PURPOSE: This rule establishes maximum contaminant levels and monitoring requirements for synthetic organic chemical contaminants.

1. (1) The following are the maximum contaminant levels (MCLs) for synthetic organic chemical contaminants.

   Maximum

   Contaminant Level,

Contaminant Milligrams Per Liter 1. Alachlor 2. Atrazine 3. Benzo(a)pyrene 4. Carbofuran 5. Chlordane 6. Dalapon 7. Di(2-ethylhexyl) adipate 8. Dibromochloropropane (DBCP) 9. Di(2-ethylhexyl) phthlate 10. Dinoseb 11. Diquat 12. Endothall 13. Endrin 14. 2,4-D 15. Ethylene dibromide (EDB) 16. Glyphosate 17. Heptachlor 18. Heptachlor epoxide 19. Hexachlorobenzene 20. Hexachlorocyclopentadiene 21. Lindane 22. Methoxychlor 23. Oxamyl (Vydate) 24. Picloram 25. Polychlorinated biphenyls (PCBs)

1. 26. Pentachlorophenol
2. 27. Simazine
3. 28. Toxaphene
4. 29. 2,3,7,8-TCDD (Dioxin) 0.00000003
5. 30. 2,4,5-TP (Silvex) 0.002 0.003 0.0002 0.04 0.002 0.2

0.4

0.0002

0.006 0.007 0.02 0.1 0.002 0.07

0.00005 0.7 0.0004 0.0002 0.001

0.05 0.0002 0.04 0.2 0.5

0.0005 (as determined by Method 508A only) 0.001 0.004 .003

0.05 (2) For the purpose of determining compliance with MCLs, a supplier of water must collect samples of the product water for analysis as follows:

1. (A) During the initial three (3)-year compliance period, all community and nontransient noncommunity water systems must collect an initial round of four (4) consecutive quarterly samples unless a waiver has been granted by the department. The department will designate the year in which each system samples within this compliance period;
2. (B) All public water systems shall sample at points in the distribution system representative of each water source or at each entry point to the distribution system. The sampling point will be after the application of treatment, if any. Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant;
3. (C) If the system draws water from more than one (1) source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions; and
4. (D) The department may require more frequent monitoring than specified in this section of the rule and may require confirmation samples for positive or negative results, at its discretion.

1. (3) If contaminants are not detected during the initial sampling as indicated in section (2) of this rule, systems may decrease their sampling frequency beginning in the next three (3)-year compliance period.

   1. (A) Systems that serve greater than three thousand three hundred (>3,300) persons may reduce their sampling frequencies to two

2. (2) quarterly samples at each sampling point in one (1) year in each compliance period.

   1. (B) Systems that serve less than or equal to three thousand three hundred ((cid:2)3,300) persons may reduce their sampling frequencies to one (1) sample in each compliance period.
3. (4) The department may allow sampling data collected between January 1, 1990 and December 31, 1995, to satisfy the initial base sampling requirements, if the sampling was completed as required by subsections (2)(B) and (C) of this rule.

4. (5) If contaminants are detected in any sample, then systems must sample quarterly beginning in the next quarter at each sampling point which resulted in a detection.

   1. (A) Groundwater systems must sample a minimum of two (2) quarters and surface water must sample a minimum of four (4) quarters to establish a baseline.
   2. (B) If the MCL is exceeded as described in subsection (5)(E) or (F) of this rule, then systems must sample quarterly beginning in the next quarter. Systems must sample a minimum of four (4) quarters to establish a baseline.
   3. (C) If the baseline indicates a system’s analytical results are reliably and consistently below the MCL, the department may reduce the system’s sampling frequency to annually. (Annual sampling must be conducted during the quarter which previously yielded the highest analytical result.)
   4. (D) Systems which have three (3) consecutive annual samples with no detection of a contaminant may apply to the department for a waiver.
   5. (E) If a system conducts sampling more frequently than annually, the system will be in violation when the running annual average at any sampling point exceeds the MCL.
   6. (F) If a system conducts sampling annually or on a less frequent basis, the system will be in violation when one (1) sample (or the average of the initial and confirmation samples) at any point exceeds the MCL.
   7. (G) If monitoring results in detection of one (1) or more of certain related contaminants (aldicarb, aldicarb sulfone, aldicarb sulfoxide and heptachlor, heptachlor epoxide), then subsequent monitoring shall analyze for all related contaminants.

5. (6) A public water system may apply to the department for a waiver from required sampling. Systems are eligible for reduced monitoring in the initial three (3)-year compliance period. The waiver is effective for one (1) compliance period. It must be renewed in subsequent compliance periods or the system must conduct sampling as required by subsection (2)(A) of this rule.

   1. (A) A public water system may apply to the department for a use waiver for reduced monitoring from required sampling if previous use of the chemical can be ruled out as required by 10 CSR 60-6.060(2).
   2. (B) A public water system may apply to the department for a susceptibility waiver for reduced monitoring contingent on the conduct of a thorough vulnerability assessment as required by 10 CSR 60-6.060(3).
6. (7) As determined by the department, a confirmation sample may be required for either positive or negative results. If a confirmation sample is used, the compliance determination is based on the average of the results of both the confirmation sample and the initial sample. The department has the discretion to delete results of obvious sampling errors from this calculation.
7. (8) Any public water system violating MCLs or monitoring and reporting requirements for any of the contaminants listed in section (1) of this rule must notify the department within seven (7) days and give public notice as required by 10 CSR 60-8.010.

8. (9) Treatment Techniques.

   1. (A) All public water systems shall use treatment techniques in lieu of MCLs for specified contaminants.
   2. (B) Each public water system must certify annually in writing to the department (using third-party or manufacturers’ certification) that when acrylamide and epichlorohydrin are used in drinking water systems, the combination (or product) of dose and monomer level does not exceed the levels specified as follows:

Acrylamide = 0.05% dosed at 1 part per million (ppm) (or equivalent) Epichlorohydrin = 0.01% dosed at 20 ppm (or equivalent) Certifications can rely on manufacturers or third parties, as approved by the department.

AUTHORITY: section 640.100, RSMo 1994.* Original rule filed May 4, 1979, effective Sept. 14, 1979. Amended: Filed April 14, 1981, effective Oct. 11, 1981. Rescinded and readopted: Filed March 31, 1992, effective Dec. 3, 1992. Amended: Filed May 4, 1993, effective Jan. 13, 1994. Amended: Filed Feb. 1, 1996, effective Oct. 30, 1996. *Original authority: 640.100, RSMo 1939, amended 1978, 1981, 1982, 1988, 1989, 1992, 1993, 1995.