S.C. Code Regs. § § 61-58.10.H

Current through Register Vol. 48, 12, December 27, 2024

Section 61-58.10.H - Enhanced Filtration and Disinfection-Systems Serving 10,000 or More People (Interim Enhanced Surface Water Treatment Rule)

(1) General requirements.

(a) The requirements of these regulations constitute national primary drinking water regulations. These regulations establish requirements for filtration and disinfection that are in addition to criteria under which filtration and disinfection are required under Sections B through G above. The requirements of this section are applicable to public water systems supplied by a surface water source and public water systems supplied by a ground water source under the direct influence of surface water serving at least 10,000 people, beginning January 1, 2002 unless otherwise specified. These regulations establish or extend treatment technique requirements in lieu of maximum contaminant levels for the following contaminants: Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, Cryptosporidium, and turbidity. Each public water system supplied by a surface water source or a ground water source under the direct influence of surface water system serving at least 10,000 people must provide treatment of its source water that complies with these treatment technique requirements and are in addition to those identified in Sections B through G above. The treatment technique requirements consist of installing and properly operating water treatment processes which reliably achieve:

(i) At least 99 percent (2-log) removal of Cryptosporidium between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer for filtered systems, or Cryptosporidium control under the watershed control plan for unfiltered systems.

(ii) Compliance with the profiling and benchmark requirements under the provisions of paragraph (3) of this section.

(b) A public water system subject to the requirements of these regulations is considered to be in compliance with the requirements of paragraph (1) of this section if:

(i) It meets the requirements for avoiding filtration in R.61-58.10(C)(C) and R.61-58.10(H)(2)(H)(2) and the disinfection requirements in R.61-58.10(D)(D) and R.61-58.10(H)(3)(H)(3); or

(ii) It meets the applicable filtration requirements in either R.61-58.10(E)(E) or R.61-58.10(D)(H)(4) and the disinfection requirements inR.61-58.10(H)(3)(D) and R.61-58.10(H)(61-58.10(H)(3)).

(c) Systems are not permitted to begin construction of uncovered finished water storage facilities beginning February, 16, 1999.

(d) Systems with a surface water source or a ground water source under the direct influence of surface water that did not conduct optional monitoring under Section H(3) because they served fewer than 10,000 persons when such monitoring was required, but served at least 10,000 persons prior to January 1, 2005 must comply with Section H. These systems must also consult with the Department to establish a disinfection benchmark. A system that decides to make a significant change to its disinfection practice, as described in Section H(3)(c)(i) must consult with the Department prior to making such change.

(2) Criteria for avoiding filtration.

In addition to the requirements of R.61-58.10(C)(C), a public water system subject to the requirements of this section that does not provide filtration must meet all of the conditions of paragraphs (2)(a) and (2)(b) of this section.

(a) Site-specific conditions. In addition to site-specific conditions in R.61-58.10(C)(2)(C)(2), systems must maintain the watershed control program under R.61-58.10(C)(2)(b)(C)(2)(b) to minimize the potential for contamination by Cryptosporidium oocysts in the source water. The watershed control program must, for Cryptosporidium:

(i) Identify watershed characteristics and activities which may have an adverse effect on source water quality; and

(ii) Monitor the occurrence of activities which may have an adverse effect on source water quality.

(b) During the onsite inspection conducted under the provisions of R.61-58.10(C)(2)(c)(C)(2)(c), the Department must determine whether the watershed control program established under 58.10(C)(2)(b) is adequate to limit potential contamination by Cryptosporidium oocysts. The adequacy of the program must be based on the comprehensiveness of the watershed review; the effectiveness of the system's program to monitor and control detrimental activities occurring in the watershed; and the extent to which the water system has maximized land ownership and/or controlled land use within the watershed.

(3) Disinfection profiling and benchmarking.

(a) Using data gathered from monitoring conducted by the Department during the time period of January 1, 1999 through March 1, 2000, any system having either a TTHM annual average greater than or equal to 0.064 mg/L or an HAA5 annual average greater than or equal to 0.048 mg/L during this period must comply with paragraph (3)(b) of this section.

(b) Disinfection profiling.

(i) Any system that meets the criteria in paragraph (3)(a) of this section must develop a disinfection profile of its disinfection practice for a period of up to three years.

(ii) The system must monitor daily for a period of twelve (12) consecutive calendar months to determine the total logs of inactivation for each day of operation, based on the CT_99.9 values in Tables 1.1--1.6, 2.1, and 3.1 of R.61-58.10.F(2), as appropriate, through the entire treatment plant. This system must begin this monitoring not later than March 16, 2000. As a minimum, the system with a single point of disinfectant application prior to entrance to the distribution system must conduct the monitoring in paragraphs (3)(b)(ii) (A) through (D) of this section. A system with more than one point of disinfectant application must conduct the monitoring in paragraphs (3)(b)(i) through (iv) of this section for each disinfection segment. The system must monitor the parameters necessary to determine the total inactivation ratio, using EPA approved analytical methods specified in 40 CFR 141, as follows:

(A) The temperature of the disinfected water must be measured once per day at each residual disinfectant concentration sampling point during peak hourly flow.

(B) If the system uses chlorine, the pH of the disinfected water must be measured once per day at each chlorine residual disinfectant concentration sampling point during peak hourly flow.

(C) The disinfectant contact time(s) ("T") must be determined for each day during peak hourly flow.

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

(iii) In lieu of the monitoring conducted under the provisions of paragraph (b)(ii) of this section to develop the disinfection profile, the system may elect to meet the requirements of paragraph (b)(iii)(A) of this section. In addition to the monitoring conducted under the provisions of paragraph (b)(ii) of this section to develop the disinfection profile, the system may elect to meet the requirements of paragraph (b)(iii)(B) of this section.

(A) A PWS that has three years of existing operational data may submit those data, a profile generated using those data, and a request that the State approve use of those data in lieu of monitoring under the provisions of paragraph (b)(2) of this section not later than March 16, 2000. The State must determine whether these operational data are substantially equivalent to data collected under the provisions of paragraph (b)(ii) of this section. These data must also be representative of Giardia lamblia inactivation through the entire treatment plant and not just of certain treatment segments. Until the State approves this request, the system is required to conduct monitoring under the provisions of paragraph (b)(ii) of this section.

(B) In addition to the disinfection profile generated under paragraph (3)(b)(ii) of this section, a PWS that has existing operational data may use those data to develop a disinfection profile for additional years. Such systems may use these additional yearly disinfection profiles to develop a benchmark under the provisions of paragraph (3)(c) of this section. The State must determine whether these operational data are substantially equivalent to data collected under the provisions of paragraph (3)(b)(ii) of this section. These data must also be representative of inactivation through the entire treatment plant and not just of certain treatment segments.

(iv) If the system uses only one point of disinfectant application, the system may determine the total inactivation ratio for the disinfection segment based on either of the methods in paragraph (3)(b)(iv)(A) or (3)(b)(iv)(B) of this section.

(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. Under this alternative, 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 (508)Y (CTcalc/CT_99.9)).

(v) If the system uses more than one point of disinfectant application before the first customer, the system 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 (508)D (CTcalc/CT_99.9)) must be calculated using the method in paragraph (3)(b)(iv) of this section.

(vi) The system must determine the total logs of inactivation by multiplying the value calculated in paragraph (b)(iv)(A) or (B) of this section by 3.0.

(vii) A system that uses either chioramines or ozone for primary disinfection must also calculate the logs of inactivation for viruses using a method approved by the Department.

(viii) The system must retain disinfection profile data in graphic form, as a spreadsheet, or in some other format acceptable to the Department for review as part of the sanitary survey.

(c) Disinfection Benchmarking

(i) Any system required to develop a disinfection profile under the provisions of paragraphs (3)(a) and (3)(b) of this section and that decides to make a significant change to its disinfection practice must consult with the Department prior to making such change. Significant changes to disinfection practice are:

(A) Changes to the point of disinfection;

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

(C) Changes to the disinfection process; and

(D) Any other modification identified by the Department.

(ii) Any system that is modifying its disinfection practice must calculate its disinfection benchmark using the following procedure:

(A) For each year of profiling data collected and calculated under paragraph (b) of this section, the system must determine the lowest average monthly Giardia lamblia inactivation in each year of profiling data. The system must determine the average Giardia lamblia inactivation for each calendar month for each year of profiling data by dividing the sum of daily Giardia lamblia of inactivation by the number of values calculated for that month.

(B) The disinfection benchmark is the lowest monthly average value (for systems with one year of profiling data) or average of lowest monthly average values (for systems with more than one year of profiling data) of the monthly logs of Giardia lamblia inactivation in each year of profiling data.

(iii) A system that uses either chloramines or ozone for primary disinfection must also calculate the disinfection benchmark for viruses using a method approved by the Department.

(iv) The system must submit information in paragraphs (3)(c)(iv)(A) through (C) of this section to the Department as part of its consultation process.

(A) A description of the proposed change:

(B) The disinfection profile for Giardia lamblia (and, if necessary, viruses) under paragraph (b) of this section and benchmark as required by paragraph (c)(2) of this section; and

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

(4) Filtration

A public water system subject to the requirements of this section that does not meet all of the criteria in Section C above, and paragraph (2) of this section for avoiding filtration must provide treatment consisting of both disinfection, as specified in Section D above, and filtration treatment which complies with the requirements of paragraph 4(a) or 4(b) of this section or Section E (2) or (3) above, by December 31, 2001.

(a) Conventional filtration treatment or direct filtration.

(i) For systems using conventional filtration or direct filtration, the turbidity level of representative samples of a system's filtered water must be less than or equal to 0.3 NTU in at least ninety-five (95) percent of the measurements taken each month, measured as specified in Section F(1)(d) and (3)(a) above.

(ii) The turbidity level of representative samples of a system's filtered water must at no time exceed one (1) NTU, measured as specified in Section F(1)(d) and (3)(a) above.

(iii) A system that uses lime softening may acidify representative samples prior to analysis using a protocol approved by the Department.

(b) Filtration technologies other than conventional filtration treatment, direct filtration, slow sand filtration, or diatomaceous earth filtration.

A public water system may use a filtration technology not listed in paragraph (4)(a) of this section or in R.61-58.10(D)(E) (61-58.10(E) (2) or (3)) or (3) if it demonstrates to the Department, using pilot plant studies or other means, that the alternative filtration technology, in combination with disinfection treatment that meets the requirements of R.61-58.10(E) (2) or (3)(D), consistently achieves 99.9 percent removal and/or inactivation of Giardia lamblia cysts and 99.99 percent removal and/or inactivation of viruses, and 99 percent removal of Cryptosporidium oocysts, and the Department approves the use of the filtration technology. For each approval, the Department will set turbidity performance requirements that the system must meet at least 95 percent of the time and that the system may not exceed at any time at a level that consistently achieves 99.9 percent removal and/or inactivation of Giardia lamblia cysts, 99.99 percent removal and/or inactivation of viruses, and 99 percent removal of Cryptosporidium oocysts.

(5) Filtration sampling requirements

(a) Monitoring requirements for systems using filtration treatment. In addition to monitoring required by Section F above, a public water system subject to the requirements of this section that provides conventional filtration treatment or direct filtration must conduct continuous monitoring of turbidity for each individual filter using an approved method in Section F above, and must calibrate turbidimeters using the procedure specified by the manufacturer. Systems must record the results of individual filter monitoring every fifteen (15) minutes.

(b) If there is a failure in the continuous turbidity monitoring equipment, the system must conduct grab sampling every four hours in lieu of continuous monitoring, but for no more than five working days following the failure of the equipment.

(6) Reporting and recordkeeping requirements.

In addition to the reporting and recordkeeping requirements in Section G above, a public water system subject to the requirements of this section that provides conventional filtration treatment or direct filtration must report monthly to the Department the information specified in paragraphs (6)(a) and (6)(b) of this section beginning December 31, 2001. In addition to the reporting and recordkeeping requirements in Section G above, a public water system subject to the requirements of this section that provides filtration approved under paragraph (4)(b) of this section must report monthly to the Department the information specified in paragraph (a) of this section beginning December 31, 2001. The reporting in paragraph (6)(a) of this section is in lieu of the reporting specified in Section G above.

(a) Turbidity measurements as required by paragraph (4) of this section must be reported within 10 days after the end of each month the system serves water to the public. Information that must be reported includes:

(i) The total number of filtered water turbidity measurements taken during the month.

(ii) The number and percentage of filtered water turbidity measurements taken during the month which are less than or equal to the turbidity limits specified in paragraph (4)(a) or (4)(b) of this section.

(iii) The date and value of any turbidity measurements taken during the month which exceed 1 NTU for systems using conventional filtration treatment or direct filtration, or which exceed the maximum level set by the Department under paragraph (4)(b) of this section.

(b) Systems must maintain the results of individual filter monitoring taken under paragraph (5) of this section for at least three years. Systems must report that they have conducted individual filter turbidity monitoring under paragraph (5) of this section within 10 days after the end of each month the system serves water to the public. Systems must report individual filter turbidity measurement results taken under paragraph (5) of this section within 10 days after the end of each month the system serves water to the public only if measurements demonstrate one or more of the conditions in paragraphs (6)(b)(i) through (iv) of this section. Systems that use lime softening may apply to the Department for alternative exceedance levels for the levels specified in paragraphs (6)(b)(i) through (iv) of this section if they can demonstrate that higher turbidity levels in individual filters are due to lime carryover only and not due to degraded filter performance.

(i) For any individual filter that has a measured turbidity level of greater than 1.0 NTU in two consecutive measurements taken 15 minutes apart, the system must report the filter number, the turbidity measurement, and the date(s) on which the exceedance occurred. In addition, the system must either produce a filter profile for the filter within 7 days of the exceedance (if the system is not able to identify an obvious reason for the abnormal filter performance) and report that the profile has been produced or report the obvious reason for the exceedance.

(ii) For any individual filter that has a measured turbidity level of greater than 0.5 NTU in two consecutive measurements taken 15 minutes apart at the end of the first four hours of continuous filter operation after the filter has been backwashed or otherwise taken offline, the system must report the filter number, the turbidity, and the date(s) on which the exceedance occurred. In addition, the system must either produce a filter profile for the filter within 7 days of the exceedance (if the system is not able to identify an obvious reason for the abnormal filter performance) and report that the profile has been produced or report the obvious reason for the exceedance.

(iii) For any individual filter that has a measured turbidity level of greater than 1.0 NTU in two consecutive measurements taken 15 minutes apart at any time in each of three consecutive months, the system must report the filter number, the turbidity measurement, and the date(s) on which the exceedance occurred. In addition, the system must conduct a self-assessment of the filter within 14 days of the exceedance and report that the self-assessment was conducted. The self assessment must consist of at least the following components; assessment of filter performance; development of a filter profile; identification and prioritization of factors limiting filter performance; assessment of the applicability of corrections; and preparation of a filter self-assessment report.

(iv) For any individual filter that has a measured turbidity level of greater than 2.0 NTU in two consecutive measurements taken 15 minutes apart at any time in each of two consecutive months, the system must report the filter number, the turbidity measurement, and the date(s) on which the exceedance occurred. In addition, the system must arrange for the conduct of a comprehensive performance evaluation by the Department or a third party approved by the Department no later than 30 days following the exceedance and have the evaluation completed and submitted to the Department no later than 90 days following the exceedance.

(c) Additional reporting requirements.

(i) If at any time the turbidity exceeds one (1) NTU in representative samples of filtered water in a system using conventional filtration treatment or direct filtration, the system must inform the Department as soon as possible, but no later than the end of the next business day.

(ii) If at any time the turbidity in representative samples of filtered water exceeds the maximum level set by the Department under paragraph 4(b) of this section for filtration technologies other than conventional filtration treatment, direct filtration, slow sand filtration, or diatomaceous earth filtration, the system must inform the Department as soon as possible, but no later than the end of the next business day.

S.C. Code Regs. § 61-58.10.H