Siting study for Test Area North potable water deep well project. FY-94 LL GPP

摘要

This study was conducted to evaluate the suitability of various locations for a new potable ground water well at Test Area North (TAN). The new well is proposed to replace two existing wells located within a trichloroethylene (TCE) plume. Several locations were evaluated using computer simulations based on the hydrogeology of the site. The modeling effort involved: (1) producing a water table map, (2) superimposing the effects of pumping the proposed new production well on the water table map using the model CAPZONE, and (3) calculating the capture zone for these wells using the GWPATH model. A three dimensional contaminant transport model was used to evaluate siting a well in a deeper horizon of the aquifer. The following scenarios were investigated: (1) placing a new well 500 ft north of the existing wells; (2) locating a well 3,000 ft northwest of the existing wells; (3) deepening one of the existing wells 100 to 150 ft to produce water from beneath an interbed that acts as a hydraulic barrier; and (4) drilling a new well about 500 ft northwest of the existing wells to produce water from beneath the interbed. The recommended new well site (fourth scenario) is northwest of the existing wells, with the well completed from 500 to 600 ft below land surface to produce water from beneath the Q-R interbed. Locating the well northwest of the existing wells places the new well out of the TCE plume and reduces the possibility of transporting contaminated water across the interbed.