Water quality: Historic values and impact of drilling activities during FY 1988 at the reference repository location in southeastern Washington

The purpose of the Environmental Monitoring Program was to monitor the characterization activities related to the Basalt Waste Isolation Project (BWIP) at boreholes DC-24CX and DC-25CX and document any environmental impacts as a result of these activities including contamination and/or degradation of the aquifer water quality from the invasion of drilling fluids into the formation and surface contamination from the disposal of drilling fluid at the land surface. The first phase of this program involved describing the baseline water quality at the Reference Repository Location (RRL) including data for spring and surface waters, and both the unconfined and confined aquifers. The second phase involved the collection and analysis of samples collected during drilling operations at wells DC-24CX and DC-25CX. Five surface water and 25 spring sampling sites were designated for chemical and radiological background data collection for BWIP. Chemical and radiological background data from 61 wells that obtain water from the unconfined aquifers indicate that the chemistry of these aquifers is similar to the spring and surface water samples. However, some of the wells show contamination from existing operations and past operations of various facilities on the Hanford Site. These contaminants are both chemical and radiological in nature with nitratemore » as the primary chemical constituent and tritium as the major radiological constituent. 20 refs., 9 figs., 8 tabs.« less