Mich. Admin. Code R. 325.10610c - Control of disinfection byproduct (DBP) precursors; treatment technique

Rule 610c.

(1) This rule applies to Subpart H supplies subject to R 325.10610b(1) that use conventional filtration. These public water supplies are considered "water supplies" or "supplies" in this rule. Compliance with this rule is based on all of the following:

(a) Subpart H systems using conventional filtration shall operate with enhanced coagulation or enhanced softening to achieve the TOC percent removal levels specified in subrule (2) of this rule unless the supply meets at least 1 of the alternative compliance criteria listed in subdivision (b) or (c) of this subrule.

(b) Subpart H systems using conventional filtration may use the following alternative compliance criteria to comply with this rule instead of complying with subrule (2) of this rule. Supplies using alternative compliance criteria shall still comply with TOC monitoring requirements in R 325.10719e(4):

(i) The supply's source water TOC level is less than 2.0 mg/l, calculated quarterly as a running annual average.

(ii) The supply's treated water TOC level is less than 2.0 mg/l, calculated quarterly as a running annual average.

(iii) The supply's source water TOC level is less than 4.0 mg/l, calculated quarterly as a running annual average; the source water alkalinity, measured under R 325.10605, is more than 60 mg/l as calcium carbonate, calculated quarterly as a running annual average; and either the TTHM and HAA5 running annual averages are not more than 0.040 mg/l and 0.030 mg/l, respectively, or before the effective date for compliance in R 325.10610(2), the supply has made a clear and irrevocable financial commitment to use technologies that will limit the levels of TTHM and HAA5 to not more than 0.040 mg/l and 0.030 mg/l, respectively. Supplies shall 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 the effective date for compliance in R 325.10610(2). These technologies shall be installed and operating not later than June 30, 2005. Failure to install and operate these technologies by the date in the approved schedule is a violation of these rules.

(iv) The TTHM and HAA5 running annual averages are not more than 0.040 mg/l and 0.030 mg/l, respectively, and the supply uses only chlorine for primary disinfection and maintenance of a residual in the distribution system.

(v) The supply's source water SUVA, before any treatment and measured monthly, is less than or equal to 2.0 liters per milligram meter (l/mg m), calculated quarterly as a running annual average.

(vi) The supply's finished water SUVA, measured monthly, is less than or equal to 2.0 l/mg m, calculated quarterly as a running annual average.

(c) Water supplies practicing enhanced softening that cannot achieve the TOC removals required by subrule (2)(b) of this rule may use the following alternative compliance criteria instead of complying with subrule (2) of this rule; however, supplies using alternative compliance criteria shall still comply with TOC monitoring requirements in R 325.10719e(4)(b):

(i) Softening that results in lowering the treated water alkalinity to less than 60 mg/l as calcium carbonate, measured monthly and calculated quarterly as a running annual average.

(ii) Softening that results in removing not less than 10 mg/l of magnesium hardness as calcium carbonate, measured monthly and calculated quarterly as an annual running average.

(2) All of the following provisions are enhanced coagulation and enhanced softening performance requirements:

(a) Water supplies shall achieve the percent reduction of TOC specified in subdivision (b) of this subrule between the source water and the combined filter effluent, unless the department approves a supply's request for alternate minimum TOC removal (step 2) requirements under subdivision (c) of this subrule.

(b) Required step 1 TOC reductions, indicated in table 1 of this rule, are based on specified source water parameters. Supplies practicing softening are required to meet the step 1 TOC reductions in the far right column "source water alkalinity >120 mg/l" for the specified source water TOC.

Table 1 Step 1 required removal of TOC by enhanced coagulation and enhanced softening for subpart H supplies usingconventional filtration ^{A, B}

Source-water

Source-water TOC, mg/l	alkalinity, mg/l as calcium carbonate
	0-60	>60-120	>120C
>2.0-4.0	35.0%	25.0%	15.0%
>4.0-8.0	45.0%	35.0%	25.0%
>8.0	50.0%	40.0%	30.0%

^A Supplies meeting at least 1 of the conditions in subrule (1) (b) (i) to (vi) of this rule are not required to operate with enhanced coagulation.

^B Supplies with softening systems meeting 1 of the alternative compliance criteria in subrule (1) (c) of this rule are not required to operate with enhanced softening.

^C Supplies practicing softening shall meet the TOC removal requirements in this column.

(c) Subpart H supplies using conventional filtration systems that cannot achieve the step 1 TOC removals required by subdivision (b) of this subrule due to water quality parameters or operational constraints shall apply to the department, within 3 months of failure to achieve the TOC removals required by subdivision (b) of this subrule, for approval of alternative minimum TOC removal (step 2) requirements submitted by the supply. If the department approves the step 2 requirements, then a supply's failure to meet the step 1 TOC removals will not be considered a treatment technique violation during the interim time period between the end of the 12 month data gathering monitoring period in R 325.10610b (4) and receipt of the department's approval. Until the department approves the step 2 requirements, the supply shall meet the step 1 TOC removals contained in subdivision (b) of this subrule.

(d) Applications made to the department by water supplies with enhanced coagulation systems for approval of alternative minimum TOC removal (step 2) requirements under subdivision (c) of this subrule shall include, at a minimum, results of bench or pilot scale testing conducted under paragraph

(i) of this subdivision to determine the alternate enhanced coagulation level. All of the following apply:

(i) Alternate enhanced coagulation level is defined as coagulation at a coagulant dose and pH as determined by the method described in paragraphs (i) to (v) of this subdivision such that an incremental addition of 10 mg/l of alum, or equivalent amount of ferric salt, results in a TOC removal of less than or equal to 0.3 mg/l. The percent removal of TOC at this point is the minimum TOC removal required for the supply. Once approved by the department, this minimum requirement supersedes the minimum TOC removal required by table 1 of this rule. This requirement will be effective until the department approves a new value based on the results of a new bench and pilot scale test. Failure to achieve department set alternative minimum TOC removal levels is a violation of these rules.

(ii) Bench or pilot scale testing of enhanced coagulation shall be conducted by using representative water samples and adding 10 mg/l increments of alum, or equivalent amounts of ferric salt, 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:

Table 2 Enhanced coagulation step 2 target pH

Alkalinity (mg/l as calcium carbonate)	Target pH
0-60	5.5
>60-120	6.3
>120-240	7.0
>240	7.5

(iii) 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 supply shall 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.

(iv) The supply may operate at any coagulant dose or pH necessary, and consistent with these rules, to achieve the minimum TOC percent removal approved under subdivision (c) of this subrule.

(v) 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 considered to contain TOC not amenable to enhanced coagulation. The supply may then apply to the department for a waiver of enhanced coagulation requirements. The department's determination will be made on a case-by-case basis and the department will consider supporting documentation from the water supply of bench or pilot scale testing designed to demonstrate the best level of TOC removal that is feasibly attainable, given the unique characteristics of the raw water to be treated.

(3) Water supplies shall calculate compliance using the methods in either of the following provisions, as applicable:

(a) Subpart H supplies, other than those identified in subrule (1) (b) or (c) of this rule, shall comply with requirements contained in subule (2) (b) or (c) of this rule. Supplies shall calculate compliance quarterly, beginning after the supply 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 table 1 of this rule or from subrule (2) (c) of this rule.

(iii) Divide the value in paragraph (i) of this subdivision by the value in paragraph (ii) of this subdivision.

(iv) Add together the results of paragraph (iii) of this subdivision for the last 12 months and divide by 12.

(v) If the value calculated in paragraph (iv) of this subdivision is less than 1.00, then the supply is not in compliance with the TOC percent removal requirements.

(b) Supplies may use the provisions in paragraphs (i) to (v) of this subdivision instead of the calculations in subdivision (a) (i) to (v) of this subrule to determine compliance with TOC percent removal requirements, as follows:

(i) In any month that the supply's treated or source water TOC level is less than 2.0 mg/l, the supply may assign a monthly value of 1.0, instead of the value calculated in subdivision (a) (iii) of this subrule, when calculating compliance under subdivision (a) of this subrule.

(ii) In any month that a supply practicing softening removes not less than 10 mg/l of magnesium hardness as calcium carbonate, the supply may assign a monthly value of 1.0, instead of the value calculated in subdivision (a) (iii) of this subrule, when calculating compliance under subdivision (a) of this subrule.

(iii) In any month that the supply's source water SUVA, before any treatment, is less than or equal to 2.0 l/mg m, the supply may assign a monthly value of 1.0, instead of the value calculated in subdivision (a) (iii) of this subrule, when calculating compliance under subdivision (a) of this subrule.

(iv) In any month that the supply's finished water SUVA is less than or equal to 2.0 l/mg m, the supply may assign a monthly value of 1.0, instead of the value calculated in subdivision (a) (iii) of this subrule, when calculating compliance under subdivision (a) of this subrule.

(v) In any month that a supply practicing enhanced softening lowers alkalinity below 60 mg/l as calcium carbonate, the supply may assign a monthly value of 1.0, instead of the value calculated in subdivision (a) (iii) of this subrule, when calculating compliance under subdivision (a) of this subrule.

(4) The treatment techniques to control the level of disinfection byproduct precursors in drinking water treatment and distribution systems for subpart H supplies using conventional filtration is enhanced coagulation or enhanced softening.

Notes

Mich. Admin. Code R. 325.10610c

2003 AACS; 2009 AACS