AGEE, Cindy, cagee@clemson.edu, MURDOCH, L., lmurdoch@clemson.edu, and BENTON, Trevor, Department of Geological Sciences, Clemson University, Clemson, SC 29634-0976

Pilot-scale tests indicated that it was possible to accelerate the biodegradation of chlorinated solvents by injecting a molasses-rich solution at 40-acre site underlain by saprolite in Greenville, South Carolina.  However, the effectiveness of this remedial technique is called into question at such a large site because of the meager rates at which the molasses solution can be injected into conventional wells penetrating the low permeability saprolite.  Hydraulic fracturing is being investigated as a possible method to increase the rate of injection and improve remedial performance.  Six hydraulic fractures were created and filled with sand at depths from 2.7 m to 13.4 m, and individual well casings were completed to each fracture.  Samples taken from four borings were used to determine the position and thickness of the sand-filled fractures, and then the borings were completed as multi-level piezometers screened in, or near, the fractures.  Slug tests were performed on both fracture-wells and piezometers intersecting fractures, and then the Bouwer and Rice method for partially penetrating wells was used to estimate the effective hydraulic conductivity, Ke, of the hydraulically fractured saprolite.  The results indicate that Ke is between 4 x 10-6 and 100 x 10-6m/s according to tests at the fracture wells, whereas it is between 0.5 x 10-6 and 1 x 10-6m/s according to tests at piezometers intersecting fractures.  In contrast, the Ke of the saprolite is approximately 10-8 m/s, according to slug tests at two nearby wells unaffected by the hydraulic fractures.   Preliminary results of injection tests give similar relative results.  They indicate that the specific capacity of conventional wells is approximately 10-7 m3/s.m; whereas it is 10-5 m3/s.m for the deepest fracture well.  These results indicate that the performance of the fracture wells is roughly two orders of magnitude greater than wells created at this site using conventional drilling and completion methods.  We plan to use more sophisticated analytical and numerical models, combined with additional field tests, to evaluate the effect of hydraulic fractures on well performance at this site in more detail.