Missouri Code of State Regulations › Title 10 - DEPARTMENT OF NATURAL RESOURCES › Division 60 - Safe Drinking Water Commission › Chapter 4 - Contaminant Levels and Monitoring › Section 10 CSR 60-4.100 - Maximum Volatile Organic Chemical Contaminant Levels and Monitoring Requirements

Current through Register Vol. 49, No. 14, July 15, 2024
PURPOSE: The amendment will remove language that has
				  sunset and correct other regulation citations.
(1) This rule applies to community and
				non-transient noncommunity public water systems.
(2) The following are the maximum contaminant
				levels (MCLs) for volatile organic chemicals (VOCs).
Maximum
Contaminant Level,
Milligrams
Contaminant
Per Liter
(A) Eight (8) original VOCs
1. Benzene
0.005
2. Carbon tetrachloride
0.005
3. 1,2-dichloroethane
0.005
4. 1,1-dichloroethylene
0.007
5. para-dichlorobenzene
0.075
6. 1,1,1-trichloroethane
0.2
7. Trichloroethylene
0.005
8. Vinyl chloride
0.002
Maximum
Contaminant Level,
Milligrams
Contaminant
Per Liter
(B) Thirteen (13) VOCs
1. cis-1,2-dichloroethylene 0.07
2. Dichloromethane
0.005
3. 1,2-dichloropropane
0.005
4. Ethylbenzene
0.7
5. Monochlorobenzene
0.1
6. o-dichlorobenzene
0.6
7. Styrene
0.1
8. Tetrachloroethylene
0.005
9. Toluene
1
10. 1,2,4-Trichlorobenzene 0.07
11. 1,1,2-Trichloroethane 0.005
12. trans-1,2-
dichloroethylene
0.1
13. Xylenes (total)
10
(3)
				For the purpose of determining compliance with MCLs, a supplier of water must
				collect samples of the product water for analyses as follows:
(A) During the initial three (3)-year
				compliance, all community and nontransient noncommunity water systems must
				collect an initial round of four (4) consecutive quarterly samples for each of
				the contaminants listed in section (2) unless a waiver has been granted by the
				department. The department will designate the year in which each system samples
				within this compliance period;
(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. Each sample must be taken at the same sampling point, unless conditions
				make another sampling point more representative of each source or treatment
				plant. The sampling point will be after the application of treatment, if
				any;
(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;
(D) The department may require more frequent
				monitoring than specified in subsection (3)(A) of this rule and may require
				confirmation samples for positive and negative results at its discretion;
				and
(E) If one (1) sampling point
				is in violation of an MCL, the system is in violation of the MCL.
1. For systems monitoring more than once per
				year, compliance with the MCL is determined by a running annual average at each
				sampling point.
2. Systems
				monitoring annually or less frequently whose sample result exceeds the MCL must
				begin quarterly sampling. The system will not be considered in violation of the
				MCL until it has completed one (1) year of quarterly sampling.
3. If any sample result will cause the
				running annual average to exceed the MCL at any sampling point, the system is
				out of compliance with the MCL immediately.
4. If a system fails to collect the required
				number of samples, compliance will be based on the total number of samples
				collected.
5. If a sample result is
				less than the detection limit, zero will be used to calculate the annual
				average.