Mo. Code Regs. tit. 10 § 60-15.090

Current through Register Vol. 49, No. 23, December 2, 2024

Section 10 CSR 60-15.090 - Monitoring Requirements for Lead and Copper in Source Water

PURPOSE: This rule establishes monitoring requirements for lead and copper in source waters.

(1) Sample Location, Collection Methods, and Number of Samples.

(A) A water system that fails to meet the lead or copper action level on the basis of tap samples collected in accordance with 10 CSR 60-15.070 shall collect lead and copper source water samples in accordance with the following requirements regarding sample location, number of samples, and collection methods:

1. Ground water systems shall take a minimum of one (1) sample at every entry point to the distribution system which is representative of each well after treatment (hereafter called a sampling point). The system shall take one (1) sample at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant;

2. Surface water systems shall take a minimum of one (1) sample at every entry point to the distribution system after any application of treatment or in the distribution system at a point which is representative of each source after treatment (hereafter called a sampling point). The system shall take each sample at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant (Note: For the purposes of this requirement, surface water systems include systems with a combination of surface and ground sources);

3. If a 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 (that is, when water is representative of all sources being used); and

4. The department may reduce the total number of samples which must be analyzed by allowing the use of compositing. Compositing of samples must be done by certified laboratory personnel. Composite samples from a maximum of five (5) samples are allowed, provided that if the lead concentration in the composite sample is greater than or equal to 0.001 mg/L or the copper concentration is greater than or equal to 0.160 mg/L, then either:

A. A follow-up sample shall be taken and analyzed within fourteen (14) days at each sampling point included in the composite; or

B. If duplicates of or sufficient quantities from the original samples from each sampling point used in the composite are available, the system may use these instead of resampling.

(B) Where the results of sampling indicate an exceedance of maximum permissible source water levels established under 10 CSR 60-5.040(2)(C), the department may require that one (1) additional sample be collected as soon as possible after the initial sample was taken (but not to exceed two (2) weeks) at the same sampling point. If the department-required confirmation sample is taken for lead or copper, then the results of the initial and confirmation sample shall be averaged in determining compliance with maximum permissible levels. Any sample value below the detection limit shall be considered to be zero (0). Any value above the detection limit but below the practical quantification level (PQL) shall be as the measured value or be considered one-half (1/2) PQL.

(2) Monitoring Frequency After System Exceeds Tap Water Action Level. Any system which exceeds the lead or copper action level at the tap shall collect one (1) source water sample from each entry point to the distribution system no later than six (6) months after the end of the monitoring period during which the lead or copper action level was exceeded. For monitoring periods that are annual or less frequent, the end of the monitoring period is September 30 of the calendar year in which the sampling occurs, or if the department has established an alternate monitoring period, the last day of that period.

(3) Monitoring Frequency After Installation of Source Water Treatment. Any system which installs source water treatment pursuant to 10 CSR 60-15.040 shall collect an additional source water sample from each entry point to the distribution system during two (2) consecutive six- (6-) month monitoring periods by the deadline specified in 10 CSR 60-15.040(1)(D).

(4) Monitoring Frequency After the Department Specifies Maximum Permissible Source Water Levels or Determines that Source Water Treatment is not Needed.

(A) A system shall monitor at the following specified frequency in cases where the department specifies maximum permissible source water levels under 10 CSR 60-15.040(2)(C) or determines that the system is not required to install source water treatment under 10 CSR 60-15.040(2)(A):

1. A water system using only ground water shall collect samples once during the three- (3-) year compliance period in effect when the applicable department determination under subsection (4)(A) of this rule is made. Those systems shall collect samples once during each subsequent compliance period. Triennial samples shall be collected every third calendar year; and

2. A water system using surface water (or a combination of surface and ground water) shall collect samples once during each calendar year, the first annual monitoring period to begin during the year in which the applicable department determination is made under subsection (4)(A) of this rule.

(B) A system is not required to conduct source water sampling for lead, copper, or both, if the system meets the action level for the specific contaminant in tap water samples during the entire source water sampling period applicable to the system under subsection (4)(A) of this rule.

(5) Reduced Monitoring Frequency.

(A) A water system using only ground water may reduce the monitoring frequency for lead and copper in source water to once during each nine- (9-) year compliance cycle (as that term is defined in 10 CSR 60-2.015 ) provided that the samples are collected no later than every ninth calendar year and if the system meets any one (1) of the following criteria:

1. The system demonstrates that finished drinking water entering the distribution system has been maintained below the maximum permissible lead and copper concentrations specified in 10 CSR 60-15.040(2)(C) during at least three (3) consecutive compliance periods under subsection (4)(A) of this rule; or

2. The department has determined that source water treatment is not needed and the system demonstrates that, during at least three (3) consecutive compliance periods in which sampling was conducted under subsection (4)(A) of this rule, the concentration of lead in source water was less than or equal to 0.005 mg/L and the concentration of copper in source water was less than or equal to 0.65 mg/L.

(B) A water system using surface water (or a combination of surface and ground waters) may reduce the monitoring frequency in paragraph (4)(A)2. of this rule to once during each nine- (9-) year compliance cycle (as that term is defined in 10 CSR 60-2.015 ) provided that the samples are collected no later than every ninth calendar year and if the system meets one (1) of the following criteria:

2. The department has determined that source water treatment is not needed and the system demonstrates that, during at least three (3) consecutive years, the concentration of lead in source water was less than or equal to 0.005 mg/L and the concentration of copper in source water was less than or equal to 0.65 mg/L.

(C) A water system that uses a new source of water is not eligible for reduced monitoring for lead, copper, or both, until concentrations in samples collected from the new source during three (3) consecutive monitoring periods are below the maximum permissible lead and copper concentrations.

10 CSR 60-15.090

AUTHORITY: section 640.100, RSMo Supp. 2011.* Original rule filed Aug. 4, 1992, effective 5/6/1993. Amended: Filed Aug. 14, 2001, effective 4/30/2002. Amended: Filed Oct. 17, 2011, effective 5/30/2012.

*Original authority: 640.100, RSMo 1939, amended 1978, 1981, 1982, 1988, 1989, 1992, 1993, 1995, 1996, 1998, 1999, 2002, 2006.