5 Colo. Code Regs. § 1002-11.22

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

Section 5 CCR 1002-11.22 - RADIONUCLIDES RULE

11.22(1)Applicability and Definitions

(a) For all community water systems, the supplier must comply with the requirements specified in this rule.

(i) The supplier is not required to comply with the beta particle and photon radioactivity requirements, unless the Department determines the system is vulnerable to beta particle and photon radioactivity contamination or the system is using sources contaminated by effluents from nuclear facilities.

(b) "BETA PARTICLE AND PHOTON RADIOACTIVITY" means the radiation from a group of 179 man-made radionuclides, including tritium, strontium-90, and iodine-131, that emit beta and photon radiation. These man-made beta particle and photon emitters are listed in the Maximum Permissible Body Burdens and Maximum Permissible Concentration of Radionuclides in Air or Water for Occupational Exposure, NBS Handbook 69, except the daughter products of thorium-232, uranium-235 and uranium-238.

(c) "GROSS ALPHA PARTICLE ACTIVITY" means the radiation from all radionuclides emitting alpha radiation, including radium-226, excluding radon and uranium.

(d) "GROSS BETA PARTICLE ACTIVITY" means the radiation from all radionuclides that emit beta radiation. This measurement is used as part of the calculation to determine the beta particle and photon radioactivity.

(e) "PICOCURIE" or "pCi" means the quantity of radioactive material producing 2.22 nuclear transformations per minute.

(f) "REM" means the unit of dose equivalent from ionizing radiation to the total body or any internal organ or organ system. A "millirem (mrem)" is 1/1000 of a rem.

11.22(2)MCL Requirements for Radionuclides

(a) The radionuclide MCLs are as follows:

TABLE 11.22-I RADIONUCLIDE MCLs
Contaminant	MCL
Gross alpha particle activity (including radium-226, excluding radon1 and uranium)	15 pCi/L
Combined radium-226 and radium-2282	5 pCi/L
Uranium3	30 µg/L
Beta particle and photon radioactivity4	4 mrem/yr

1 Radon is not currently regulated in drinking water.

2 Radium-228 is an individual alpha particle activity emitter, however it is not included in the gross alpha particle activity and is measured separately. Radium-228 sample results are combined with radium-226 sample results for the purposes of determining compliance.

3 Uranium is an individual alpha particle activity emitter, however it is not included in the gross alpha particle activity and is measured separately. If uranium is determined by mass, a 0.67 pCi/µg of uranium conversion factor must be used. This conversion factor is based on the 1:1 activity ratio of U-234 and U-238 that is characteristic of naturally occurring uranium.

4 The average annual concentration of beta particle and photon radioactivity from man-made radionuclides in drinking water must not produce an annual dose equivalent to the total body or any internal organ greater than (>) 4 mrem/yr.

(b) The cited detection limits for radionuclides are specified in 40 CFR 141.25(c).

(c) The BATs for achieving compliance with the MCLs for radionuclides are specified in 40 CFR 141.66(g).

(d) The SSCTs for systems supplying less than or equal to ([LESS THAN EQUAL TO]) 10,000 people for achieving compliance with the MCL for radionuclides are specified in 40 CFR 141.66(h).

11.22(3)Sampling Requirements for Radionuclides

(a)General Radionuclide Sampling Requirements for Radionuclides

(i) To determine compliance with the radionuclide MCLs, the supplier must comply with the sampling requirements specified in this section, 11.22(3).

(ii) The supplier must sample at the time specified by the Department during each monitoring period.

(iii) The Department may:

(A) Require the supplier to sample more frequently than the minimum requirements specified in this section, 11.22(3).

(B) Require the supplier to collect a confirmation sample for any sample result.

(C) Invalidate sample results based on sampling or analytic errors.

(b)Sampling Requirements for Gross Alpha Particle Activity, Combined Radium-226 and Radium-228, and Uranium

(i) To determine compliance with the MCLs for gross alpha particle activity, combined radium-226 and radium-228, and uranium, the supplier must comply with the sampling requirements specified in this section, 11.22(3)(b).

(ii) For new systems, new sources, or reclassified systems that now meet the applicability of this rule, the supplier must collect four consecutive quarterly samples at each entry point no later than one year after beginning supplying water to the public or one year after being reclassified.

(A) If the sample results from the first two quarters are less than (<) the detection limit at an entry point, the Department may waive the final two quarters of initial sampling at that entry point and initial sampling will be considered complete at that entry point.

(iii) After completing initial sampling, if the LRAA of the initial sample results is greater than (>) the MCL, the supplier must continue to sample quarterly at that entry point.

(A) The supplier must continue to sample quarterly until the sample results from four consecutive quarters are less than or equal to ([LESS THAN EQUAL TO]) the MCL, unless the supplier enters into another schedule as part of a formal compliance agreement with the Department.

(iv) If the LRAA is less than or equal to ([LESS THAN EQUAL TO]) the MCL after completing initial sampling, the

Department may allow the supplier to reduce the sampling frequency. There is no routine sampling frequency for gross alpha particle activity, combined radium-226 and radium-228, and uranium. Sampling frequencies will be based on the LRAA of the initial sample results at each entry point. If the LRAA is:

(A) Less than (<) the detection limit, the supplier must collect at least one sample for that radionuclide every nine years at that entry point.

(B) Greater than or equal to (>=) the detection limit and less than or equal to ([LESS THAN EQUAL TO]) one-half the MCL, the supplier must collect at least one sample for that radionuclide every six years at that entry point.

(C) Greater than (>) one-half the MCL and less than or equal to ([LESS THAN EQUAL TO]) the MCL, the supplier must collect at least one sample for that radionuclide every three years at that entry point.

(v) Each time sample results are received subsequent sampling frequencies will be determined as follows:

(A) If a sample result is less than or equal to ([LESS THAN EQUAL TO]) the MCL:

(I) Subsequent sampling frequencies will be determined as specified in 11.22(3)(b)(iv)(A-C).

(B) If a sample result is greater than (>) the MCL, the supplier must increase the sampling frequency to quarterly at that entry point.

(I) The supplier must continue to sample quarterly until the sample results from four consecutive quarters are less than or equal to ([LESS THAN EQUAL TO]) the MCL, unless the supplier enters into another schedule as part of a formal compliance agreement with the Department.

(II) Subsequent sampling frequencies will be determined as specified in 11.22(3)(b)(iv)(A-C) based on the LRAA of the sample results.

(vi) The supplier may substitute the gross alpha particle activity sample result for the radium-226 sample result if the gross alpha particle activity sample result meets all of the following criteria:

(A) The sample result is less than or equal to ([LESS THAN EQUAL TO]) 5 pCi/L.

(B) The sample result has a confidence interval of 95 percent (1.65s, where s is the standard deviation of the net counting rate of the sample).

(vii) The supplier may substitute the gross alpha particle activity sample result for uranium, if the gross alpha particle activity sample result meets both the following criteria:

(A) Is less than or equal to ([LESS THAN EQUAL TO]) 15 pCi/L.

(B) Has a confidence interval of 95 percent (1.65s, where s is the standard deviation of the net counting rate of the sample).

(viii) If the supplier substitutes the gross alpha particle activity sample result for radium-226 and/or uranium, the gross alpha particle activity sample result will be used to determine the sampling frequency for radium-226 and radium-228 and/or uranium.

(A) If the gross alpha particle activity sample result is less than (<) the detection limit, one-half the detection limit for gross alpha particle activity will be used to determine compliance and the sampling frequency.

(ix) The Department may require the supplier to sample more frequently in the event of possible contamination, or when changes in the distribution system or treatment processes occur that may increase the concentration of radioactivity in finished water.

(c)Sampling Requirements for Beta Particle and Photon Radioactivity

(i) To determine compliance with the MCL for beta particle and photon radioactivity the supplier must comply with the sampling requirements specified in this section, 11.22(3)(c).

(ii) If the Department determines a system is vulnerable to beta particle and photon radioactivity, the supplier must sample at each entry point as follows:

(A) For beta emitters, quarterly.

(B) For tritium and strontium-90, annually.

(iii) If the Department determines a system uses source waters contaminated by effluents from nuclear facilities, the supplier must sample at each entry point as follows:

(A) For beta emitters, monthly.

(I) The supplier may composite three monthly samples.

(II) The supplier must submit the sample results quarterly.

(B) For iodine-131, daily for five consecutive days each quarter.

(I) The supplier must composite the samples.

(II) If iodine-131 is detected in the finished water, the Department may require the supplier to sample more frequently.

(C) For tritium and strontium-90, quarterly.

(I) The supplier may composite four consecutive quarterly samples.

(II) The supplier must submit the sample results annually.

(iv) If the Department requires the supplier to sample for beta particle and photon radioactivity, the supplier must begin sampling no later than one quarter after receiving Department notification.

(v) For systems near a nuclear facility, if the Department determines environmental surveillance data collected by the nuclear facility applies to the system, the Department may allow the supplier to use that data instead of sampling as specified 11.22(3)(c)(ii) or 11.22(3)(c)(iii).

(A) If there is a nuclear release from a nuclear facility, the supplier must begin sampling as specified in 11.22(3)(c)(ii) or 11.22(3)(c)(iii).

(vi) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity has a LRAA less than or equal to ([LESS THAN EQUAL TO]) 15 pCi/L at an entry point, the Department may allow the supplier to reduce the sampling frequency at that entry point to once every three years.

(vii) If a sample result is greater than (>) the MCL, the supplier must increase the sampling frequency to monthly at that entry point beginning the month following the exceedance.

(A) If the LRAA of three consecutive monthly samples is less than (<) the MCL, the supplier may reduce the sampling frequency to quarterly.

(B) After reducing the sampling frequency to quarterly, the Department may allow the supplier to further reduce the sampling frequency as specified in 11.22(3)(c)(vi).

(viii) The supplier must continue to sample until the Department reviews and either reaffirms or removes the designation that the system is vulnerable to beta particle and photon radioactivity contamination.

11.22(4)Compliance Determination for Radionuclides

(a)General Compliance Determination for Radionuclides

(i) If the supplier samples more frequently than annually, MCL compliance is based on the LRAA:

(A) If a confirmation sample is required, the original sample result will be replaced with the average of the original sample result and the confirmation sample result when calculating the LRAA.

(I) If the supplier fails to collect the confirmation sample, the original sample result will be used when calculating the LRAA.

(B) If a sample result is less than (<) the cited detection limit, the sample result will be given a value of zero when calculating the LRAA.

(I) If the supplier is substituting the gross alpha particle activity sampling result for radium-226 and/or uranium and the sample result is less than (<) the cited detection limit, the sample result will be given a value of one-half the cited detection limit to calculate the LRAA for radium-226 and/or uranium.

(C) If the supplier collects more than the required number of samples, all sample results must be used to determine compliance.

(ii) The Department may determine compliance or initiate enforcement action based on sample results and other information gathered by Department representatives and agencies.

(b)Additional Compliance Determination for Beta Particle and Photon Radioactivity

(i) In addition to the compliance determination requirements specified in 11.22(4)(a), the supplier must comply with the requirements specified in this section, 11.22(4)(b), to determine compliance with the gross beta particle and photon radioactivity MCL.

(ii) The supplier may analyze for naturally occurring potassium-40 beta particle activity from the same sample used for the gross beta particle activity analysis.

(iii) The supplier may subtract the potassium-40 beta particle activity result from the total gross beta particle activity result to determine if the screening level, 15 pCi/L, is exceeded.

(iv) The potassium-40 beta particle activity must be calculated by multiplying elemental potassium concentrations (in mg/L) by a factor of 0.82.

(v) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity is greater than the screening level of (>) 15 pCi/L:

(A) The sample must be analyzed to identify the major radioactive constituents present in the sample.

(B) To determine compliance with the MCL, the appropriate doses must be calculated and summed.

(I) Except tritium and strontium-90, the concentration of man-made radionuclides causing 4 mrem total body or organ dose equivalents must be calculated on the basis of 2 liter per day drinking water intake using the 168 hour data list in the Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in Water for Occupational Exposure, NBS (National Bureau of Standards) Handbook 69 as amended August 1963, U.S. Department of Commerce.

(a) Copies of this document are available from the National Technical Information Service, NTIS ADA 280 282, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. The toll-free number is 800-553-6847. Copies may be inspected at EPA's Drinking Water Docket, 401 M Street, SW, Washington, DC 20460; or at the Office of the Federal Register, 800 North Capitol Street, NW, Suite 700, Washington, DC.

(II) To determine compliance, doses must also be calculated and combined for measured levels of tritium and strontium as specified in Table 11.22-II below.

TABLE 11.22-II AVERAGE ANNUAL CONCENTRATIONS ASSUMED TO PRODUCE A TOTAL BODY OR ORGAN DOSE OF 4 mrem/yr

Radionuclide	Critical organ	picoCurie per liter (pCi/L)
Tritium	Total body	20,000
Strontium-90	Bone Marrow	8

11.22(5)MCL Violations for Radionuclides

The following constitute radionuclide MCL violations:

(a) The LRAA at any entry point is greater than (>) the MCL for any radionuclide.

(b) The LRAA, calculated before four consecutive quarters of samples have been collected at any entry point, is greater than (>) the MCL for any radionuclide, regardless of the subsequent sample results.

11.22(6)Response to MCL Violations for Radionuclides

In the event of a radionuclide MCL violation, the supplier must:

(a) Notify the Department no later than 48 hours after the violation occurs.

(b) Distribute Tier 2 public notice as specified in 11.33.

5 CCR 1002-11.22

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