5 Colo. Code Regs. § 1002-64.22
The provisions of Colorado Revised Statute Sections 25-8-202(1)(c) and (2), 25-8-205(1)(e), 25-8-501(1) and (2), and 25-8-509 C.R.S., (1989 Repl. Vol. and 1993 Supp.) provide the specific statutory authority these amendments to the Colorado Biosolids Regulations adopted by the Commission. The Commission has also adopted, in compliance with Colorado Revised Statute Section 24-4-203(4) C.R.S., (1988 Repl. Vol. and 1992 Supp.), the following Statement of Basis and Purpose.
BASIS AND PURPOSE
The Water Quality Control Commission adopted the Colorado Biosolids Regulations, 4.9.0 on November 2, 1993. While the regulations were being heard there was also ongoing litigation at the federal level concerning the technical basis for numeric molybdenum criteria contained in the federal sludge regulations at 40 CFR Part 503 . The Commission opted to incorporate the federal numeric molybdenum standards into the Biosolids Regulations as they appeared in the Part 503 regulation at that time. The Statement of Basis, Specific Statutory Authority, and Purpose ( §4.9.18) adopted anticipated potential future action relative to the federal molybdenum standards and indicated the Commission's intention to consider similar action. The Administrator of the United States Environmental Protection Agency on February 18, 1994 announced amendments to the 40 CFR Part 503 regulations. These amendments became effective the following day. The modification deletes annual and cumulative loading limits for molybdenum as well as the molybdenum concentration limit which corresponds to the state's Grade I molybdenum limit. The maximum allowable molybdenum concentration limit (Grade 2) remains unaffected by the federal amendments. This amendment to the Biosolids Regulations provides conformance with the revised federal criteria for molybdenum.
The state regulations at §4.9.10.A and at §4.9.15 A(5) also require a determination of historic metals loadings to land application sites as part of the permitting process. Sites which have previously received biosolids after July 31, 1993 must have loadings of arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium and zinc quantified. This amendment deletes molybdenum from that requirement. Monitoring for molybdenum levels in biosolids, products derived from biosolids and application site soils are, however, retained as a feature of the regulation.
The Commission anticipates that these provisions will be reassessed again in the future, following further consideration and action concerning this issue by EPA.
5 CCR 1002-64.22