Green Remediation Focus
British Petroleum Site
Casper, Wyoming
WY Voluntary Cleanup
Image Gallery
2.4-Day Teatment Process
Engineered Wetland System
Cleanup Objectives: Remediate gasoline-contaminated ground water for 50 to 100 years
Green Remediation Strategy: Installed radial-flow engineered wetlands operating in tandem with free-water surface wetlands and a cascading aeration system
- Employed Smart Growth principles to complement conversion of the site's former refinery to an office park and recreational facilities
- Designed wetland components for subsurface locations as much as possible to increase operational control and reduce offensive odors or insects
- Constructed radial-flow treatment beds consisting of crushed concrete previously reclaimed during refinery demolition
- Insulated wetland treatment beds with a six-inch layer of mulch to accommodate temperatures reaching -35°F
- Planted emergent wetland plants such as bulrushes, switchgrass, and cordgrass in each of the four wetland areas
Results:
- Treats up to 700,000 gallons of contaminated ground water each day
- Achieves a 50% reduction in BTEX concentrations when compared to influent of the pre-wetlands aeration process
- Achieves non-detectable concentrations of benzene and other hydrocarbons in water prior to discharge into a basin created by former refinery effluent discharge
- Operates year-round despite cold climate
- Incurred construction cost of $3.4 million, in contrast to projected $15.9 million for alternative pump-and-treat system employing air stripping and catalytic oxidation
- Found beneficial use for onsite demolition material
- Uses passive-energy systems to biodegrade contaminants
- Allowed for office park occupation within 10 months after the aerated/engineered wetland system began operating
Point of Contact: Vickie Meredith, WY Department of Environmental Quality
