16 Del. Admin. Code § 4462-15.0
Current through Register Vol. 28, No. 7, January 1, 2025
Section 4462-15.0 - Radioactivity15.1 Limits 15.1.1 Maximum Contaminant Levels for radionuclides:15.1.1.2 MCL for radium-226 and -228: The MCL for combined radium-226 and radium-228 is five (5) pCi/L. The combined radium-226 and radium-228 value is determined by the addition of the results of the analysis radium-226 and the analysis for radium-228.15.1.1.3 MCL for gross alpha particle activity (excluding radon and uranium): The MCL for gross alpha particle activity (including radium-226 but excluding radon and uranium) is fifteen (15) pCi/L.15.1.1.4 MCL for beta particle and photon radioactivity:15.1.1.4.1 The average annual concentration of beta particle and photon radioactivity for man-made radionuclides in drinking water must not produce an annual dose equivalent to the total body or any internal organ greater than four (4) millirems per year.15.1.1.4.2 Except for those listed in Table A below, the concentration of man-made radionuclides causing four (4) millirems total body or organ dose equivalents must be calculated on the basis of a two (2) liters per day drinking water intake using the 168 hour data listed in "Maximum Permissible Body Burdens and Maximum Permissible Concentration of Radionuclides in Air or Water for Occupational Exposure," NBS (National Bureau of Standards) Handbook 69 as amended August 1963, U.S. Department of Commerce. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 522(a) and 1 CFR part 51 . 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. If two (2) or more radionuclides are present, the sum of their annual dose equivalent to the total body or to any organ shall not exceed four (4) millirems per year. Table A: Average Annual Concentrations Assumed to Produce a Total Body or Organ Dose of 4 Millirems/Year
| Radionuclide | Critical Organ | pCi/L |
| Tritium | Total Body | 20,000 |
| Strontium | Bone Marrow | 8 |
15.1.1.5 MCL for uranium: The MCL for uranium is 30 ug/L.15.1.1.6 Compliance dates:15.1.1.6.1 Compliance dates for the combined radium-226 and -228, gross alpha particle activity, gross beta particle and photon radioactivity, and uranium: Community water systems must comply with the MCLs listed subsections 15.1.1.2, 15.1.1.3, 15.1.1.4, and 15.1.1.5 beginning December 8, 2003 and compliance shall be determined in accordance with the requirements of subsections 15.2.1 and 15.2.4. Compliance with reporting requirements for the radionuclides Section 4.0 is required on December 8, 2003.15.1.1.7 Best Available Technologies (BATs) for radionuclides: The Administrator of the U.S. Environmental Protection Agency, pursuant to section 1412 of the Safe Drinking Water Act, hereby identifies as indicated in the following table the best technology available for achieving compliance with the MCLs for combined radium-226 and -228, uranium, gross alpha particle activity, and beta particle and photon radioactivity. Table B: BAT for Combined Radium-226 and Radium-228, Uranium, Gross Alpha Particle Activity, and Beta Particle and Photon Radioactivity
| Contaminant | BAT |
| Combined radium-226 and -228 | Ion exchange, reverse osmosis, lime softening |
| Uranium | Ion exchange, reverse osmosis, lime softening, coagulation/filtration |
| Gross alpha particle activity (excluding radon and uranium) | Reverse osmosis |
| Beta particle and photon radioactivity | Ion exchange, reverse osmosis |
15.1.1.8 Small systems compliance technologies list for radionuclides. Table C: List of Small Systems Compliance Technologies for Radionuclides and Limitations of Use
| Unit Technologies | Limitations (see footnotes) | Operator Skill Level Required1 | Raw Water Quality Range and Considerations |
| 1. Ion Exchange (IE) | a | Intermediate | All ground waters |
| 2. Point-of-Use (POU2) IE | b | Basic | All ground waters |
| 3. Reverse Osmosis (RO) | c | Advanced | Surface waters usually require pre-filtration |
| 4. POU2 RO | b | Basic | Surface waters usually require pre-filtration |
| 5. Lime softening | d | Advanced | All waters |
| 6. Greens and filtration | e | Basic | |
| 7. Co-precipitation with barium sulfate | f | Intermediate to advanced | Ground waters with suitable water quality |
| 8. Electrodialysis/Electrodialysis reversal | | Basic to intermediate | All ground waters |
| 9. Pre-formed hydrous manganese oxide filtration | g | Intermediate | All ground waters |
| 10. Activated alumina | a, h | Advanced | All ground waters; competing anion concentrations may affect regeneration frequency |
| 11. Enhanced coagulation/filtration | i | Advanced | Can treat a wide range of water qualities |
1 National Research Council (NRC). Safe Water from Every Tap: Improving Water Service to Small Communities, National Academy Press, Washington, D.C., 1997.
2 A POU, or "point-of-use" technology, is a treatment device installed at a single tap used for the purpose of reducing contaminants in drinking water at the one tap. POU devices are typically installed at the kitchen tap.
Limitations Footnotes: Technologies for Radionuclides
a. The regeneration solution contains high concentrations of the contaminant ions. Disposal options should be carefully considered before choosing this technology.b. When POU devices are used for compliance, programs for long-term operation, maintenance and monitoring must be provided by the water provider to ensure proper performance.c. Reject water disposal options should be carefully considered before choosing this technology. See other RO limitations described Surface Water Rule Compliance Technologies Table.d. The combination of variable source water quality and the complexity of the water chemistry involved may make this technology too complex for small surface water systems.e. Removal efficiencies can vary depending on water quality.f. This technology may be very limited application to small systems. Since the process requires static mixing, detention basins, and filtration, it is most applicable to systems with sufficiently high sulfate levels that already have a suitable filtration treatment train in place.g. This technology is most applicable to small systems that already have filtration in place.h. Handling of chemicals required during regeneration and pH adjustment may be too difficult for small systems.i. Assumes modification to a coagulation/filtration process already in place. Table D: Compliance Technologies by System Size Category for Radionuclide National Primary Drinking Water Regulations (NPDWR's)
| Contaminant | Compliance technologies1 for system size categories (population served) | 3,301-10,000 |
| 25-500 | 501-3,300 |
| Combined radium-226 and radium-228 | 1,2,3,4,5,6,7,8,9 | 1,2,3,4,5,6,7,8,9 | 1,2,3,4,5,6,7,8,9 |
| Gross alpha particle activity | 3,4 | 3,4 | 3,4 |
| Beta particle and photon radioactivity | 1,2,3,4 | 1,2,3,4 | 1,2,3,4 |
| Uranium | 1,2,4,10,11 | 1,2,3,4,5,10,11 | 1,2,3,4,5,10,11 |
1 Numbers correspond to those technologies found listed in "Table C: List of Small Systems Compliance Technologies for Radionuclides and Limitations on Use"
15.2 Monitoring frequency and compliance requirements for radionuclides in community water systems. 15.2.1 Monitoring and compliance requirements for gross alpha particle activity, radium-226, radium-228, and uranium. 15.2.1.1 Community water systems (CWSs) must conduct initial monitoring to determine compliance with subsection 15.1 by December 31, 2007. For the purpose of monitoring for gross alpha particle activity, radium-226, radium-228, uranium, and beta particle and photon radioactivity in drinking water, "detection limit" is defined as in 40 CFR 141.25(c). 15.2.1.1.1 Applicability and sampling location for existing community water systems or sources. All existing CWSs using groundwater, surface water or systems using both ground and surface water (for the purpose of this section hereafter referred to as systems) must sample at every entry point to the distribution system that is representative of all sources being used (hereafter called a sample point) under normal operating conditions. The system must take each sample at the sampling point unless conditions make another sampling point more representative of each source or the Division has designated a distribution system location, in accordance with subsection 15.2.1.2.2.3.15.2.1.1.2 Applicability and sampling location for new community water systems or sources. All CWSs or CWSs that use a new source of water must begin to conduct initial monitoring for the new source within the first quarter after initiating use of the source. CWSs must conduct more frequent monitoring when ordered by the Division 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.15.2.1.2 Initial monitoring: Systems must conduct initial monitoring for gross alpha particle activity, radium-226, radium-228, and uranium as follows: 15.2.1.2.1 Systems without acceptable historical data, as defined below, must collect four consecutive quarterly samples at all sampling points before December 31, 2007.15.2.1.2.2 Grandfathering of data: The Division may allow historical monitoring data collected at a sampling point to satisfy the initial monitoring requirements for that sampling point, for the following situations.15.2.1.2.2.1 To satisfy initial monitoring requirements, a community water system having only one entry point to the distribution system may use the monitoring data from the last compliance monitoring period that began between June 2000 and December 8, 2003.15.2.1.2.2.2 To satisfy initial monitoring requirements, a community water system with multiple entry points and having appropriate historical monitoring data for each entry point to the distribution system may use the monitoring data from the last compliance monitoring period that began between June 2000 and December 8, 2003.15.2.1.2.2.3 To satisfy initial monitoring requirements, a community water system with appropriate historical data for a representative point in the distribution system may use the monitoring data from the last compliance monitoring period that began between June 2000 and December 8, 2003, provided that the Division finds that the historical data satisfactorily demonstrate that each entry point to the distribution system is expected to be in compliance based upon the historical data and reasonable assumptions about the variability of contaminant levels between entry points. The Division must make a written finding indicating how the data conforms to these requirements.15.2.1.2.3 For gross alpha particle activity, uranium, radium-226, and radium-228 monitoring, the Division may waive the final two quarters of initial monitoring for a sampling point if the results of the samples from the previous two quarters are below the detection limit.15.2.1.2.4 If the average of the initial monitoring results for a sampling point is above the MCL, the system must collect and analyze quarterly samples at that sampling point until the system has results from four consecutive quarters that are at or below the MCL, unless the system enters into another schedule as part of a formal compliance agreement with the Division.15.2.1.3 Reduced monitoring: The Division may allow CWSs to reduce the future frequency of monitoring from once every three years to once every six or nine years at each sampling point, based on the following criteria.15.2.1.3.1 If the average of the initial monitoring results for each contaminant (i.e., gross alpha particle activity, uranium, radium-226, or radium-228) is below the detection limit specified in subsection 15.2.4.3.1 Table A, the system must collect and analyze for that contaminant using at least one sample at that sampling point every nine years.15.2.1.3.2 For gross alpha particle activity and uranium, if the average of the initial monitoring results for each contaminant is at or above the detection limit but at or below 1/2 the MCL, the system must collect and analyze for that contaminant using at least one sample at that sampling point every six years. For combined radium-226 and radium-228, the analytical results must be combined. If the average of the combined initial monitoring results for radium-226 and radium-228 is at or above the detection limit but at or below 1/2 the MCL, the system must collect and analyze for that contaminant using at least one sample at that sampling point every six years.15.2.1.3.3 For gross alpha particle activity and uranium, if the average of the initial monitoring results for each contaminant is above 1/2 the MCL but at or below the MCL, the system must collect and analyze at least one sample at that sampling point every three years. For combined radium-226 and radium-228, the analytical results must be combined. If the average of the combined initial monitoring results for radium-226 and radium-228 is above 1/2 the MCL but at or below the MCL, the system must collect and analyze at least one sample at that sampling point every three years.15.2.1.3.4 Systems must use the samples collected during the reduced monitoring period to determine the monitoring frequency for subsequent monitoring periods (e.g., if a system's sampling point is on a nine year monitoring period, and the sample result is above 1/2 the MCL, then the next monitoring period for that sampling point is three years).15.2.1.3.5 If a system has a monitoring result that exceeds the MCL while on reduced monitoring, the system must collect and analyze quarterly samples at that sampling point until the system has results from four consecutive quarters that are below the MCL, unless the system enters into another schedule as part of a formal compliance agreement with the Division.15.2.1.4 Compositing: To fulfill quarterly monitoring requirements for gross alpha particle activity, radium-226, radium-228, or uranium, a system may composite up to four consecutive quarterly samples from a single entry point if analysis is done within a year of the first sample. The Division will treat analytical results from the composited as the average analytical result to determine compliance with the MCLs and the future monitoring frequency. If the analytical result from the composited sample is greater than 1/2 the MCL, the Division may direct the system to take additional quarterly samples before allowing the system to sample under a reduced monitoring schedule.15.2.1.5 A gross alpha particle activity measurement may be substituted for the required radium-226 measurement provided that the measured gross alpha particle activity does not exceed 5 pCi/L. A gross alpha particle activity measurement may be substituted for the required uranium measurement provided that the measured gross alpha particle activity does not exceed 15 pCi/L. The gross alpha measurement shall have a confidence interval of 95% (1.65s, where s is the standard deviation of the net counting rate of the sample) for radium-226 and uranium. When a system uses a gross alpha particle activity measurement in lieu of radium-226 and/or uranium measurement, the gross alpha particle activity analytical result will be used to determine the future monitoring frequency for radium-226 and/or uranium. If the gross alpha particle activity result is less than detection, 1/2 the detection limit will be used to determine compliance and the future monitoring frequency.15.2.2 Monitoring and compliance requirements for beta particle and photon radioactivity. To determine compliance with the maximum contaminant levels in subsection 15.1.1.4 for beta particle and photon radioactivity, a system must monitor at a frequency as follows. 15.2.2.1 Community water systems (both surface and ground water) designated by the Division as vulnerable must sample for beta particle and photon radioactivity. Systems must collect quarterly samples for beta emitters and annual samples for tritium and strontium-90 at each entry point to the distribution system (hereafter called a sampling point), beginning within one quarter after being notified by the Division. Systems already designated by the Division must continue to sample until the Division reviews and either reaffirms or removes the designation. 15.2.2.1.1 If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at a sampling point has a running annual average (computed quarterly) less than or equal to 50 pCi/L (screening level), the Division may reduce the frequency of monitoring at that sampling point to once every three years. Systems must collect all samples required in subsection 15.2.2.1 during the reduced monitoring period.15.2.2.1.2 For systems in the vicinity of a nuclear facility, the Division may allow the CWS to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring at the system's entry point(s), where the Division determines if such data is applicable to a particular water system. In the event that there is a release from a nuclear facility, systems that are using surveillance data must begin monitoring at the community water system's entry point(s) in accordance with subsection 15.2.2.1.15.2.2.2 Community water systems (both surface and ground water) designated by the Division as utilizing waters contaminated by effluents from nuclear facilities must sample for beta particle and photon radioactivity. Systems must collect quarterly samples for beta emitters and iodine-131 and annual samples for tritium and strontium-90 at each entry point to the distribution system (hereafter called a sampling point), beginning within one quarter after being notified by the Division. Systems already designated by the Division as systems using waters contaminated by effluents from nuclear facilities must continue to sample until the Division reviews and either reaffirms or removes the designation. 15.2.2.2.1 Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples or the analysis of a composite of three monthly samples. The former is recommended.15.2.2.2.2 For iodine-131, a composite of five consecutive daily samples shall be analyzed once each quarter. As ordered by the Division, more frequent monitoring shall be conducted when iodine-131 is identified in the finished water.15.2.2.2.3 Annual monitoring for strontium-90 and tritium shall be conducted by means of a composite of four consecutive quarterly samples or analysis of four quarterly samples. The latter procedure is recommended.15.2.2.2.4 If the gross beta particle activity beta minus the naturally occurring potassium-40 beta particle at a sampling point has a running annual average (computed quarterly) less than or equal to 15 pCi/L, the Division may reduce the frequency of monitoring at that sampling point to every three years. Systems must collect all samples required in subsection 15.2.2.1 during the reduced monitoring period.15.2.2.2.5 For systems in the vicinity of a nuclear facility, the Division may allow the CWS to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring at the system's entry point(s), where the Division determines if such data is applicable to a particular water system. In the event that there is a release from a nuclear facility, systems that are using surveillance data must begin monitoring at the community water system's entry point(s) in accordance with subsection 15.2.2.2.15.2.2.3 Community water systems designated by the Division to monitor for beta particle and photon radioactivity cannot apply to the Division for a waiver from the monitoring frequencies specified in subsections 15.2.2.1 or 15.2.2.2.15.2.2.4 Community water systems may analyze for naturally occurring potassium-40 beta particle activity from the same or equivalent sample used for the gross beta particle activity analysis. Systems are allowed to subtract the potassium-40 beta particle activity value from the total gross beta particle activity value to determine if the screening level is exceeded. The potassium-40 beta particle activity must be calculated by multiplying elemental potassium concentrations (in mg/L) by a factor of 0.82.15.2.2.5 If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity exceeds the appropriate screening level, an analysis of the sample must be performed to identify the major radioactive constituents present in the sample and the appropriate doses must be calculated and summed to determine compliance with subsection 15.1.1, using the formula in subsection 15.1.1.4.2. Doses must also be calculated and combined for measured levels of tritium and strontium to determine compliance.15.2.2.6 Systems must monitor monthly at the sampling point(s) that exceed the MCL in subsection 15.1.1 beginning the month after the exceedance occurs. Systems must continue monthly monitoring until the system has established, by a rolling average of three monthly samples, that the MCL is being met. Systems who establish that the MCL is being met must return to quarterly monitoring until they meet the requirements set forth in subsections 15.2.2.1.2 or 15.2.2.2.1.15.2.3 General monitoring and compliance requirements for radionuclides. 15.2.3.1 The Division may require more frequent monitoring than specified in subsections 15.2.1 and 15.2.2, or may require confirmation samples at its discretion. The results of the initial and confirmation samples will be averaged for use in compliance determinations.15.2.3.2 Each public water system shall monitor at the time designated by the Division during each compliance period.15.2.3.3 Compliance: Compliance with subsection 15.1.1 will be determined based on the analytical result(s) obtained at each sampling point. If one sampling point is in violation of an MCL, the system is in violation of the MCL. 15.2.3.3.1 For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point. If the average of any sampling point is greater than the MCL, then the system is out of compliance with the MCL.15.2.3.3.2 For systems monitoring more than once per year, if any sample result will cause the running annual average to exceed the MCL at any sample point, the system is out of compliance with the MCL immediately.15.2.3.3.3 Systems must include all samples taken and analyzed under the provisions of this section in determining compliance, even if that number is greater than the minimum required.15.2.3.3.4 If a system does not collect all required samples when compliance is based on a running annual average of quarterly samples, compliance will be based on the running average of the samples collected.15.2.3.3.5 If a sample result is less than the detection limit, zero will be used to calculate the annual average, unless a gross alpha particle activity is being used in lieu of radium-226 and/or uranium. If the gross alpha particle activity result is less than detection, 1/2 the detection limit will be used to calculate the annual average.15.2.3.4 The Division has the discretion to delete results of obvious sampling or analytical errors.15.2.3.5 If the MCL for radioactivity set forth in subsection 15.1.1 is exceeded, the operator of a community water system must give notice to the Division pursuant to subsection 4.1.2 and to the public as required in subsection 4.2.15.2.4 Analytical Methodology: 15.2.4.1 The methods specified in 40 CFR 141.25(a), copies may be obtained from the Office of Drinking Water, are to be used to determine compliance with Section 15.0.15.2.4.2 When the identification and measurement of radionuclides other than those listed in subsection 15.2.4.1 is required, the following references are to be used, except in cases where alternative methods have been approved in accordance with 40 CFR 141.27. 15.2.4.2.1 Procedures for Radiochemical Analysis of Nuclear Reactor Aqueous Solutions, H. L. Krieger and S. Gold, EPA-R4-73-014. USEPA, Cincinnati, Ohio, May 197315.2.4.2.2 HASL Procedure Manual, Edited by John H. Harley. HASL 300, ERDA Health and Safety Laboratory, New York, NY. 197315.2.4.3 For the purpose of monitoring radioactivity concentrations in drinking water, the required sensitivity of the radioanalysis is defined in terms of a detection limit. The detection limit shall be that concentration which can be counted with a precision of plus or minus one hundred (100) percent at the ninety-five (95) percent confidence level (1.96o where o is the standard deviation of the net counting rate of the sample).15.2.4.3.1 To determine compliance with subsections 15.1.1.2, 15.1.1.3, and 15.1.1.5 the detection limit shall not exceed the concentrations in Table A to this paragraph. Table A. - Detection Limits for Gross Alpha Particle Activity, Radium 226, Radium 228, and Uranium
| Contaminant | Detection Limit |
| Gross alpha particle activity | 3 pCi/L |
| Radium 226 | 1 pCi/L |
| Radium 228 | 1 pCi/L |
| Uranium | 1ug/L |
15.2.4.3.2 To determine compliance with subsection 15.1.1.4 the detection limits shall not exceed the concentrations listed in Table B to this paragraph. Table B. - Detection Limits for Man-Made Beta Particle and Photon Emitters
| Radionuclide | Detection Limit |
| Tritium | 1,000 pCi/L |
| Strontium-89 | 10 pCi/L |
| Strontium-90 | 2 pCi/L |
| Iodine-131 | 1 pCi/L |
| Cesium-134 | 10 pCi/L |
| Gross beta | 4 pCi/L |
| Other radionuclides | 1/10 of the applicable limit |
15.2.4.4 To judge compliance with the maximum contaminant levels listed in subsections 15.1.1.2 and 15.1.1.4 averages of the data shall be used and shall be rounded to the same number of significant figures as the maximum contaminant level for the substance in question.15.2.4.5 The Division has the authority to determine compliance or initiate enforcement action based on analytical results or other information compiled by sanctioned representatives and agencies.15.2.5 Monitoring of consecutive public water systems. When a public water system supplies water to one or more other public water systems, the division may modify the monitoring requirements imposed by this part to the extent that the interconnection of the systems justifies treating them as a single system for monitoring purposes. Any modified monitoring shall be conducted pursuant to a schedule specified by the Division and concurred in by the Administrator of the U.S. Environmental Protection Agency.16 Del. Admin. Code § 4462-15.0
24 DE Reg. 794(2/1/2021)
24 DE Reg. 904( 4/1/2021) (Errata)