National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List: Partial Deletion of the Mystery Bridge Road/U.S. Highway 20 Superfund Site

The Environmental Protection Agency (EPA) Region 8 is publishing a direct final notice of Partial Deletion of the property currently owned by Tallgrass Energy Partners, LP, (formerly owned by KM Upstream LLC and hereinafter referred to as the former KMI Property), on the Mystery Bridge Road/U.S. Highway 20 Site (Site) from the National Priorities List (NPL). The Site is located in Natrona County, northeast of Casper, Wyoming. The NPL, promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, is an appendix of the National Oil and Hazardous Substances Pollution and Contingency Plan (NCP). This direct final partial deletion is being published by EPA with the concurrence of the State of Wyoming through the Wyoming Department of Environmental Quality (WDEQ) because EPA has determined that all appropriate response actions under CERCLA, other than maintenance of institutional controls and five-year reviews, have been completed for the former KMI source area and the resultant groundwater contamination. However, this deletion does not preclude future actions under Superfund. This partial deletion pertains to the former KMI Property. EPA is proposing to delete the entire former KMI Property from the NPL, including the groundwater (OU1) and the soil/former source area (OU2). The remaining areas and media of the Site for both OU1 and OU2 containing the volatile halogenated organic chemicals (VHOs) source soils and plume, which are attributable to the Dow Chemical Company/ Dowell Schlumberger, Inc. (DOW/DSI) facility, will remain on the NPL and are not being considered for deletion as part of this action. However, this partial deletion does not preclude future actions under Superfund.