MODELING ANALYSIS OF ENHANCED BIOREMEDIATION AT THE SRS SANITARY LANDFILL

WEEBER, PHILIP A., HSI GeoTrans, 1080 Holcomb Bridge Road, Bldg. 100, Suite 190, Roswell, GA 30076, NEAL D. DURANT, HSI GeoTrans, 46050 Manekin Plaza, Suite 100, Sterling VA 20166 and DENNIS G. JACKSON, SRTC – Environmental Science and Technology, 773-42A, Aiken, SC 29808

Enhanced bioremediation can be attained through the injection of select gases into the subsurface to enhance the degradation of groundwater contaminants. The Westinghouse Savannah River Company has proposed to use this technology to treat contaminants in the groundwater at the SRS sanitary landfill (SLF). The most widespread contaminants that exhibit separate and distinct plume-like characteristics are trichloroethene (TCE) and vinyl chloride (VC). Enhanced bioremediation will be accomplished with two horizontal wells; utilizing cometabolic (methanotrophic) biodegradation for TCE and aerobic biodegradation for VC. The performance of the SLF bioremediation system was predicted with the resourceful linking of three complementary numerical codes. The first model (MODFLOW) was used to establish the three-dimensional groundwater flow field in and around the SLF. A second model (TRAMPP) was used to simulate bioactive zones occurring at and above the horizontal injection wells. The TRAMPP simulations provided a prediction of the performance efficiency, as well as a prediction of the radius of influence extending from the injection wells. The third model (RT3D) was used to simulate the reactive transport of the solutes (TCE and VC) from the landfill, through the bioactive zone, and to the downgradient wetlands and Upper Three Runs Creek. The three models collectively provided a basis for predicting the flow and biological degradation of chlorinated compounds in the SLF groundwater.