Effective Date: January 17, 2018
5-1.60 Applicability. Surface water systems or systems using ground water under the direct influence of surface water that are community or nontransient noncommunity systems serve 15 or more service connections or serve 25 or more persons, and use conventional filtration treatment must operate with enhanced coagulation to achieve the total organic carbon (TOC) percent removal levels specified in section 5-1.63 of this Subpart, unless the system meets the alternative compliance criteria described in section 5-1.62 of this Subpart.
5-1.61 Monitoring requirements for disinfection byproduct precursors.
Monitoring for Disinfection byproduct precursors shall be in accordance with the following table.
|Source Type||System Type||Filtration Type||Sampling location at each plant||Routine||Reduced1|
|Monitoring requirements||Frequency2||Running annual average TOC results||Frequency|
|Surface water and GWUDI||Community and NTNC||Conventional||Combined Filter effluent3||TOC4||Monthly||<2.0 mg/L for two consecutive years or <1.0 mg/L for one year||1 TOC (paired) per plant/quarter|
|All other types||Raw||TOC||Monthly||≤4.0 mg/L||1 TOC quarterly|
1Routine monitoring shall begin in the month following the quarter when the running annual average TOC is ≥2.0 mg/L for systems using conventional filtration and >4.0 mg/L for systems using all other types of filtration
2TOC monitoring for disinfection precursors for both treated and source water shall be collected at the same time. These samples (source water and treated water) are referred to as paired samples
3Samples collected for TOC shall be collected no further downstream than point of combined filter effluent turbidity monitoring and representative of treated water.
4Systems shall take one paired TOC sample and one source water alkalinity sample per month per plant at a time representative of normal operating conditions and influent water quality. The alkalinity sample shall be collected at the same time as the source water TOC sample.
5-1.62 Alternative compliance criteria for enhanced coagulation.
Systems may use one of the following alternative compliance criteria instead of enhanced coagulation. Systems using the alternative compliance criteria shall still comply with the monitoring requirements stated in section 5-1.61 of this Subpart.
|Water Type||Parameter||Concentration||Calculation Frequency|
|Source water||TOC||≤2.0 mg/L||Quarterly RAA|
|Treated water||TOC||≤2.0 mg/L||Quarterly RAA|
|Source water1,2||SUVA||≤2.0 L/mg-m||Quarterly RAA|
|Treated water2||SUVA||≤2.0 L/mg-m||Quarterly RAA|
|Source water||TOC||<4.0 mg/L||Quarterly RAA|
|Alkalinity (as CaCO3)||>60 mg/L||Quarterly RAA|
|TTHM||≤0.040 mg/L||LRAA of all sites|
|HAA5||≤0.030 mg/L||LRAA of all sites|
|Treated water in the distribution system3||TTHM||≤0.040 mg/L||LRAA of all sites|
|HAA5||≤0.030 mg/L||LRAA of all sites|
1Prior to any treatment
3System uses only chlorine for primary disinfection and maintains a residual in the distribution system.
Effective Date: May 26, 2004
5-1.63 Enhanced coagulation performance requirements. Systems must achieve the percent reduction of TOC specified in subdivision (a) of this section (Step 1) between the source water and the combined filter effluent, unless the State approves a system's request for alternate minimum TOC removal (Step 2) requirements, which are provided in subdivision (d) of this section.
(a) Required (Step 1) TOC reductions, which are provided in the following table, are based upon specified source water TOC and alkalinity levels:
|Source Water TOC (mg/L)||Source Water Alkalinity|
|0-60 mg/L as CaCO3(percent removal required)||>60-120 mg/L as CaCO3(percent removal required)||>120 mg/L as CaCO3(percent removal required)|
|>2.0 - 4.0||35.0||25.0||15.0|
|>4.0 - 8.0||45.0||35.0||25.0|
(b) Systems that must comply with the requirements contained in subdivision (a) of this section must calculate compliance using the method provided in either paragraph (1) of this subdivision or the applicable provisions of paragraph (2) of this subdivision.
(1) Systems must calculate compliance quarterly, beginning after the system has collected 12 months of data, by determining an annual average using the following method:
(i) Determine actual monthly TOC percent removal, equal to: (1 - (treated water TOC/source water TOC)) X 100.
(ii) Determine the required monthly TOC percent removal from either subdivision (a) or (d) of this section.
(iii) Divide the value in subparagraph (i) of this paragraph by the value in subparagraph (ii) of this paragraph.
(iv) Add together the results of subparagraph (iii) of this paragraph for the last 12 months and divide by 12.
(v) If the value calculated in subparagraph (iv) of this paragraph is less than 1.00, the system is not in compliance with the TOC percent removal requirements.
(2) Systems may use the provisions in subparagraphs (i) through (iii) of this paragraph instead of the calculations in paragraph (1) of this subdivision to determine compliance with TOC percent removal requirements.
(i) In any month that the system's treated or source water TOC level is less than or equal to 2.0 mg/L, the system may assign a monthly value of 1.00 (instead of the value calculated in paragraph (1) of this subdivision) when calculating compliance under the provisions of subdivision (a) of this section.
(ii) In any month that the system's source water SUVA, prior to any treatment, is less than or equal to 2.0 L/mg-m, the system may assign a monthly value of 1.00 (instead of the value calculated in paragraph (1) of this subdivision) when calculating compliance under the provisions of subdivision (a) of this section.
(iii) In any month that the system's finished water SUVA is less than or equal to 2.0 L/mg-m, the system may assign a monthly value of 1.00 (instead of the value calculated in paragraph (1) of this subdivision) when calculating compliance under the provisions of subdivision (a) of this section.
(c) Systems that cannot achieve the (Step 1) TOC removals required by subdivision (a) of this section due to water quality parameters or operational constraints must apply to the State, within three months of failure to achieve the TOC removals required by (Step 1), for approval of alternate minimum TOC removal (Step 2) requirements, described in subdivision (d) of this section. Until the State approves the alternate minimum TOC removal (Step 2) requirements, the system must meet the (Step 1) TOC removals contained in subdivision (a) of this section.
(d) Alternate minimum TOC removal (Step 2) requirements. Applications made to the State by enhanced coagulation systems for approval of alternate minimum TOC removal (Step 2) requirements must include, as a minimum, results of bench- or pilot-scale testing conducted using the methodology prescribed in paragraph (1) of this subdivision to determine the alternate enhanced coagulation level. Applications for alternate minimum TOC (Step 2) requirements must be approved by the State before they can replace the previous (Step 1) TOC removal requirements. The alternate TOC removal is determined by the method described in paragraphs (1) through (5) of this subdivision.
(1) The alternate minimum TOC removal is the percentage of TOC removed at the point where an incremental addition of 10 mg/L of alum, or equivalent amount of iron coagulant (ferric salt), results in a TOC removal of ≤0.3 mg/L. This TOC removal percentage is then defined as the minimum TOC removal required for the system. Once approved by the State, this minimum TOC removal requirement supersedes the minimum TOC (Step 1) removal required by the table in subdivision (a) of this section. This requirement will be effective until such time as the State approves a new value based on the results of a new bench- and pilot-scale test. Failure to achieve State-set alternative minimum TOC removal levels is a violation.
(2) Bench- or pilot-scale testing of enhanced coagulation must be conducted by using representative water samples and adding 10 mg/L increments of alum, or equivalent amounts of iron coagulant, until the pH is reduced to a level less than or equal to the enhanced coagulation (Step 2) target pH shown in the following table:
|Alkalinity (mg/L as CaCO3)||Target pH|
|0 - 60||5.5|
|>60 - 120||6.3|
|>120 - 240||7.0|
(3) For waters with alkalinities of less than 60 mg/L for which addition of small amounts of alum or equivalent addition of iron coagulant drives the pH below 5.5 before significant TOC removal occurs, the system must add necessary chemicals to maintain the pH between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/L per 10 mg/L alum added, or equivalent addition of iron coagulant, is reached.
(4) The system may operate at any coagulant dose or pH necessary (consistent with the State Sanitary Code) to achieve the minimum TOC percent removal approved under paragraph (1) of this section.
(5) If the TOC removal is consistently less than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose at all dosages of alum (or equivalent addition of iron coagulant), the water is deemed to contain TOC not amenable to enhanced coagulation. The system may then apply for a waiver of enhanced coagulation requirements.
Effective Date: January 17, 2018
5-1.64 Operational Evaluation Levels.
(a) If a system exceeds the operational evaluation level at any monitoring location when the sum of the two previous quarters’ TTHM results plus twice the current quarter’s TTHM result, divided by 4 to determine the average, exceeds 0.080 mg/L, or when the sum of the two previous quarters’ HAA5 results plus twice the current quarter’s HAA5 result, divided by 4 to determine the average, exceeds 0.060 mg/L.
(b) If a system exceeds the operational evaluation level, it shall conduct an operational evaluation and submit a written report of the evaluation to the State no later than 90 days after being notified of the analytical result that caused the exceedance of the operational evaluation level. The written report shall be made available to the public upon request.
(c) The operational evaluation shall include an examination of the operational practices for system treatment(s) and the distribution system, including storage tank operations, excess storage capacity, distribution system flushing, changes in sources or source water quality, and treatment changes or problems that may contribute to TTHM and HAA5 formation and what steps could be considered to minimize future exceedances.
(1) A system may request, and the State may allow, limiting the scope of the evaluation if the system is able to identify the cause of the operational evaluation level exceedance.
(2) The request to limit the scope of the evaluation does not extend the schedule in subdivision (b) of this section for submitting the written report. The State shall approve this limited scope of evaluation in writing, and the system shall keep that approval with the completed report.
5-1.65 Best Available Technologies (BATs) for Disinfection Byproduct Control.
The following is a table of the best available technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for Bromate, Chlorite, TTHM and HAA5, for public water systems that disinfect their source water.
|Water system type||Source type||Disinfection byproduct||Best available technology1|
|All systems that disinfect their source water||GW; SW; GWUDI||Bromate||Control of ozone treatment process to reduce production of bromate|
|Chlorite||Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes to reduce disinfectant levels|
|All systems that disinfect their source water||Total trihalomethanes (TTHM); Haloacetic acids (five) (HAA5)||Enhanced coagulation or enhanced softening, plus GAC10; or nanofiltration with a molecular weight cutoff ≤1000 Daltons; or GAC20|
|Consecutive systems: applies only to the disinfected water that consecutive systems buy or otherwise receive||Total trihalomethanes (TTHM); Haloacetic acids (five) (HAA5)||Systems serving ≥10,000: Improved distribution system and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance|
|Systems serving <10,000: Improved distribution system and storage tank management to reduce residence time|
1Softening that results in removing at least 10 mg/L of magnesium hardness (as CaCO3), measured monthly and calculated quarterly as a running annual average can be the best available technology for controlling disinfection byproduct precursors.