Mo. Code Regs. tit. 10 § 60-4.052

Current through Register Vol. 49, No. 23, December 2, 2024

Section 10 CSR 60-4.052 - Source Water Monitoring and Enhanced Treatment Requirements

PURPOSE: This amendment corrects regulation citations due to concurrent rulemaking amendments in 10 CSR 60-4.

(1) Enhanced Treatment for Cryptosporidium General Requirements.

(A) The requirements of this rule are national primary drinking water regulations. The regulations in this rule establish or extend treatment technique requirements in lieu of maximum contaminant levels for Cryptosporidium. These requirements are in addition to requirements for filtration and disinfection in 10 CSR 60-4.050 and 10 CSR 60-4.055.

(B) Applicability.

1. The requirements of this rule apply to all public water systems supplied by a surface water source and public water systems supplied by a ground water source under the direct influence of surface water.

2. Wholesale systems, as defined in 10 CSR 60-2.015, must comply with the requirements of this rule based on the population of the largest system in the combined distribution system.

(C) Requirements. Systems subject to this rule must comply with the following requirements:

1. Systems must conduct an initial and a second round of source water monitoring for each plant that treats a surface water or ground water under the direct influence of surface water (GWUDISW) source. This monitoring may include sampling for Cryptosporidium, E. coli, and turbidity as described in sections (2)-(6) of this rule, to determine what level, if any, of additional Cryptosporidium treatment they must provide;

2. Systems that plan to make a significant change to their disinfection practice must develop disinfection profiles and calculate disinfection benchmarks, as described in sections (8) and (9) of this rule;

3. Filtered systems must determine their Cryptosporidium treatment bin classification as described in section (10) of this rule and provide additional treatment for Cryptosporidium, if required, as described in section (11) of this rule. Filtered systems must implement Cryptosporidium treatment according to the schedule in section (12) of this rule;

4. Systems required to provide additional treatment for Cryptosporidium must implement microbial toolbox options that are designed and operated as described in sections (13)-(18) of this rule; and

5. Systems must comply with the applicable record-keeping and reporting requirements described in 10 CSR 60-7.010 and 10 CSR 60-9.010.

(2) Source Water Monitoring Requirements.

(A) Initial Round of Source Water Monitoring. Systems must conduct the following monitoring on the schedule in subsection (2)(C) of this rule unless they meet the monitoring exemption criteria in subsection (2)(D) of this rule.

1. Filtered systems serving at least ten thousand (10,000) people must sample their source water for Cryptosporidium, E. coli, and turbidity at least monthly for twenty-four (24) months.

2. Filtered systems serving fewer than ten thousand (10,000) people must sample their source water for E. coli at least once every two (2) weeks for twelve (12) months.

3. A filtered system serving fewer than ten thousand (10,000) people may avoid E. coli monitoring if the system notifies the department that it will monitor for Cryptosporidium as described in paragraph (2)(A)4. of this rule. The system must notify the department no later than three (3) months prior to the date the system is otherwise required to start E. coli monitoring under subsection (2)(C) of this rule.

4. Filtered systems serving fewer than ten thousand (10,000) people must sample their source water for Cryptosporidium at least twice per month for twelve (12) months or at least monthly for twenty-four (24) months if they meet one (1) of the following, based on monitoring conducted under paragraphs (2)(A)2. and 3. of this rule.

A. For systems using lake or reservoir sources, the annual mean E. coli concentration is greater than 10 E. coli/100 mL.

B. For systems using flowing stream sources, the annual mean E. coli concentration is greater than 50 E. coli/100 mL.

C. The system does not conduct E. coli monitoring as described in paragraphs (2)(A)2. and 3. of this rule.

D. Systems using ground water under the direct influence of surface water (GWUDISW) must comply with the requirements of paragraph (2)(A)4. of this rule based on the E. coli level that applies to the nearest surface water body. If no surface water body is nearby, the system must comply based on the requirements that apply to systems using lake/reservoir sources.

5. For filtered systems serving fewer than ten thousand (10,000) people, the department may approve monitoring for an indicator other than E. coli under paragraph (2)(A)2. of this rule. The department also may approve an alternative to the E. coli concentration in subparagraph (2)(A)4.A., B., or D. of this rule to trigger Cryptosporidium monitoring. This approval by the department must be provided to the system in writing and must include the basis for the department's determination that the alternative indicator and/or trigger level will provide a more accurate identification of whether a system will exceed the Bin 1 Cryptosporidium level in section (10) of this rule.

6. Systems may sample more frequently than required under this section if the sampling frequency is evenly spaced throughout the monitoring period.

(B) Second Round of Source Water Monitoring. Systems must conduct a second round of source water monitoring that meets the requirements for monitoring parameters, frequency, and duration described in subsection (2)(A) of this rule, unless they meet the monitoring exemption criteria in subsection (2)(D) of this rule. Systems must conduct this monitoring on the schedule in subsection (2)(C) of this rule.

(C) Monitoring Schedule. Systems must begin the monitoring required in subsection (2)(A) and subsection (2)(B) of this rule no later than the month beginning with the date listed in this table-

Source Water Monitoring Starting Dates Table

Systems that serve:	Must begin the first round of source water monitoring no later than the month beginning:	And must begin the second round of source water monitoring no later than the month beginning:
At least 100,000 people	October 1, 2006	April 1, 2015
From 50,000 to 99,999	April 1, 2007	October 1, 2015
From 10,000 to 49,999	April 1, 2008	October 1, 2016
Fewer than 10,000 and monitor for E. coli	October 1, 2008	October 1, 2017
Fewer than 10,000 and monitor for Cryptosporidium (Applies to filtered systems that meet the conditions of paragraph (2)(A)3. of this rule.)	April 1, 2010	April 1, 2019

(D) Monitoring Avoidance.

1. Filtered systems are not required to conduct source water monitoring under this rule if the system will provide a total of at least 5.5-log of treatment for Cryptosporidium, equivalent to meeting the treatment requirements of Bin 4 in section (11) of this rule.

2. If a system chooses to provide the level of treatment in paragraph (2)(D)1. of this rule as applicable, rather than start source water monitoring, the system must notify the department in writing no later than the date the system is otherwise required to submit a sampling schedule for monitoring under section (3) of this rule. Alternatively, a system may choose to stop sampling at any point after it has initiated monitoring if it notifies the department in writing that it will provide this level of treatment. Systems must install and operate technologies to provide this level of treatment by the applicable treatment compliance date in section (12) of this rule.

(E) Plants Operating Only Part of the Year. Systems with plants that operate for only part of the year must conduct source water monitoring in accordance with this rule, but with the following modifications:

1. Systems must sample their source water only during the months that the plant operates unless the department specifies another monitoring period based on plant operating practices.

2. Systems with plants that operate less than six (6) months per year and that monitor for Cryptosporidium must collect at least six (6) Cryptosporidium samples per year during each of two (2) years of monitoring. Samples must be evenly spaced throughout the period the plant operates.

(F) New Source Requirements.

1. A system that begins using a new source of surface water or GWUDISW after the system is required to begin monitoring under subsection (2)(C) of this rule must monitor the new source on a schedule the department approves. Source water monitoring must meet the requirements of this rule. The system must also meet the bin classification and Cryptosporidium treatment requirements of sections (10) and (11) of this rule, as applicable, for the new source on a schedule the department approves.

2. The requirements of subsection (2)(F) of this rule apply to surface water systems and ground water under the direct influence of surface water systems that begin operation after the monitoring start date applicable to the system's size under subsection (2)(C) of this rule.

3. The system must begin a second round of source water monitoring no later than six (6) years following initial bin classification under section (10) of this rule.

(G) Failure to collect any source water sample required under this section in accordance with the sampling schedule, sampling location, analytical method, approved laboratory, and reporting requirements of sections (3) through (6) of this rule is a monitoring violation.

(H) Grandfathering Monitoring Data. Systems may use (i.e., may "grandfather") monitoring data collected prior to the applicable monitoring start date in subsection (2)(C) to meet the initial source water monitoring requirements in subsection (2)(A) of this rule. Grandfathered data may substitute for an equivalent number of months at the end of the monitoring period. All data submitted under subsection (2)(H) must meet the requirements in section (7) of this rule.

(3) Sampling Schedules.

(A) Systems required to conduct source water monitoring under section (2) of this rule must submit a sampling schedule that specifies the calendar dates when the system will collect each required sample.

1. Systems must submit sampling schedules no later than three (3) months prior to the applicable date listed in subsection (2)(C) of this rule for each round of required monitoring.

2. Systems serving at least ten thousand (10,000) people must submit their sampling schedule for the initial round of source water monitoring under subsection (2)(A) of this rule to the Environmental Protection Agency (EPA) electronically at the web address specified by the E PA for this purpose. If a system is unable to submit the sampling schedule electronically, the system may use an alternative approach for submitting the sampling schedule that the E PA approves.

3. Systems serving fewer than ten thousand (10,000) people must submit their sampling schedules for the initial round of source water monitoring in subsection (2)(A) of this rule to the department.

4. Systems must submit sampling schedules for the second round of source water monitoring in subsection (2)(B) of this rule to the department.

5. If the E PA or the department does not respond to a system regarding its sampling schedule, the system must sample at the reported schedule.

(B) Systems must collect samples within two (2) days before or two (2) days after the dates indicated in their sampling schedule (that is, within a five (5)-day period around the schedule date) unless one (1) of the conditions of paragraph (3)(B)1. or 2. applies.

1. If an extreme condition or situation exists that may pose danger to the sample collector, or that cannot be avoided and causes the system to be unable to sample in the scheduled five (5)-day period, the system must sample as close to the scheduled date as is feasible unless the department approves an alternative sampling date. The system must submit an explanation for the delayed sampling date to the department concurrent with the shipment of the sample to the laboratory.

2. If a system is unable to report a valid analytical result for a scheduled sampling date due to equipment failure, loss of or damage to the sample, failure to comply with the analytical method requirements, including the quality control requirements in 10 CSR 60-5.010, or the failure of an approved laboratory to analyze the sample, then the system must collect a replacement sample. The system must collect the replacement sample not later than twenty-one (21) days after receiving information that an analytical result cannot be reported for the scheduled date unless the system demonstrates that collecting a replacement sample within this time frame is not feasible or the department approves an alternative resampling date. The system must submit an explanation for the delayed sampling date to the department concurrent with the shipment of the sample to the laboratory.

(C) Systems that fail to meet the criteria of subsection (3)(B) of this rule for any source water sample required under section (2) of this rule must revise their sampling schedules to add dates for collecting all missed samples. Systems must submit the revised schedule to the department for approval prior to when the system begins collecting the missed samples.

(4) Sampling Locations.

(A) Systems required to conduct source water monitoring under section (2) of this rule must collect samples for each plant that treats a surface water or GWUDISW source. Where multiple plants draw water from the same influent, such as the same pipe or intake, the department may approve one (1) set of monitoring results to be used to satisfy the requirements of section (2) of this rule for all plants.

(B) Systems must collect source water samples prior to chemical treatment, such as coagulants, oxidants, and disinfectants, unless the system meets the condition of paragraph (4)(B)1. of this rule.

1. The department may approve a system to collect a source water sample after chemical treatment. To grant this approval, the department must determine that collecting a sample prior to chemical treatment is not feasible for the system and that the chemical treatment is unlikely to have a significant adverse effect on the analysis of the sample.

(C) Systems that recycle filter backwash water must collect source water samples prior to the point of filter backwash water addition.

(D) Bank Filtration Requirements.

1. Systems that receive Cryptosporidium treatment credit for bank filtration under 10 CSR 60-4.050(2)(F) as applicable, must collect source water samples in the surface water prior to bank filtration.

2. Systems that use bank filtration as pretreatment to a filtration plant must collect source water samples from the well (i.e., after bank filtration). Use of bank filtration during monitoring must be consistent with routine operational practice. Systems collecting samples after a bank filtration process may not receive treatment credit for the bank filtration under subsection (15)(C) of this rule.

(E) Multiple Sources. Systems with plants that use multiple water sources, including multiple surface water sources and blended surface water and ground water sources, must collect samples as specified in paragraph (4)(E)1. or 2. of this rule. The use of multiple sources during monitoring must be consistent with routine operational practice.

1. If a sampling tap is available where the sources are combined prior to treatment, systems must collect samples from the tap.

2. If a sampling tap where the sources are combined prior to treatment is not available, systems must collect samples at each source near the intake on the same day and must follow either sub-paragraph (4)(E)2.A. or B. of this rule for sample analysis.

A. Systems may take composite samples from each source into one (1) sample prior to analysis. The volume of sample from each source must be weighted according to the proportion of the source in the total plant flow at the time the sample is collected.

B. Systems may analyze samples from each source separately and calculate a weighted average of the analysis results for each sampling date. The weighted average must be calculated by multiplying the analysis result for each source by the fraction the source contributed to total plant flow at the time the sample was collected and then summing these values.

(F) Additional Requirements. Systems must submit a description of their sampling location(s) to the department at the same time as the sampling schedule required under section (3) of this rule. This description must address the position of the sampling location in relation to the system's water source(s) and treatment processes, including pretreatment, points of chemical treatment, and filter backwash recycle. If the department does not respond to a system regarding sampling location(s), the system must sample at the reported location(s).

(5) Approved Laboratories.

(A)Cryptosporidium. Systems must have Cryptosporidium samples analyzed by a laboratory that is approved under the EPA's Laboratory Quality Assurance Evaluation Program for Analysis of Cryptosporidium in Water or a laboratory that has been certified for Cryptosporidium analysis by an equivalent state laboratory certification program.

(B)E. Coli. Any laboratory certified by the EPA, the National Environmental Laboratory Accreditation Conference, or the department for total coliform or fecal coliform analysis under 10 CSR 60-5.010(3) is approved for E. coli analysis under this rule when the laboratory uses the same technique for E. coli that the laboratory uses for 10 CSR 60-5.010(3).

(C) Turbidity. Measurements of turbidity must be made by a party approved by the department.

(6) Reporting Source Water Monitoring Results.

(A) Systems must report results from the source water monitoring required under section (2) of this rule no later than ten (10) days after the end of the first month following the month when the sample is collected.

(B) All systems serving at least ten thousand (10,000) people must report the results from the initial source water monitoring required under subsection (2)(A) of this rule to the E PA electronically at the web address specified by the E PA for this purpose. If a system is unable to report monitoring results electronically, the system may use an alternative approach for reporting monitoring results that the E PA approves.

(C) Systems serving fewer than ten thousand (10,000) people must report results from the initial source water monitoring required under subsection (2)(A) of this rule to the department.

(D) All systems must report results from the second round of source water monitoring required under subsection (2)(B) of this rule to the department.

(E) Systems must report the following applicable information for the source water monitoring required under section (2) of this rule:

1. For each Cryptosporidium analysis-

A.Systems must report the following data elements:

(I) Public water system (PWS) ID;

(II) Facility ID;

(III) Sample collection date;

(IV) Sample type (field or matrix spike);

(V) Sample volume filtered (L), to nearest;

(VI) Was one hundred percent (100%) of filtered volume examined; and

(VII) Number of oocysts counted;

B. For matrix spike samples, systems must also report the sample volume spiked and estimated number of oocysts spiked. These data are not required for field samples;

C. For samples in which less than ten (10) L is filtered or less than one hundred percent (100%) of the sample volume is examined, systems must also report the number of filters used and the packed pellet volume; and

D. For samples in which less than one hundred percent (100%) of sample volume is examined, systems must also report the volume of resuspended concentrate and volume of this resuspension processed through immunomagnetic separation; and

2. For each E. coli analysis, systems must report the following data elements:

A. PWS ID;

B. Facility ID;

C. Sample collection date;

D. Analytical method number;

E. Method type;

F. Source type (flowing stream, lake/reservoir, GWUDISW);

G.E. coli/100 mL; and

H. Turbidity. (Systems serving fewer than ten thousand (10,000) people that are not required to monitor for turbidity under section (2) of this rule are not required to report turbidity with their E. coli results.)

(7) Grandfathering Previously Collected Data.

(A) Systems may use previously collected data to comply with the initial source water monitoring requirements of subsection (2)(A) by grandfathering sample results that were collected before the system is required to begin monitoring. To be grandfathered, the sample results and analysis must meet the criteria in this section and must be approved by the department. A filtered system may grandfather Cryptosporidium samples to meet the requirements of subsection (2)(A) when the system does not have corresponding E. coli and turbidity samples. A system that grandfathers Cryptosporidium samples without E. coli and turbidity samples is not required to collect E. coli and turbidity samples when the system completes the requirements for Cryptosporidium monitoring under subsection (2)(A).

(B)E. Coli Sample Analysis. The analysis of E. coli samples must meet the analytical method and approved laboratory requirements of 10 CSR 60-5.010(3) and section (5) of this rule.

(C)Cryptosporidium Sample Analysis. The analysis of Cryptosporidium samples must meet the criteria in this subsection.

1. Laboratories must have analyzed Cryptosporidium samples using one (1) of these analytical methods:

A. Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA, 2005, United States Environmental Protection Agency, EPA-815-R-05-002;

B. Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 2005, United States Environmental Protection Agency, EPA-815-R-05-001;

C. Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA, 2001, United States Environmental Protection Agency, EPA-821-R-01-025;

D. Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 2001, United States Environmental Protection Agency, EPA-821-R-01-026;

E. Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA, 1999, United States Environmental Protection Agency, EPA-821-R-99-006; and

F. Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 1999, United States Environmental Protection Agency, EPA-821-R-99-001.

2. For each Cryptosporidium sample, the laboratory analyzed at least ten (10) L of sample or at least two (2) mL of packed pellet or as much volume as could be filtered by two (2) filters that E PA approved for the methods listed in paragraph (7)(C)1.

(D) Sampling Location. The sampling location must meet the conditions in section (4) of this rule.

(E) Sampling Frequency. Cryptosporidium samples were collected no less frequently than each calendar month on a regular schedule, beginning no earlier than January 1999. Sample collection intervals may vary for the conditions specified in paragraphs (3)(B)1. and 2. of this rule if the system provides documentation of the condition when reporting monitoring results.

1. The department may approve grandfathering of previously collected data where there are time gaps in the sampling frequency if the system conducts additional monitoring the department specifies to ensure that the data used to comply with the initial source water monitoring requirements of subsection (2)(A) of this rule are seasonally representative and unbiased.

2. Systems may grandfather previously collected data where the sampling frequency varied within each month. If the Cryptosporidium sampling frequency varied, systems must follow the monthly averaging procedure in paragraph (10)(B)5. of this rule, as applicable, when calculating the bin classification for filtered systems.

(F) Reporting Monitoring Results for Grandfathering. Systems that request to grandfather previously collected monitoring results must report the following information by the applicable dates listed in this subsection. Systems serving at least ten thousand (10,000) people must report this information to the EPA unless the department approves reporting to the department rather than the EPA. Systems serving fewer than ten thousand (10,000) people must report this information to the department.

1. Systems must report that they intend to submit previously collected monitoring results for grandfathering. This report must specify the number of previously collected results the system will submit, the dates of the first and last sample, and whether a system will conduct additional source water monitoring to meet the requirements of subsection (2)(A) of this rule. Systems must report this information no later than the date the sampling schedule under section (3) of this rule is required.

2. Systems must report previously collected monitoring results for grandfathering, along with the associated documentation listed in the following subparagraphs no later than two (2) months after the applicable date listed in subsection (2)(C) of this rule:

A. For each sample result, systems must report the applicable data elements in section (6) of this rule;

B. Systems must certify that the reported monitoring results include all results the system generated during the time period beginning with the first reported result and ending with the final reported result. This applies to samples that were collected from the sampling location specified for source water monitoring under this rule, not spiked, and analyzed using the laboratory's routine process for the analytical methods listed in this section;

C. Systems must certify that the samples were representative of a plant's source water(s) and the source water(s) have not changed. Systems must report a description of the sampling location(s), which must address the position of the sampling location in relation to the system's water source(s) and treatment processes, including points of chemical addition and filter backwash recycle; and

D. For Cryptosporidium samples, the laboratory or laboratories that analyzed the samples must provide a letter certifying that the quality control criteria specified in the methods listed in paragraph (7)(C)1. were met for each sample batch associated with the reported results. Alternatively, the laboratory may provide bench sheets and sample examination report forms for each field, matrix spike, Initial Precision and Recovery (IPR), Ongoing Precision and Recovery (OPR), and method blank sample associated with the reported results.

(G) If the department determines that a previously collected data set submitted for grandfathering was generated during source water conditions that were not normal for the system, such as a drought, the department may disapprove the data. Alternatively, the department may approve the previously collected data if the system reports additional source water monitoring data, as determined by the department, to ensure that the data set used under section (10) of this rule represents average source water conditions for the system.

(H) If a system submits previously collected data that fully meet the number of samples required for initial source water monitoring under subsection (2)(A) of this rule and some of the data are rejected due to not meeting the requirements of this section, systems must conduct additional monitoring to replace rejected data on a schedule the department approves. Systems are not required to begin this additional monitoring until two (2) months after notification that data have been rejected and additional monitoring is necessary.

(8) Disinfection Profiling and Benchmarking Requirements.

(A) Following the completion of initial source water monitoring, a system that plans to make a significant change to its disinfection practice, as defined in this section, must develop disinfection profiles and calculate disinfection benchmarks for Giardia lamblia and viruses as described in section (9) of this rule. Prior to changing the disinfection practice, the system must notify the department and must include in this notice the following information:

1. A completed disinfection profile and disinfection benchmark for Giardia lamblia and viruses as described in section (9) of this rule;

2. A description of the proposed change in disinfection practice; and

3. An analysis of how the proposed change will affect the current level of disinfection.

(B) Significant changes to disinfection practice are defined as follows:

1. Changes to the point of disinfection;

2. Changes to the disinfectant(s) used in the treatment plant;

3. Changes to the disinfection process; or

4. Any other modification identified by the department as a significant change to disinfection practice.

(9) Developing the Disinfection Profile and Benchmark.

(A) Systems required to develop disinfection profiles under section (8) of this rule must follow the requirements of this section. Systems must monitor at least weekly for a period of twelve (12) consecutive months to determine the total log inactivation for Giardia lamblia and viruses. If systems monitor more frequently, the monitoring frequency must be evenly spaced. Systems that operate for fewer than twelve (12) months per year must monitor weekly during the period of operation. Systems must determine log inactivation for Giardia lamblia through the entire plant, based on CT_99.9 values in the Guidance Manual for Surface Water System Treatment Requirements, January 1992, as applicable. Systems must determine log inactivation for viruses through the entire treatment plant based on a protocol approved by the department.

(B) Systems with a single point of disinfectant application prior to the entrance to the distribution system must conduct the monitoring specified here. Systems with more than one (1) point of disinfectant application must conduct this monitoring for each disinfection segment. Systems must monitor the parameters necessary to determine the total inactivation ratio, using analytical methods in 10 CSR 60- 5.010.

1. For systems using a disinfectant other than ultraviolet light (UV), the temperature of the disinfected water must be measured at each residual disinfectant concentration sampling point during peak hourly flow or at an alternative location approved by the department.

2. For systems using chlorine, the pH of the disinfected water must be measured at each chlorine residual disinfectant concentration sampling point during peak hourly flow or at an alternative location approved by the department.

3. The disinfectant contact time(s), (t), must be determined during peak hourly flow.

4. The residual disinfectant concentration(s), (C), of the water before or at the first customer and prior to each additional point of disinfectant application must be measured during peak hourly flow.

(C) In lieu of conducting new monitoring under subsection (9)(B), systems may elect to meet the requirements of paragraph (9)(C)1. or 2.

1. Systems that have at least one (1) year of existing data that are substantially equivalent to data collected under the provisions of subsection (9)(B) may use these data to develop disinfection profiles as specified in this section if the system has neither made a significant change to its treatment practice nor changed sources since the data were collected. Systems may develop disinfection profiles using up to three (3) years of existing data.

2. Systems may use disinfection profile(s) developed under 10 CSR 60-4.055(6)(C) in lieu of developing a new profile if the system has neither made a significant change to its treatment practice nor changed sources since the profile was developed. Systems that have not developed a virus profile under 10 CSR 60-4.055(6)(C) must develop a virus profile using the same monitoring data on which the Giardia lamblia profile is based.

(D) Systems must calculate the total inactivation ratio for Giardia lamblia as specified here.

1. Systems using only one (1) point of disinfectant application may determine the total inactivation ratio for the disinfection segment based on either of the methods in subparagraph (9)(D)1.A. or B.

A. Determine one (1) inactivation ratio (CTcalc/CT_99.9) before or at the first customer during peak hourly flow.

B. Determine successive CTcalc/ CT_99.9 values, representing sequential inactivation ratios, between the point of disinfectant application and a point before or at the first customer during peak hourly flow. The system must calculate the total inactivation ratio by determining (CTcalc/CT_99.9) for each sequence and then adding the (CTcalc/ CT_99.9) values together to determine (+

(CTcalc/CT_99.9)).

2. Systems using more than one (1) point of disinfectant application before the first customer must determine the CT value of each disinfection segment immediately prior to the next point of disinfectant application, or for the final segment, before or at the first customer, during peak hourly flow. The (CTcalc/CT_99.9) value of each segment and (+ (CTcalc/CT_99.9)) must be calculated using the method in subparagraph (9)(D)1.A. of this section.

3. The system must determine the total logs of inactivation by multiplying the value calculated in paragraph (9)(D)1. or 2. by three (3).

4. Systems must calculate the log of inactivation for viruses using a protocol approved by the department.

(E) Systems must use the procedures specified in paragraphs (9)(E)1. and 2. to calculate a disinfection benchmark.

1. For each year of profiling data collected and calculated under subsections (9)(A)-(D) of this rule, systems must determine the lowest mean monthly level of both Giardia lamblia and virus inactivation. Systems must determine the mean Giardia lamblia and virus inactivation for each calendar month for each year of profiling data by dividing the sum of daily or weekly Giardia lamblia and virus log inactivation by the number of values calculated for that month.

2. The disinfection benchmark is the lowest monthly mean value (for systems with one (1) year of profiling data) or the mean of the lowest monthly mean values (for systems with more than one (1) year of profiling data) of Giardia lamblia and virus log inactivation in each year of profiling data.

(10) Bin Classification for Filtered Systems.

(A) Following completion of the initial round of source water monitoring required under subsection (2)(A) of this rule, filtered systems must calculate an initial Cryptosporidium bin concentration for each plant for which monitoring was required. Calculation of the bin concentration must use the Cryptosporidium results reported under subsection (2)(A) of this rule and must follow the procedures in subsection (10)(B) of this rule.

(B) Procedures for Bin Determination.

1. For systems that collect a total of at least forty-eight (48) samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.

2. For systems that collect a total of at least twenty-four (24) samples, but not more than forty-seven (47) samples, the bin concentration is equal to the highest arithmetic mean of all sample concentrations in any twelve (12) consecutive months during which Cryptosporidium samples were collected.

3. For systems that serve fewer than ten thousand (10,000) people and monitor for Cryptosporidium for only one (1) year (that is, collect twenty-four (24) samples in twelve (12) months), the bin concentration is equal to the arithmetic mean of all sample concentrations.

4. For systems with plants operating only part of the year that monitor fewer than twelve (12) months per year under subsection (2)(E) of this rule, the bin concentration is equal to the highest arithmetic mean of all sample concentrations during any year of Cryptosporidium monitoring.

5. If the monthly Cryptosporidium sampling frequency varies, systems must first calculate a monthly average for each month of monitoring. Systems must then use these monthly average concentrations, rather than individual sample concentrations, in the applicable calculation for bin classification in paragraphs (10)(B)1.-5. of this rule.

(C) Filtered systems must determine their initial bin classification from the following table and using the Cryptosporidium bin concentration calculated under subsections (10)(A) and (B).

Bin Classification Table for Filtered Systems

For systems that are:	With a Cryptosporidiumbin concentration (based on calculations in subsection (10)(A) or (10)(B) as applicable) of:	The bin classification is:
Required to monitor forCryptosporidiumunder section (2) of this rule.	Cryptosporidium< 0.075 oocyst/LBin 1
	0.075 oocysts/L <=Cryptosporidium<1.0 oocysts/L	Bin 2
	1.0 oocysts/L<= Cryptosporidium< 3.0 oocysts/L	Bin 3
	Cryptosporidium >=3.0 oocysts/L	Bin 4
Serving fewer than 10,000 people and NOT required to monitor forCryptosporidiumunder paragraph (2)(A)3.	NA	Bin 1

(D) Following completion of the second round of source water monitoring required under subsection (2)(B), filtered systems must recalculate their Cryptosporidium bin concentration using the Cryptosporidium results reported under subsection (2)(B) and following the procedures in paragraphs (10)(B)1. through 4. Systems must then redetermine their bin classification using this bin concentration and the table in subsection (10)(C) of this rule.

(E) Reporting Bin Classification Requirements.

1. Filtered systems must report their initial bin classification under subsection (10)(C) to the department for approval no later than six (6) months after the system is required to complete initial source water monitoring based on the schedule in subsection (2)(C) of this rule.

2. Systems must report their bin classification under subsection (10)(D) to the department for approval no later than six (6) months after the system is required to complete the second round of source water monitoring based on the schedule in subsection (2)(C) of this rule.

3. The bin classification report to the department must include a summary of source water monitoring data and the calculation procedure used to determine bin classification.

(F) Failure to comply with the conditions of subsection (10)(E) of this rule is a violation of the treatment technique requirement.

(11) Additional Cryptosporidium Treatment Requirements.

(A) Filtered systems must provide the level of additional treatment for Cryptosporidium specified in this subsection based on their bin classification as determined under section (10) of this rule and according to the schedule in section (12) of this rule.

If the system bin classification is:	And the system uses the following filtration treatment in full compliance with 10 CSR 60-4.050, 10 CSR 60-4.055, and 10 CSR 60-7.010(as applicable), then the additionalCryptosporidiumtreatment requirements are:
If the system bin classification is:	Conventional filtration treatment (including softening)	Direct Filtration	Slow sand or diatomaceous earth filtration	Alternative filtration technologies
Bin 1	No additional treatment	No additional treatment	No additional treatment	No additional treatment
Bin 2	1-log treatment	1.5-log treatment	1-log treatment	As determined by the department such that the totalCryptosporidiumremoval and inactivation is at least 4.0-log.
Bin 3	2-log treatment	2.5-log treatment	2-log treatment	As determined by the department such that the totalCryptosporidiumremoval and inactivation is at least 5.0-log.
Bin 4	2.5-log treatment	3-log treatment	2.5-log treatment	As determined by the department such that the totalCryptosporidiumremoval and inactivation is at least 5.5-log.

(B) Filtered systems must use one (1) or more of the treatment and management options listed in section (13) of this rule, termed the Microbial Toolbox, to comply with the additional Cryptosporidium treatment required in subsection (11)(A) of this rule.

1. Systems classified in Bin 3 and Bin 4 must achieve at least 1-log of the additional Cryptosporidium treatment required under subsection (11)(A) of this rule using either one (1) or a combination of the following: bag filters, bank filtration, cartridge filters, chlorine dioxide, membranes, ozone, or UV, as described in sections (14) through (18) of this rule.

(C) Failure by a system in any month to achieve treatment credit by meeting criteria in sections (14) through (18) of this rule for microbial toolbox options that is at least equal to the level of treatment required in subsection (11)(A) of this rule is a violation of the treatment technique requirement.

(D) If the department determines during a sanitary survey or an equivalent source water assessment that, after a system completed the monitoring conducted under subsection (2)(A) or (2)(B) of this rule, significant changes occurred in the system's watershed that could lead to increased contamination of the source water by Cryptosporidium, the system must take actions specified by the department to address the contamination. These actions may include additional source water monitoring and/or implementing microbial toolbox options listed in section (13) of this rule.

(12) Schedule for Compliance With Cryptosporidium Treatment Requirements.

(A) Following initial bin classification under subsection (10)(C), filtered systems must provide the level of treatment for Cryptosporidium required under section (11) according to the following Cryptosporidium treatment compliance dates.

Cryptosporidium Treatment Compliance Dates Table
Systems that serve:	Must comply withCryptosporidiumtreatment requirements no later than the following dates, except that the department may allow up to an additional two (2) years for complying with the treatment requirement for systems making capital improvements:
1. At least 100,000 people	April 1, 2012
2. From 50,000 to 99,999 people	October 1, 2012
3. From 10,000 to 49,999 people	October 1, 2013
4. Fewer than 10,000 people	October 1, 2014

(B) If the bin classification for a filtered system changes following the second round of source water monitoring, as determined under subsection (10)(D) of this rule, the system must provide the level of treatment for Cryptosporidium required under section (11) of this rule on a schedule the department approves.

(13) Microbial Toolbox Options for Meeting Cryptosporidium Treatment Requirements.

(A) Systems receive the treatment credit listed in the table in subsection (13)(B) of this rule by meeting the conditions for microbial toolbox options described in sections (14) through (18) of this rule. Systems apply these treatment credits to meet the treatment requirements in section (11) of this rule, as applicable.

(B) The following table summarizes options in the microbial toolbox:

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

Toolbox Option	Cryptosporidium treatment credit with design and implementation criteria
Source Protection and Management Toolbox Options
Watershed control program	0.5-log credit for department-approved program comprising required elements, annual program status report to the department, and regular watershed survey. Specific criteria are in subsection (14)(A).
Alternative source/intake management	No prescribed credit. Systems may conduct simultaneous monitoring for treatment bin classification at alternative intake locations or under alternative management strategies. Specific criteria are in subsection (14)(B).
Pre-Filtration Toolbox Options
Presedimentation basin with coagulation	0.5-log credit during any month that presedimentation basins achieve a monthly mean reduction of 0.5-log or greater in turbidity or alternative department-approved performance criteria. To be eligible, basins must be operated continuously with coagulant addition and all plant flow must pass through basins. Specific criteria are in subsection (15)(A).
Two-stage lime softening	0.5-log credit for two-stage softening where chemical addition and hardness precipitation occur in both stages. All plant flow must pass through both stages. Single-stage softening is credited as equivalent to conventional treatment. Speciflc criteria are in subsection (15)(B).
Bank filtration	0.5-log credit for 25-foot setback; 1.0-log credit for 50-foot setback; aquifer must be unconsolidated sand containing at least ten percent (10%) flnes; average turbidity in wells must be less than one (1) NTU. Systems using wells followed by filtration when conducting source water monitoring must sample the well to determine bin classiflcation and are not eligible for additional credit. Specific criteria are in subsection (15)(C).
Treatment Perfomance Toolbox Options
Combined filter performance	0.5-log credit for combined filter effluent turbidity less than or equal to 0.15 NTU in at least ninety-five percent (95%) of measurements each month. Specific criteria are in subsection (16)(A).
Individual filter performance	0.5-log credit (in addition to 0.5-log combined filter performance credit) if individual filter effluent turbidity is less than or equal to 0.15 NTU in at least ninety-flve percent (95%) of samples each month in each filter and is never greater than 0.3 NTU in two consecutive measurements in any filter. Specific criteria are in subsection (16)(B).
Demonstration of performance	Credit awarded to unit process or treatment train based on a demonstration to the department with a department-approved protocol. Specific criteria are in subsection (16)(C).
Bag or cartridge filters (individual filters)	Up to 2-log credit based on the removal efficiency demonstrated during challenge testing with a 1.0-log factor of safety. Specific criteria are in subsection (17)(A).
Bag or cartridge filters (in series)	Up to 2.5-log credit based on the removal efficiency demonstrated during challenge testing with a 0.5-log factor of safety. Specific criteria are in subsection (17)(A).
Membrane filtration	Log credit equivalent to removal efficiency demonstrated in challenge test for device if supported by direct integrity testing. Specific criteria are in subsection (17)(B).
Second stage filtration	0.5-log credit for second separate granular media filtration stage if treatment train includes coagulation prior to first filter. Specific criteria are in subsection (17)(C).
Slow sand filtration	2.5-log credit as a secondary filtration step; 3.0-log credit as a primary filtration process. No prior chlorination for either option. Specific criteria are in subsection (17)(D).
Inactivation Toolbox Options
Chlorine dioxide	Log credit based on measured CT in relation to CT table. Specific criteria in subsection (18)(B).
Ozone	Log credit based on measured CT in relation to CT table. Speciflc criteria in subsection (18)(B).
Ultra-violet	Log credit based on validated UV dose in relation to UV dose table; reactor validation testing required to establish UV dose and associated operating conditions. Specific criteria in subsection (18)(D).

(14) Source Toolbox Components.

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

1. Systems that intend to apply for the watershed control program credit must notify the department of this intent no later than two (2) years prior to the treatment compliance date applicable to the system in section (12) of this rule.

2. Systems must submit to the department a proposed watershed control plan no later than one (1) year before the applicable treatment compliance date in section (12) of this rule. The department must approve the watershed control plan for the system to receive watershed control program treatment credit. The watershed control plan must include the elements in subparagraphs (14)(A)2.A.-D. of this rule.

A. Identification of an "area of influence" outside of which the likelihood of Cryptosporidium or fecal contamination affecting the treatment plant intake is not significant. This is the area to be evaluated in future watershed surveys under subparagraph (14)(A)5.B.

B. 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.

C. 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.

D. A statement of goals and specific actions the system will undertake to reduce source water Cryptosporidium levels. The plan must 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.

3. Systems with existing watershed control programs (that is, programs in place on January 5, 2006) are eligible to seek this credit. Their watershed control plans must meet the criteria in paragraph (14)(A)2. of this rule and must specify ongoing and future actions that will reduce source water Cryptosporidium levels.

4. If the department does not respond to a system 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 such approval.

5. Systems must complete the actions in subparagraphs (14)(A)5.A.-C. of this rule to maintain the 0.5-log credit.

A. Submit an annual watershed control program status report to the department. The annual watershed control program status report must describe the system's implementation of the approved plan and assess the adequacy of the plan to meet its goals. It must 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 subparagraph (14)(A)5.B. of this rule. It must 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 system must notify the department prior to making any such changes. If any change is likely to reduce the level of source water protection, the system must also list in its notification the actions the system will take to mitigate this effect.

B. Undergo a watershed sanitary survey every three (3) years for community water systems and every five (5) years for noncommunity water systems and submit the survey report to the department. The survey must be conducted according to department guidelines and by persons the department approves.

(I) The watershed sanitary survey must 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.

(II) If the department determines that significant changes may have occurred in the watershed since the previous watershed sanitary survey, systems must undergo another watershed sanitary survey by a date the department requires, which may be earlier than the regular date in subparagraph (14)(A)5.B. of this rule.

C. The system must make the watershed control plan, annual status reports, and watershed sanitary survey reports available to the public upon request. These documents must be in a plain language style and include criteria by which to evaluate the success of the program in achieving plan goals. The department may approve systems to withhold from the public portions of the annual status report, watershed control plan, and watershed sanitary survey based on water supply security considerations.

6. If the department determines that a system is not carrying out the approved watershed control plan, the department may withdraw the watershed control program treatment credit.

(B) Alternative Source Requirements.

1. 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 system may determine its bin classification under section (10) of this rule based on the alternative source monitoring results.

2. If systems conduct alternative source monitoring under paragraph (14)(B)1. of this rule, systems must also monitor their current plant intake concurrently as described in section (2) of this rule.

3. Alternative source monitoring under paragraph (14)(B)1. of this rule must meet the requirements for source monitoring to determine bin classification, as described in sections (2)-(6) of this rule. Systems must report the alternative source monitoring results to the department, along with supporting information documenting the operating conditions under which the samples were collected.

4. If a system determines its bin classification under section (10) of this rule 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 must relocate the intake or permanently adopt the withdrawal procedure, as applicable, no later than the applicable treatment compliance date in section (12) of this rule.

(15) Pre-Filtration Treatment Toolbox Components.

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

1. The presedimentation basin must be in continuous operation and must treat the entire plant flow taken from a surface water or GWUDISW source.

2. The system must continuously add a coagulant to the presedimentation basin.

3. The presedimentation basin must achieve the performance criteria in subparagraph (15)(A)3.A. or B. of this rule.

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

B. Complies with department-approved performance criteria that demonstrate at least 0.5-log mean removal of micron-sized particulate material through the presedimentation process.

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

(C) 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 subsection (2)(A) of this rule must collect samples as described in subsection (4)(D) of this rule and are not eligible for this credit.

1. Wells with a ground water flow path of at least twenty-five feet (25') receive 0.5-log treatment credit; wells with a ground water flow path of at least fifty feet (50') receive 1.0-log treatment credit. The ground water flow path must be determined as specified in paragraph (15)(C)4. of this rule.

2. 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 must characterize the aquifer at the well site to determine aquifer properties. Systems must extract a core from the aquifer and demonstrate that, in at least ninety percent (90%) of the core length, grains less than 1.0 mm in diameter constitute at least ten percent (10%) of the core material.

3. Only horizontal and vertical wells are eligible for treatment credit.

4. For vertical wells, the ground water flow path is the measured distance from the edge of the surface water body under high flow conditions (determined by the one hundred (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 ground water flow path is the measured distance from the bed of the river under normal flow conditions to the closest horizontal well lateral screen.

5. Systems must monitor each wellhead for turbidity at least once every four (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 (1) nephelometric turbidity unit (NTU), the system must report this result to the department and conduct an assessment within thirty (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.

6. Springs and infiltration galleries are not eligible for treatment credit under this section but are eligible for credit under subsection (16)(C) of this rule.

7. Bank filtration demonstration of performance. The department may approve Cryptosporidium treatment credit for bank filtration based on a demonstration of performance study that meets the criteria in this subsection. This treatment credit may be greater than 1.0-log and may be awarded to bank filtration that does not meet the criteria in paragraphs (15)(C)1.-5. of this rule.

A. The study must follow a department-approved protocol and must 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.

B. The study must include sampling both from the production well(s) and from monitoring wells that are screened and located along the shortest flow path between the surface water source and the production well(s).

(16) Treatment Performance Toolbox Components.

(A) Combined Filter Performance. 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 must be less than or equal to 0.15 NTU in at least ninety-five percent (95%) of the measurements. Turbidity must be measured as described in 10 CSR 60-4.050(2) and 10 CSR 60-4.080(3).

(B) Individual Filter Performance. Systems using conventional filtration treatment or direct filtration treatment receive 0.5-log Cryptosporidium treatment credit, which can be in addition to the 0.5-log credit under subsection (16)(A) during any month the system meets the criteria in this subsection. Compliance with these criteria must be based on individual filter turbidity monitoring as described in 10 CSR 60-4.050(2)(D) and 10 CSR 60-7.010(6).

1. The filtered water turbidity for each individual filter must be less than or equal to 0.15 NTU in at least ninety-five percent (95%) of the measurements recorded each month.

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

3. Any system that has received treatment credit for individual filter performance and fails to meet the requirements of paragraph (16)(B)1. or 2. of this rule during any month does not receive a treatment technique violation under subsection (11)(C) of this rule if the department determines the following:

A. The failure was due to unusual and short-term circumstances that could not reasonably be prevented through optimizing treatment plant design, operation, and maintenance; and

B. The system has experienced no more than two (2) such failures in any calendar year.

(C) 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 section (11) or section (15) through section (18) of this rule and may be awarded to treatment processes that do not meet the criteria for the prescribed credits.

1. Systems cannot receive the prescribed treatment credit for any toolbox option in sections (15) through (18) if that toolbox option is included in a demonstration of performance study for which treatment credit is awarded under this paragraph.

2. The demonstration of performance study must follow a department-approved protocol and must demonstrate the level of Cryptosporidium reduction the treatment process will achieve under the full range of expected operating conditions for the system.

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

(17) Additional Filtration Toolbox Components.

(A) Bag and Cartridge Filters. 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 paragraphs (17)(A)1. through 10. of this section. To be eligible for this credit, systems must report the results of challenge testing that meets the requirements of paragraphs (17)(A)2. through 9. to the department. The filters must treat the entire plant flow taken from a surface water or ground water under the direct influence of surface water source.

1. The Cryptosporidium treatment credit awarded to bag or cartridge filters must be based on the removal efficiency demonstrated during challenge testing that is conducted according to the criteria in paragraphs (17)(A)2. through 9. 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 must 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 paragraphs (17)(A)2. through 9.

2. Challenge testing must 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 must be challenge tested in the same configuration that the system will use, either as individual filters or as a series configuration of filters.

3. Challenge testing must 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 must be determined using a method capable of discretely quantifying the specific microorganism or surrogate used in the test; gross measurements such as turbidity may not be used.

4. The maximum feed water concentration that can be used during a challenge test must be based on the detection limit of the challenge particulate in the filtrate (i.e., filtrate detection limit) and must be calculated using the following equation:

Maximum Feed Concentration = 1 x 10 ⁴ x (Filtrate Detection Limit).

5. Challenge testing must be conducted at the maximum design flow rate for the filter as specified by the manufacturer.

6. Each filter evaluated must be tested for a duration sufficient to reach one hundred percent (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 rule.

7. Removal efficiency of a filter must be determined from the results of the challenge test and expressed in terms of log removal values using the following equation:

LRV = LOG₁₀ (C_f) - LOG₁₀ (C_p)

Where:

LRV = log removal value demonstrated during challenge testing C_f = the feed concentration measured during the challenge test C_p = the filtrate concentration measured during the challenge test

In applying this equation, the same units must be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, then the term C_p must be set equal to the detection limit.

8. Each filter tested must be challenged with the challenge particulate during three (3) periods over the filtration cycle: within two (2) hours of start-up of a new filter; when the pressure drop is between forty-five percent and fifty-five percent (45%-55%) of the terminal pressure drop; and at the end of the cycle after the pressure drop has reached one hundred percent (100%) of the terminal pressure drop. An LRV must be calculated for each of these challenge periods for each filter tested. The LRV for the filter (LRV_filter) must be assigned the value of the minimum LRV observed during the three (3) challenge periods for that filter.

9. If fewer than twenty (20) filters are tested, the overall removal efficiency for the filter product line must be set equal to the lowest LRV_filter among the filters tested. If twenty (20) or more filters are tested, the overall removal efficiency for the filter product line must be set equal to the 10th percentile of the set of LRV_filter 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.

10. 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 must be conducted and submitted to the department.

(B) Membrane Filtration Requirements.

1. 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 10 CSR 60-2.015 are eligible for this credit. The level of treatment credit a system receives is equal to the lower of the values determined under sub-paragraphs (17)(B)1.A. and B.

A. The removal efficiency demonstrated during challenge testing conducted under the conditions in paragraph (17)(B)2.

B. The maximum removal efficiency that can be verified through direct integrity testing used with the membrane filtration process under the conditions in paragraph (17)(B)3.

2. Challenge testing. The membrane used by the system must undergo challenge testing to evaluate removal efficiency, and the system must report the results of challenge testing to the department. Challenge testing must be conducted according to the criteria in subparagraphs (17)(B)2.A. through H. Systems may use data from challenge testing conducted prior to January 5, 2006, if the prior testing was consistent with the criteria in subparagraphs (17)(B)2.A. through G.

A. Challenge testing must 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. A module is defined as the smallest component of a membrane unit in which a specific membrane surface area is housed in a device with a filtrate outlet structure.

B. Challenge testing must 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, must 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.

C. The maximum feed water concentration that can be used during a challenge test is based on the detection limit of the challenge particulate in the filtrate and must be determined according to the following equation:

Maximum Feed Concentration = 3.16 x 10 ⁶ x (Filtrate Detection Limit)

D. Challenge testing must be conducted under representative hydraulic conditions at the maximum design flux and maximum design process recovery specified by the manufacturer for the membrane module. Flux is defined as the throughput of a pressure-driven membrane process expressed as flow per unit of membrane area. Recovery is defined as 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 (i.e., backwashing).

E. Removal efficiency of a membrane module must be calculated from the challenge test results and expressed as a log removal value according to the following equation:

LRV = LOG₁₀ (C_f) - LOG₁₀ (C_p) Where:

LRV = log removal value demonstrated during the challenge test

C_f = the feed concentration measured during the challenge test

C_p = the filtrate concentration measured during the challenge test

Equivalent units must be used for the feed and filtrate concentrations. If the challenge particulate is not detected in the filtrate, the term C_p is set equal to the detection limit for the purpose of calculating the LRV. An LRV must be calculated for each membrane module evaluated during the challenge test.

F. The removal efficiency of a membrane filtration process demonstrated during challenge testing must be expressed as a log removal value (LRV_C-Test). If fewer than twenty (20) modules are tested, then LRV_C-Test is equal to the lowest of the representative LRVs among the modules tested. If twenty (20) or more modules are tested, then LRV_C-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.

G. The challenge test must establish a quality control release value (QCRV) for a non-destructive performance test that demonstrates the Cryptosporidium removal capability of the membrane filtration module. This performance test must be applied to each production membrane module used by the system that was not directly challenge tested in order to verify Cryptosporidium removal capability. Production modules that do not meet the established QCRV are not eligible for the treatment credit demonstrated during the challenge test.

H. If a previously tested membrane is modified in a manner that could change the removal efficiency of the membrane or the applicability of the non-destructive performance test and associated QCRV, additional challenge testing to demonstrate the removal efficiency of, and determine a new QCRV for, the modified membrane must be conducted and submitted to the department.

3. Direct integrity testing. Systems must conduct direct integrity testing in a manner that demonstrates a removal efficiency equal to or greater than the removal credit awarded to the membrane filtration process and meets the requirements described in sub-paragraphs (17)(B)3.A.-G. of this rule. A direct integrity test is defined as a physical test applied to a membrane unit in order to identify and isolate integrity breaches (that is, one (1) or more leaks that could result in contamination of the filtrate).

A. The direct integrity test must be independently applied to each membrane unit in service. A membrane unit is defined as a group of membrane modules that share common valving that allows the unit to be isolated from the rest of the system for the purpose of integrity testing or other maintenance.

B. The direct integrity method must have a resolution of three (3) micrometers or less, where resolution is defined as the size of the smallest integrity breach that contributes to a response from the direct integrity test.

C. The direct integrity test must have a sensitivity sufficient to verify the log treatment credit awarded to the membrane filtration process by the department, where sensitivity is defined as the maximum log removal value that can be reliably verified by a direct integrity test. Sensitivity must be determined using the approach in either part (17)(B)3.C.(I) or (II) of this section as applicable to the type of direct integrity test the system uses.

(I) For direct integrity tests that use an applied pressure or vacuum, the direct integrity test sensitivity must be calculated according to the following equation:

LRV_DIT = LOG₁₀ (Q_p /(VCF x Q_breach))

Where:

LRV_DIT = the sensitivity of the direct integrity test

Q_p = total design filtrate flow from the membrane unit

Q_breach = flow of water from an integrity breach associated with the smallest integrity test response that can be reliably measured

VCF = volumetric concentration factor

The volumetric concentration factor is the ratio of the suspended solids concentration on the high pressure side of the membrane relative to that in the feed water.

(II) For direct integrity tests that use a particulate or molecular marker, the direct integrity test sensitivity must be calculated according to the following equation:

LRV_DIT = LOG₁₀ (C_f) - LOG₁₀ (C_p)

Where:

LRV_DIT = the sensitivity of the direct integrity test

C_f = the typical feed concentration of the marker used in the test

C_p = the filtrate concentration of the marker from an integral membrane unit

D. Systems must establish a control limit within the sensitivity limits of the direct integrity test that is indicative of an integral membrane unit capable of meeting the removal credit awarded by the department.

E. If the result of a direct integrity test exceeds the control limit established under subparagraph (17)(B)3.D., the system must remove the membrane unit from service. Systems must conduct a direct integrity test to verify any repairs and may return the membrane unit to service only if the direct integrity test is within the established control limit.

F. Systems must conduct direct integrity testing on each membrane unit at a frequency of not less than once each day that the membrane unit is in operation. The department may approve less frequent testing, based on demonstrated process reliability, the use of multiple barriers effective for Cryptosporidium, or reliable process safeguards.

4. Indirect integrity monitoring. Systems must conduct continuous indirect integrity monitoring on each membrane unit according to the criteria in subparagraphs (17)(B)4.A. through E. Indirect integrity monitoring is defined as monitoring some aspect of filtrate water quality that is indicative of the removal of particulate matter. A system that implements continuous direct integrity testing of membrane units in accordance with the criteria in subparagraphs (17)(B)3.A. through E. of this section is not subject to the requirements for continuous indirect integrity monitoring. Systems must submit a monthly report to the department summarizing all continuous indirect integrity monitoring results triggering direct integrity testing and the corrective action that was taken in each case.

A. Unless the department approves an alternative parameter, continuous indirect integrity monitoring must include continuous filtrate turbidity monitoring.

B. Continuous monitoring must be conducted at a frequency of no less than once every fifteen (15) minutes.

C. Continuous monitoring must be separately conducted on each membrane unit.

D. If indirect integrity monitoring includes turbidity and if the filtrate turbidity readings are above 0.15 NTU for a period greater than fifteen (15) minutes (i.e., two (2) consecutive fifteen (15)-minute readings above 0.15 NTU), direct integrity testing must immediately be performed on the associated membrane unit as specified in sub-paragraphs (17)(B)3.A. through E.

E. If indirect integrity monitoring includes a department-approved alternative parameter and if the alternative parameter exceeds a department-approved control limit for a period greater than fifteen (15) minutes, direct integrity testing must immediately be performed on the associated membrane units as specified in subparagraphs (17)(B)3.A. through E.

(C) Second Stage Filtration. Systems receive 0.5-log Cryptosporidium treatment credit for a separate second stage of filtration that consists of sand, dual media, granular activated carbon (GAC), or other fine grain media following granular media filtration if the department approves. To be eligible for this credit, the first stage of filtration must be preceded by a coagulation step, and both filtration stages must treat the entire plant flow taken from a surface water or GWUDISW source. A cap, such as GAC, on a single stage of filtration is not eligible for this credit. The department must approve the treatment credit based on an assessment of the design characteristics of the filtration process.

(D) Slow Sand Filtration (as Secondary Filter). Systems are eligible to receive 2.5-log Cryptosporidium treatment credit for a slow sand filtration process that follows a separate stage of filtration if both filtration stages treat entire plant flow taken from a surface water or GWUDISW source and no disinfectant residual is present in the influent water to the slow sand filtration process. The department must approve the treatment credit based on an assessment of the design characteristics of the filtration process. This subsection does not apply to treatment credit awarded to slow sand filtration used as a primary filtration process.

(18) Inactivation Toolbox Components.

(A) Calculation of CT Values.

1. CT is the product of the disinfectant contact time (T, in minutes) and disinfectant concentration (C, in milligrams per liter). Systems with treatment credit for chlorine dioxide or ozone under subsection (18)(B) or (C) must calculate CT at least once each day, with both C and T measured during peak hourly flow as specified in 10 CSR 60-5.010, 10 CSR 60-5.020, and the Missouri Guidance Manual for Surface Water System Treatment Requirements, 1992.

2. Systems with several disinfection segments in sequence may calculate CT for each segment, where a disinfection segment is defined as a treatment unit process with a measurable disinfectant residual level and a liquid volume. Under this approach, systems must add the Cryptosporidium CT values in each segment to determine the total CT for the treatment plant.

(B) CT Values for Chlorine Dioxide and Ozone.

1. Systems receive the Cryptosporidium treatment credit listed in this table by meeting the corresponding chlorine dioxide CT value for the applicable water temperature, as described in subsection (18)(A). Systems may use this equation to determine log credit between the indicated values:

Log credit = (0.001506 x (1.09116)^Temp) x CT

CT Values (MG-MIN/L) for Cryptosporidium Inactivation By Chlorine Dioxide

Log credit	Water temperature, ^oC
Log credit	<=0.5	1	2	3	5	7	10	15	20	25	30
0.25	159	153	140	128	107	90	69	45	29	19	12
0.5	319	305	279	256	214	180	138	89	58	38	24
1.0	637	610	558	511	429	360	277	179	116	75	49
1.5	956	915	838	767	643	539	415	268	174	113	73
2.0	1275	1220	1117	1023	858	719	553	357	232	150	98
2.5	1594	1525	1396	1278	1072	899	691	447	289	188	122
3.0	1912	1830	1675	1534	1286	1079	830	536	347	226	147

2. Systems receive the Cryptosporidium treatment credit listed in this table by meeting the corresponding ozone CT values for the applicable water temperature, as described in subsection (18)(A) of this rule.

CT Values (MG-MIN/L) for Cryptosporidium Inactivation by Ozone Systems may use this equation to determine log credit between the indicated values: Log credit = (0.0397 x (1.09757)^temp) x CT
Log credit	Water Temperature, ^oC
Log credit	<=0.5	1	2	3	5	7	10	15	20	25	30
0.25	6.0	5.8	5.2	4.8	4.0	3.3	2.5	1.6	1.0	0.6	0.39
0.5	12	12	10	9.5	7.9	6.5	4.9	3.1	2.0	1.2	0.78
1.0	24	23	21	19	16	13	9.9	6.2	3.9	2.5	1.6
1.5	36	35	31	29	24	20	15	9.3	5.9	3.7	2.4
2.0	48	46	42	38	32	26	20	12	7.8	4.9	3.1
2.5	60	58	52	48	40	33	25	16	9.8	6.2	3.9
3.0	72	69	63	57	47	39	30	19	12	7.4	4.7

(C) Site-Specific Study. The department may approve alternative chlorine dioxide or ozone CT values to those listed in subsection (18)(B) on a site-specific basis. The department must base this approval on a site-specific study a system conducts that follows a department-approved protocol.

(D) Ultraviolet Light. Systems receive Cryptosporidium, Giardia lamblia, and virus-treatment credits for ultraviolet (UV) light reactors by achieving the corresponding UV dose values shown in paragraph (18)(D)1. Systems must validate and monitor UV reactors as described in paragraphs (18)(D)2. and 3. to demonstrate that they are achieving a particular UV dose value for treatment credit.

1. UV dose table. The treatment credits listed in this table are for UV light at a wavelength of two hundred fifty-four nanometers (254 nm) as produced by a low pressure mercury vapor lamp. To receive treatment credit for other lamp types, systems must demonstrate an equivalent germicidal dose through reactor validation testing, as described in paragraph (18)(D)2. of this rule. The UV dose values in this table are applicable only to post-filter applications of UV in filtered systems.

UV Dose Table for Cryptosporidium, Giardia lamblia, and Virus Inactivation Credit
Log credit	Cryptosporidium UV dose (mJ/cm²)	Giardia lamblia UV dose (mJ/cm²)	Virus UV dose (mJ/cm²)
0.5	1.6	1.5	39
1.0	2.5	2.1	58
1.5	3.9	3.0	79
2.0	5.8	5.2	100
2.5	8.5	7.7	121
3.0	12	11	143
3.5	15	15	163
4.0	22	22	186

2. Reactor validation testing. Systems must use UV reactors that have undergone validation testing to determine the operating conditions under which the reactor delivers the UV dose required in paragraph (18)(D)1. (i.e., validated operating conditions). These operating conditions must include flow rate, UV intensity as measured by a UV sensor, and UV lamp status.

A. When determining validated operating conditions, systems must account for the following factors: UV absorbance of the water; lamp fouling and aging; measurement uncertainty of online sensors; UV dose distributions arising from the velocity profiles through the reactor; failure of UV lamps or other critical system components; and inlet and outlet piping or channel configurations of the UV reactor.

B. Validation testing must include the following: Full-scale testing of a reactor that conforms uniformly to the UV reactors used by the system and inactivation of a test microorganism whose dose response characteristics have been quantified with a low pressure mercury vapor lamp.

C. The department may approve an alternative approach to validation testing.

3. Reactor monitoring requirements.

A. Systems must monitor their UV reactors to determine if the reactors are operating within validated conditions, as determined under paragraph (18)(D)2. This monitoring must include UV intensity as measured by a UV sensor, flow rate, lamp status, and other parameters the department designates based on UV reactor operation. Systems must verify the calibration of UV sensors and must recalibrate sensors in accordance with a protocol the department approves.

B. To receive treatment credit for UV light, systems must treat at least ninety-five percent (95%) of the water delivered to the public during each month by UV reactors operating within validated conditions for the required UV dose, as described in paragraphs (18)(D)1. and 2. Systems must demonstrate compliance with this condition by the monitoring required under subparagraph (18)(D)3.A. of this rule.

(19) Reporting Requirements.

(A) Systems must report sampling schedules under section (3) of this rule and source water monitoring results under section (6) of this rule unless they notify the department that they will not conduct source water monitoring due to meeting the criteria of subsection (2)(D) of this rule.

(B) Filtered systems must report their Cryptosporidium bin classification as described in section (10) of this rule.

(C) Systems must report disinfection profiles and benchmarks to the department as described in sections (8) through (9) of this rule prior to making a significant change in disinfection practice.

(D) Systems must report to the department in accordance with the following table for any microbial toolbox options used to comply with treatment requirements under section (11) of this rule. 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
Toolbox option	Systems must submit the following information	On the following schedule
Watershed control program (WCP)	(I) Notice of intention to develop a new or continue an existing watershed control program	No later than two years before the applicable treatment compliance date in section (12) of this rule
	(II) Watershed control plan	No later than one year before the applicable treatment compliance date in
	(III) Annual watershed control program status report	Every 12 months, beginning one year after the applicable treatment compliance date in section (12) of this rule
	(IV) Watershed sanitary survey report	For community water systems, every three years beginning three years after the applicable treatment compliance date in section (12) of this rule. For noncommunity water systems, every five years beginning five years after the applicable treatment compliance date in section (12) of this rule
Alternative source/intake management	Verification that system has relocated the intake or adopted the intake withdrawal procedure reflected in monitoring results	No later than the applicable treatment compliance date in section (12) of this rule
Presedimentation	Monthly verification of the following: (I) Continuous basin operation; (II) Treatment of 100% of the flow; (III) Continuous addition of a coagulate; and (IV) At least 0.5-log mean reduction of influent turbidity or compliance with alternative department-approved performance criteria	Monthly reporting within 10 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Two-stage lime softening	Monthly verification of the following: (I) Chemical addition and hardness precipitation occurred in two separate and sequential softening stages prior to filtration; and (II) Both stages treated 100% of the plant flow	Monthly reporting within 10 days following the month in which the monitoring was conducted beginning on the applicable treatment compliance date in section (12) of this rule
Bank filtration	(I) Initial demonstration of the following: (A) Unconsolidated, predominantly sandy aquifer; and (B) Setback distance of at least 25 ft. (0.5-log credit) or 50 ft. (1.0-log credit)	No later than the applicable treatment compliance date in section (12) of this rule
Bank filtration	(II) If monthly average of daily max turbidity is greater than 1 NTU, then the system must report result and submit an assessment of the cause	Report within 30 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule

Combined filter performance	Monthly verification of combined filter effluent (CFE) turbidity levels less than or equal to 0.15 NTU in at least 95% of the 4 hour CFE measurements taken each month	Monthly reporting within 10 days following the month in which the monitoring was conducted beginning on the applicable treatment compliance date in section (12) of this rule
Individual filter performance	Monthly verification of the following: (I) Individual filter effluent (IFE) turbidity levels less than or equal to 0.15 NTU in at least 95% of samples each month in each filter; and (II) No individual filter greater than 0.3 NTU in two consecutive readings 15 minutes apart	Monthly reporting within 10 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Demonstration of performance	(I) Results from testing following a department approved protocol	No later than the applicable treatment compliance date in section (12) of this rule
Demonstration of performance	(II) As required by the department, monthly verification of operation within conditions of department approval for demonstration of performance credit	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Bag filters and cartridge filters	(I) Demonstration that the following criteria are met: (A) Process meets the definition of bag or cartridge filtration; and (B) Removal efficiency established through challenge testing that meets criteria in this	No later than the applicable treatment compliance date in section (12) of this rule
Bag filters and cartridge filters	(II) Monthly verification that 100% of plant flow was filtered	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Membrane filtration	(I) Results of verification testing demonstrating the following: (A) Removal efficiency established through challenge testing that meets criteria in this rule; and (B) Integrity test method and parameters, including resolution, sensitivity, test frequency, control limits, and associated baseline	No later than the applicable treatment compliance date in section (12) of this rule
Membrane filtration	(II) Monthly report summarizing the following: (A) All direct integrity tests above the control limit; and (B) If applicable, any turbidity or alternative department approved indirect integrity monitoring results triggering direct integrity testing and the corrective action that was taken	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule

Second stage filtration	Monthly verification that 100% of flow was filtered through both stages and that first stage was preceded by coagulation step	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Slow sand filtration (as secondary filter)	Monthly verification that both a slow sand filter and a preceding separate stage of filtration treated 100% of flow from surface water and ground water under the direct influence of	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Chlorine dioxide	Summary of CT values for each day as described in section (18) of this rule	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
Ozone	Summary of CT values for each day as described in section (18) of this rule	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule
UV	Validation test results demonstrating operating conditions that achieve required UV dose	No later than the applicable treatment compliance date in section (12) of this rule
UV	Monthly report summarizing the percentage of water entering the distribution system that was not treated by UV reactors operating within validated conditions for the required dose specified in subsection (18)(D) of this rule	Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule

10 CSR 60-4.052

AUTHORITY: section 640.100, RSMo Supp. 2008.* Original rule filed Feb. 27, 2009, effective 10/30/2009.

Amended by Missouri Register January 2, 2019/Volume 44, Number 1, effective 2/28/2019

*Original authority: 640.100, RSMo 1939, amended 1978, 1981, 1982, 1988, 1989, 1992, 1993, 1995, 1996, 1998, 1999, 2002, 2006.