S.C. Code Regs. § 61-58.10.I

Current through Register Vol. 48, No. 07, July 26, 2024

Section 61-58.10.I - Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People (Long Term 1 Enhanced Surface Water Treatment Rule)

(1) General Requirements

(a) The requirements of this regulation 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 for systems with surface water sources or ground water sources under the influence of surface water. This regulation establishes or extends treatment technique requirements in lieu of maximum contaminant levels for the following contaminants: Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, Cryptosporidium and turbidity. 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; and

(ii) Compliance with the profiling and benchmark requirements in paragraphs (4) and (5) of this section.

(b) Who is subject to the requirements of this section?--You are subject to these requirements if your system:

(i) Is a public water system;

(ii) Uses surface water or GWUDI as a source; and

(iii) Serves fewer than 10,000 persons.

(c) When must my system comply with these requirements? You must comply with these requirements in this regulation beginning January 1, 2005 except where otherwise noted.

(d) What does this regulation require?--There are seven (7) requirements of this subpart, and you must comply with all requirements that are applicable to your system. These requirements are:

(i) You must cover any finished water reservoir that you began to construct on or after March 15, 2002 as described in paragraph (2) of this section;

(ii) If your system is an unfiltered system, you must comply with the updated watershed control requirements described in paragraph (3) of this section;

(iii) If your system is a community or non-transient non-community water systems you must develop a disinfection profile as described in paragraph (4) of this section;

(iv) If your system is considering making a significant change to its disinfection practices, you must develop a disinfection benchmark and consult with the Department for approval of the change as described in paragraph (5) of this section;

(v) If your system is a filtered system, you must comply with the combined filter effluent requirements as described in paragraph (6) of this section;

(vi) If your system is a filtered system that uses conventional or direct filtration, you must comply with the individual filter turbidity requirements as described in paragraph (7) of this section; and,

(vii) You must comply with the applicable reporting and recordkeeping requirements as described in paragraph (8) of this section.

(2) Finished Water Reservoirs

(a) Is my system subject to the new finished water reservoir requirements?--All surface water systems and ground water systems under the direct influence of surface water which serve fewer than 10,000 people are subject to this requirement.

(b) What is required of new finished water reservoirs?--If your system begins construction of a finished water reservoir on or after March 15, 2002 the reservoir must be covered. Finished water reservoirs for which your system began construction prior to March 15, 2002 are not subject to this requirement.

(3) Additional Watershed Control Requirements for Unfiltered Systems

(a) Is my system subject to the updated watershed control requirements?--If you are a surface water system or a ground water system under the direct influence of surface water serving fewer than 10,000 persons which does not provide filtration, you must continue to comply with all of the filtration avoidance criteria in Section C, as well as the additional watershed control requirements in paragraph (3)(b) of this section.

(b) What updated watershed control requirements must my unfiltered system implement to continue to avoid filtration?--Your system must take any additional steps necessary to minimize the potential for contamination by Cryptosporidium oocysts in the source water. Your system's 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.

(c) How does the Department determine whether my system's watershed control requirements are adequate?--During an onsite inspection conducted under the provisions of Section C(2)(c), the Department must determine whether your watershed control program 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 your program to monitor and control detrimental activities occurring in the watershed; and the extent to which your system has maximized land ownership and/or controlled land use within the watershed.

(4) Disinfection Profile

(a) What is a Disinfection Profile and who must develop one?--A disinfection profile is a graphical representation of your system's level of Giardia lamblia or virus inactivation measured during the course of a year. If you are a surface water system or a ground water system under the direct influence of surface water which serves fewer than 10,000 persons, your system must develop a disinfection profile unless the Department determines that your system's profile is unnecessary. The Department may approve the use of a more representative data set for disinfection profiling than the data set required under paragraph (4) (c) through (f) of this section.

(b) What criteria must the Department use to determine that a profile is unnecessary? The Department may only determine that a system's profile is unnecessary if a system's TTHM and HAA5 levels are below 0.064 mg/L and 0.048 mg/L, respectively. To determine these levels, TTHM and HAA5 samples must be collected after January 1, 1998, during the month with the warmest water temperature, and at the point of maximum residence time in your distribution system. The Department may approve a more representative TTHM and HAA5 data set to determine these levels.

(c) How does my system develop a Disinfection Profile and when must it begin?--A disinfection profile consists of three steps:

(i) First, your system must collect data for several parameters from the plant as discussed in paragraph (4)(d) of this section, over the course of twelve (12) months. If your system serves between 500 and 9,999 persons you must begin to collect data no later than July 1, 2003. If your system serves fewer than 500 persons you must begin to collect data no later than January 1, 2004.

(ii) Second, your system must use this data to calculate weekly log inactivation as discussed in paragraphs (4)(e) and (f) of this section.

(iii) Third, your system must use these weekly log inactivations to develop a disinfection profile as specified in paragraph (4)(g) of this section.

(d) What data must my system collect to calculate a Disinfection Profile?--Your system must monitor the following parameters to determine the total log inactivation using the analytical methods in Section F, once per week on the same calendar day, over twelve (12) consecutive months:

(i) The temperature of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow;

(ii) If your system uses chlorine, the pH of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow;

(iii) The disinfectant contact time(s) ('T') during peak hourly flow; and

(iv) The residual disinfectant concentration(s) ('C') of the water before or at the first customer and prior to each additional point of disinfection during peak hourly flow.

(e) How does my system use this data to calculate an inactivation ratio? Use the tables in R-61.58.10.F(1)(c)(v) to determine the appropriate CT_99.9 value. Calculate the total inactivation ratio as follows, and multiply the value by 3.0 to determine log inactivation of Giardia lamblia:

If your system * * *	Your system must determine * * *
(a) Uses only one point of disinfectant application	(1) One inactivation ratio (CTcalc/CT9 9.9) before or at the first customer during peak hourly flow or
	(2) Successive CTcalc/CT99.9 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, your system must calculate the total inactivation ratio by determining (CTcalc/CT99.9) for each sequence and then adding the (CTcalc/CT99.9) values together to determine (<<SIGMA>>CTcalc/CT99.9).
(b) Uses more than one point of disinfectant application before the first customer	The (CTcalc/CT99.9) 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 using the procedure specified in paragraph (a)(2) of this section.

(f) What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?--If your system uses chloramines, ozone, or chlorine dioxide for primary disinfection, you must also calculate the logs of inactivation for viruses and develop an additional disinfection profile for viruses using methods approved by the Department.

(g) My system has developed an inactivation ratio; what must we do now?--Each log inactivation serves as a data point in your disinfection profile. Your system will have obtained fifty-two (52) measurements (one (1) for every week of the year). This will allow your system and the Department the opportunity to evaluate how microbial inactivation varied over the course of the year by looking at all fifty-two (52) measurements (your Disinfection Profile). Your system must retain the Disinfection Profile data in graphic form, such as a spreadsheet, which must be available for review by the Department as part of a sanitary survey. Your system must use this data to calculate a benchmark if you are considering changes to disinfection practices.

(5) Disinfection Benchmark

(a) Who has to develop a Disinfection Benchmark?--If you are a surface water system or a ground water system under the direct influence of surface water you are required to develop a disinfection profile under paragraphs (4)(a) through (g) of this section. Your system must develop a Disinfection Benchmark if you decide to make a significant change to your disinfection practice. Your system must consult with the Department for approval before you can implement a significant disinfection practice change.

(b) What are significant changes to disinfection practice?--Significant changes to disinfection practice include:

(i) Changes to the point of disinfection;

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

(iii) Changes to the disinfection process; or

(iv) Any other modification identified by the Department.

(c) What must my system do if we are considering a significant change to disinfection practices?--If your system is considering a significant change to its disinfection practice, your system must calculate a disinfection benchmark(s) as described in paragraphs (5)(c) and (d) of this section, and provide the benchmark(s) to the Department. Your system may only make a significant disinfection practice change after consulting with the Department for approval. Your system must submit the following information to the Department as part of the consultation and approval process:

(i) A description of the proposed change;

(ii) The disinfection profile for Giardia lamblia (and, if necessary, viruses) and disinfection benchmark;

(iii) An analysis of how the proposed change will affect the current levels of disinfection; and

(iv) Any additional information requested by the Department.

(d) How is the Disinfection Benchmark calculated?--If your system is making a significant change to its disinfection practice, it must calculate a disinfection benchmark using the procedure specified in the following table.

To calculate a disinfection benchmark your system must perform the following steps
Step 1:	Using the data your system collected to develop the Disinfection Profile, determine the average Giardia lamblia inactivation for each calendar month by dividing the sum of all Giardia lamblia inactivations for that month by the number of values calculated for that month.
Step 2:	Determine the lowest monthly average value out of the twelve (12) values. This value becomes the disinfection benchmark.

(e) What if my system uses chloramines, ozone, or chlorine dioxide for primary disinfection?--If your system uses chloramines, ozone or chlorine dioxide for primary disinfection your system must calculate the disinfection benchmark from the data your system collected for viruses to develop the disinfection profile in addition to the Giardia lamblia disinfection benchmark calculated under paragraph (5)(d) of this section. This viral benchmark must be calculated in the same manner used to calculate the Giardia lamblia disinfection benchmark in paragraph (5)(d) of this section.

(6) Combined Filter Effluent Requirements

(a) Is my system required to meet this regulation's combined filter effluent turbidity limits?--All surface water systems and ground water systems under the direct influence of surface water which serve populations fewer than 10,000, and that utilize filtration other than slow sand filtration or diatomaceous earth filtration, must meet the combined filter effluent turbidity requirements of paragraphs (6)(b) through (d) of this section If your system uses slow sand or diatomaceous earth filtration you are not required to meet the combined filter effluent turbidity limits of this regulation, but you must continue to meet the combined filter effluent turbidity limits in Section E.

(b) What strengthened combined filter effluent turbidity limits must my system meet?--Your system must meet two strengthened combined filter effluent turbidity limits.

(i) The first combined filter effluent turbidity limit is a "95th percentile" turbidity limit that your system must meet in at least ninety five (95) percent of the turbidity measurements taken each month. Measurements must continue to be taken as described in Section F(1) and (3). Monthly reporting must be completed according to paragraph (8) of this section. The following table describes the required limits for specific filtration technologies.

If your system consists of * * *	Your 95th percentile turbidity value is * * *
(1) Conventional Filtration or Direct Filtration ............	0.3 NTU
(2) All other 'Alternative' Filtration ...................	A value determined by the Department (not to exceed 1 NTU) based on the demonstration described in paragraph (6)(c)of this section.

(ii) The second combined filter effluent turbidity limit is a "maximum" turbidity limit which your system may at no time exceed during the month. Measurements must continue to be taken as described in Sections F(1) and C. Monthly reporting must be completed according to paragraph (8) of this section The following table describes the required limits for specific filtration technologies.

If your system consists of * * *	Your maximum turbidity value is * * *
(1) Conventional Filtration or Direct Filtration.............	1 NTU
(2) All other 'Alternative' Filtration ...................	A value determined by the Department (not to exceed 5 NTU) based on the demonstration as described in paragraph (6)(c) of this section.

(c) My system consists of "alternative filtration" and is required to conduct a demonstration what is required of my system and how does the Department establish my turbidity limits?

(i) If your system consists of alternative filtration (filtration other than slow sand filtration, diatomaceous earth filtration, conventional filtration, or direct filtration) you are required to conduct a demonstration (see tables in paragraph (6)(b) of this section). Your system must demonstrate to the Department, using pilot plant studies or other means, that your system's filtration, in combination with disinfection treatment, consistently achieves:

(A) 99 percent removal of Cryptosporidium oocysts;

(B) 99.9 percent removal and/or inactivation of Giardia lamblia cysts; and

(C) 99.99 percent removal and/or inactivation of viruses.

(ii) [Reserved]

(d) My system practices lime softening is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may acidify representative combined filter effluent turbidity samples prior to analysis using a protocol approved by the Department.

(7) Individual Filter Turbidity Requirements

(a) Is my system subject to individual filter turbidity requirements? If your system is a surface water system or a ground water system under the direct influence of surface water serving fewer than 10,000 people and utilizing conventional filtration or direct filtration, you must conduct continuous monitoring of turbidity for each individual filter at your system. The following requirements apply to continuous turbidity monitoring:

(i) Monitoring must be conducted using an approved method in Section F(1);

(ii) Calibration of turbidimeters must be conducted using procedures specified by the manufacturer;

(iii) Results of turbidity monitoring must be recorded at least every fifteen (15) minutes;

(iv) Monthly reporting must be completed according to paragraph (8) of this section; and

(v) Records must be maintained according to paragraph (8)(b) of this section.

(b) What happens if my system's turbidity monitoring equipment fails? If there is a failure in the continuous turbidity monitoring equipment, your system must conduct grab sampling every four hours in lieu of continuous monitoring until the turbidimeter is back on line. Your system has fourteen (14) days to resume continuous monitoring before a violation is incurred.

(c) My system only has two or fewer filters is there any special provision regarding individual filter turbidity monitoring? Yes, if your system only consists of two (2) or fewer filters, you may conduct continuous monitoring of combined filter effluent turbidity in lieu of individual filter effluent turbidity monitoring. Continuous monitoring must meet the same requirements set forth in paragraphs (7)(a) through(d) of this section.

(d) What follow up action is my system required to take based on continuous turbidity monitoring? Follow up action is required according to the following tables:

If * * *	Your system must * * *
(a) The turbidity of an individual filter (or the turbidity of combined filter effluent (CFE) for systems with 2 filters that monitor CFE in lieu of individual filters) exceeds 1.0 NTU in two consecutive recordings 15 minutes apart.	Report to the Department by the 10th of the following month and include the filter number(s), corresponding date(s), turbidity value(s) which exceeded 1.0 NTU, and the cause (if known) for the exceedance(s).
If a system was required to report to the Department * * *	Your system must * * *
(b) For three months in a row and turbidity exceeded 1.0 NTU in two consecutive recordings 15 minutes apart at the same filter (or CFE for systems with 2 filters that monitor CFE in lieu of individual filters).	Conduct a self-assessment of the filter(s) within 14 days of the day the filter exceeded 1.0 NTU in two consecutive measurements for the third straight month unless a CPE as specified in paragraph (c) of this section was required. Systems with 2 filters that monitor CFE in lieu of individual filters must conduct a self-assessment on both filters. 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.
(c) For two months in a row and turbidity exceeded 2.0 NTU in 2 consecutive recordings 15 minutes apart at the same filter (or CFE for systems with 2 filters that monitor CFE in lieu of individual filters).	Arrange to have a comprehensive performance evaluation (CPE) conducted by the Department or a third party approved by the Department not later than 60 days following the day the filter exceeded 2.0 NTU in two consecutive measurements for the second straight month. If a CPE has been completed by the Department or a third party approved by the Department within the 12 prior months or the system and the Department are jointly participating in an ongoing Comprehensive Technical Assistance (CTA) project at the system, a new CPE is not required. If conducted, a CPE must be completed and submitted to the Department no later than 120 days following the day the filter exceeded 2.0 NTU in two consecutive measurements for the second straight month.

(e) My system practices lime softening is there any special provision regarding my individual filter turbidity monitoring? If your system utilizes lime softening, you may apply to the Department for alternative turbidity exceedance levels for the levels specified in the table in paragraph (7)(d) of this section. You must be able to demonstrate to the Department that higher turbidity levels are due to lime carryover only, and not due to degraded filter performance.

(8) Reporting and Recordkeeping Requirements

(a) What does this section require that my system report to the Department? This section requires your system to report several items to the Department. The following table describes the items which must be reported and the frequency of reporting. Your system is required to report the information described in the following table, if it is subject to the specific requirement shown in the first column.

Corresponding requirement	Description of information to report	Frequency
(a) Combined Filter Effluent Requirements. (paragraphs (6)(a) through (d) of this section).	(1) The total number of filtered water turbidity measurements taken during the month.	By the 10th of the following month.
	(2) The number and percentage of filtered water turbidity measurements taken during the month which are less than or equal to your system's required 95th percentile limit.	By the 10th of the following month.
	(3) The date and value of any turbidity measurements taken during the month which exceed the maximum turbidity value for your filtration system.	By the 10th of the following month
(b) Individual Turbidity Requirements. (paragraph (7)(a) through (e) of this section).	(1) That your system conducted individual filter turbidity monitoring during the month.	By the 10th of the following month.
	(2) The filter number(s), corresponding date(s), and the turbidity value(s) which exceeded 1.0 NTU during the month, and cause (if known) for the exceedance(s), but only if 2 consecutive measurements exceeded 1.0 NTU.	By the 10th of the following month.
	(3) If a self-assessment is required, the date that it was triggered and the date that it was completed.	By the 10th of the following month (or 14 days after the self-assessment was triggered only if the self-assessment was triggered during the last four days of the month)
	(4) If a CPE is required, that the CPE is required and the date that it was triggered.	By the 10th of the following month.
	(5) Copy of completed CPE report........	Within 120 days after the CPE was triggered.
(c) Disinfection Profiling..... (paragraphs (4)(a) through (g) of this section)	(1) Results of optional monitoring which show TTHM levels 0.064 mg/L and HAA5 levels 0.048 mg/L (only if your system wishes to forgo profiling) or that your system has begun disinfection profiling.	(i) For systems serving 500-9,999 by July 1, 2003; (ii) For systems serving fewer than 500 by January 1, 2004.
(d) Disinfection Benchmarking (paragraph (5)(a) through (e) of this section)	(1) A description of the proposed change in disinfection, your system's disinfection profile for Giardia lamblia (and, if necessary, viruses) and disinfection benchmark, and an analysis of how the proposed change will affect the current levels of disinfection.	Anytime your system is considering a significant change to its disinfection practice.

(b) What records does this regulation require my system to keep? Your system must keep several types of records based on the requirements of this regulation, in addition to recordkeeping requirements under Section G. The following table describes the necessary records, the length of time these records must be kept, and for which requirement the records pertain. Your system is required to maintain records described in this table, if it is subject to the specific requirement shown in the first column.

Corresponding requirement	Description of necessary records	Duration of time records must be kept
(a) Individual Filter Turbidity Requirements (paragraphs (7)(a) through (e) of this section) ........................	Results of individual filter monitoring .....	At least 3 years.
(b) Disinfection Profiling (paragraphs (4)(a) through (g) of this section) ........................	Results of Profile (including raw data and analysis) .........	Indefinitely-y.
(c) Disinfection Benchmarking (paragraphs (5)(a) through (e) of this section) ........................	Benchmark (including raw data and analysis) ....	Indefinitely-y.

S.C. Code Regs. 61-58.10.I