Optimization of Constructed Treatment Wetland System for Treatment of Dissolved Phase Chlorinated Ethene Plume(ABSTRACT)

摘要

In 1998, Atlantic Richfield Company (ARC), a BP affiliated company, constructed a treatment wetland to remediate shallow groundwater impacted with chlorinated ethenes at a rural site located in the Midwest (Site). An NPDES permit with discharge standards set by the regulatory agency was issued. Optimization of the constructed treatment wetland system has resulted in ongoing successful treatment of the chlorinated ethene impacted plume and avoidance of deterioration of system performance. The Site was utilized to transport hazardous materials from approximately 1964 to 1971, including trichloroethene (TCE) and hydraulic oils. A still that was used to separate TCE and hydraulic oils was also operated at the Site. The disposal of still bottoms and other waste materials created chlorinated ethene source areas and accompanying downgradient dissolved phase impacts. The treatment wetland was constructed by lowering a portion of the surface grade which allows groundwater to infiltrate the wetland passively. A 12-foot-deep infiltration trench was constructed at the upgradient boundary to provide a preferential pathway for groundwater to the wetland, enhancing plume capture efficiency. Deep transverse trenches were created to promote mixing of water within each cell and to minimize the potential for short-circuiting.