310 CMR, § 22.20G

Current through Register 1533, October 25, 2024

Section 22.20G - Long Term Two Enhanced Surface Water Treatment Rule

(1)General Requirements.

(a)310 CMR 22.20G establishes or extends Treatment Technique requirements in lieu of Maximum Contaminant Levels for Cryptosporidium. These requirements are in addition to requirements for Filtration and Disinfection in 310 CMR 22.20A, 22.20D, and 22.20F.

(b) Applicability. 310 CMR 22.20G applies to all suppliers of water using a Surface Water Source, or groundwater source under the direct influence of surface water.

1. Wholesale Systems, as defined in 310 CMR 22.02, must comply with the requirements of 310 CMR 22.20G based on the population of the largest system in the Combined Distribution System.

2. The requirements of 310 CMR 22.20G for filtered systems apply to systems required by National Primary Drinking Water Regulations and 310 CMR 22.00 to provide Filtration treatment, whether or not the system is currently operating a Filtration system.

3. The requirements of 310 CMR 22.20G for unfiltered systems apply only to unfiltered systems that timely met and continue to meet the Filtration avoidance criteria in 310 CMR 22.20A, 22.20D, and 22.20F, as applicable.

(c)Requirements. Systems subject to 310 CMR 22.20G must comply with the following requirements:

1. Systems must conduct an initial and a second round of source water monitoring for each plant supplied by a Surface Water Source, or groundwater source under the direct influence of surface water. This monitoring may include sampling for Cryptosporidium, E. coli, and Turbidity as described in 310 CMR 22.20G(2) through (7), to determine what level, if any, of additional Cryptosporidium treatment the public water supplier 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 310 CMR 22.20G(9) through (10).

3. Filtered systems must determine their Cryptosporidium treatment bin classification as described in 310 CMR 22.20G(11) and provide additional treatment for Cryptosporidium, if required, as described in 310 CMR 22.20G(12). All unfiltered systems must provide treatment for Cryptosporidium as described in 310 CMR 22.20G(13). Filtered and unfiltered systems must implement Cryptosporidium treatment according to the schedule in 310 CMR 22.20G(14).

4. Systems with uncovered finished water storage facilities must comply with the requirements to cover the facility or treat the discharge from the facility as described in 310 CMR 22.20G(15).

5. Systems required to provide additional treatment for Cryptosporidium must implement microbial toolbox options that are designed and operated as described in 310 CMR 22.20G(19) through (23).

6. Systems must comply with the applicable recordkeeping and reporting requirements described in 310 CMR 22.20G(16) and (17).

(2)Source Water Monitoring.

(a)Initial Round of Source Water Monitoring. Systems must conduct the following monitoring on the schedule in 310 CMR 22.20G(2)(c) unless they meet the monitoring exemption criteria in 310 CMR 22.20G(2)(d).

1. Filtered systems serving at least 10,000 people must sample their source water for Cryptosporidium, E. coli, and Turbidity at least monthly for 24 months.

2. Unfiltered systems serving at least 10,000 people must sample their source water for Cryptosporidium at least monthly for 24 months.

a. Filtered systems serving fewer than 10,000 people must sample their source water for E. coli at least once every two weeks for 12 months.

b. A filtered system serving fewer than 10,000 people may avoid E. coli monitoring if the system notifies the Department that it will monitor for Cryptosporidium as described in 310 CMR 22.20G(2)(a)4. The system must notify the Department no later than three months prior to the date the system is otherwise required to start E. coli monitoring under 310 CMR 22.20G(2)(c).

4. Filtered systems serving fewer than 10,000 people must sample their source water for Cryptosporidium at least twice per month for 12 months or at least monthly for 24 months if they meet one of the following, based on monitoring conducted in accordance with the requirements of 310 CMR 22.20G(2)(a)3.:

a. For systems using Lake/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 310 CMR 22.20G(2)(a)3.

d. Systems using Groundwater under the Direct Influence of Surface Water must comply with the requirements of 310 CMR 22.20G(2)(a)4. 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 10,000 people, the Department may approve monitoring for an indicator other than E. coli under 310 CMR 22.20G(2)(a)3. The Department also may approve an alternative to the E. coli concentration as specified in 310 CMR 22.20G(2)(a)4.a., b. or d. to trigger Cryptosporidium monitoring. This approval by the Department will be provided to the system in writing and will 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 310 CMR 22.20G(11).

6. Unfiltered systems serving fewer than 10,000 people must sample their source water for Cryptosporidium at least twice per month for 12 months or at least monthly for 24 months.

7. Systems may sample more frequently than required under 310 CMR 22.20G(2) 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 310 CMR 22.20G(2)(a), unless they meet the monitoring exemption criteria in 310 CMR 22.20G(2)(d). Systems must conduct this monitoring on the schedule in 310 CMR 22.20G(2)(c).

(c)Monitoring Schedule. Systems must begin the monitoring required in 310 CMR 22.20G(2)(a) and (b) no later than the month beginning with the date listed in 310 CMR 22.20G: Table 1.

310 CMR 22.20G: Table 1

SOURCE WATER MONITORING STARTING DATES

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 people	April 1, 2007	October 1, 2015
From 10,000 to 49,999 people	April 1, 2008	October 1, 2016
Fewer than 10,000 and monitor for E. coli¹	October 1, 2008	October 1, 2017
Fewer than 10,000 and monitor for Cryptosporidium²	April 1, 2010	April 1, 2019

¹ Applies only to filtered systems.

² Applies to filtered systems that meet the conditions of 310 CMR 22.20G(2)(a)4. and unfiltered systems.

(d)Monitoring Avoidance.

1. Filtered systems are not required to conduct source water monitoring under 310 CMR 22.20G 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 310 CMR 22.20G(12).

2. Unfiltered systems are not required to conduct source water monitoring under 310 CMR 22.20G if the system will provide a total of at least 3-log Cryptosporidium inactivation, equivalent to meeting the treatment requirements for unfiltered systems with a mean Cryptosporidium concentration of greater than 0.01 oocysts/L in 310 CMR 22.20G(13).

3. If a system chooses to provide the level of treatment in 310 CMR 22.20G(2)(d)1. or 2., 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 310 CMR 22.20G(3). 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 310 CMR 22.20G(14).

(e)Plants Operating Only Part of the Year. Suppliers of water with plants served by a Surface Water Source or groundwater source under the direct influence of surface water that operate for only part of the year must conduct source water monitoring in accordance with 310 CMR 22.20G, 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 months per year and that monitor for Cryptosporidium must collect at least six Cryptosporidium samples per year during each of two years of monitoring. Samples must be evenly spaced throughout the period the plant operates.

(f)

1.New Sources. A system that begins using a New Source of Surface Water or groundwater under the direct influence of surface water after the system is required to begin monitoring under 310 CMR 22.20G(2)(c) must monitor the New Source on a schedule the Department approves. Source water monitoring must meet the requirements of 310 CMR 22.20G. The system must also meet the bin classification and Cryptosporidium treatment requirements of 310 CMR 22.20G(11) and (12) or (13), as applicable, for the New Source on a schedule the Department approves.

2. The requirements of 310 CMR 22.20G(2)(f) apply to suppliers of water with a Surface Water Source or groundwater source under the direct influence of surface water that begin operation after the monitoring start date applicable to the system's size under 310 CMR 22.20G(2)(c).

3. The system must begin a second round of source water monitoring no later than six years following initial bin classification under 310 CMR 22.20G(11) or determination of the mean Cryptosporidium level under 310 CMR 22.20G(13), as applicable.

(g) Failure to collect any source water sample required under 310 CMR 22.20G(2) in accordance with the sampling schedule, sampling location, analytical method, approved laboratory, and reporting requirements of 310 CMR 22.20G(3) through (7) is a monitoring violation.

(h)Grandfathering Monitoring Data. Systems may use (grandfather) monitoring data collected prior to the applicable monitoring start date in 310 CMR 22.20G(2)(c) to meet the initial source water monitoring requirements in 310 CMR 22.20G(a). Grandfathered data may substitute for an equivalent number of months at the end of the monitoring period. All data submitted under 310 CMR 22.20G(2)(h) must meet the requirements in 310 CMR 22.20G(8).

(3)Sampling Schedules.

(a) Systems required to conduct source water monitoring under 310 CMR 22.20G(2) 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 months prior to the applicable date listed in 310 CMR 22.20G(2)(c) for each round of required monitoring.

a. Systems serving at least 10,000 people must submit their sampling schedule for the initial round of source water monitoring under 310 CMR 22.20G(2)(a) to EPA electronically at https://intranet.epa.gov/lt2/ [File Link Not Available].

b. If a system is unable to submit the sampling schedule electronically, the system may use an alternative approach for submitting the sampling schedule that EPA or the Department approves.

3. Systems serving fewer than 10,000 people must submit their sampling schedules for the initial round of source water monitoring 310 CMR 22.20G(2)(a) to the Department.

4. Systems must submit sampling schedules for the second round of source water monitoring 310 CMR 22.20G(2)(b) to the Department.

5. If 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 days before or two days after the dates indicated in their sampling schedule (i.e., within a five-day period around the schedule date) unless one of the conditions of 310 CMR 22.20G(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-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.

a. 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 310 CMR 22.20G(5), or the failure of an approved laboratory to analyze the sample, then the system must collect a replacement sample.

b. The system must collect the replacement sample not later than 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 310 CMR 22.20G(3)(b) for any source water sample required under 310 CMR 22.20G(2) 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 310 CMR 22.20G(2) must collect samples for each plant that treats a Surface Water Source, or a groundwater source under the direct influence of surface water. Where multiple plants draw water from the same influent, such as the same pipe or intake, the Department may approve one set of monitoring results to be used to satisfy the requirements of 310 CMR 22.20G(2) for all plants.

(b)

1. Systems must collect source water samples prior to chemical treatment, such as coagulants, oxidants and disinfectants, unless the system meets the condition specified in 310 CMR 22.20G(4)(b)2.

2. The Department may approve a system to collect a source water sample after chemical treatment. To grant this approval, the Department will 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.

1. Systems that receive Cryptosporidium treatment credit for Bank Filtration under 310 CMR 22.20D(4)(b) or 22.20F(6)(c), 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 the Massachusetts Drinking Water Guidelines and Policies, Appendix N, Requirements for Microbial Toolbox Options for Meeting Cryptosporidium Treatment Requirements under the Long Term 2 Enhanced Surface Water Treatment Rule for Public Water Systems.

(e)Multiple Sources. Systems with plants that use multiple water sources, including multiple Surface Water Sources and blended Surface Water and groundwater sources, must collect samples as specified in 310 CMR 22.20G(4)(e)1. or 2. 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 310 CMR 22.20G(4)(e)2.a. or b. for sample analysis.

a. Systems may composite samples from each source into one 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 310 CMR 22.20G(3). 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)Analytical Methods.

(a)Cryptosporidium. Systems must analyze for Cryptosporidium using Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA, 2005, United States Environmental Protection Agency, EPA-815-R-05-002 or Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 2005, United States Environmental Protection Agency, EPA-815-R-05-001, which are incorporated by reference.

1. Systems must analyze at least a 10 L sample or a packed pellet volume of at least 2 mL as generated by the methods listed in 310 CMR 22.20G(5)(a). Systems unable to process a 10 L sample must analyze as much sample volume as can be filtered by two filters approved by EPA and the Department for the methods listed in 310 CMR 22.20G(5)(a), up to a packed pellet volume of at least 2 mL.

2. Matrix spike (MS) samples, as required by the methods in 310 CMR 22.20G(5)(a), must be spiked and filtered by a laboratory approved for Cryptosporidium analysis under 310 CMR 22.20G(6). If the volume of the MS sample is greater than 10 L, the system may filter all but 10 L of the MS sample in the field, and ship the filtered sample and the remaining 10 L of source water to the laboratory. In this case, the laboratory must spike the remaining 10 L of water and filter it through the filter used to collect the balance of the sample in the field.

3. Flow cytometer-counted spiking suspensions must be used for MS samples and ongoing precision and recovery (OPR) samples.

(b)E. coli. Systems must use methods for enumeration of E. coli in source water approved in accordance with 310 CMR 22.26(3)(c).

1. The time from sample collection to initiation of analysis may not exceed 30 hours unless the system meets the condition of 310 CMR 22.20G(5)(b)2.

2. The Department may approve on a case-by-case basis the holding of an E. coli sample for up to 48 hours between sample collection and initiation of analysis if the Department determines that analyzing an E. coli sample within 30 hours is not feasible. E. coli samples held between 30 to 48 hours must be analyzed by the Colilert reagent version of Standard Method 9223B as listed in 310 CMR 22.26(3)(c).

3. Systems must maintain samples between 0°C and 10°C during storage and transit to the laboratory.

(c)Turbidity. Systems must use methods for Turbidity measurement approved in 310 CMR 22.20A(5)(a)1.

(6)Approved Laboratories.

(a)Cryptosporidium. Systems must have Cryptosporidium samples analyzed by a laboratory that is approved under 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 Department 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 310 CMR 22.20A(5) is approved for E. coli analysis under 310 CMR 22.20G when the laboratory uses the same technique for E. coli that the laboratory uses for 310 CMR 22.20A(5).

(c)Turbidity. Measurements of Turbidity must be made by a party approved by the Department.

(7)Reporting Source Water Monitoring Results.

(a) Systems must report results from the source water monitoring required under 310 CMR 22.20G(2) no later than ten days after the end of the first month following the month when the sample is collected.

(b) All systems serving at least 10,000 people must report the results from the initial source water monitoring required under 310 CMR 22.20G(2)(a) to EPA electronically at https://intranet.epa.gov/lt2/ [File Link Not Available]. If a system is unable to report monitoring results electronically, the system may use an alternative approach for reporting monitoring results that EPA approves.

(c) Systems serving fewer than 10,000 individuals must report results from the initial source water monitoring required under 310 CMR 22.20G(2)(a) to the Department.

(d) All systems must report results from the second round of source water monitoring required under 310 CMR 22.20G(2)(b) to the Department.

(e) Systems must report the applicable information in paragraphs 310 CMR 22.20G(7)(e)1. and 2. for the source water monitoring required under 310 CMR 22.20G(2).

1. Systems must report the following data elements for each Cryptosporidium analysis:

a. PWS ID;

b. Facility ID;

c. Sample collection date;

d. Sample type (field or matrix spike);

e. Sample volume filtered (L), to nearest 1/4 L;

f. Was 100% of filtered volume examined; and

g. Number of oocysts counted.

i. 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.

ii. For samples in which less than 10 L is filtered or less than 100% of the sample volume is examined, systems must also report the number of filters used and the packed pellet volume.

iii. For samples in which less than 100% of sample volume is examined, systems must also report the volume of resuspended concentrate and volume of this resuspension processed through immunomagnetic separation.

2. Systems must report the following data elements for each E. coli analysis:

a. PWS ID;

b. Facility ID;

c. Sample collection date;

d. Analytical method number;

e. Method type;

f. Source type (flowing stream, Lake/Reservoir, GWUDI);

g.E. coli/100 mL; and

h. Turbidity.¹

¹ Systems serving fewer than 10,000 individuals that are not required to monitor for Turbidity as specified in 310 CMR 22.20G(2) are not required to report Turbidity with their E. coli results.

(8)Grandfathering Previously Collected Data.

(a)

1. Systems may comply with the initial source water monitoring requirements of 310 CMR 22.20G(2)(a) by grandfathering sample results collected before the system is required to begin monitoring (i.e., previously collected data). To be grandfathered, the sample results and analysis must meet the criteria in 310 CMR 22.20G(8) and the Department must approve.

2. A filtered system may grandfather Cryptosporidium samples to meet the requirements of 310 CMR 22.20G(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 310 CMR 22.20G(2)(a).

(b)E. coli Sample Analysis. The analysis of E. coli samples must meet the analytical method and approved laboratory requirements of 310 CMR 22.20G(5) through (6).

(c)Cryptosporidium Sample Analysis. The analysis of Cryptosporidium samples must meet the criteria in 310 CMR 22.20G(8)(c).

1. Laboratories analyzed Cryptosporidium samples using one of the analytical methods in 310 CMR 22.20G(8)(c)1.a. through f., which are incorporated by reference.

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-82 1-R-99-006.

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

2. For each Cryptosporidium sample, the laboratory analyzed at least 10 L of sample or at least 2 mL of packed pellet or as much volume as could be filtered by two filters that EPA and the Department approved for the methods listed in 310 CMR 22.20G(8)(c)1.

(d)Sampling Location. The sampling location must meet the conditions as specified in 310 CMR 22.20G(4).

(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 310 CMR 22.20G(3)(b)1. and 2. 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 310 CMR 22.20G(2)(a) are seasonally representative and unbiased.

2. Systems may grandfather previously collected data where the sampling frequency within each month varied. If the Cryptosporidium sampling frequency varied, systems must follow the monthly averaging procedure in 310 CMR 22.20G(11)(b)5. or 310 CMR 22.20G(13)(a)3., as applicable, when calculating the bin classification for filtered systems or the mean Cryptosporidium concentration for unfiltered 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 310 CMR 22.20G(3).

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 310 CMR 22.20G(2)(a). Systems must report this information no later than the date required by the sampling schedule under 310 CMR 22.20G(3).

2. Systems must report previously collected monitoring results for grandfathering, along with the associated documentation listed in 310 CMR 22.20G(8)(f)(2) a. through d., no later than two months after the applicable date listed in 310 CMR 22.20G(2)(c).

a. For each sample result, systems must report the applicable data elements in 310 CMR 22.20G(7).

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 310 CMR 22.20G, not spiked, and analyzed using the laboratory's routine process for the analytical methods listed in 310 CMR 22.20G.

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.

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 310 CMR 22.20G(8)(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, IPR, 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 310 CMR 22.20G(11) or (13) 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 310 CMR 22.20G(2)(a) and some of the data are rejected due to not meeting the requirements of 310 CMR 22.20G(8), 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 months after notification that data have been rejected and additional monitoring is necessary.

(9)Requirements When Making a Significant Change in Disinfection Practice.

(a) Following the completion of initial source water monitoring under 310 CMR 22.20G(2)(a), a system that plans to make a significant change to its Disinfection practice, as defined in 310 CMR 22.20G(9)(b), must develop Disinfection Profiles and calculate Disinfection benchmarks for Giardia lamblia and Viruses as described in 310 CMR 22.20G(10). Prior to changing the Disinfection practice, the system must notify the Department and must include in this notice the information in 310 CMR 22.20G(9)(a)1. through 3.

1. A completed Disinfection Profile and Disinfection benchmark for Giardia lamblia and Viruses as described in 310 CMR 22.20G(10).

2. A description of the proposed change in Disinfection practice.

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.

(10)Developing the Disinfection Profile and Benchmark.

(a) Systems required to develop Disinfection Profiles under 310 CMR 22.20G(9) must follow the requirements of 310 CMR 22.20G(10). Systems must monitor at least weekly for a period of 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 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 CT99.9 values in 310 CMR 22.20A(5)(b): Tables 1.1 through 1.6, 2.1, and 3.1 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 in 310 CMR 22.20G(10)(b)1. through 4. Systems with more than one Point of Disinfectant Application must conduct the monitoring in 310 CMR 22.20G(10)(b)1. through 4. for each Disinfection segment. Systems must monitor the parameters necessary to determine the total inactivation ratio, using analytical methods in 310 CMR 22.20A(5)(a).

1. For systems using a Disinfectant other than 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 310 CMR 22.20G(10)(b), systems may elect to meet the requirements of 310 CMR 22.20G(10)(c)1. or 2.

1. Systems that have at least one year of existing data that are substantially equivalent to data collected under the provisions of 310 CMR 22.20G(10)(b) may use these data to develop Disinfection Profiles as specified in 310 CMR 22.20G(10) 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 years of existing data.

2. Systems may use Disinfection Profile(s) developed under 310 CMR 22.20D(3) or (4) 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 310 CMR 22.20D(3) or 22.20F(4) 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 in 310 CMR 22.20G(10)(d)1. through 3.

1. Systems using only one Point of Disinfectant Application may determine the total inactivation ratio for the Disinfection segment based on either of the methods in 310 CMR 22.2G(10)(d)1.a. or b.

a. Determine one 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 ( G (CTcalc/CT_99.9)).

2. Systems using more than one 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 310 CMR 22.20G(10)(d)1.b.

3. The system must determine the total logs of inactivation by multiplying the value calculated in 310 CMR 22.20G(10)(d)1. or 2. by 3.0.

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 310 CMR 22.20G(10)(e)1. and 2. to calculate a Disinfection benchmark.

1. For each year of profiling data collected and calculated under 310 CMR 22.20G(10)(a) through (d), 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 year of profiling data) or the mean of the lowest monthly mean values (for systems with more than one year of profiling data) of Giardia lamblia and Virus log inactivation in each year of profiling data.

(11)Bin Classification for Filtered Systems.

(a) Following completion of the initial round of source water monitoring required under 310 CMR 22.20G(2)(a), 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 310 CMR 22.20G(2)(a) and must follow the procedures in 310 CMR 22.20G(11)(b)1. through 5.

(b)

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

3. For systems that serve fewer than 10,000 people and monitor for Cryptosporidium for only one year (i.e., collect 24 samples in 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 12 months per year under 310 CMR 22.20G(2)(e) 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 310 CMR 22.20G(11)(b)1. through 4.

(c) Filtered systems must determine their initial bin classification from 310 CMR 22.20G: Table 2 and using the Cryptosporidium bin concentration calculated under 310 CMR 22.20G(11)(a) and (b):

310 CMR 22.20G: Table 2

BIN CLASSIFICATION TABLE FOR FILTERED SYSTEMS

For Systems that are:	With a Cryptosporidium bin concentration of ...¹	The bin classification is...
Required to monitor for Cryptosporidium under 310 CMR 22.20G(2)	Cryptosporidium <0.075 oocysts/L	Bin 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 for Cryptosporidium under 310 CMR 22.20G(2)(a)4.	N/A	Bin 1

¹ Based on calculations in 310 CMR 22.20G(11)(a) or (d), as applicable.

(d) Following completion of the second round of source water monitoring required under 310 CMR 22.20G(2)(b) filtered systems must recalculate their Cryptosporidium bin concentration using the Cryptosporidium results reported under 310 CMR 22.20G(7)(d) and following the procedures in 310 CMR 22.20G(11)(b)1. through 4. Systems must then redetermine their bin classification using this bin concentration and the table in 310 CMR 22.20G(11)(c).

(e)

1. Filtered systems must report their initial bin classification under 310 CMR 22.20G(11)(c) to the Department for approval no later than six months after the system is required to complete initial source water monitoring based on the schedule in 310 CMR 22.20G(2)(c).

2. Systems must report their bin classification under 310 CMR 22.20G(11)(d) to the Department for approval no later than six months after the system is required to complete the second round of source water monitoring based on the schedule in 310 CMR 22.20G(2)(c).

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 310 CMR 22.20G(11)(e) is a violation of the Treatment Technique requirement.

(12)Filtered System Additional Cryptosporidium Treatment Requirements.

(a) Filtered systems must provide the level of additional treatment for Cryptosporidium specified in 310 CMR 22.20G(12)(a) based on their bin classification as determined under 310 CMR 22.20G(11) and according to the schedule in 310 CMR 22.20G(14).

310 CMR 22.20G: Table 3

FILTERED SYSTEM ADDITIONAL CRYPTOSPORIDIUM TREATMENT REQUIREMENTS

If the system bin classification is ...	And the system uses the following Filtration treatment in full compliance with 310 CMR 22.20A, 310 CMR 22.20D, and 310 CMR 22.20F (as applicable), then the additional Cryptosporidium treatment requirements are ...
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	-1
Bin 3	2-log treatment	2.5-log treatment	2-log treatment	-2
Bin 4	2.5-log treatment	3-log treatment	2.5-log treatment	-3

¹ As determined by the Department such that the total Cryptosporidium removal and inactivation is at least 4.0-log.

² As determined by the Department such that the total Cryptosporidium removal and inactivation is at least 5.0-log.

³ As determined by the Department such that the total Cryptosporidium removal and inactivation is at least 5.5-log.

(b)

1. Filtered systems must use one or more of the treatment and management options listed in 310 CMR 22.20G(18) to comply with the additional Cryptosporidium treatment required in 310 CMR 22.20G(12)(a).

2. Systems classified in Bin 3 and Bin 4 must achieve at least 1-log of the additional Cryptosporidium treatment required under 310 CMR 22.20G(12)(a) using either one or a combination of the following: Bag Filters, Bank Filtration, Cartridge Filters, chlorine dioxide, membranes, ozone, or UV, in accordance with 310 CMR 22.20G(19) through (23).

(c) Failure by a system in any month to achieve treatment credit by meeting criteria in 310 CMR 22.20G(19) through (23), that is at least equal to the level of treatment required in 310 CMR 22.20G(12)(a) 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 310 CMR 22.20G(2)(a) or (b), 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 in accordance with 310 CMR 22.20G(18) through (23).

(13)Unfiltered System Cryptosporidium Treatment Requirements.

(a)Determination of Mean Cryptosporidium Level.

1. Following completion of the initial source water monitoring required under 310 CMR 22.20G(2)(a) unfiltered systems must calculate the arithmetic mean of all Cryptosporidium sample concentrations reported under 310 CMR 22.20G(2)(a). Systems must report this value to the Department for approval no later than six months after the month the system is required to complete initial source water monitoring based on the schedule in 310 CMR 22.20G(2)(c).

2. Following completion of the second round of source water monitoring required under 310 CMR 22.20G(2)(b) unfiltered systems must calculate the arithmetic mean of all Cryptosporidium sample concentrations reported under 310 CMR 22.20G(2)(b). Systems must report this value to the Department for approval no later than six months after the month the system is required to complete the second round of source water monitoring based on the schedule in 310 CMR 22.20G(2)(c).

3. 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 calculation of the mean Cryptosporidium level in 310 CMR 22.20G(13)(a)1. or 2.

4. The report to the Department of the mean Cryptosporidium levels calculated under 310 CMR 22.20G(13)(a)1. and 2. must include a summary of the source water monitoring data used for the calculation.

5. Failure to comply with the conditions of 310 CMR 22.20G(13)(a) is a violation of the Treatment Technique requirement.

(b)Cryptosporidium Inactivation Requirements. Unfiltered systems must provide the level of inactivation for Cryptosporidium specified in 310 CMR 22.20G(13)(b)1. and 2., based on their mean Cryptosporidium levels as determined under 310 CMR 22.20G(13)(a) and according to the schedule in 310 CMR 22.20G(14).

1. Unfiltered systems with a mean Cryptosporidium level of 0.01 oocysts/L or less must provide at least 2-log Cryptosporidium inactivation.

2. Unfiltered systems with a mean Cryptosporidium level of greater than 0.01 oocysts/L must provide at least 3-log Cryptosporidium inactivation.

(c)Inactivation Treatment Technology Requirements. Unfiltered systems must use chlorine dioxide, ozone, or UV; in accordance with 310 CMR 22.20G(23); in order to meet the Cryptosporidium inactivation requirements of 310 CMR 22.20G(13).

1. Systems that use chlorine dioxide or ozone and fail to achieve the Cryptosporidium inactivation required in 310 CMR 22.20G(13)(b) on more than one day in the calendar month are in violation of the Treatment Technique requirement.

2. Systems that use UV light, and fail to achieve the Cryptosporidium inactivation required in 310 CMR 22.20G(13)(b) by meeting the criteria in 310 CMR 22.20G(23)(b)1.d., are in violation of the Treatment Technique requirement.

(d)Use of Two Disinfectants. Unfiltered systems must meet the combined Cryptosporidium inactivation requirements of 310 CMR 22.20G(13) and Giardia lamblia and Virus inactivation requirements of 310 CMR 22.20A(3)(a) using a minimum of two Disinfectants, and each of two Disinfectants must separately achieve the total inactivation required for Cryptosporidium, Giardia lamblia, or Viruses.

(14)Schedule for Compliance with Cryptosporidium Treatment Requirements.

(a) Following initial bin classification under 310 CMR 22.20G(11)(c), filtered systems must provide the level of treatment for Cryptosporidium required under 310 CMR 22.20G(12) according to the schedule in 310 CMR 22.20G(14)(c).

(b) Following initial determination of the mean Cryptosporidium level under 310 CMR 22.20G(13)(a)1., unfiltered systems must provide the level of treatment for Cryptosporidium required under 310 CMR 22.20G(13) according to the schedule in 310 CMR 22.20G(14)(c).

(c)Cryptosporidium Treatment Compliance Dates.

310 CMR 22.20G: Table 4

Cryptosporidium TREATMENT COMPLIANCE DATES TABLE

Systems that serve ...	Must comply with Cryptosporidium treatment requirements no later than...*
(1) At least 100,000 individuals	April 1, 2012
(2) From 50,000 to 99,999 individuals	October 1, 2012
(3) From 10,000 to 49,999 individuals	October 1, 2013
(4) Fewer than 10,000 individuals	October 1, 2014

* The Department may allow up to an additional two years for complying with the treatment requirement for systems making capital improvements.

(d) If the bin classification for a filtered system changes following the second round of source water monitoring, as determined under 310 CMR 22.20G(11)(d), the system must provide the level of treatment for Cryptosporidium required under 310 CMR 22.20G(12) on a schedule the Department approves.

(e) If the mean Cryptosporidium level for an unfiltered system changes following the second round of monitoring, as determined under 310 CMR 22.20G(13)(a)2. and if the system must provide a different level of Cryptosporidium treatment under 310 CMR 22.20G(13) due to this change, the system must meet this treatment requirement on a schedule the Department approves.

(15)Requirements for Uncovered Finished Water Storage Facilities.

(a) Systems using uncovered finished water storage facilities must comply with the conditions of 310 CMR 22.20G(15).

(b) Systems must notify the Department of the use of each Uncovered Finished Water Storage Facility no later than April 1, 2008.

(c) Systems must meet the conditions of 310 CMR 22.20G(15)(c)1. or 2. for each Uncovered Finished Water Storage Facility or be in compliance with a Department-approved schedule to meet these conditions no later than April 1, 2009.

1. Systems must cover any Uncovered Finished Water Storage Facility.

2. Systems must treat the discharge from the Uncovered Finished Water Storage Facility to the Distribution System to achieve inactivation and/or removal of at least 4-log Virus, 3-log Giardia lamblia, and 2-log Cryptosporidium using a protocol approved by the Department.

(d) Failure to comply with the requirements of 310 CMR 22.20G(15) is a violation of the Treatment Technique requirement.

(16)Reporting Requirements.

(a) Systems must report sampling schedules under 310 CMR 22.20G(3) and source water monitoring results under 310 CMR 22.20G(7) unless they notify the Department that they will not conduct source water monitoring due to meeting the criteria of 310 CMR 22.20G(2)(d).

(b) Systems must report the use of uncovered finished water storage facilities to the Department as described in 310 CMR 22.20G(15).

(c) Filtered systems must report their Cryptosporidium bin classification as described in 310 CMR 22.20G(11).

(d) Unfiltered systems must report their mean source water Cryptosporidium level as described in 310 CMR 22.20G(13).

(e) Systems must report Disinfection Profiles and benchmarks to the Department as described in 310 CMR 22.20G(9) through (10) prior to making a significant change in disinfection practice.

(f) Systems must report to the Department in accordance with the following table for any microbial toolbox options used to comply with treatment requirements under 310 CMR 22.20G(12) or (13). 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.

310 CMR 22.20G: Table 5

MICROBIAL TOOLBOX REPORTING REQUIREMENTS

Toolbox option	Systems must submit the following information	On the following schedule
(1) Watershed control program.	(i) Notice of intention to develop a new or continue an existing watershed control program... (ii) Watershed control plan... (iii) Annual watershed control program status report...... (iv) Watershed sanitary survey report..........	No later than two years before the applicable treatment compliance date in 310 CMR 22.20G(14). No later than one year before the applicable treatment compliance date in 310 CMR 22.20G(14). Every 12 months, beginning one year after the applicable treatment compliance date in 310 CMR 22.20G(14). For Community Water Systems, every three years beginning three years after the applicable treatment compliance date in 310 CMR 22.20G(14). For Noncommunity Water Systems, every five years beginning five years after the applicable treatment compliance date in 310 CMR 22.20G(14).
(2) 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 310 CMR 22.20G(14).
(3) Pre-sediments	Monthly verification of the following: (i) Continuous basin operation (ii) Treatment of 100% of the flow (iii) Continuous addition of a coagulant (iv) At least 0.5-log mean reduction of influent Turbidity or compliance with alternative Department approved performance criteria.	Monthly reporting within ten days following the month in which the monitoring was conducted beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(4) 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 (ii) Both stages treated 100% of the plant flow.	Monthly reporting within ten days following the month in which the monitoring was conducted beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(5) Bank Filtration	(i) Initial demonstration of the following: (A) Unconsolidated, predominantly sandy aquifer (B) Setback distance of at least 25 ft. (0.5-log credit) or 50 ft. (1.0-log credit). (ii) If monthly average of daily max Turbidity is greater than one NTU then system must report result and submit an assessment of the cause.	No later than the applicable treatment compliance date in 310 CMR 22.20G(14). Report within 30 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(6) 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 four hour CFE measurements taken each month.	Monthly reporting within ten days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(7) 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. (ii) No individual filter greater than 0.3 NTU in two consecutive readings 15 minutes apart.	Monthly reporting within ten days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(8) Demonstration of performance	(i) Results from testing following a Department-approved protocol. (ii) As required by the Department, monthly verification of operation within conditions of Department approval for demonstration of performance credit.	No later than the applicable treatment compliance date in 310 CMR 22.20G(14). Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(9) Bag Filters and Cartridge Filters	(i) Demonstration that the following criteria are met: (A) Process meets the definition of bag or cartridge Filtration; (B) Removal efficiency established through challenge testing that meets criteria in 310 CMR 22.20G(22)(a). (ii) Monthly verification that 100% of plant flow was filtered.	No later than the applicable treatment compliance date in 310 CMR 22.20G(14). Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(10) Membrane Filtration	(i) Results of verification testing demonstrating the following: (A) Removal efficiency established through challenge testing that meets criteria in 310 CMR 22.20G(22)(b). (B) Integrity test method and parameters, including resolution, sensitivity, test frequency, control limits, and associated baseline. (ii) Monthly report summarizing the following: (A) All direct integrity tests above the control limit; (B) If applicable, any Turbidity or alternative Department approved indirect integrity monitoring results triggering direct integrity testing and the corrective action that was taken.	No later than the applicable treatment compliance date in 310 CMR 22.20G(14). Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(11) Second stage Filtration	Monthly verification that 100% of flow was filtered through both stages and that first stage was preceded by Coagulation step.	Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(12) 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 Sources or Groundwater Under the Direct Influence of Surface Water.	Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(13) Chlorine dioxide	Summary of CT values for each day as described in 310 CMR 22.20G(23), as applicable.	Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(14) Ozone	Summary of CT values for each day as described in 310 CMR 22.20G(23), as applicable.	Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).
(15) UV	(i) Validation test results demonstrating operating conditions that achieve required UV dose. (ii) 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 as specified in 310 CMR 22.20G(23), as applicable.	No later than the applicable treatment compliance date in 310 CMR 22.20G(14). Within ten days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in 310 CMR 22.20G(14).

(17)Recordkeeping Requirements.

(a) Systems must keep results from the initial round of source water monitoring under 310 CMR 22.20G(2)(a) and the second round of source water monitoring under 310 CMR 22.20G(2)(b) until three years after bin classification under 310 CMR 22.20G(11) for filtered systems or determination of the mean Cryptosporidium level under 310 CMR 22.20G(11) for unfiltered systems for the particular round of monitoring.

(b) Systems must keep any notification to the Department that they will not conduct source water monitoring due to meeting the criteria of 310 CMR 22.20G(2)(d) for three years.

(c) Systems must keep the results of treatment monitoring associated with microbial toolbox options under 310 CMR 22.20G(18) through (23) and with uncovered finished water reservoirs under 310 CMR 22.20G(15), as applicable, for three years.

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

(a) A Public Water System may receive the Cryptosporidium treatment credits listed in 310 CMR22.20G(18)(b) Table 6, by meeting the conditions for microbial toolbox options described in 310 CMR 22.20G(19) through (23), provided however that unfiltered systems shall only be eligible for Cryptosporidium treatment credits for the microbial toolbox options described in 310 CMR 22.20G(23). A Supplier of Water may apply these Cryptosporidium treatment credits to meet the treatment requirements set forth in 310 CMR 22.20G(12) and (13), as applicable.

(b) The following table summarizes options in the microbial toolbox set forth in 310 CMR 22.20G(19) through (23). In the event of conflict between this table and the provisions of 310 CMR 22.20G(19) through (23), the latter shall control.

310 CMR 22.20G: Table 6

MICROBIAL TOOLBOX SUMMARY TABLE: OPTIONS, TREATMENT CREDITS AND CRITERIA

Toolbox Option	Log Credit	Cryptosporidium treatment credit with design and implementation criteria
SOURCE PROTECTION AND MANAGEMENT TOOLBOX OPTIONS
1. Watershed control program	0.5-log	For Department-approved program comprising required elements, annual program status report to Department, and regular watershed survey. Unfiltered systems are not eligible for credit. Specific criteria are in 310 CMR 22.20G(19)(a).
2. Alternative source/intake management	No prescribed credit	Suppliers of Water may conduct simultaneous monitoring for treatment bin classification at alternative intake locations or under alternative intake management strategies. Specific criteria are in 310 CMR 22.20G(19)(b).
PRE FILTRATION TOOLBOX OPTIONS
3. Pre-sedimentation basin with Coagulation	0.5-log credit	Credit is given during any month that pre-sedimentation 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 310 CMR 22.20G(20)(a).
4. Two-stage Lime Softening	0.5-log credit	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. Specific criteria are in 310 CMR 22.20G(20)(b).
5. Bank Filtration	0.5-log	For 25-foot setback¹. Specific criteria are in 310 CMR 22.20G(20)(c).
1.0-log	For 50-foot setback¹. Specific criteria are in 310 CMR 22.20G(20)(c).
TREATMENT PERFORMANCE TOOLBOX OPTIONS
6. Combined filter performance	0.5-log	Credit for combined filter effluent Turbidity less than or equal to 0.15 NTU in at least 95% of measurements each month. Specific criteria are in 310 CMR 22.20G(21)(a).
7. Individual filter performance	0.5-log	Credit is given in addition to 0.5-log combined filter performance credit. Credit is given if individual filter effluent Turbidity is less than or equal to 0.15 NTU in at least 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 310 CMR 22.20G(21)(b).
8. Demonstration of performance	Credit awarded	Credit awarded to unit process or treatment train based on a demonstration to the Department with a Department-approved protocol. Specific criteria are in 310 CMR 22.20G(21)(c).
ADDITIONAL FILTRATION TOOLBOX OPTIONS
9. Bag or Cartridge Filters (individual filters)	Up to 2-log	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 310 CMR 22.20G(22)(a).
10. Bag or Cartridge Filters (in series)	Up to 2.5-log	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 310 CMR 22.20G(22)(a).
11. Membrane Filtration	Log credit	Log credit equivalent to removal efficiency demonstrated in challenge test for device if supported by direct integrity testing. Specific criteria are in 310 CMR 22.20G(22)(b).
12. Second stage Filtration	0.5-log	0.5-log credit for second separate granular media Filtration stage if treatment train includes Coagulation prior to first filter. Specific criteria are in 310 CMR 22.20G(22)(c).
13. Slow sand filters	2.5-log	Credit as a secondary Filtration step². Specific criteria are in 310 CMR 22.20G(22)(d).
3.0-log	Credit as a primary Filtration process^2.Specific criteria are in 310 CMR 22.20G(22)(d).
INACTIVATION TOOLBOX OPTIONS
14. Chlorine dioxide	CT table	Log credit based on measured CT in relation to CT table. Specific criteria in 310 CMR 22.20G(23)(a).
15. Ozone	CT table	Log credit based on measured CT in relation to CT table. Specific criteria in 310 CMR 22.20G(23)(a).
16. UV	UV dose	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 310 CMR 22.20G(23)(b).

¹ Aquifer must be unconsolidated sand containing at least 10% fines; average Turbidity in wells must be less than one NTU. Suppliers of Water using wells followed by Filtration when conducting source water monitoring must sample the well to determine bin classification and are not eligible for additional credit.

² No prior chlorination for either option.

(19)Source Toolbox Components.

(a)Watershed Control Program. Suppliers of Water may apply for a 0.5-log Cryptosporidium treatment credit for implementing an approved watershed control program, in accordance with the following requirements:

1. provide advance written notice to the Department of the intent to apply for the watershed control program credit no later than two years prior to the treatment compliance date applicable to the Public Water System in 310 CMR 22.20G(14), Schedule for Compliance with Cryptosporidium Treatment requirements.

2. if no approved watershed control program is in place, then submit to the Department for approval a proposed, written watershed control plan no later than one year before the applicable treatment compliance date in 310 CMR 22.20G(14). The availability of the watershed control program treatment credit shall be contingent on Department approval of the watershed control plan based on the inclusion and adequacy of all of the following elements:

a. identification of an area outside of which the likelihood of Cryptosporidium or fecal contamination affecting the treatment Plant Intake is not significant ("area of influence"). The area of influence shall be evaluated in future watershed surveys, as required in 310 CMR 22.20G(19)(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 Supplier of Water will undertake to reduce source water Cryptosporidium levels, including:

i. an explanation of how the actions are expected to contribute to specific goals;

ii. identification of Watershed resource requirements and commitments; and

iii. a schedule for implementing the watershed control plan, once approved, including deadlines for completing specific actions identified in the watershed control plan.

3. if an approved watershed control program is in place as of January 5, 2006, then submit to the Department for approval written documentation demonstrating that the existing watershed control plan complies with the following:

a. the existing watershed control plan must meet the above criteria listed in 310 CMR 22.20G(19)(a)2. in addition to any criteria met in the existing approval; and

b. the existing watershed control plan must specify ongoing and future actions that will reduce source water Cryptosporidium levels.

4.Credit in the Absence of Department Response. If within 90 days of the Department's receipt of a watershed control plan submitted under 310 CMR 22.20G(19)(a), the Department does not respond to the Supplier of Water regarding approval of that watershed control plan, and the Supplier of Water otherwise meets the requirements of 310 CMR 22.20G(19)(a), the watershed control plan will be considered approved and 0.5 log Cryptosporidium treatment credit will be awarded, unless and until the Department subsequently withdraws such approval.

5. Maintaining the 0.5-log Cryptosporidium treatment credit for implementing an approved watershed control program. In order to maintain a 0.5-log Cryptosporidium treatment credit for implementing an approved watershed control program, the Supplier of Water shall satisfy the following requirements:

a. submit an annual watershed control program status report to the Department. The annual watershed control program status report shall describe the Supplier of Water's implementation of the approved plan and assess the adequacy of the plan to meet its goals. It must explain how the Supplier of Water is addressing any shortcomings in plan implementation, including those previously identified by the Department or as the result of the watershed survey conducted under 310 CMR 22.20G(19)(a)5.b. The Supplier of Water shall also describe any significant changes that have occurred in the Watershed since the last watershed sanitary survey. If a Supplier of Water, based upon implementation of an approved watershed control program, believes that a significant change to the approved watershed control program is necessary, the Supplier of Water shall notify the Department in writing of the changes it proposes to make to its approved watershed control plan. Any such change to an approved watershed control plan shall be subject to:

i. the Department's approval based upon the plan's continued inclusion of and adequacy of the elements in 310 CMR 22.20G(19)(a)2.; and

ii. if any change is likely to reduce the level of source water protection, the Supplier of Water's notification shall include a plan and strategy indicating how the proposed actions will mitigate this effect.

If within 60 days of the Department's receipt of a notification of a change to an approved watershed control plan, the Department does not respond to the Supplier of Water regarding approval of that change, and the Supplier of Water otherwise meets the requirements of 310 CMR 22.20G(19)(a)5.a.i. and ii., then the changes to the approved watershed control plan will be considered approved, unless and until the Department subsequently withdraws such approval, based upon failure to meet such requirements.

b. undergo a watershed sanitary survey every three years for Community Water Systems and every five years for Non-community Water Systems which:

i. encompasses the area of influence identified in the Department-approved watershed control plan;

ii. assesses the implementation of actions to reduce source water Cryptosporidium levels; and

iii. identifies any significant New Sources of Cryptosporidium;

iv. unless performed by the Department, is performed by a qualified Person approved by the Department, based on demonstrated knowledge and experience in:

A. conducting watershed inspections and reviewing and assessing impacts to public water supplies from existing land use practices, stormwater discharges, aquatic and terrestrial invasive species, wildlife, public access and recreation, agriculture, local zoning and non zoning controls;

B. recommending source water protection measures to address impacts; and

C. assisting with multi-town coordination and public education for water supply protection.

Suppliers of Water shall submit the survey report to the Department, unless the survey is performed by the Department. If the Department determines that significant changes have occurred in the Watershed since the previous watershed sanitary survey, the Department may establish an earlier date than otherwise required in 310 CMR 22.20G(19)(a)5.b. by which Public Water Systems shall undergo another watershed sanitary survey.

c. The Supplier of Water shall make the watershed control plan, annual status reports, and watershed sanitary survey reports available to the public in electronic or printed form, upon request. These documents shall be in plain language and include criteria by which to evaluate the success of the program in achieving plan goals. A Supplier of Water may request in writing the Department's written approval to withhold from the public portions of the annual status report, watershed control plan, and watershed sanitary survey based on water supply security considerations. Any such request must identify with specificity the security considerations relevant to each portion proposed to be withheld.

6. A Supplier of Water's watershed control program treatment credit shall be subject to withdrawal if the Department determines that the Supplier of Water is not performing the approved watershed control plan.

(b)Alternative Source.

1. A Supplier of Water 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). A Supplier of Water, subject to the Department's written approval, may determine its bin classification under 310 CMR 22.20G(11) based on the alternative source monitoring results.

2. If a Supplier of Water conducts alternative source monitoring under 310 CMR 22.20G(19)(b), the Supplier of Water shall also monitor its current Plant Intake concurrently, as described in 310 CMR 22.20G(2).

3. Alternative source monitoring under 310 CMR 22.20G(19)(b)1. shall meet the requirements for source monitoring to determine bin classification, as described in 310 CMR 22.20G(2) through (7). The Supplier of Water shall report the alternative source monitoring results in writing to the Department, along with supporting information documenting the operating conditions under which the samples were collected.

4. If a Supplier of Water determines its bin classification under 310 CMR 22.20G(11) 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 Supplier of Water shall relocate the intake or permanently adopt the withdrawal procedure, as applicable, no later than the applicable treatment compliance date in 310 CMR 22.20G(14)(c).

(20)Pre-filtration Treatment Toolbox Components.

(a)Pre-sedimentation. A Supplier of Water using Pre-sedimentation, subject to the Department's review and written approval, shall receive a 0.5-log Cryptosporidium treatment credit for any month the Public Water System meets the following criteria:

1. the Pre-sedimentation is in continuous operation and treats the entire plant flow taken from a Surface Water Source or a Groundwater under the Direct Influence of Surface Water source;

2. the Supplier of Water continuously adds a coagulant to the Pre-sedimentation basin; and

3. the Pre-sedimentation basin achieves the following performance criteria:

a. demonstrates at least 0.5-log mean reduction of influent Turbidity. This reduction must be determined using daily Turbidity measurements in the Pre-sedimentation influent and effluent and must be calculated as follows: log10(monthly mean of daily influent Turbidity) - log10(monthly mean of daily effluent Turbidity); or

b. demonstrates at least 0.5-log mean removal of micron-sized particulate material through the Pre-sedimentation, in accordance with 310 CMR 22.20G(22) b.2.

(b)Two-stage Lime Softening. A Supplier of Water using Two-stage Lime Softening, subject to the Department's satisfactory review and written approval, shall receive a 0.5-log Cryptosporidium treatment credit, if chemical addition and hardness precipitation occur in two separate and sequential softening stages prior to Filtration, and both softening stages treat the entire plant flow taken from a Surface Water Source or a Groundwater under the Direct Influence of Surface Water Source.

(c)Bank Filtration. A Supplier of Water using Bank Filtration that serves as pretreatment to a Filtration plant, subject to the Department's satisfactory review and written approval of the Bank Filtration data, shall receive Cryptosporidium treatment credit, as set forth in 310 CMR 22.20G(2)(c)1. through 8., by meeting the following criteria:

1. Suppliers of Water shall receive either 0.5-log treatment credit for wells with a groundwater flow path of at least 25 feet or a 1.0-log treatment credit for wells with a groundwater flow path of at least 50 feet, whichever is less. The groundwater flow path shall be determined as specified in 310 CMR 22.20G(20)(c)4.;

2. the wells must be located in granular aquifers. Granular aquifers are comprised of sand, clay, silt, rock fragments, pebbles or larger particles, and minor cement. A Supplier of Water must characterize the aquifer at the well site to determine aquifer properties. A Supplier of Water must extract a core from the aquifer and demonstrate that in at least 90% of the core length, grains less than 1.0 mm in diameter constitute at least 10% of the core material;

3. the wells must be horizontal or vertical;

4. for vertical wells, the groundwater flow path is the measured distance from the edge of the Surface Water body under high flow conditions (determined by the 100 year floodplain elevation boundary or by the floodway, as defined in Federal Emergency Management Agency flood hazard maps effective as of March 31, 2016) to the well screen. For horizontal wells, the groundwater flow path is the measured distance from the bed of the river under normal flow conditions to the closest horizontal well lateral screen;

5. each wellhead must be monitored for Turbidity at least once every four hours while the Bank Filtration is in operation and shall be subject to the following requirements:

a. if monthly average Turbidity levels, based on daily maximum values in any of the wells being monitored, exceed one NTU, the Supplier of Water shall report this result to the Department and conduct an assessment within 30 days to determine the cause of the high Turbidity levels in the well; and

b. the Supplier of Water's treatment credit shall be subject to revocation if the Department determines that microbial removal has been compromised, until such time as the Supplier of Water implements corrective actions, as approved by the Department, to remediate the problem;

6.Springs and Infiltration Galleries.

a. Springs and infiltration galleries shall not be eligible for a Bank Filtration treatment credit;

b. Springs and infiltration galleries shall be eligible for credit pursuant to 310 CMR 22.20G(21)(c);

7.Bank Filtration Demonstration of Performance. A Supplier of Water, subject to the Department's review and written approval, shall receive Cryptosporidium treatment credit for Bank Filtration based on submittal of a demonstration of performance study meeting the following criteria:

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; and

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).

Treatment credit based on a performance study may be greater than 1.0-log and may be awarded for Bank Filtration that does not meet the criteria in 310 CMR 22.20G(20)(c)1. through 5.; and

8. Suppliers of Water using Bank Filtration when they begin source water monitoring under 310 CMR 22.20G(2)(a) shall collect samples as described in 310 CMR 22.20G(4)(d), but shall not be eligible for this credit.

(21)Treatment Performance Toolbox Components.

(a)Combined Filter Performance. A Supplier of Water using Conventional Filtration Treatment or Direct Filtration, subject to the Department's review and written approval, shall receive a 0.5 log Cryptosporidium treatment credit during any month the combined filter effluent (CFE) Turbidity is less than or equal to 0.15 NTU in at least 95% of the measurements. Turbidity must be measured as described in 310 CMR 22.20A(5)(a) and (c). Such credit shall be in addition to any other Cryptosporidium treatment credit granted to the Public Water System pursuant to 310 CMR 22.20G.

(b)Individual Filter Performance.

1. A Supplier of Water using conventional Filtration treatment or Direct Filtration treatment, subject to the Department's review and written approval, shall receive 0.5-log Cryptosporidium treatment credit during any month the Public Water System meets the following criteria:

a. the filtered water Turbidity for each individual filter must be less than or equal to 0.15 NTU in at least 95% of the measurements recorded each month; and

b. no individual filter has a measured Turbidity greater than 0.3 NTU in two consecutive measurements taken 15 minutes apart.

2. A Public Water System that has received Cryptosporidium treatment credit for individual filter performance that fails to meet the requirements as specified in 310 CMR 22.20G(21)(b)1.a. or b. during any month shall not receive a Treatment Technique violation as a result of such failure, for the month in which the failure occurred, under 310 CMR 22.20G(12)(c), if the Supplier of Water demonstrates both of the following to the Department's satisfaction:

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 Public Water System has experienced no more than two such failures in any calendar year.

3. Compliance with these criteria shall be based on individual filter Turbidity monitoring as described in 310 CMR 22.20A(5) or 22.20D, as applicable. Such credit shall be in addition to any other Cryptosporidium treatment credit granted to the Public Water System pursuant to 310 CMR 22.20G(21)(a).

(c)Demonstration of Performance.

1. A Supplier of Water, subject to the Department's review and written approval, may be granted Cryptosporidium treatment credit for drinking water treatment processes based on a demonstration of performance study that meets the following criteria:

a. the demonstration of performance study must follow a Department-approved protocol and must demonstrate the level of reduction the treatment process will achieve under the full range of expected operating conditions for the Public Water System; and

b. the Supplier of Water must demonstrate and report on any monitoring and treatment performance criteria designated by the Department, where necessary to verify that the conditions under which the demonstration of performance credit was approved are maintained during routine operation.

2. The Cryptosporidium treatment credit may be greater than or less than the prescribed treatment credits in 310 CMR 22.20G(12) or (20) through (23) and may be awarded to treatment processes that do not meet the criteria for the prescribed credits.

3. A Public Water System that receives a Cryptosporidium treatment credit pursuant to 310 CMR 22.20G(21)(c) shall be subject to revocation if the Department determines that the Public Water System no longer satisfies the criteria set forth in 310 CMR 22.20G(21)(c)1.

4. A Public Water System that receives a Cryptosporidium treatment credit for a demonstration of performance study shall not receive a Cryptosporidium treatment credit for any toolbox option specified in 310 CMR 22.20G(20) through (23).

(22)Additional Filtration Toolbox Components.

(a)Bag Filters and Cartridge Filters. A Supplier of Water using Bag Filters or Cartridge Filters that treat the entire plant flow taken from a Surface Water Source, or Groundwater under the Direct Influence of Surface Water Source, subject to the Department's review and written approval, shall receive Cryptosporidium treatment credit, in accordance with the following:

1.Calculation of Credit. A Cryptosporidium treatment credit of up to 2.0-log for an individual Bag Filter or Cartridge Filter and up to a 2.5-log for Bag Filters or Cartridge Filters operated in series shall be granted based on the removal efficiency demonstrated during challenge testing conducted according to the criteria in 310 CMR 22.20G(22)(a)2.a. through i. A factor of safety equal to 1-log for individual Bag Filters or Cartridge Filters and 0.5-log for Bag Filters or Cartridge Filters in series shall be applied to challenge testing results to determine the Cryptosporidium treatment credit. Suppliers of Water may use results from challenge testing conducted prior to January 5, 2006, if the prior testing was consistent with the criteria specified in 310 CMR 22.20G(22)(a)2.a. through i.

2.Challenge Testing and Reporting Procedures.

a. challenge testing must be performed on full-scale Bag Filters 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 Filters or Cartridge Filters must be challenge tested in the same configuration that the Public Water System will use, either as individual filters or as a series configuration of filters;

b. 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 discreetly quantifying the specific microorganism or surrogate used in the test; gross measurements such as Turbidity may not be used;

c. the maximum feed water concentration that may 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 ×10⁴ × (Filtrate Detection Limit);

d. challenge testing must be conducted at the maximum design flow rate for the filter as specified by the manufacturer;

e. each filter evaluated must be tested for a duration sufficient to reach 100% of the terminal pressure drop, which establishes the maximum pressure drop under which the filter may be used while remaining in compliance with the requirements of 310 CMR 22.20G(22)(a);

f. 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:

Click to view image

Where:

LRV = log removal value demonstrated during challenge testing;

C_f = the feed concentration measured during the challenge test; and

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;

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

h. if fewer than 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 20 or more filters are tested, the overall removal efficiency for the filter product line must be set equal to the tenth 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 tenth percentile may be calculated using linear interpolation; and

i. the results of challenge testing must be reported to the Department.

3.Retesting Requirement. 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 for a determination of whether such change will result in an adjustment to the overall Cryptosporidium treatment credit previously awarded.

(b)Membrane Filtration. A Supplier of Water using Membrane Filtration, subject to the Department's review and written approval, shall receive Cryptosporidium treatment credit, in accordance with the following:

1.Calculation of Credit. The level of Cryptosporidium treatment credit a Public Water System receives shall be equal to the lower of the values determined in 310 CMR 22.20G(22)(b)1.a. and b.

a. The removal efficiency demonstrated during challenge testing conducted under the conditions in 310 CMR 22.20G(22)(b)2.a.

b. The maximum removal efficiency that can be verified through direct integrity testing used with Membrane Filtration under the conditions in 310 CMR 22.20G(22)(b)2.b.

2.Testing and Reporting Procedures.

a.Challenge Testing. The membrane used by the Public Water System must undergo challenge testing to evaluate removal efficiency and the Supplier of Water must report the results of challenge testing to the Department. Suppliers of Water may use data from challenge testing conducted prior to January 5, 2006, if the prior testing was consistent with the criteria specified in 310 CMR 22.20G(22)(b)2.a.i. through viii. Challenge testing must be conducted in accordance with the following:

i. challenge testing must be conducted on either a full-scale membrane module, identical in material and construction to the membrane modules used in the Public Water System's treatment facility, or a smaller-scale membrane module, identical in material and similar in construction to the full-scale module.

"Module" as used herein means the smallest component of a membrane unit in which a specific membrane surface area is housed in a device with a filtrate outlet structure;

ii. 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;

iii. the maximum feed water concentration that may be used during a challenge test must be 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 x10⁶ x (Filtrate Detection Limit);

iv. 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" as used in 310 CMR 22.20G means the throughput of a pressure driven membrane process expressed as flow per unit of membrane area. "Recovery" as used in 310 CMR 22.20G means the volumetric percent of feed water that is converted to filtrate over the course of an operating cycle uninterrupted by events such as chemical cleaning or a solids removal process (i.e., backwashing);

v. 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:

Click to view image

Where:

LRV = log removal value demonstrated during the challenge test;

C_f = the feed concentration measured during the challenge test; and

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 must be 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;

vi. 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 20 modules are tested, then LRV_C-Test must be equal to the lowest of the representative LRVs among the modules tested. If 20 or more modules are tested, then LRV_C-Test is equal to the tenth 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 tenth percentile may be calculated using linear interpolation;

vii. 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 in the Public Water System's treatment facility 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 Cryptosporidium treatment credit demonstrated during the challenge test; and

viii. 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, 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 for a determination of whether such change will result in an adjustment to the previously awarded LRV, and an award of a new LRV_C-Test.

b.Direct Integrity Testing. The membrane used by the Public Water System must undergo direct integrity testing in a manner that demonstrates a removal efficiency equal to or greater than the Cryptosporidium treatment credit received pursuant to 310 CMR 22.20G(22)(b)2.a. A "direct integrity test" as used in 310 CMR 22.00G means a physical test applied to a membrane unit in order to identify and isolate integrity breaches (i.e., one or more leaks that could result in contamination of the filtrate). Direct integrity testing must be conducted in accordance with the following:

i. the direct integrity test must be independently applied to each membrane unit in service. A "membrane unit" as used herein means a group of membrane modules that share common valving that allows the unit to be isolated from the rest of the Public Water System for the purpose of integrity testing or other maintenance;

ii. the direct integrity method must have a resolution of three micrometers or less, where "resolution" as used in 310 CMR 22.20G means the size of the smallest integrity breach that contributes to a response from the direct integrity test;

iii. the direct integrity test must have sensitivity sufficient to verify the Cryptosporidium treatment credit received pursuant to 310 CMR 22.20G(22)(b)2.a, where "sensitivity" as used in 310 CMR 22.20G means the maximum log removal value that can be reliably verified by a direct integrity test. Sensitivity must be determined using the approach in 310 CMR 22.20G(22)(b)2.b.iii.A. or B., as applicable to the type of direct integrity test the system uses.

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

Click to view image

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; and

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.

B. For direct integrity tests that use a particulate or molecular marker, the direct integrity test sensitivity shall be calculated according to the following equation:

Click to view image

Where:

LRV_DIT = the sensitivity of the direct integrity test;

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

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

iv. Suppliers of Water 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 Cryptosporidium treatment credit awarded by the Department;

v. if the result of a direct integrity test exceeds the control limit established under 310 CMR 22.20G(22)(b)2.b.iv., the Supplier of Water must remove the membrane unit from service. The Supplier of Water 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; and

vi. Suppliers of Water 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, unless otherwise approved by the Department, based on demonstrated process reliability, the use of multiple barriers effective for Cryptosporidium, or reliable process safeguards.

c.Indirect Integrity Monitoring. Each membrane used by the Public Water System must undergo continuous indirect integrity monitoring according to the criteria specified in 310 CMR 22.20G(22)(b)2.c.i. through v. "Indirect integrity monitoring" as used in 310 CMR 22.20G means monitoring some aspect of filtrate water quality that is indicative of the removal of particulate matter. A Supplier of Water that implements continuous direct integrity testing of membrane units in accordance with the criteria in 310 CMR 22.20G(22)(b)2.b.i. through v. is not subject to the requirements for continuous indirect integrity monitoring. Monthly reports must be submitted to the Department summarizing all continuous indirect integrity monitoring results triggering direct integrity testing and the corrective action that was taken in each case. Indirect integrity monitoring must be conducted in accordance with the following:

i. unless the Department approves an alternative parameter, continuous indirect integrity monitoring must include continuous filtrate Turbidity monitoring;

ii. continuous monitoring must be conducted at a frequency of no less than once every 15 minutes;

iii. continuous monitoring must be separately conducted on each membrane unit;

iv. if indirect integrity monitoring includes Turbidity and if the filtrate Turbidity readings are above 0.15 NTU for a period greater than 15 minutes (i.e., two consecutive 15-minute readings above 0.15 NTU), direct integrity testing must immediately be performed on the associated membrane unit as specified in 310 CMR 22.20G(22)(b)2.b.i. through v.; and

v. 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 15 minutes, direct integrity testing must immediately be performed on the associated membrane units as specified in 310 CMR 22.20G(22)(b)2.b.i. through v.

(c)Second stage Filtration. A Supplier of Water using second stage Filtration that consists of sand, dual media, GAC, or other fine grain media following granular media Filtration, subject to the Department's review and written approval based on an assessment of the design characteristics of the Filtration process, shall receive 0.5-log Cryptosporidium treatment credit, in accordance with the following:

1. the first stage of Filtration must be preceded by a Coagulation step;

2. both Filtration stages must treat the entire plant flow taken from a Surface Water Source or Groundwater under the Direct Influence of Surface Water Source; and

3. a cap, such as GAC, on a single stage of Filtration shall not be eligible for this Cryptosporidium treatment credit.

(d)Slow Sand Filtration (as Secondary Filter). A Supplier of Water using Slow Sand Filtration (as secondary filter) that follows a separate stage of Filtration, subject to the Department's review and written approval based on an assessment of the design characteristics of the Filtration process, shall receive 2.5-log Cryptosporidium treatment credit, in accordance with the following:

1. both Filtration stages must treat the entire plant flow taken from a Surface Water Source or Groundwater Under the Direct Influence of Surface Water Source;

2. no Disinfectant residual may be present in the influent water to the Slow Sand Filtration process; and

3. Slow Sand Filtration used as a primary Filtration process shall not be eligible for this Cryptosporidium treatment credit.

(23)Inactivation Toolbox Components.

(a)Inactivation by Chlorine Dioxide and Ozone. A Supplier of Water using chlorine dioxide or ozone, subject to the Department's review and written approval, shall receive Cryptosporidium treatment credit, in accordance with the following:

1.Calculation of Credit.

a. A Public Water System meeting the chlorine dioxide CT value in 310 CMR 22.20G(23): Table 7 for the applicable water temperature shall receive the corresponding Cryptosporidium treatment credit.

310 CMR 22.20G: Table 7

CT VALUES (MG ·MIN/L) FOR Cryptosporidium INACTIVATION BY CHLORINE DIOXIDE¹

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

¹ A Supplier of Water may use this equation to determine log credit between the indicated values: log credit = (0.001506 x (1.09116)Temp) x CT.

b. A Public Water System meeting the ozone CT value in 310 CMR 22.20G: Table 8 for the applicable water temperature shall receive the corresponding Cryptosporidium treatment credit.

310 CMR 22.20G: Table 8

CT VALUES (MG MIN/L) FOR Cryptosporidium INACTIVATION BY OZONE¹

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

¹ A Supplier of Water may use this equation to determine log credit between the indicated values: log credit = (0.0397 x (1.09757)Temp) x CT.

c. CT must be calculated at least once each day, with both C and T being measured during peak hourly flow as specified in 310 CMR 22.20A(5)(a) through (b).

d. for a Public Water System which includes several Disinfection segments in sequence, CT must be calculated for each segment. "Disinfection segment" as used herein means a treatment unit process with a measurable Disinfectant residual level and a liquid volume.

2.Site-specific Study. A Supplier of Water may conduct a site-specific study, using a protocol pre-approved by Department, demonstrating a higher inactivation in support of a greater Cryptosporidium treatment credit than shown in 310 CMR 22.20G: Table 7 or Table 8.

(b)Inactivation by Ultraviolet Light. A Supplier of Water using UV light, subject to the Department's review and written approval, shall receive Cryptosporidium, Giardia lamblia, and Virus treatment credits, in accordance with the following:

1. Calculation of credits.

a. achieve the UV dose values in 310 CMR 22.20G: Table 9 to receive the corresponding Cryptosporidium, Giardia lamblia, and Virus treatment credits;

310 CMR 22.20G: Table 9

UV DOSE TABLE FOR Cryptosporidium, Giardia lamblia, and VIRUS INACTIVATION CREDIT

Log credit	Cryptospridium\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

b. the treatment credits listed in 310 CMR 22.20G: Table 9 shall apply to UV light at a wavelength of 254 nm as produced by a low-pressure mercury vapor lamp. To receive treatment credit for other lamp types, demonstrate an equivalent germicidal dose through reactor validation testing, as described in 310 CMR 22.20G(23)(b)4.;

c. the UV dose values in 310 CMR 22.20G: Table 9 are applicable only to post-filter applications of UV in filtered Public Water Systems, and to unfiltered Public Water Systems; and

d. treat at least 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 310 CMR 22.20G(23)(b)1.a. and 4.

2.Water Quality Monitoring. Prior to validation testing, a Supplier of Water shall satisfy the following requirements:

a. sample the water quality at a location that is immediately upstream from where the UV reactor is to be installed.

b. ensure monitoring:

i. represents storm events, reservoir turnover, seasonal changes, source blending and any variation in upstream treatment;

ii. is conducted up to the period of time specified in 310 CMR 22.20G: Table 10. The Department may approve a shorter period of monitoring if the Supplier of Water can demonstrate that the water quality is stable and does not change seasonally; and

iii. meets the water quality limits, specified in 310 CMR 22.20G: Table 10:

310 CMR 22.20G: Table 10

UV RAW WATER QUALITY CRITERIA

Parameter	Frequency¹	Limits
pH (field measurement)	Monthly	NA
Temp. (field measurement)	Bi-weekly for one year	NA
Dissolved iron (mg/L)	Quarterly for one year	0.1
Dissolved manganese (mg/L)	Quarterly for one year	0.05
Turbidity (NTU)	Bi-weekly for one year	0.3
Color (color units)	Monthly	15
Total Hardness (mg/L as CaCO₃)	Quarterly for one year	120
Hydrogen Sulfide² (mg/L)	Quarterly for one year	0.2
Alkalinity (mg/L as CaCO₃)	Quarterly for one year	NA
Suspended Solids (mg/L)	Quarterly for one year	10.0
UV Transmittance at 254nm	Bi-weekly for one year	NA
Spectral Absorbance³	Bi-weekly for one year	NA
Algae Counts (cells/mL)⁴	Bi-weekly for one year	NA⁵

¹ The Department may allow the use of historical data collected at higher frequencies

² Groundwater only

³ For the use of medium pressure reactors only. Absorbance to be measured at 200 - 300 nm

⁴ Unfiltered supplies only

⁵ At algae concentration > 70,000 cells/mL additional piloting may be required as part of the UV validation testing

3.Additional Raw Water Treatment. If a Public Water System fails to satisfy the requirements set forth in 310 CMR 22.20G(23)(b)2.b.iii., the Supplier of Water may propose and, subject to Department approval pursuant to 310 CMR 22.04, implement additional treatment for raw water in order to achieve the limits specified in 310 CMR 22.20G: Table 10.

4.Reactor Validation Testing. A Supplier of Water must use UV reactors that have undergone validation testing to determine the operating conditions under which the reactors deliver the UV dose required in 310 CMR 22.20G(23)(b)1.a. for the applicable credit, subject to the following:

a. validation testing must include either full scale testing of a reactor that conforms uniformly to the UV reactors used by the Public Water System and inactivation of a test microorganism whose dose response characteristics have been quantified with a low pressure mercury vapor lamp, or an alternative approach in accordance with 310 CMR 22.20G(23)(b)4.b.; or

b. any alternative approach to UV validation using protocols established in:

i.Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse, 3^rdEdition, August 2012, published by National Water Research Institute in collaboration with AWWA Research Foundation, pp 1-78; or

ii.Ultraviolet Microbiological Water Treatment Systems, NSF/ANSI 55-2014, October 16, 2014, Appendix A and B, pp.1-36, published by NSF/ANSI; and

c. operating conditions must include flow rate, UV intensity as measured by a UV sensor, and UV lamp status; which must account for the following factors: UV absorbance of the water; lamp fouling and aging; measurement uncertainty of on-line 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.

5.Reactor Monitoring, Verification and Calibration.

a. A Supplier of Water must monitor UV reactors to determine if the reactors are operating within validated conditions, as identified in 310 CMR 22.20G(23)(b)4.

b. A Supplier of Water must submit monitoring results to the Department on a monthly basis on a form approved by the Department for review and evaluation in a format approved by the Department.

c. A Supplier of Water must monitor UV intensity as measured by a UV sensor(s), flow rate, lamp status, UV transmittance, or "UVT", and other appropriate parameters based on UV reactor operation.

d. A Supplier of Water must calibrate the UV reactor flow meters annually.

e. A Supplier of Water must verify the calibration of the UV sensors monthly and recalibrate the sensors annually, each in accordance with manufacturer's specifications.

f. A Supplier of Water must verify the calibration of UVT analyzers annually for UV reactors using the "Setpoint Approach". The Setpoint Approach, also called "Operational Setpoint", uses a specific value for a critical parameter, such as UV intensity, that is related to UV dose. Setpoints are established during validation testing. During operations, the PWS compares the measured parameter to the setpoint to confirm performance.

g. A Supplier of Water must verify the calibration of UV transmittance analyzers weekly for UV reactors using the "Calculated Dose Approach". The Calculated Dose Approach uses a dose-monitoring equation to estimate the UV dose based on operating conditions (typically flow rate, UV intensity, and UVT).

h. A Supplier of Water must verify the UVT reading of the reactor by comparing the UVT obtained from the on-line UVT transmitter against the UVT of a grab sample. The difference in reading between the on-line analyzer reading and the grab sample must be less than or equal to two percent of the UVT.

310 CMR, § 22.20G

Amended by Mass Register Issue 1309, eff. 3/25/2016.