5 Colo. Code Regs. § 1002-11.27

Current through Register Vol. 47, No. 20, October 25, 2024

Section 5 CCR 1002-11.27 - COMPOSITING SAMPLES RULE

11.27(1)Applicability and Definitions

(a) For all public water systems, the supplier may composite samples if they comply with the requirements specified in this rule.

(b) "COMPOSITING" means combining samples before analysis, to reduce the total number of samples analyzed.

11.27(2)Compositing Samples for Nitrate, Nitrite, Inorganic Chemicals, VOCs, and SOCs

(a) To composite inorganic chemical, nitrate, nitrite, VOC, or SOC samples collected under 11.18, 11.19, 11.20, and 11.21 the supplier must comply with the requirements specified in this section 11.27(2).

(b) The supplier may composite samples from up to five entry points.

(i) For systems supplying greater than (>) 3,300 people, the supplier must only composite samples from entry points within a single public water system.

(ii) For systems supplying less than or equal to ([LESS THAN EQUAL TO]) 3,300 people, the supplier may composite samples with other public water systems.

(c) Compositing of samples must be performed by certified laboratory personnel.

(d) Composite samples must be analyzed using a method where the method detection limit is less than (<) one-fifth (1/5) of the MCL.

(e) For VOCs and SOCs, the composite sample must be analyzed no later than 14 days after the first sample was collected.

(f) If a composite sample result is greater than or equal to (>=) one-fifth (1/5) the MCL for nitrate, nitrite, or an inorganic chemical, or greater than or equal to (>=) the cited detection limit for VOCs or SOCs, the supplier must collect a confirmation sample at each entry point included in the composite sample.

(i) The supplier must collect the confirmation samples no later than 14 days after receiving notification of the composite result.

(ii) The confirmation samples must be analyzed for the chemical that was:

(A) For nitrate, nitrite, or an inorganic chemical, greater than or equal to (>=) one-fifth (1/5) of the MCL; or

(B) For VOCs or SOCs, greater than or equal to (>=) the cited detection limit.

(iii) If duplicates of the original sample collected from each entry point used in the composite sample are available, the supplier may use these samples instead of collecting confirmation samples.

(A) The duplicate samples must be analyzed and the supplier must submit the sample results no later than 14 days after receiving the results of the original composite sample.

11.27(3)Compositing Samples for Gross Alpha Particle Activity, Combined Radium-226 and Radium-228, and Uranium

(a) To composite gross alpha particle activity, combined radium-226 and radium-228, and uranium samples collected under 11.22, the supplier must comply with the requirements specified in this section 11.27(3).

(b) The supplier may composite samples from up to four consecutive quarters from a single entry point.

(c) The composite sample must be analyzed no later than one year after the first sample was collected.

(d) The Department shall consider the composite sample result as an average of the individual samples included in the composite sample to determine compliance with the MCLs and to determine the future sampling frequency.

(e) If the composite sample result is greater than (>) one-half (1/2) the MCL, the Department may require the supplier to collect additional quarterly samples before allowing the supplier to sample at a reduced frequency.

11.27(4)Compositing Samples for Lead and Copper Entry Point Samples

(a) To composite lead and copper entry point samples collected under 11.17 or 11.26, the supplier must comply with the requirements specified in this section 11.27(4).

(b) The supplier may composite samples from no more than five entry points.

(c) Compositing of samples must be performed by certified laboratory personnel.

(d) If the lead concentration in the composite sample is greater than or equal to (>=) 0.001 mg/L or the copper concentration in the composite sample is greater than or equal to (>=) 0.160 mg/L, the supplier must collect confirmation samples no later than 14 days after receiving notification of the composite result.

(i) Instead of collecting confirmation samples, the supplier may use one of the following:

(A) Duplicates of each original sample used in the composite sample.

(B) The original samples used in the composite sample, if a sufficient volume is available.

5 CCR 1002-11.27

38 CR 07, April 10, 2015, effective 4/30/2015

41 CR 11, June 10, 2018, effective 6/30/2018

41 CR 23, December 10, 2018, effective 12/30/2018

43 CR 07, April 10, 2020, effective 4/30/2020

43 CR 17, September 10, 2020, effective 9/30/2020

45 CR 24, December 25, 2022, effective 1/14/2023

46 CR 18, September 25, 2023, effective 10/15/2023