5 Colo. Code Regs. § 1002-41.23
The provisions of section 25-8-202(1)(a), (b) and (2); 25-8-203; and 25-8-204; C.R.S., provide the specific statutory authority for adoption. The Commission also adopted, in compliance with section 24-4-103(4) C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE
This hearing was held to consider changes recommended in the triennial informational hearing for the ground water standards and classifications regulation "The Basic Standards for Ground Water" 41. Significant changes were made to Table A "Ground Water Organic Chemical Standards" with the addition of new chemical standards and changes to existing standards. The changes are in keeping with the Commission's Policy 96-2 to coordinate surface and ground water standards. The changes and additions to Table A reflect the changes to the surface water Human Health Based Water Supply Standards adopted by the Commission in the Basic Standards and Methodologies for Surface Water, Regulation 31, triennial review hearing July 10, 2000.
Many of the surface water standards are based upon EPA-established drinking water standards, under the Safe Drinking Water Act (SDWA), or water quality criteria developed pursuant or section 304(a) of the federal Clean Water Act. Since these standards and criteria are modified from time to time, it is necessary to review the existing Colorado standards in comparison to the latest available information. As a result of this review, the Commission adopted revisions to the standards to conform with the latest available information as to protective levels for the various chemicals.
In adopting these standards for ground water, 39 new organic chemical standards were added to Table A, 25 existing standards were changed, and two chemicals were renamed. Two organic Chemicals were renamed in Table A: Dichloromethane CAS No. 75-09-2 is now Methylene chloride C , and Di(2 ethylhexyl)phthalate C CAS No. 117-81-7 is now Ethylhexyl phthalate (BIS-2) C.
The Commission has adopted amendments to section 41.5.B to provide for the establishment of alternative standards to the site-specific water quality standards for the Domestic Use - Quality classification. Prior to this amendment this alternative was not possible because section 41.5.B.3.a provided that the human health standards (Table 1) and the secondary drinking water standards (Table 2) apply to ground water classified Domestic Use - Quality. No alternative standards to the Table 1 and 2 standards were provided for in the original regulation. The Commission believes that the option of site-specific standards should be allowed taking into account the factors set forth in § 25-8-204(4) C.R.S. The language adopted by the Commission is similar to the language included in section 41.5.D.2 that allows the Commission to adopt sitespecific standards for radioactive materials and organic pollutants.
Additional changes proposed to Regulation 41 were of a "housekeeping" nature to update the regulation and to correct typographical errors.
PARTIES TO THE RULEMAKING
5 CCR 1002-41.23