5 Colo. Code Regs. § 1002-42.37
The provisions of C.R.S. sections 25-8-202; 25-8-203; 25-8-204; 25-8-402, provide the specific statutory authority for adoption of this regulation. The Commission also adopted, in compliance with section 24-4-103(4) the following statement of basis and purpose.
BASIS AND PURPOSE:
Site-Specific Classification
The Use Classifications adopted by the WQCC in 1993 for specified area 7 (Section 42.2) are appropriate for the current and future uses of the aquifer. Therefore, as a result of this hearing, the Commission maintained the current classifications of Domestic Use-Quality and Agricultural Use-Quality for specified area 7.
Site-Specific Numeric Standards
The Commission considered the factors set forth in C.R.S. § 25-8-204(4) to establish site-specific standards for the Specified Area.
Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS) are two perfluorinated compounds (PFCs) that have been linked to negative effects on human health. The U.S. Environmental Protection Agency (EPA) states in its May 2016 health advisories that PFOA and PFOS have the following toxicological effects: development effects, liver toxicity, kidney toxicity, immune effects, and cancer. PFCs are highly persistent chemicals that do not readily breakdown in the environment. Unlike many other persistent organic chemicals, PFCs are relatively water soluble and thus highly migratory within an aquifer. The seasonal nature of the contamination is unknown.
Results from the Third Unregulated Contaminant Monitoring Rule (UCMR3), which required testing for six PFCs in large public drinking water systems, found these chemicals in alluvial aquifers in central El Paso County. Based on review of Colorado's UCMR3 data, no other large public drinking water systems in the state were identified as having elevated levels of PFOA/PFOS. As such, the standard being proposed is site-specific, applying only to the area of the state where drinking water sources are known to have been affected by PFOA/PFOS contamination.
The U.S. Air Force has begun an investigatory process at Peterson Air Force Base (AFB), immediately upgradient of the known contamination, to determine possible sources of the PFOA/PFOS. The Air Force has not completed its remedial investigation, which would define the full extent of the contamination stemming from the base. However, the site investigation performed by Peterson AFB showed that PFOA and PFOS contamination originate, at least in part, from firefighting activities at Peterson AFB. The treatment of PFOA and PFOS has yet to begin on Peterson AFB, as a remedy will not be selected until the remedial investigation and feasibility study are conducted. Additionally, other sources of the PFOA/PFOS contamination in the specified area may be identified in the future. This site specific standard will act as the cleanup level for remediation of PFOA and PFOS by identified responsible parties.
The Commission added the sum of PFOA and PFOS = 0.070 micrograms per liter as a site specific standard for this specified area. The standard for the sum of PFOA and PFOS is consistent with the U.S. Environmental Protection Agency Drinking Water Health Advisories of May 2016.
* Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA), United States Environmental Protection Agency, Office of Water, EPA 822-R-16-005, May 2016.
* Drinking Water Health Advisory for Perfluorooctane Sulfonate (PFOS), United States Environmental Protection Agency, Office of Water, EPA 822-R-16-004, May 2016.
Based on the information contained in the health advisory documents, the commission determined that the value of 0.070 micrograms per liter is protective of both short-term and chronic exposure scenarios.
The Commission recognizes that PFOS and PFOA occur in multiple forms in the environment and intends for the standard to include these various forms, including the acid and conjugate base as well as the linear and branched isoforms of each compound. This is consistent with EPA's health advisories.
This modification also added the Radioactive Materials Standards Table and the organic chemical standards in Table A of the Basic Standards for Ground Water (5 CCR 1002-41) which are assigned to all groundwater, regardless of whether it is classified or unclassified, unless the commission has assigned other values for specific substances.
Modification of Specified Area
In this hearing, the Commission modified the spatial extent of specified area 7 located in central El Paso County in the vicinity of Fountain Creek. This modification of specified area 7 changed the spatial extent as follows:
* The western extent was moved to incorporate all areas contributing groundwater to the greater Widefield-Fountain aquifer area. The boundary integrates a recharge zone in the northwest region, follows a bedrock outcrop that serves as a hydrogeologic barrier along the western edge, and incorporates alluvial outcrops on the west side of the hydrogeologic barrier that flow from west to east, contributing groundwater to the greater aquifer area.
* The northern extent was moved to cover the northernmost recharge zone of these aquifers.
* The eastern boundary was extended to cover the extent of the affected alluvial aquifers and their recharge zones.
* The southern extent was moved to cover all wells that exhibited concentrations of PFCs above the EPA health advisory level of 70 ppt.
As hydrogeologic data has an inherent level of uncertainty, township and range was used to delineate the spatial boundary. Using township and range creates a buffer zone that can account for this uncertainty while also providing a legally-defensible boundary.
It should be emphasized that these use classifications and standards assignments do not preclude holding public hearings to set site-specific classifications and numerical standards as the need for such arises. Colorado Springs Utilities proposed a portion of its Clear Springs Ranch property be excluded from specified area 7, but the commission determined that there was enough evidence to show there is a hydrologic connection between the groundwater proposed to be excluded and the remainder of specified area 7, and did not have enough evidence to determine that the facility was hydrologically disconnected from the rest of the specified area. If new data is developed by Colorado Springs Utilities or any other entity which points to a need to reconfigure the boundary of the specified area 7, a request for a site-specific hearings will, of course, be considered by the commission.
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-42.37