Region 8
Serving Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming and 27 Tribal Nations
Superfund Program
National Information
Regional Information
Site Information
National Priorities List (NPL) History
Proposed Date
6/24/1988
Final Date
8/30/1990
Construction Completion Date
12/16/1993
Mystery Bridge at Highway 20
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Site Type: Final NPL City: Casper County: Natrona Street Address: U.S. Hwy 20, 28 and Mystery Bridge Rd. Zip Code: 82636 EPA ID#: WYD981546005 Site ID#: 0800852 Site Aliases: Brookhurst Subdivision, Evansville Congressional District(s): At Large |
Site Description
The Mystery Bridge Rd/Highway 20 site, also known as Brookhurst, is located in the Brookhurst and Mystery Bridge subdivisions, in Natrona County, one mile east of Evansville, Wyoming. Operators of the two areas of the Superfund site have cleaned up soil and groundwater contamination as part of an agreement with the Environmental Protection Agency (EPA) and the State of Wyoming.
One area of the site, the Kinder Morgan (formerly KN Energy) facility, is a natural-gas processing facility. An unlined waste pond on this area of the site was used from 1965 until 1984. The other area of the site, operated by Dow Chemical Company and Dowell Schlumberger, Inc.(DOW/DSI), was an oil field service area. This area stored volatile organic compounds, and had a truck wash drain and an abandoned sump.
In response to citizen complaints, studies started in 1986 found volatile halogenated organics (VHOs) in area drinking-water wells. Many homes in the Brookhurst Subdivision were affected. EPA responses included connecting residents to the Evansville municipal drinking-water system. Kinder Morgan and Dow also pumped and treated groundwater and removed contaminated soil. Both companies, with EPA approval, completed cleanup actions and discontinued groundwater treatment. Groundwater continues to be monitored.
In September 2009, EPA conducted a five-year review of the remedial actions performed under the Superfund program for the Mystery Bridge Road/Highway 20 Site. This was the third five-year review for the site.
The review confirmed that the remedy continues to be protective of human health and the environment. The next Five-Year Review will be completed in 2014.
Site Risk
Two separate groundwater plumes were identified. One, originating from the Kinder Morgan property, contained benzene, ethylbenzene, toluene and xylene (BETX). The other groundwater problem originated from the DOW/DSI property and extended underneath part of the subdivision.
| Media Affected | Contaminants | Source of Contamination |
| Ground water, surface water, soil, liquid waste, sold waste, air | Benezene ethylbenzene, toulene, xylene (BETX), volatile halogenated organics (VHOs). | Unlined waste pond at a natural gas processing facility, toulene storage area, a truck wash drain, abandoned sump at oil field service company site |
Cleanup Progress
A Record of Decision (ROD) signed in 1990 outlined the way the site would be cleaned up. In addition to the ROD, several Administrative Orders under the EPA removal program addressed the cleanup of soil and groundwater contamination associated with the Kinder Morgan and DOW/DSI site.
To address the soil contamination located on site, Kinder Morgan completed soil removals and construction of a soil-vapor extraction system. The latter was operated in conjunction with air-sparging (a system that injects air into contaminated water).
Kinder Morgan also pumped and treated groundwater to clean up the BETX contamination. The system included extraction wells, an air-stripper treatment unit, and groundwater reinjection for the treated groundwater. Kinder Morgan recently discontinued this operation and is monitoring the groundwater.
Kinder Morgan and DOW/DSI continue to monitor the ground water quarterly. EPA and the State of Wyoming are working collaboratively to establish institutional controls for the properties affected by this site.
Site Documents
Five-Year Review, September 2009 (PDF, 27 pp, 6.5 MB)
In addition to this Superfund site, work at several other sites is occurring under the Resource Conservation and Recovery Act (RCRA). Groundwater contamination from the Little America Refining Company (LARCO) was detected in part of the Brookhurst subdivision. Wyoming Department of Environmental Quality (WDEQ) LARCO Cleanup Fact Sheet. Also, cleanup work is in progress under RCRA at the adjacent Texaco facility. WDEQ Texaco Cleanup Fact Sheet. Contamination from this site has not affected the cleanup of the Mystery Bridge Road Superfund site.
Contacts
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EPA Frances Costanzi John Dalton |
Wyoming Jane Francis |
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View Documents at:
EPA Superfund Records Center 1595 Wynkoop Street Denver, CO 80202-1129 (303) 312-6473 or 1-800-227-8917 ext. 6473 (Reg. 8 only) |