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Dayne L. Frary, R.G., has managed this project since the April 1994 and as a consultant since December 1996. The Problem Assessment Report was prepared (dated August 8, 1995) during tenure as manager of the Merced office of W.W. Irwin, Inc. Project Status Reports of Groundwater Monitoring for the Third and Fourth Quarters of 1996 were prepared following field work by Horizon Environmental, Inc. (D.L. Frary, R.G., Project Manager). The Problem Assessment Report, as well as all others regarding the project, was accepted by the SJCEHD. The latest groundwater conditions and updated tables are included from portions of the Project Status Report of Groundwater Monitoring for the First Quarter of 1997 (Dayne L. Frary, R.G.; February 19, 1997). Residual Impaction to Soil The overexcavation of the former tank pit was conducted by W.W. Irwin, Inc. on July 20, 1993. Approximately 260 cubic yards of soil were removed from the pit and stockpiled. Less than 6 mg/Kg of benzene were detected in one floor sample collected by backhoe at the south end of the pit (see the Site Map-Figure 2, and Table A). It is my understanding that a representative of the U.S. Army Corps of Engineers was Onsite for most of the day and ultimately ordered cessation of activities in order to minimize danger to levee integrity. The pit was fenced and later backfilled in May 1994 after the stockpiled soil was re-sampled; no gasoline components were detected. Groundwater Conditions The source of the groundwater underlying the site is Fourteen Mile Slough. Only one well, MW-6, has ever yielded water samples which have exhibited TPH-gasoline exceeding 100 µg/L and benzene levels exceeding the State MCL. This well is approximately 100 feet north of the former UST location (see Table 2 - Analytical Results. While minor concentrations may have been transported beneath the condominium complex, the plume was defined in a relatively small area including MW-6 and the cemented location of hydropunch HP-9. Further drilling to the east is not possible because development includes a somewhat steep embankment on the immediate west side of the complex that is inaccessible to a mobile rig. Groundwater was last monitored on January 22, 1997. The flow direction was approximately N811E along a gradient of 0.018. It has been easterly (away from the Slough) on every monitoring occasion. As listed in Table 3, TPH-g was reported in the sample collected from MW-6 at 2458 gg/L and benzene was reported at 374 µg/L. The lowest benzene concentration was reported at 66 gg/L for the sample collected on January 16, 1996. The highest benzene concentration was reported at 374 µg/L for the sample collected on January 22, 1997. The differences in TPH-g and BTEX concentrations from one quarterly event to another may be influenced by delta tides (listed in Table 2) and seasonal weather, depending on rainfall event intensity and amount necessary to raise the water table during wetter months. MTBE was not detected in the sample collected from MW-6 on March 18, 1996. It has not been requested for analysis since that time. DAYNE L. FRARY,GEOLOGIST 0897-012-2 2