5 Colo. Code Regs. § 1002-62.14
The provisions of 24-4-103; 25-8-202(1)(c) and (2); and 25-8-205, C.R.S. provide the specific statutory authority for consideration of the regulatory amendments proposed by this Notice. The Commission also adopted in compliance with 24-4-103(4), C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
The Commission added a new subsection 10.1.4 to the regulation. This change to the regulation is based on language found in the Secondary Treatment Regulations at 40 CFR Part 133.102 . Adoption of this provision will allow the Division to consider a variance from the current pH limits of 6.0 - 9.0 s.u. in cases where inorganic chemicals are not added to the waste stream as part of the treatment process and where industrial contributions do not cause the pH to be less than 6.0 s.u. or greater than 9.0 s.u.. A variance for a discharges to waters classified for aquatic life would only be granted in situations where the instream pH would remain within the 6.5 - 9.0 s.u. water quality standard.
This provision will principally be applied to lagoon type treatment systems which, due to the effects of naturally occuring algae, often experience pH values of greater than 9.0 s.u..
5 CCR 1002-62.14