5 Colo. Code Regs. § 1002-11.8

Current through Register Vol. 47, No. 20, October 25, 2024

Section 5 CCR 1002-11.8 - SURFACE WATER TREATMENT RULE

11.8(1) General Requirements

(a)Applicability and Definitions

(i) For all surface water systems, the supplier must comply with the requirements specified in this rule.

(ii) "COMBINED FILTER EFFLUENT" means a location representative of the filtered water quality which includes the filter effluent of all filters in use at any given time and is as close as practical to the point where all individual filter effluents combine or as approved by the Department.

(iii) "COMPREHENSIVE PERFORMANCE EVALUATION" or "CPE" means a thorough review and analysis of a treatment plant's performance capabilities and associated administrative, operational and maintenance practices. It is conducted to identify factors that may be adversely impacting a plant's capability to achieve compliance and emphasizes approaches that can be implemented without significant capital improvements. The CPE must include at least all of the following components:

(A) Assessment of plant performance.

(B) Evaluation of major unit processes.

(C) Identification and prioritization of performance limiting factors.

(D) Assessment of whether a CTAP would improve treatment plant performance.

(iv) "COMPREHENSIVE TECHNICAL ASSISTANCE PROJECT" or "CTAP" means a performance improvement project that uses CPE results to set priorities for process control improvements and to establish a long-term training program for staff and administrators.

(v) "FILTER PROFILE" means a graphical representation of individual filter performance, based on continuous turbidity measurements or total particle counts versus time for an entire filter run, from startup to backwash inclusively, that includes an assessment of filter performance while another filter is being backwashed.

(vi) "INDIVIDUAL FILTER EFFLUENT" means a location representative of the filtered water quality from an individual filter's effluent which is at a point before combining with the effluent flow from other filters.

(vii) "POINT OF DISINFECTANT APPLICATION" means the point where the disinfectant is applied and water downstream of that point is not subject to recontamination.

(b)Treatment Technique Requirements

(i) The supplier must provide filtration and disinfection of surface water sources that meets the treatment technique requirements for all of the following: Cryptosporidium, Giardia lamblia, viruses, Heterotrophic Plate Count bacteria, Legionella, and turbidity. These treatment techniques are as follows:

(A) At a point between where the source water is not subject to recontamination and the entry point, the supplier must install and properly operate water treatment processes that reliably achieve at least the following levels of treatment:

(I) 99 percent (2-log) removal of Cryptosporidium.

(II) 99.9 percent (3-log) treatment, including filtration and disinfection, of Giardia lamblia.

(III) 99.99 percent (4-log) treatment, including filtration and disinfection, of viruses.

(ii) The supplier is considered to be in compliance with the requirements specified in 11.8(1)(b)(i), if the supplier meets all of the following:

(A) The filtration requirements specified in 11.8(2)(b).

(B) The disinfection requirements specified in 11.8(3)(b).

(iii) Until March 31, 2016, the supplier must not use uncovered finished water storage facilities.

(A) "UNCOVERED FINISHED WATER STORAGE FACILITY" means, until March 31, 2016, a tank, reservoir, or other facility used to store water that will undergo no further treatment except residual disinfection and that is open to the atmosphere without properly screened vents, screened overflow pipe, or cover.

(iv) When the Department determines that a groundwater source is under the direct influence of surface water, and therefore the system is reclassified as a surface water system, the supplier must comply with the requirements specified in this section, 11.8(1)(b), no later than 18 months after receiving written notification from the Department of the source's reclassification.

11.8(2)Filtration Requirements

(a)Applicability for Filtration Requirements

(i) For all surface water systems, the supplier must comply with the requirements specified in this section, 11.8(2).

(b)Treatment Technique Requirements for the Combined Filter Effluent

(i) The combined filter effluent treatment technique requirements are as follows:

(A) At the combined filter effluent, the supplier must:

(I) Maintain treated water turbidity levels of less than or equal to ([LESS THAN EQUAL TO]) the 95^thpercentile limit specified in Table 11.8-I in at least 95 percent of the turbidity monitoring results collected each month.

(a) For systems using slow sand filtration, the Department may allow an elevated turbidity level if the Department determines there is no significant interference with disinfection at the elevated turbidity limit for that system.

(II) Maintain treated water turbidity levels that are less than or equal to ([LESS THAN EQUAL TO]) the maximum limit specified in Table 11.8-I at all times.

TABLE 11.8-I TURBIDITY LIMITS

For systems using:	95th percentile limit	Maximum limit
Conventional Filtration	0.3 NTU	1 NTU
Direct Filtration	0.3 NTU	1 NTU
Slow Sand Filtration	1 NTU	5 NTU
Diatomaceous Earth Filtration	1 NTU	5 NTU
Alternative Filtration Technologies -Bag Filtration	1 NTU	5 NTU
Alternative Filtration Technologies -Cartridge Filtration	1 NTU	5 NTU
Alternative Filtration Technologies -Membranes and all other alternative filtration	As approved by the Department, but no greater than 1 NTU	As approved by the Department, but no greater than 5 NTU

(ii) If approved by the Department, the supplier may use alternative filtration technologies including membrane filtration or filtration technologies other than those specified in Table 11.8-I.

(A) In order for the Department to approve an alternative filtration technology, the supplier must demonstrate, using pilot plant studies or other means, that the filtration technology, in combination with the disinfection treatment as specified in 11.8(3)(b), consistently achieves 99 percent (2-log) removal of Cryptosporidium, 99.9 percent (3-log) removal and inactivation of Giardia lamblia, 99.99 percent (4-log) removal and inactivation of viruses.

(B) If the Department approves the use of an alternative filtration technology, the Department shall approve combined filter effluent turbidity limits that are less than or equal to ([LESS THAN EQUAL TO]):

(I) 1 NTU in 95 percent of measurements collected each month; and

(II) 5 NTU at any time.

(iii) When the Department determines that a groundwater source is under the direct influence of surface water, and therefore the system is reclassified as a surface water system, the supplier must comply with the requirements specified in this section, 11.8(2)(b), no later than 18 months after receiving written notification from the Department of the source's reclassification.

(c)Monitoring Requirements for Combined Filter Effluent Treatment Technique Requirements

(i) To determine compliance with the combined filter effluent treatment technique requirements, the supplier must monitor turbidity at least every four hours at a location(s) representative of the combined filter effluent.

(A) The supplier may monitor turbidity continuously if the supplier validates the continuous monitoring equipment for accuracy at a Department-approved regular frequency and using a Department-approved protocol.

(B) The Department may reduce the turbidity monitoring frequency to daily if the Department determines that less frequent monitoring is sufficient to indicate effective filtration performance for systems that meet one or more of the following:

(I) The system uses filtration treatment other than conventional filtration treatment, direct filtration, or diatomaceous earth filtration.

(II) The system supplies less than or equal to ([LESS THAN EQUAL TO]) 500 people.

(ii) For systems using lime softening, the supplier may acidify turbidity samples before analysis using a Department-approved protocol.

(d)Treatment Technique Violations for Combined Filter Effluent

(i) The following constitute combined filter effluent treatment technique violations:

(A) More than 5 percent of turbidity monitoring results in any month are greater than (>) the applicable 95th percentile limits specified in Table 11.8-I.

(B) At any time a turbidity monitoring result is greater than (>) the applicable maximum turbidity limit specified in Table 11.8-I.

(e)Response to Combined Filter Effluent Treatment Technique Violations

(i) In the event of a 95^th percentile combined filter effluent turbidity limit treatment technique violation, as specified in 11.8(2)(d)(i)(A), the supplier must:

(A) Notify the Department no later than 48 hours after the violation occurs.

(B) Distribute Tier 2 public notice as specified in 11.33.

(ii) In the event of a maximum combined filter effluent turbidity limit treatment technique violation, as specified in 11.8(2)(d)(i)(B), the supplier must consult with the Department as soon as possible but no later than 24 hours after the violation occurs.

(A) The Department shall determine from the consultation whether Tier 1 or Tier 2 public notice is required to protect public health. The supplier must distribute public notice as specified by the Department.

(B) If the supplier fails to consult with the Department within 24 hours, the supplier must distribute Tier 1 public notice, as specified in 11.33, for the violation.

(f)Reporting Requirements for Combined Filter Effluent Monitoring

(i) For combined filter effluent turbidity monitoring results collected under 11.8(2)(c), the supplier must submit the following information no later than the 10^th of the following month:

(A) Number of combined filter effluent turbidity monitoring results recorded during the month.

(B) Number and percentage of combined filter effluent turbidity monitoring results recorded during the month that were greater than (>) the 95th percentile turbidity limit specified in 11.8(2)(b).

(C) The date and value of any combined filter effluent turbidity monitoring results collected during the month, which were greater than (>) the maximum turbidity limit.

(g)Monitoring Requirements for Individual Filter Effluent Turbidity

(i) For systems using conventional filtration treatment or direct filtration treatment, the supplier must monitor turbidity continuously at locations representative of each individual filter effluent.

(A) The supplier must record the individual filter effluent turbidity monitoring results at least every 15 minutes.

(B) The supplier must calibrate the continuous monitoring equipment using the manufacturer-specified procedure.

(C) If there is a failure of the continuous monitoring equipment, the supplier must monitor the individual filter effluent turbidity by collecting a grab sample no later than four hours after the last recorded monitoring result and continue collecting grab samples every four hours until the continuous monitoring equipment is returned to service.

(I) For systems supplying greater than or equal to (>=) 10,000 people, the supplier must resume continuous individual filter effluent turbidity monitoring no later than five working days after the equipment failure.

(II) For systems supplying less than (<) 10,000 people, the supplier must resume continuous individual filter effluent turbidity monitoring no later than 14 days after the equipment failure.

(D) For systems supplying less than (<) 10,000 people that consist of two or fewer filters, the supplier may conduct continuous combined filter effluent turbidity monitoring to represent individual filter effluent turbidity monitoring.

(I) Continuous combined filter effluent turbidity monitoring must meet the requirements specified in 11.8(2)(g)(i)(A-C).

(E) For systems using lime softening, the supplier may acidify turbidity samples before analysis using a Department-approved protocol.

(h)Reporting Requirements for Individual Filter Effluent Turbidity Monitoring

For individual filter effluent turbidity monitoring, the supplier must submit documentation that the monitoring was conducted, no later than the 10^th of the following month in which the monitoring was conducted.

(i)Response to Individual Filter Effluent Turbidity Monitoring Results for Systems Supplying Greater Than or Equal to (>=) 10,000 People

(i) If the individual filter effluent turbidity monitoring results at the same filter are greater than

(>) 1.0 NTU in two consecutive recordings collected 15 minutes apart, an exceedance occurs and the supplier must:

(A) Produce a filter profile no later than seven days after the exceedance if the cause for the exceedance is not known.

(B) Submit all of the following no later than the 10^th of the month following the exceedance:

(I) Which filter exceeded.

(II) Date of the exceedance.

(III) The turbidity monitoring results which exceeded 1.0 NTU.

(IV) The cause for the exceedance or if the cause of the exceedance is not known, documentation that a filter profile was produced.

(ii) If, in each month, for three consecutive months, the individual filter effluent turbidity monitoring results at the same filter are greater than (>) 1.0 NTU in two consecutive recordings collected 15 minutes apart, an exceedance occurs.

(A) The supplier must conduct a self-assessment of that filter no later than 14 days after the exceedance.

(B) The self-assessment must include at least all of the following:

(I) Assessment of filter performance.

(II) Development of a filter profile.

(III) Identification and prioritization of factors limiting filter performance.

(IV) Assessment of the applicability of corrections.

(V) Preparation of a written self-assessment report.

(C) In addition to the reporting requirements specified in 11.8(2)(i)(i)(B), the supplier must submit notification by the 10^th of the month following the exceedance that the self-assessment was conducted.

(iii) If, in each month, for two consecutive months, the individual filter effluent turbidity monitoring results at the same filter are greater than (>) 2.0 NTU in two consecutive recordings collected 15 minutes apart, an exceedance occurs.

(A) The supplier must comply with the reporting requirements specified in 11.8(2)(i)(i)(B).

(B) No later than 30 days after the exceedance occurs, the supplier must arrange for a CPE to be conducted by the Department or by a Department-approved third party.

(C) No later than 90 days after the exceedance occurs, the supplier must submit the completed CPE report.

(D) If the CPE indicates the potential for improved water system performance, the supplier must complete a CTAP.

(I) During the CTAP, the supplier must identify and systematically address plant-specific factors as outlined in the CPE and include them in a report submitted no later than 90 days after the completion of the CPE.

(iv) When a filter is brought online, if after the first four hours of operation, the individual filter effluent turbidity monitoring results at that filter are greater than (>) 0.5 NTU in two consecutive readings collected 15 minutes apart, an exceedance occurs and the supplier must:

(A) Produce a filter profile no later than seven days after the exceedance if the cause for the exceedance is not known.

(B) Submit all of the following no later than the 10^th of the month following the exceedance:

(I) Which filter exceeded.

(II) Date of the exceedance.

(III) The turbidity monitoring results which exceeded 0.5 NTU.

(IV) The cause for the exceedance or if the cause of the exceedance is not known, documentation that a filter profile was produced.

(v) For systems using lime softening, the supplier may apply to the Department for higher individual filter effluent turbidity limits than the limits specified in this section, 11.8(2)(i), if the supplier can demonstrate that higher individual filter effluent limits are due only to lime carryover and not degraded filter performance.

(j)Response to Individual Filter Effluent Turbidity Monitoring Results for Systems Supplying Less

Than (<) 10,000 People

(i) If the individual filter effluent turbidity monitoring results at the same filter are greater than

(>) 1.0 NTU in two consecutive recordings collected 15 minutes apart, an exceedance occurs and the supplier must submit all of the following no later than the 10^th of the month following the exceedance:

(A) Which filter exceeded.

(B) Date of the exceedance.

(C) Turbidity monitoring results which exceeded 1.0 NTU.

(D) Cause for the exceedance, if known.

(ii) If, in each month, for three consecutive months the individual filter effluent turbidity monitoring results at the same filter are greater than (>) 1.0 NTU in two consecutive recordings collected 15 minutes apart, an exceedance occurs.

(A) The supplier must conduct a self-assessment of that filter no later than 14 days after the exceedance occurs, unless a CPE is required as specified in 11.8(2)(j)(iii).

(I) For systems with two or fewer filters that monitor combined filter effluent instead of individual filter effluent as specified in 11.8(2)(g)(i)(D), the supplier must conduct the self-assessment on both filters.

(B) The self-assessment must include at least all of the following:

(I) Assessment of filter performance.

(II) Development of a filter profile.

(III) Identification and prioritization of factors limiting filter performance.

(IV) Assessment of the applicability of corrections.

(V) Preparation of a written self-assessment report.

(C) In addition to the reporting requirements specified in 11.8(2)(j)(i), the supplier must submit all of the following no later than the 10^th of the month following the exceedance:

(I) The date the self-assessment was triggered.

(II) The date the self-assessment was completed.

(A) No later than 60 days after the exceedance occurs, the supplier must arrange for a CPE to be conducted by the Department or by a Department-approved third party.

(B) No later than 120 days after the exceedance occurs, the supplier must submit the completed CPE report.

(C) The supplier is not required to arrange for a CPE and submit a CPE report if:

(I) A CPE has been completed by the Department or by a Department-approved third party within the last 12 months; or

(II) The supplier and Department are participating in an ongoing CTAP at the system.

(D) In addition to the reporting requirements specified in 11.8(2)(j)(i), if a CPE is required, the supplier must submit all of the following no later than the 10^th of the month following the exceedance:

(I) That a CPE is required.

(II) The date the CPE was triggered.

(E) If the CPE indicates the potential for improved water system performance, the supplier must complete a CTAP.

(iv) For systems using lime softening, the supplier may apply to the Department for higher individual filter effluent turbidity limits than the limits specified in this section, 11.8(2)(j), if the supplier can demonstrate that higher individual filter effluent turbidity limits are due only to lime carryover and not due to degraded filter performance.

11.8(3)Disinfection Treatment Technique Requirements

(a)Applicability for Disinfection Treatment Technique Requirements

(i) For all surface water systems, the supplier must comply with the disinfection treatment technique requirements specified in this section, 11.8(3).

(ii) When the Department determines that a groundwater source is under the direct influence of surface water, and therefore the system is reclassified as a surface water system, the supplier must comply with all of the following:

(A) Either Department-determined interim disinfection requirements or disinfection treatment technique requirements specified in 11.8(3)(b), no later than 60 days after written notification from the Department of the decision to change the source's classification; and

(B) All requirements specified in this section, 11.8(3), no later 18 months after written notification from the Department of the decision to change the source's classification or no later than when the filtration is installed, whichever is sooner.

(b)Treatment Technique Requirements for Disinfection

(i) The disinfection treatment technique requirements are as follows:

(A) The supplier must maintain disinfection treatment sufficient to ensure that the total treatment processes, including filtration and disinfection, achieve 99.9 percent (3-log) treatment of Giardia lamblia cysts and 99.99 percent (4-log) treatment of viruses, as determined by the Department.

(B) The supplier must maintain a residual disinfectant concentration at each entry point and throughout the distribution system.

(I) At each entry point, the residual disinfectant concentration cannot be less than (<) 0.2 mg/L for more than four hours.

(II) In the distribution system, the residual disinfectant concentration cannot be undetectable in more than 5 percent of the samples collected in each month, for two consecutive months during which the system supplies water to the public.

(III) In the distribution system, the residual disinfectant concentration must be greater than or equal to (>=) 0.2 mg/L.

(ii) No later than December 31, 2015, the supplier may apply to the Department for an extension for complying with the treatment technique requirements specified in 11.8(3)(b)(i)(B)(III).

(A) In the application, the supplier must include all of the following information:

(I) An explanation of why the supplier is unable to comply with the treatment technique requirements specified in 11.8(3)(b)(i)(B)(III).

(II) A distribution system disinfectant residual data analysis demonstrating the inability to comply with the treatment technique requirements specified in 11.8(3)(b)(i)(B)(III).

(III) An engineering report prepared by a professional engineer registered in the state of Colorado demonstrating that capital improvements are necessary to comply with the treatment technique requirements specified in 11.8(3)(b)(i)(B)(III).

(IV) A proposed schedule for completing the system modifications.

(B) The Department shall consider the following criteria when determining if an extension will be granted:

(I) The supplier submitted a complete application that included the information specified above;

(II) The supplier has complied with the monitoring requirements specified in 11.17 in the last 36 months; and

(III) The supplier has not incurred an MCL violation specified in 11.17(9) in the last 36 months.

(iii) The Department will only grant an extension for up to four years.

(iv) If the supplier receives written Department-approval for an extension, the supplier must:

(A) Continue to comply with the treatment technique requirements specified in 11.8(3)(b)(i)(B)(II) and is subject to the violation specified in 11.8(3)(d)(i)(B) until the capital improvements are completed or the extension expires, whichever comes first; and

(B) Comply with any Department-specified requirements.

(c)Monitoring Requirements for Disinfection Treatment Technique Requirements

(i) To determine compliance with the disinfection treatment technique requirements, the supplier must monitor the residual disinfectant concentration.

(A) At each entry point, the supplier must continuously monitor the residual disinfectant concentration.

(I) The supplier must record the lowest monitoring result each day.

(II) If there is a failure of the continuous monitoring equipment, the supplier must monitor the residual disinfectant concentration by collecting a grab sample no later than four hours after the equipment failure and continue collecting grab samples every four hours until the continuous monitoring equipment is returned to service.

(a) The supplier must resume continuous residual disinfectant concentration monitoring no later than five working days after the equipment failure.

(III) For systems supplying less than or equal to ([LESS THAN EQUAL TO]) 3,300 people, the supplier is not required to monitor continuously if the supplier collects grab samples at the frequency specified in Table 11.8-II.

(a) If more than one sample per day is required, the supplier must collect the samples throughout the day. The sampling intervals are subject to Department approval.

(b) If any grab sample result is less than (<) 0.2 mg/L, the supplier must increase the monitoring frequency of the residual disinfectant concentration at that entry point to at least every four hours until the residual disinfectant concentration is greater than or equal to (>=) 0.2 mg/L.

TABLE 11.8-II MINIMUM GRAB SAMPLES
Population supplied by the system	Samples per day
[LESS THAN EQUAL TO] 500	1
501 - 1,000	2
1,001 - 2,500	3
2,501 - 3,300	4

(B) In the distribution system, the supplier must monitor the residual disinfectant concentration at the same time and at the same sampling locations that total coliform samples are collected under 11.16(4).

(I) The supplier must measure the residual disinfectant concentration as free chlorine unless the supplier uses a disinfection process that results in a monochloramine residual disinfectant, then the supplier must measure the residual disinfectant concentration as total chlorine. If the supplier uses a different type of chemical disinfectant (e.g., ozone or chlorine dioxide), the supplier must measure the appropriate residual disinfectant concentration.

(II) For systems using both surface water and groundwater sources, the Department may allow the supplier to collect residual disinfectant concentration samples at locations other than the total coliform sampling locations if the Department determines that other locations are more representative of finished water quality in the distribution system.

(III) A supplier may monitor for heterotrophic bacteria, measured as Heterotrophic Plate Count (HPC), instead of disinfectant residual, pursuant to 11.8(3)(g).

(d)Treatment Technique Violations for Disinfection

(i) The following constitute disinfection treatment technique violations:

(A) At any entry point, the residual disinfectant concentration is less than (<) 0.2 mg/L for more than four hours.

(B) In the distribution system, the residual disinfectant concentration is not detectable in more than 5 percent of the samples collected in each month, for two consecutive months that the system supplies water to the public.

(I) If the Department grants an extension under 11.8(3)(b)(ii), the supplier is subject to this violation after March 31, 2016 and until capital improvements are completed or the extension expires, whichever comes first.

(C) In the distribution system:

(I) If the supplier collects greater than or equal to (>=) 40 residual disinfectant concentration samples per month, the residual disinfectant concentration is less than (<) 0.2 mg/L in more than 5 percent of the samples collected.

(II) If the supplier collects greater than (>) one but less than (<) 40 residual disinfectant concentration samples per monitoring period, the residual disinfectant concentration is less than (<) 0.2 mg/L in more than one sample collected.

(III) If the supplier collects greater than (>) one but less than (<) 40 residual disinfectant concentration samples per monitoring period, the residual disinfectant concentration is less than (<) 0.2 mg/L in more than 5 percent of the samples collected in each month for two consecutive months that the system supplies water to the public.

(IV) If the supplier collects only one residual disinfectant concentration sample per monitoring period, the residual disinfectant concentration is less than (<) 0.2 mg/L.

(D) Any time the supplier fails to comply with the treatment technique requirements specified in 11.8(3)(b)(i)(A).

(e)Response to Disinfection Treatment Technique Violations

(i) In the event of an entry point disinfection treatment technique violation as specified in 11.8(3)(d)(i)(A), the supplier must:

(A) Notify the Department no later than the end of the next business day.

(B) Distribute Tier 2 public notice as specified in 11.33.

(ii) In the event of a disinfection treatment technique violation as specified in 11.8(3)(d)(i)(B-

D), the supplier must:

(A) Notify the Department no later than 48 hours after the violation occurs.

(B) Distribute Tier 2 public notice as specified in 11.33.

(f)Reporting Requirements for Disinfection Monitoring

(i) If at any time the entry point residual disinfectant concentration is less than (<) 0.2 mg/L, the supplier must notify the Department as soon as possible but no later than the end of the next business day.

(A) The supplier must also report, no later than the end of the next business day, whether the entry point residual disinfectant concentration was restored to at least 0.2 mg/L within four hours.

(ii) For residual disinfectant concentration samples collected under 11.8(3)(c), the supplier must submit all of the following information no later than the 10^th of the following month:

(A) For each entry point, the lowest daily residual disinfectant concentration result in mg/L.

(B) The date and duration of each period when the entry point residual disinfectant concentration fell below 0.2 mg/L and when the Department was notified of the occurrence.

(C) For distribution system residual disinfectant concentration samples:

(I) The number of sample results that were less than (<) 0.2 mg/L.

(II) The percentage of sample results that were less than (<) 0.2 mg/L for each of the last two months.

(g)Monitoring Requirements for Alternative Disinfection- Heterotrophic Bacteria

(i) In the distribution system, the supplier may monitor for heterotrophic bacteria, measured as Heterotrophic Plate Count (HPC), instead of residual disinfectant concentration, pursuant to 11.8(3)(c).

(A) If the supplier is monitoring for heterotrophic bacteria instead of residual disinfectant concentration, the samples must be analyzed under 11.46(2)(f). Heterotrophic bacteria concentrations less than or equal to ([LESS THAN EQUAL TO]) 500 CFU/ml are considered to have a detectable residual disinfectant concentration for purposes of determining compliance with the treatment technique requirement specified in 11.8(3)(b)(i)(B)(II) and must be included with the reporting requirements specified in 11.8(3)(f)(ii)(C).

(B) If the supplier is monitoring for heterotrophic bacteria, the supplier is not required to comply with the requirements for the distribution system residual disinfectant concentration specified in this section, 11.8(3) if the Department determines that the supplier meets all of the following criteria:

(I) Providing adequate disinfection in the distribution system.

(II) Not capable of having a sample transported and analyzed for HPC by a certified laboratory within the required time and temperature conditions specified by approved analytical methods.

11.8(4)Disinfection Profiling

The purpose of disinfection profiling and benchmarking is to allow the supplier and the Department to assess whether a change in disinfection practices creates a microbial risk. The supplier must develop a disinfection profile, calculate a benchmark (lowest monthly inactivation) based on the profile, and consult with the Department before making a significant change to disinfection.

(a)Applicability and Definitions for Disinfection Profiling

(i) For new surface water systems or reclassified systems that now meet the applicability of this rule, applicability for this section, 11.8(4), is determined by evaluating TTHM and HAA5 sample results. Applicability must be determined no later than 12 months after the system is classified as a surface water system.

(A) The supplier must collect TTHM and HAA5 samples that meet the routine sampling requirements specified in 11.25(1)(c) and submit the results to the Department. Alternatively, the supplier may:

(I) Request that the Department approve the use of a more appropriate data set for determination of applicability; or

(II) Choose not to collect the TTHM and HAA5 data, if the supplier notifies the Department of the decision. The supplier must then develop a disinfection profile to determine log inactivation of Giardia lamblia under 11.8(4)(a)(i)(B).

(B) The supplier must comply with the treatment technique requirement to develop a disinfection profile to determine log inactivation of Giardia lamblia if the system meets either of the following criteria:

(I) A system supplying greater than or equal to (>=) 10,000 people and has a TTHM annual average of quarterly samples greater than or equal to (>=) 0.064 mg/L or has an HAA5 annual average of quarterly samples greater than or equal to (>=) 0.048 mg/L.

(II) A community or non-transient, non-community water systems supplying less than (<) 10,000 people and has a TTHM sample result greater than or equal to (>=) 0.064 mg/L or has an HAA5 sample result greater than or equal to (>=) 0.048 mg/L.

(C) For systems that use chloramines, ozone, or chlorine dioxide that meet the criteria specified in 11.8(4)(a)(i)(B), the supplier must also develop a disinfection profile to determine log inactivation of viruses.

(ii) If a supplier plans to make a significant change in disinfection practices, the supplier must comply with the treatment technique requirement to develop a disinfection profile to determine log inactivation of Giardia lamblia and log inactivation of viruses before making the change.

(iii) "DISINFECTION PROFILE" means the graphical representation of a system's microbial inactivation over 12 consecutive months.

(iv) "SIGNIFICANT CHANGES IN DISINFECTION PRACTICE" means one or more of the following:

(A) Changes to the point of disinfection.

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

(C) Changes to the disinfection process.

(D) Any other modification identified by the Department.

(b)Monitoring Requirements for Disinfection Profiling

(i) To determine the log inactivation ratio(s) for each disinfection segment before the distribution system, the supplier must monitor the following set of parameters during daily peak hourly flow:

(A) The residual disinfectant concentration(s) (C) at each entry point.

(I) For systems with one point of disinfectant application and multiple disinfection segments, the supplier must also monitor before each sequential segment of disinfection.

(II) For systems with multiple points of disinfectant application, the supplier must also monitor before each additional point of disinfectant application.

(B) The temperature of the disinfected water at each residual disinfectant concentration sampling location or at an alternative Department-approved location(s).

(C) For systems using chlorine, the pH of the disinfected water at each residual disinfectant concentration sampling location or at an alternative Department-approved location(s).

(D) System-specific parameters to determine the disinfectant contact time(s) (T).

(ii) The supplier must monitor the set of parameters specified in 11.8(4)(b)(i) at the following frequencies:

(A) For systems meeting the criteria as specified in 11.8(4)(a)(i)(B)(I), at least daily for 12 consecutive months.

(B) For systems meeting the criteria as specified in 11.8(4)(a)(i)(B)(II) or 11.8(4)(a)(ii), at least weekly on the same calendar day for 12 consecutive months.

(C) For seasonal systems, at the frequency specified above in 11.8(4)(b)(ii)(A) or 11.8(4)(b)(ii)(B) only when the system operates.

(D) If the supplier monitors more frequently than required, the monitoring frequency must be evenly spaced.

(iii) For systems meeting the criteria specified in 11.8(4)(a)(ii) the supplier is not required to conduct monitoring as specified in 11.8(4)(b)(i-ii), if the system meets one of the following criteria:

(A) If the supplier has at least one year of existing data that are substantially equivalent to the data set required under 11.8(4)(b)(i-ii), the supplier may use this data to develop a disinfection profile(s), with the all of the following conditions:

(I) If the supplier has made a significant change to treatment practices or changed sources since the data was collected, the supplier must not use previously collected data.

(II) The supplier may develop a disinfection profile(s) using up to three years of existing data.

(B) If the supplier was required to develop a disinfection profile as specified in 11.8(4)(a)(i)(B), the supplier may use the previously developed disinfection profile(s) and is not required to develop a new disinfection profile, with all of the following conditions:

(I) If the supplier has made a significant change to treatment practices or changed sources since the disinfection profile(s) was developed, the supplier must not use a previously developed disinfection profile(s).

(II) If a virus disinfection profile(s) was not previously developed, the supplier must develop a virus disinfection profile(s) using the same monitoring data on which the Giardia lamblia disinfection profile(s) is based.

(c)Disinfection Profiling Calculations

(i) For each set of parameters collected under 11.8(4)(b), the supplier must calculate total inactivation ratio(s) and total logs of inactivation for Giardia lamblia based on the CT99.9 values in 11.46 as follows:

(A) The supplier must determine the total inactivation ratio as follows:

Inactivation ratio is equal to: (CTcalc /CT99.9).

(I) For a supplier monitoring at a single location, calculate one inactivation ratio.

(II) For a supplier monitoring at multiple locations:

(a) Determine the inactivation ratio value for each segment.

(b) Add all inactivation ratio values to determine the total inactivation ratio: ([SIGMA] (CTcalc /CT99.9)).

(B) The supplier must determine the total logs of inactivation by multiplying the total inactivation ratio by 3.0.

Total logs of inactivation is equal to: 3.0 x [SIGMA] (CTcalc /CT99.9).

(ii) If the supplier is required to calculate the logs of inactivation for viruses as specified in 11.8(4)(a)(i)(C) or 11.8(4)(a)(ii), the supplier must use a Department-approved calculation method.

(iii) The supplier must maintain disinfection profile data in graphic form, as a spreadsheet, or in a Department-accepted format for review as part of sanitary surveys.

(d)Treatment Technique Violations and Response for Disinfection Profiling

(i) If the supplier fails to comply with the requirements specified in this section, 11.8(4), a disinfection profiling treatment technique violation occurs.

(ii) In the event of a disinfection profile treatment technique violation, the supplier must:

(A) Notify the Department no later than 48 hours after the violation occurs.

(B) Distribute Tier 2 public notice as specified in 11.33.

11.8(5)Disinfection Benchmarking

(a)Applicability and Definitions for Disinfection Benchmarking

(i) If the supplier was required to develop a disinfection profile for Giardia lamblia and/or viruses as specified in 11.8(4) and plans to make a significant change in disinfection practices, as defined in 11.8(4)(a)(iv), the supplier must comply with all of the following treatment technique requirements before making the change:

(A) Calculate a disinfection benchmark for each profile developed under 11.8(4)(c).

(B) Consult with the Department.

(ii) "DISINFECTION BENCHMARK" means the lowest monthly average of total log inactivation values calculated in the disinfection profile. The disinfection benchmark is used as a baseline of inactivation when considering changes in the disinfection process.

(b)Disinfection Benchmarking Calculations

(i) The supplier must calculate a disinfection benchmark as follows:

(A) Calculate the average log inactivation for each month using the total logs of inactivation value(s) calculated in the disinfection profile developed under 11.8(4)(c).

(B) If the supplier has collected one year of data, the lowest monthly average log inactivation value is the disinfection benchmark.

(C) If the supplier has collected more than one year of data, the average of the lowest monthly average log inactivation value for each calendar year is the disinfection benchmark.

(c)Reporting Requirements for Department Consultation

(i) The supplier must submit all of the following information as part of the consultation process:

(A) A description of the proposed change in disinfection practice.

(B) The disinfection profile and benchmark for Giardia lamblia.

(C) If required to be developed, the disinfection profile and benchmark for viruses.

(D) An analysis of how the proposed change will affect the current levels of disinfection.

(E) Any additional information requested by the Department.

(d)Treatment Technique Violations and Response for Disinfection Benchmarking

(i) If the supplier fails to comply with the requirements specified in this section, 11.8(5), a disinfection benchmarking treatment technique violation occurs.

(ii) In the event of a disinfection benchmark treatment technique violation, the supplier must:

(A) Notify the Department no later than 48 hours after the violation occurs.

(B) Distribute Tier 2 public notice as specified in 11.33.

5 CCR 1002-11.8

38 CR 07, April 10, 2015, effective 4/30/2015

41 CR 11, June 10, 2018, effective 6/30/2018

41 CR 23, December 10, 2018, effective 12/30/2018

43 CR 07, April 10, 2020, effective 4/30/2020

43 CR 17, September 10, 2020, effective 9/30/2020

45 CR 24, December 25, 2022, effective 1/14/2023