Chapter NR 810

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.

NR 810.44(3)(a) (a) Systems cannot receive the prescribed treatment credit for any toolbox box option in ss. NR 810.43 to 810.46 if that toolbox option is included in a demonstration of performance study for which treatment credit is awarded under this subsection.

NR 810.44(3)(b) (b) The demonstration of performance study shall follow a department-approved protocol and shall demonstrate the level of Cryptosporidium reduction the treatment process will achieve under the full range of expected operating conditions for the system.

NR 810.44(3)(c) (c) Approval by the department shall be in writing and may include monitoring and treatment performance criteria that the water supplier for the system shall demonstrate and report on an ongoing basis to remain eligible for the treatment credit. The department may designate the criteria where necessary to verify that the conditions under which the demonstration of performance credit was approved are maintained during routine operation.

NR 810.44 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.45 NR 810.45 Additional filtration toolbox components.

NR 810.45(1) (1) Bag or cartridge filters. Public water systems receive Cryptosporidium treatment credit of up to 2.0-log for individual bag or cartridge filters and up to 2.5-log for bag or cartridge filters operated in series by meeting the criteria in pars. (a) to (j). To be eligible for this credit, water suppliers for systems shall report the results of challenge testing that meets the requirements of pars. (b) to (i) to the department. The filters shall treat the entire plant flow taken from a surface water or GWUDI source.

NR 810.45(1)(a) (a) The Cryptosporidium treatment credit awarded to bag or cartridge filters shall be based on the removal efficiency demonstrated during challenge testing that is conducted according to the criteria in pars. (b) to (i). A factor of safety equal to 1-log for individual bag or cartridge filters and 0.5-log for bag or cartridge filters in series shall be applied to challenge testing results to determine removal credit. Systems may use results from challenge testing conducted prior to January 5, 2006 if the prior testing was consistent with the criteria specified in pars. (b) to (i).

NR 810.45(1)(b) (b) Challenge testing shall be performed on full-scale bag or cartridge filters, and the associated filter housing or pressure vessel, that are identical in material and construction to the filters and housings the system will use for removal of Cryptosporidium. Bag or cartridge filters shall be challenge tested in the same configuration that the system will use, either as individual filters or as a series configuration of filters.

NR 810.45(1)(c) (c) Challenge testing shall be conducted using Cryptosporidium or a surrogate that is removed no more efficiently than Cryptosporidium. The microorganism or surrogate used during challenge testing is referred to as the challenge particulate. The concentration of the challenge particulate shall be determined using a method capable of discreetly quantifying the specific microorganism or surrogate used in the test; gross measurements such as turbidity may not be used.

NR 810.45(1)(d) (d) The maximum feed water concentration that can be used during a challenge test shall be based on the detection limit of the challenge particulate in the filtrate, including filtrate detection limit, and shall be calculated using the following equation:

Maximum Feed Concentration = 1 ´ 104 ´ (Filtrate Detection Limit)

NR 810.45(1)(e) (e) Challenge testing shall be conducted at the maximum design flow rate for the filter as specified by the manufacturer.

NR 810.45(1)(f) (f) Each filter evaluated shall be tested for a duration sufficient to reach 100% of the terminal pressure drop, which establishes the maximum pressure drop under which the filter may be used to comply with the requirements of this chapter.

NR 810.45(1)(g) (g) Removal efficiency of a filter shall be determined from the results of the challenge test and expressed in terms of log removal values using the following equation:

LRV = LOG10(Cf)-LOG10(Cp)

Where:

LRV = log removal value demonstrated during challenge testing; Cf= the feed concentration measured during the challenge test; and Cp= the filtrate concentration measured during the challenge test. In applying this equation, the same units shall be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, then the term Cp shall be set equal to the detection limit.

NR 810.45(1)(h) (h) Each filter tested shall be challenged with the challenge particulate during 3 periods over the filtration cycle: within 2 hours of start-up of a new filter; when the pressure drop is between 45% and 55% of the terminal pressure drop; and at the end of the cycle after the pressure drop has reached 100% of the terminal pressure drop. An LRV shall be calculated for each of these challenge periods for each filter tested. The LRV for the filter (LRVfilter) shall be assigned the value of the minimum LRV observed during the 3 challenge periods for that filter.

NR 810.45(1)(i) (i) If fewer than 20 filters are tested, the overall removal efficiency for the filter product line shall be set equal to the lowest LRVfilter among the filters tested. If 20 or more filters are tested, the overall removal efficiency for the filter product line shall be set equal to the 10th percentile of the set of LRVfilter values for the various filters tested. The percentile is defined by (i/(n+1)) where i is the rank of n individual data points ordered lowest to highest. If necessary, the 10th percentile may be calculated using linear interpolation.

NR 810.45(1)(j) (j) If a previously tested filter is modified in a manner that could change the removal efficiency of the filter product line, challenge testing to demonstrate the removal efficiency of the modified filter shall be conducted and submitted to the department.

NR 810.45(2) (2) Membrane filtration.

NR 810.45(2)(a) (a) Definitions. In this subsection:

NR 810.45(2)(a)1. 1. “Flux” means the throughput of a pressure driven membrane process expressed as flow per unit of membrane area.

NR 810.45(2)(a)2. 2. “Module” means the smallest component of a membrane unit in which a specific membrane surface area is housed in a device with a filtrate outlet structure.

NR 810.45(2)(a)3. 3. “Recovery” means the volumetric percent of feed water that is converted to filtrate over the course of an operating cycle uninterrupted by events such as chemical cleaning or a solids removal process such as backwashing.

NR 810.45(2)(b) (b) Removal credit. Systems receive Cryptosporidium treatment credit for membrane filtration that meets the criteria of this paragraph. Membrane cartridge filters that meet the definition of membrane filtration in s. NR 810.02 (27) are eligible for this credit. The level of treatment credit a system receives is equal to the lower of the values determined under the following:

NR 810.45(2)(b)1. 1. The removal efficiency demonstrated during challenge testing conducted under the conditions in par. (b).

NR 810.45(2)(b)2. 2. The maximum removal efficiency that can be verified through direct integrity testing used with the membrane filtration process under the conditions in par. (c).

NR 810.45(2)(c) (c) Challenge testing. The membrane used by the system shall undergo challenge testing to evaluate removal efficiency, and the water supplier for the system shall report the results of challenge testing to the department. Challenge testing shall be conducted according to the criteria in subds. 1 to 7. Systems may use data from challenge testing conducted prior to January 5, 2006, if the prior testing was consistent with the following criteria:

NR 810.45(2)(c)1. 1. Challenge testing shall be conducted on either a full-scale membrane module, identical in material and construction to the membrane modules used in the system’s treatment facility, or a smaller-scale membrane module, identical in material and similar in construction to the full-scale module.

NR 810.45(2)(c)2. 2. Challenge testing shall be conducted using Cryptosporidium oocysts or a surrogate that is removed no more efficiently than Cryptosporidium oocysts. The organism or surrogate used during challenge testing is referred to as the challenge particulate. The concentration of the challenge particulate, in both the feed and filtrate water, shall be determined using a method capable of discretely quantifying the specific challenge particulate used in the test; gross measurements such as turbidity may not be used.

NR 810.45(2)(c)3. 3. The maximum feed water concentration that may be used during a challenge test is based on the detection limit of the challenge particulate in the filtrate and shall be determined according to the following equation:

Maximum Feed Concentration = 3.16 ´ 106 ´ (Filtrate Detection Limit)

NR 810.45(2)(c)4. 4. Challenge testing shall be conducted under representative hydraulic conditions at the maximum design flux and maximum design process recovery specified by the manufacturer for the membrane module.

NR 810.45(2)(c)5. 5. Removal efficiency of a membrane module shall be calculated from the challenge test results and expressed as a log removal value according to the following equation:

LRV = LOG10(Cf) - LOG10(Cp)

Where:

LRV = log removal value demonstrated during the challenge test; Cf = the feed concentration measured during the challenge test; and Cp= the filtrate concentration measured during the challenge test. Equivalent units shall be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, the term Cp is set equal to the detection limit for the purpose of calculating the LRV. An LRV shall be calculated for each membrane module evaluated during the challenge test.

NR 810.45(2)(c)6. 6. The removal efficiency of a membrane filtration process demonstrated during challenge testing shall be expressed as a log removal value (LRVC-Test). If fewer than 20 modules are tested, then LRVC-Test is equal to the lowest of the representative LRVs among the modules tested. If 20 or more modules are tested, then LRVC-Test is equal to the 10th percentile of the representative LRVs among the modules tested. The percentile is defined by (i/(n+1)) where i is the rank of n individual data points ordered lowest to highest. If necessary, the 10th percentile may be calculated using linear interpolation.