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Regarding groundwater gradient and flow direction, Figure 3 presents an interpretation of the water level measurement data taken from all monitoring wells and converted to Mean Sea Level (MSL) elevations The groundwater gradient is approximately 0 001 feet per foot which is shallower than previous gradients observed during 1993 The flow direction is generally inward toward the site and to the east While more eastward during this quarter than in the past, the ' flow direction is consistent with the east to southeast flow direction observed during most of the previous sampling periods With the flow direction generally east, monitor well MW -3 provided groundwater quality data downgradient from the former tank site for this sample period. While moderate concentrations of benzene and TPH have been seen in this well in the past, neither have been detected during the Iast two quarters which continues to indicate there is no discernable migration from the site Because the depth to groundwater has varied significantly at the site over the history of the project, the relationship of groundwater depth to potential hydrocarbon residues in the soils has been an issue of interest Figure 4 presents a chronology of MSL water levels at monitor well MW -2 Well MW -2 has been selected to represent water levels at the site due to its central location As shown by Figure 4, the groundwater level at the site steadily rose approximately 12 feet from ' October 1992 to December 1993 It has currently reached the maximum elevation measured since routine monitoring began As the groundwater levels have been rising, it is important to note that groundwater chemical concentrations have not increased, but rather have continued to decrease This data confirms that it is unlikely that hydrocarbons are bound up in the soils of the previously saturated zone As these trends developed in the past, the data evaluation left open the slight possibility that hydrocarbons may be present but are simply not migrating However, since the most recent data shows no observable chemical concentrations in groundwater and a rising water table with a consistent gradient, the "present but not migrating" scenano has become exceedingly improbable 3.0 REMEDIAL PROGRAM STATUS As noted in the "Future Planned Activities" section of the 1st Quarter 1993 Report, continued future quarterly monitoring was anticipated to provide seasonal data on groundwater quality, depth and direction for the purposes of evaluating remedial needs The relationship between groundwater quality and depth is particularly important now that groundwater at the site has risen without producing higher chemical concentrations As concentrations have not increased and, in fact, have decreased to non-detectable concentrations this quarter, the data suggests there are no hydrocarbons remaining to remediate and that the groundwater quality at the site is no longer an environmental issue San Joaquin County EHD has asked that feasibility work be conducted toward development of ' a remedial plan for the site by April 25, 1994 Since remediation of the soil has been completed and groundwater sample results currently indicate no hydrocarbon impact to the groundwater, WESTON recommends that EHD consider rescinding the request for a final remedial plan and Proceed with closure of this site S K\RPTSUREC4QTR WP 6 Q3f'-%W