Book Description

An investigation was performed to confirm the presence, type and distribution of groundwater contamination as previously identified in the IRP Phase II, Stage 1 reconnaissance survey. The field study included geophysical surveys, construction of 10 two-inch diameter monitoring wells and nine six-inch diameter high yield wells, sampling and analysis of more than 200 groundwater samples, and multi-seasonal observation of the piezometric surfaces in the shallow aquifer. Study findings confirm two areas contaminated by weathered petroleum products. The more contaminated site appears to be contained on the base and not migrating; the second site is near the base property line and hydrocarbon contamination has been monitored at the surface of the water table outside of the base boundaries. The contamination at both sites appears to be historical in origin, and the probable sources are identified. A third area of concern is associated with low molecular weight chlorinated hydrocarbon contamination in the groundwater near the American Lake Garden Tract. No sources of these contaminants have been identified. Remedial measures can proceed in the areas of petroleum contamination. Additional investigations, however, should be conducted in the McChord AFB/American Lake Garden Tract areas to confirm the extent and characteristics of contamination and identify probable sources of pollution prior to development of remedial actions.