Statutes, codes, and regulations
Alabama Administrative Code
Title 335 - ALABAMA DEPARTMENT OF ENVIRONMENTAL MANAGEMENTWATER DIVISION - WATER SUPPLY PROGRAM
Chapter 335-7-6 - SURFACE WATER SOURCES AND TREATMENT
Section 335-7-6-.14 - Enhanced Coagulation

Ala. Admin. Code r. 335-7-6-.14

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Current through Register Vol. 42, No. 12, September 30, 2024
Section 335-7-6-.14 - Enhanced Coagulation

Systems using surface water or groundwater under the direct influence of surface water shall operate with enhanced coagulation to achieve the TOC percent removal levels specified in this section unless the system meets at least one of the alternative compliance criteria listed below.

(a) Systems that meet any of the following criteria do not have to demonstrate that the system has achieved TOC removal percentages in this section.
1. The system's raw water TOC running annual average, calculated quarterly, is less than 2.0 mg/L.
2. The system's treated water TOC running annual average, calculated quarterly, is less than 2.0 mg/L.
3. The treatment plant's raw water TOC annual average, calculated quarterly, is less than 4.0 mg/L, the raw water alkalinity annual average, calculated quarterly, is greater than 60 mg/L (as CaCO3), and either the TTHM and HAA5 annual averages for the treatment plant's sample sites are no greater than 0.040 mg/L and 0.030 mg/L, respectively; or prior to January 1, 2001, the system has made a clear and irrevocable financial commitment not later than January 1, 2001 to use technologies that will limit the levels of TTHMs and HAA5 to no more than 0.040 mg/L and 0.030 mg/L, respectively. The water system must submit evidence of a clear and irrevocable financial commitment, in addition to a schedule containing milestones and periodic progress reports for installation and operation of appropriate technologies, to the Department for approval not later than January 1, 2001. These technologies must be installed and operating not later than June 30, 2005. Failure to install and operate these technologies by the date in the approved schedule will constitute a violation.
4. The system's TTHM and HAA5 annual averages are no greater than 0.040 mg/L and 0.030 mg/L, respectively, and the system uses only chlorine for primary disinfection and maintenance of a residual in the distribution system.
5. The treatment plant's raw water SUVA annual average, measured monthly and calculated quarterly, is less than or equal to 2.0 L/mg-m.
6. The treatment plant's finished water SUVA annual average, measured monthly and calculated quarterly, is less than or equal to 2.0 L/mg-m.
(b) Each water treatment plant in the system must achieve the percent reduction of TOC specified below (Step 1) between the raw water and the combined filter effluent, unless the Department approves the system's request for alternate minimum TOC removal (Step 2).
1. Required Step 1 TOC reductions, indicated in the following table, are based upon specified raw water parameters.

Step 1 required removal of TOC by enhanced coagulation for systems using conventional treatment:

Raw-Water TOC, mg/LSource Water alkalinity, mg/L as CaCO3
0-60 % [Greater Than] 60-120 % [Greater Than] 120 %
[Greater Than] 2.0-4.0 35.0 25.0 15.0
[Greater Than] 4.0-8.0 45.0 35.0 25.0
[Greater Than] 8.0 50.0 40.0 30.0

(c) Each water treatment plant that cannot achieve the Step 1 TOC removals due to water quality parameters or operational constraints must apply to the Department, within three months of failure to achieve the Step 1 TOC removals, for approval of alternative minimum Step 2 TOC removals. If the Department approves the alternative minimum Step 2 TOC removals, Step 2 requirements can be made retroactive for the purposes of determining compliance. Until alternate minimum Step 2 TOC removals are approved, the system must achieve the Step 1 TOC removals.
(d) Applications made to the Department for approval of alternative minimum Step 2 TOC removal must include, as a minimum, results of bench- or pilot-scale testing conducted under the requirements of this rule and used to determine the alternate enhanced coagulation level.
1. Alternate enhanced coagulation level is defined as coagulation at a coagulant dose and pH as determined by the method described in this section such that an incremental addition of 10 mg/L of alum (as aluminum) or an equivalent amount of another coagulant (if a coagulant other than alum is used) results in a TOC removal of [Less Than] 0.3 mg/L. The percent removal of TOC at this point on the "TOC removal versus coagulant dose" curve is then defined as the minimum TOC removal required for the system. Once approved by the Department, this minimum requirement supersedes the minimum Step 1 TOC removal. This requirement will be effective until such time as a new value is approved based on the results of a new bench and pilot scale test. Failure to achieve an alternate minimum TOC removal 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 (as aluminum) or equivalent amounts of an alternate coagulant until the pH is reduced to a level less than or equal to the enhanced coagulation Step 2 target pH indicated in the following table:

Alkalinity (mg/L as CaCO3)Target pH
0-60 5.5
[Greater Than] 60-120 6.3
[Greater Than] 120-240 7.0
[Greater Than] 240 7.5

3. For waters with alkalinities of less than 60 mg/L for which addition of small amounts of alum or the equivalent addition of an alternate 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 until the TOC removal of 0.3 mg/L per 10 mg/L alum added (as aluminum) or equivalent addition of an alternate coagulant is reached.
4. The system may operate at any coagulant dose or pH necessary to achieve the approved minimum TOC percent removal.
5. If the TOC removal is consistently less than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose (as aluminum) at all dosages of alum or the equivalent addition of an alternate coagulant, the water is deemed to contain TOC not amenable to enhanced coagulation. The system may then apply to the State for a waiver of enhanced coagulation requirements.
(e) Additional alternative compliance criteria for softening systems. Systems practicing enhanced softening that cannot achieve the TOC removals required by paragraph (2) of this rule may use one of the following alternative compliance criteria in lieu of complying with paragraph (2) of this rule. Systems must still comply with monitoring requirements in rule 335-7-2-.11.
1. Softening that results in lowering the treated water alkalinity to less than 60 mg/L (as CaCO3), measured monthly according to rule 335-7-2-.02 and calculated quarterly as a running annual average.
2. Softening that results in removing at least 10 mg/L of magnesium hardness (as CaCO3), measured monthly according to rule 335-7-2-.02 and calculated quarterly as a running annual average.
(f) Systems must calculate compliance quarterly, beginning after the system has collected 12 consecutive months of data, by determining an annual average using the following method:
1. For each treatment plant use the following method to determine the actual TOC percent removal and the required TOC percent removal for each month. Divide the actual TOC percent removal by the required TOC percent removal. Determine compliance by averaging these values for the previous twelve months. If this value is less than 1.00, the system is in non-compliance with TOC percent removal requirements.
2. In any month that the treatment plant's treated or raw water TOC level is less than 2.0 mg/L, the system may assign a monthly value of 1.0 when calculating compliance with TOC removal requirements.
3. In any month that the treatment plant's treated or raw water SUVA is less than or equal to 2.0 L/mg-m, the system may assign a monthly value of 1.0 when calculating compliance with TOC removal requirements.

Ala. Admin. Code r. 335-7-6-.14

New Rule: Filed May 2, 2000; effective June 6, 2000. Amended: Filed December 24, 2003; effective January 28, 2004. Repealed and New Rule: Filed November 7, 2005; effective December 12, 2005. Amended: Filed December 18, 2007; Effective January 22, 2008.

Authors: Edgar K. Hughes, Dennis D. Harrison

Statutory Authority:Code of Ala. 1975, §§ 22-23-33, 22-23-49, 22-22A-5, 22-22A-6.