An average decrease in water levels of 50.08 feet occurred between March 2002 and June 2002. This average decrease is calculated from wells screened in separate formations and open boreholes. CSSA had 4.46 inches of rainfall between March 23, 2002 and June 17, 2002. Rainfall events were spread throughout the 3-month period with the majority of rainfall occurring in March and April 2002. Two rainfall events exceeded 1 inch per 24-hour period.

The groundwater potentiometric surface map for June 2002 indicates a variety of groundwater flow directions and large fluctuations in the potentiometric gradient. In general, the maps indicate groundwater flows in a southerly direction across the post. Two exceptions to this are areas around CS-H and CS-MW4-LGR where flow appears to be in a northerly direction. Groundwater extraction from both on- and off-post drinking water supply wells, varying rates of recharge from rain events, and differences in well completions all contribute to the complexity of the potentiometric surface at CSSA.

The Lower Glen Rose potentiometric surface map for the vicinity of Building 90, indicates a groundwater flow to the south in June 2002, which is a slight deviation from March 2002 (south-southeast). The flow direction in the Cow Creek Formation which was observed to be toward the north in December 2001 has reversed directions, to the south, in the March and June 2002 events.

MCLs for PCE, TCE, and cis-1,2-DCE were exceeded in Well CS-16 during the June 2002 monitoring event. The concentrations of PCE, TCE, and cis-1,2-DCE in CS-16 were 95 mg/L, 100 mg/L, and 100 �g/L, respectively. Historically, Well CS-16 concentrations have varied (ranging from 21 �g/L to 509 �g/L) with a generally decreasing trend observed over the last two years.

Well CS-D detections for PCE, TCE, and cis-1,2-DCE exceeded the MCL with concentrations of 110 mg/L, 150 mg/L, and 140 mg/L, respectively. TCE concentrations declined slightly over the last nine months while PCE concentrations have increased in the last three months.