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Analytical results of ground4vater sampling 15 October 1991 show that '1'1'11-g concentrations have not significantly changed from those of the previous sampling (16, 17 July). Ilydrocarbon concentration-; on the site were highest in wells V 1 and V2, located just downgradient of the former lank field, at concentrations of 200,000•tncl 19(),()(0()1tg/l_,and lowest in wells P1 and 112, with concentrations of 1,300 and 1,500 pg/L, respectively. This was the first time well V2 was sampled. Hydrocarbon concentrations increased in samples from RWl and V1, decreased in samples from PI and P2, and remained constant in samples from MW11, MW12, RW2, RW4, and V3. Wells RW3 and V4 were not sampled because of the pr, ence of LPH, IW1 had hydrocarbon concentrations comparable to the two previous samplings (30 January 1991 and 2 May 1991). 'l'lte distribution of benzene dissolved in the groundwater closely resembles that of TPH-g. 6. WATER LEVEL RECORDS AND GRADIENT DETERMINATION Depths to groundwater were measured 15 October 1991. Table I is a cumulative summary of groundwater elevations,depths to water, and product thicknesses since the start of investigations at this site. Figure 4 shows groundwater elevation isocontours for 15 October 1991. Groundwater surface elevations continue to decline and had dropped by about 0.6 feet in the period between the gaugings of 16, 17 July and 15 October 1991. Groundwater flow remains roughly toward the northeast, which is consistent with previous measurements (at a hydraulic gradient of 0.01, as on 15 October 1991). 7. STATUS Or REMEDIATION SYSTEM PERMIT APPLICATIONS A combined National Pollutant Discharge Elimination System (NPDES) and Waste Discharge permit application was submitted to the Central Valley Regional Water Quality Control Board (CVRWQCB) on 6 August 1991. A letter from the CVRWQCB dated 15 August 1991 was received acknowledging receipt of Exxon's application. Pat Leary of the CVRWQCB has indicated that there will be no action on Exxon's • ormit application until the CVRWQCB's general permit for discharge of treated groundwater has been approved by the EPA. An application for an authority to construct was submitted to the San Joaquin Air Pollution Control District (SJAPCD) on 31 July 1991. A letter from the SJAPCD dated 9 August 1991 was received acknowledging receipt of a complete application. On 25 September 1991,EA sent a letter to the SJAPCD requesting accelerated processing of Exxon's.application for an Authority to Construct after learning that there were 327 applications ahead of it. The application for the Authority to Construct is now being processed. Public -notification will be required before a permit can be issued; this process is expected to take two months. WM JR3942(1)l TRWDIJrx.3 3