 (1), Table F, may be measured in lieu of residual disinfectant concentration, when approved by the department.

NR 810.38(2)(d)2. 2. If the department determines, based on site specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified in s. NR 809.311 (1), Table F, and that the system is providing adequate disinfection in the distribution system, the requirements of subd. 1. do not apply to that system.

NR 810.38 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.39 NR 810.39 Reporting requirements.

NR 810.39(1) (1) Water suppliers shall report sampling schedules under s. NR 809.332 and source water monitoring results under s. NR 809.336 to the department unless they notify the department that they will not conduct source water monitoring due to meeting the criteria of s. NR 809.331 (4).

NR 810.39(2) (2) Water suppliers for filtered systems shall report the Cryptosporidium bin classification of their system to the department as described in s. NR 810.34.

NR 810.39(3) (3) Water suppliers for unfiltered GWUDI systems shall report the mean source water Cryptosporidium level of their system to the department as described in s. NR 810.36.

NR 810.39(4) (4) Water suppliers for filtered and unfiltered systems shall report disinfection profiles and benchmarks to the department as described in s. NR 810.32 prior to making a significant change in disinfection practice.

NR 810.39(5) (5) Water suppliers for filtered and unfiltered systems shall report to the department in accordance with the following table for any microbial toolbox options used to comply with treatment requirements under s. NR 810.35 or 810.36. Alternatively, the department may approve a system to certify operation within required parameters for treatment credit rather than reporting monthly operational data for toolbox options.

Microbial Toolbox Reporting Requirements

NR 810.39 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.40 NR 810.40 Recordkeeping requirements.

NR 810.40(1) (1) Public water systems shall keep results from the initial round of source water monitoring under s. NR 809.331 (1) and the second round of source water monitoring under s. NR 809.331 (2) until 3 years after bin classification under s. NR 810.34 for filtered systems or determination of the mean Cryptosporidium level under s. NR 810.35 for unfiltered GWUDI systems for the particular round of monitoring.

NR 810.40(2) (2) Public water systems shall keep any notification to the department that the systems will not conduct source water monitoring due to meeting the criteria of s. NR 809.331 (4) for 3 years from the date of notification.

NR 810.40(3) (3) Public water systems shall keep the results of treatment monitoring associated with microbial toolbox options under ss. NR 810.42 to 810.46 for 3 years from the date of monitoring.

NR 810.40 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

subch. III of ch. NR 810 Subchapter III — Toolbox Options for Meeting Enhanced Treatment for Cryptosporidium Requirements

NR 810.41 NR 810.41 Microbial toolbox options.

NR 810.41(1) (1) 

NR 810.41(1)(a) (a) Public water systems receive the treatment credits listed in the table in sub. (2) by meeting the conditions for microbial toolbox options described in ss. NR 810.42 to 810.46. Systems apply these treatment credits to meet the treatment requirements in s. NR 810.35 or 810.36, as applicable.

NR 810.41(1)(b) (b) Unfiltered GWUDI systems are eligible for treatment credits for the microbial toolbox options described in s. NR 810.46 only.

NR 810.41(2) (2) The following table summarizes options in the microbial toolbox:

Microbial Toolbox Summary Table: Options, Treatment Credits, and Criteria

NR 810.41 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.42 NR 810.42 Source toolbox components.

NR 810.42(1) (1) Watershed control program. Systems receive 0.5-log Cryptosporidium treatment credit for implementing a watershed control program that meets the requirements of this section.

NR 810.42(1)(a) (a) Water suppliers for systems that intend to apply for the watershed control program credit shall notify the department of this intent no later than 2 years prior to the treatment compliance date applicable to the system in s. NR 810.37.

NR 810.42(1)(b) (b) Water suppliers for systems shall submit to the department a proposed watershed control plan no later than one year before the applicable treatment compliance date in s. NR 810.37. The department shall approve the watershed control plan for the system to receive watershed control program treatment credit. The watershed control plan shall include the following elements:

NR 810.42(1)(b)1. 1. Identification of an “area of influence” outside of which the likelihood of Cryptosporidium or fecal contamination affecting the treatment plant intake is not significant. The area of influence is the area to be evaluated in future watershed surveys under subd. 2.

NR 810.42(1)(b)2. 2. Identification of both potential and actual sources of Cryptosporidium contamination and an assessment of the relative impact of these sources on the system’s source water quality.

NR 810.42(1)(b)3. 3. An analysis of the effectiveness and feasibility of control measures that could reduce Cryptosporidium loading from sources of contamination to the system’s source water.

NR 810.42(1)(b)4. 4. A statement of goals and specific actions the system will undertake to reduce source water Cryptosporidium levels. The plan shall explain how the actions are expected to contribute to specific goals, identify watershed partners and their roles, identify resource requirements and commitments, and include a schedule for plan implementation with deadlines for completing specific actions identified in the plan.

NR 810.42(1)(c) (c) Public water systems with existing watershed control programs in place on or before January 5, 2006, are eligible to seek this credit. The watershed control plans shall meet the criteria in par. (b) and shall specify ongoing and future actions that will reduce source water Cryptosporidium levels.

NR 810.42(1)(d) (d) If the department does not respond to a water supplier regarding approval of a watershed control plan submitted under this section and the system meets the other requirements of this section, the watershed control program will be considered approved and 0.5 log Cryptosporidium treatment credit will be awarded unless and until the department subsequently withdraws the approval.

NR 810.42(1)(e) (e) Systems shall complete the following actions to maintain the 0.5-log credit:

NR 810.42(1)(e)1. 1. Submit an annual watershed control program status report to the department. The annual watershed control program status report shall describe the system’s implementation of the approved plan and assess the adequacy of the plan to meet its goals. The status report shall explain how the system is addressing any shortcomings in plan implementation, including those previously identified by the department or as the result of the watershed survey conducted under subd. 2. It shall also describe any significant changes that have occurred in the watershed since the last watershed sanitary survey. If a system determines during implementation that making a significant change to its approved watershed control program is necessary, the water supplier shall notify the department prior to making any changes. If any change is likely to reduce the level of source water protection, the water supplier shall also list in this notification the actions the system will take to mitigate this effect.

NR 810.42(1)(e)2. 2. Undergo a watershed sanitary survey every 3 years for community water systems and every 5 years for noncommunity water systems and submit the survey report to the department. The survey shall be conducted according to department guidelines and by persons the department approves.

NR 810.42(1)(e)2.a. a. The watershed sanitary survey shall meet the following criteria: encompass the region identified in the department-approved watershed control plan as the area of influence; assess the implementation of actions to reduce source water Cryptosporidium levels; and identify any significant new sources of Cryptosporidium.

NR 810.42(1)(e)2.b. b. If the department determines that significant changes may have occurred in the watershed since the previous watershed sanitary survey, systems shall undergo another watershed sanitary survey by a date the department requires, which may be earlier than the regular date in this subdivision.

NR 810.42(1)(e)3. 3. The water supplier for the system shall make the watershed control plan, annual status reports, and watershed sanitary survey reports available to the public upon request. These documents shall be in a plain language style and include criteria by which to evaluate the success of the program in achieving plan goals.

NR 810.42(1)(f) (f) If the department determines that a system is not complying with the approved watershed control plan, the department may withdraw the watershed control program treatment credit.

NR 810.42(2) (2) Alternative source.

NR 810.42(2)(a) (a) A water supplier for a system may conduct source water monitoring that reflects a different intake location, either in the same source or for an alternate source, or a different procedure for the timing or level of withdrawal from the source (alternative source monitoring). If the department approves, a water supplier for that system may determine its bin classification under s. NR 810.34 based on the alternative source monitoring results.

NR 810.42(2)(b) (b) If water suppliers for systems conduct alternative source monitoring under this subsection, water suppliers shall also monitor the current plant intake for the system concurrently as described in s. NR 809.331.

NR 810.42(2)(c) (c) Alternative source monitoring under par. (a) shall meet the requirements for source monitoring to determine bin classification, as described in ss. NR 809.331 to 809.336. Water suppliers shall report the alternative source monitoring results to the department, along with supporting information documenting the operating conditions under which the samples were collected.

NR 810.42(2)(d) (d) If the water supplier for a system determines the system bin classification under s. NR 810.34 using alternative source monitoring results that reflect a different intake location or a different procedure for managing the timing or level of withdrawal from the source, the system shall relocate the intake or permanently adopt the withdrawal procedure, as applicable, no later than the applicable treatment compliance date in s. NR 810.37.

NR 810.42 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.43 NR 810.43 Pre-filtration treatment toolbox components.

NR 810.43(1) (1) Presedimentation. Systems receive 0.5-log Cryptosporidium treatment credit for a presedimentation basin during any month the process meets the criteria in this subsection.

NR 810.43(1)(a) (a) The presedimentation basin shall be in continuous operation and shall treat the entire plant flow taken from a surface water or GWUDI source.

NR 810.43(1)(b) (b) The system shall continuously add a coagulant to the presedimentation basin.

NR 810.43(1)(c) (c) The presedimentation basin shall achieve the following performance criteria:

NR 810.43(1)(c)1. 1. Demonstrates at least 0.5-log mean reduction of influent turbidity. This reduction shall be determined using daily turbidity measurements in the presedimentation process influent and effluent and shall be calculated as follows: log10(monthly mean of daily influent turbidity)-log10(monthly mean of daily effluent turbidity).

NR 810.43(1)(c)2. 2. Complies with department-approved performance criteria that demonstrate at least 0.5-log mean removal of micron-sized particulate material through the presedimentation process.

NR 810.43(2) (2) Two-stage lime softening. Systems receive an additional 0.5-log Cryptosporidium treatment credit for a 2-stage lime softening plant if chemical addition and hardness precipitation occur in 2 separate and sequential softening stages prior to filtration. Both softening stages shall treat the entire plant flow taken from a surface water or GWUDI source.

NR 810.43(3) (3) Bank filtration. Systems receive Cryptosporidium treatment credit for bank filtration that serves as pretreatment to a filtration plant by meeting the criteria in this subsection. Systems using bank filtration when they begin source water monitoring under s. NR 809.331 (1) shall collect samples as described in s. NR 809.333 (4) and are not eligible for this credit.

NR 810.43(3)(a) (a) Wells with a groundwater flow path of at least 25 feet receive 0.5-log treatment credit; wells with a groundwater flow path of at least 50 feet receive 1.0-log treatment credit. The groundwater flow path shall be determined as specified in par. (d).

NR 810.43(3)(b) (b) Only wells in granular aquifers are eligible for treatment credit. Granular aquifers are those comprised of sand, clay, silt, rock fragments, pebbles or larger particles, and minor cement. A system shall characterize the aquifer at the well site to determine aquifer properties. Systems shall extract a core from the aquifer and demonstrate that in at least 90% of the core length, grains less than 1.0 mm in diameter constitute at least 10% of the core material.

NR 810.43(3)(c) (c) Only horizontal and vertical wells are eligible for treatment credit.

NR 810.43(3)(d) (d) For vertical wells, the groundwater flow path is the measured distance from the edge of the surface water body under high flow conditions, determined by the 100-year floodplain elevation boundary or by the floodway, as defined in federal emergency management agency flood hazard maps, to the well screen. For horizontal wells, the groundwater flow path is the measured distance from the bed of the river under normal flow conditions to the closest horizontal well lateral screen.

NR 810.43(3)(e) (e) The water supplier for the system shall monitor each wellhead for turbidity at least once every 4 hours while the bank filtration process is in operation. If monthly average turbidity levels, based on daily maximum values in the well, exceed one NTU, the water supplier for the system shall report this result to the department and conduct an assessment within 30 days to determine the cause of the high turbidity levels in the well. If the department determines that microbial removal has been compromised, the department may revoke treatment credit until the system implements corrective actions approved by the department to remediate the problem.

NR 810.43(3)(f) (f) Springs and infiltration galleries are not eligible for treatment credit under this section, but are eligible for credit under s. NR 810.44 (3).

NR 810.43(3)(g) (g) The department may approve Cryptosporidium treatment credit for bank filtration based on a demonstration of performance study that meets the criteria in this paragraph. This treatment credit may be greater than 1.0-log and may be awarded to bank filtration that does not meet the criteria in pars. (a) to (e).

NR 810.43(3)(g)1. 1. The study shall follow a department-approved protocol and shall involve the collection of data on the removal of Cryptosporidium or a surrogate for Cryptosporidium and related hydrogeologic and water quality parameters during the full range of operating conditions.

NR 810.43(3)(g)2. 2. The study shall include sampling both from the production well or wells and from monitoring wells that are screened and located along the shortest flow path between the surface water source and the production well or wells.

NR 810.43 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.44 NR 810.44 Treatment performance toolbox components.

NR 810.44(1) (1) Combined filter performance. Public water systems using conventional filtration treatment or direct filtration treatment receive an additional 0.5-log Cryptosporidium treatment credit during any month the system meets the criteria in this subsection. Combined filter effluent (CFE) turbidity shall be less than or equal to 0.15 NTU in at least 95% of the measurements. Turbidity shall be measured as described in s. NR 809.113 (1), Tables A and B.

NR 810.44(2) (2) Individual filter performance. Public water systems using conventional filtration treatment or direct filtration treatment receive 0.5-log Cryptosporidium treatment credit, which may be in addition to the 0.5-log credit under sub. (1), during any month the system meets the criteria in this subsection. Compliance with these criteria shall be based on individual filter turbidity monitoring as described in s. NR 809.113 (1) Tables A and B, as applicable.

NR 810.44(2)(a) (a) The filtered water turbidity for each individual filter shall be less than or equal to 0.15 NTU in at least 95% of the measurements recorded each month.

NR 810.44(2)(b) (b) No individual filter may have a measured turbidity greater than 0.3 NTU in 2 consecutive measurements taken 15 minutes apart.

NR 810.44(2)(c) (c) Any system that has received treatment credit for individual filter performance and fails to meet the requirements of par. (a) or (b) during any month does not receive a treatment technique violation under s. NR 810.35 (3) if the department determines the following:

NR 810.44(2)(c)1. 1. The failure was due to unusual and short-term circumstances that could not reasonably be prevented through optimizing treatment plant design, operation, and maintenance.

NR 810.44(2)(c)2. 2. The system has experienced no more than 2 such failures in any calendar year.

NR 810.44(3) (3) Demonstration of performance. The department may approve Cryptosporidium treatment credit for drinking water treatment processes based on a demonstration of performance study that meets the criteria in this subsection. This treatment credit may be greater than or less than the prescribed treatment credits in s. NR 810.35 or ss. NR 810.43 to 810.46 and may be awarded to treatment processes that do not meet the criteria for the prescribed credits.