Borehole completion data package for SWL facility wells 699-22-35 and 699-23-34B

摘要

Two groundwater monitoring wells were drilled at the Hanford Solid Waste Landfill in 1993 and 1994 in support of the WAC 173-304 groundwater monitoring program at that size. The wells, 699-22-35 and 699-23-34B, were constructed in accordance with the requirements of WAC 173-160. However, a waver was received from the Washington State Department of Ecology to complete the wells with 10.7-m (35-ft) screens to allow for the expected drop in the water table in the vicinity of the landfill. The wells, drilled with an ODEX air rotary drilling rig, were completed at depths of 54.8 m (180 ft) and 49.8 m (163.5 ft), respectively, and were completed with 4-in. stainless steel casing and continuous-wrap wire screen with a sand pack of 20-40 mesh silica sand. The wells were developed and equipped with Hydrostar sampling pumps. Sampling with the SEAMIST membrane system during drilling indicated significant quantities of carbon tetrachloride vapor to depths of at least 35.6 m (120 ft) within the vadose zone.