(a)
(1) Variances and exemptions from the maximum contaminant levels for combined radium-226 and radium-228, uranium, gross alpha particle activity (excluding Radon and Uranium), and beta particle and photon radioactivity.
(i) The Administrator, pursuant to section 1415(a)(1)(A) of the Act, hereby identifies the following as the best available technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for the radionuclides listed in §141.66(b), (c), (d), and (e) of this chapter, for the purposes of issuing variances and exemptions, as shown in Table A to this paragraph.
Table A—BAT for Radionuclides Listed in §141.66
| Contaminant | BAT |
|---|---|
| Combined radium-226 and radium-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. |
(ii) In addition, the Administrator hereby identifies the following as the best available technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for the radionuclides listed in §141.66(b), (c), (d), and (e) of this chapter, for the purposes of issuing variances and exemptions to small drinking water systems, defined here as those serving 10,000 persons or fewer, as shown in Table C to this paragraph.
Table B—List of Small Systems Compliance Technologies for Radionuclides and Limitations to Use
| Unit technologies | Limitations (see footnotes) | Operator skill level required1 | Raw water quality range & considerations1 |
|---|---|---|---|
| 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. Green sand 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. |
1National Research Council (NRC). Safe Water from Every Tap: Improving Water Service to Small Communities. National Academy Press. Washington, D.C. 1997.
2A 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 that one tap. POU devices are typically installed at the kitchen tap. See the April 21, 2000 NODA for more details.
Limitations Footnotes: Technologies for Radionuclides:
aThe regeneration solution contains high concentrations of the contaminant ions. Disposal options should be carefully considered before choosing this technology.
bWhen POU devices are used for compliance, programs for long-term operation, maintenance, and monitoring must be provided by water utility to ensure proper performance.
cReject water disposal options should be carefully considered before choosing this technology. See other RO limitations described in the SWTR compliance technologies table.
dThe 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.
eRemoval efficiencies can vary depending on water quality.
fThis technology may be very limited in 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.
gThis technology is most applicable to small systems that already have filtration in place.
hHandling of chemicals required during regeneration and pH adjustment may be too difficult for small systems without an adequately trained operator.
iAssumes modification to a coagulation/filtration process already in place.
Table C—BAT for Small Community Water Systems for the Radionuclides Listed in §141.66
| Contaminant | Compliance technologies1 for system size categories (population served) | ||
|---|---|---|---|
| 25-500 | 501-3,300 | 3,300-10,000 | |
| 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 activity and photon activity | 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. |
1Note: Numbers correspond to those technologies found listed in the table B to this paragraph.
(2) A State shall require community water systems to install and/or use any treatment technology identified in Table A to this section, or in the case of small water systems (those serving 10,000 persons or fewer), Table B and Table C of this section, as a condition for granting a variance except as provided in paragraph (a)(3) of this section. If, after the system's installation of the treatment technology, the system cannot meet the MCL, that system shall be eligible for a variance under the provisions of section 1415(a)(1)(A) of the Act.
(3) If a community water system can demonstrate through comprehensive engineering assessments, which may include pilot plant studies, that the treatment technologies identified in this section would only achieve a de minimus reduction in the contaminant level, the State may issue a schedule of compliance that requires the system being granted the variance to examine other treatment technologies as a condition of obtaining the variance.
(4) If the State determines that a treatment technology identified under paragraph (a)(3) of this section is technically feasible, the Administrator or primacy State may require the system to install and/or use that treatment technology in connection with a compliance schedule issued under the provisions of section 1415(a)(1)(A) of the Act. The State's determination shall be based upon studies by the system and other relevant information.
(5) The State may require a community water system to use bottled water, point-of-use devices, point-of-entry devices or other means as a condition of granting a variance or an exemption from the requirements of §141.66 of this chapter, to avoid an unreasonable risk to health.
(6) Community water systems that use bottled water as a condition for receiving a variance or an exemption from the requirements of §141.66 of this chapter must meet the requirements specified in either §142.62(g)(1) or §142.62(g)(2) and (g)(3).
(7) Community water systems that use point-of-use or point-of-entry devices as a condition for obtaining a variance or an exemption from the radionuclides NPDWRs must meet the conditions in §142.62(h)(1) through (h)(6).
(b) [Reserved]
[65 FR 76751, Dec. 7, 2000]
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