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r Geological Technics Incc..'� Page 2 Fortner Moresco Property Additional Site Characterization Work Plan Project No.251.2 October 13, 1995 Since this initial assessment work the site has come under the local oversight program (LOP). In early September 1995 the SJCPHSEHD responded to the May 12, 1995 report and directed that a work pian proposing further investigation be submitted by September 15, 1995. Due to the very short notice Mr. McGranahan requested a 30 day extension for the due date for the work plan. 2.0 PROPOSED INVESTIGATION To further investigate the vertical and lateral extent of soil impacted with gasoline range petroleum hydrocarbons, Geological Technics Inc. proposes to advance one (1) soil boring to the north and install one (1) groundwater monitoring well through the suspected the point of release (Figure 2 Site Map). Although it has been demonstrated that an approximate 40 foot buffer of "clean" sediments exist between the deepest detected contamination and the groundwater, we recommend that a single well be installed through the suspected point of release. Data obtained from this well will provide conclusive evidence of the condition of the groundwater before, during and after remedial action. 2.1 Soil Boring Installation Prior to commencing work soil boring/monitoring well permits will be secured and the SJCPHSEHD will be notified 48 hours in advance. The subsurface will be cleared of underground utilities by notifying Underground Service Alert. In all cases, any boring will be extended to a depth of twenty feet past the last field evidence of contamination or until it intercepts groundwater. The expected depth- to-groundwater in this area is approximately 90 feet below grade, based on information from the 1985 San Joaquin County Flood Control Map, Lines of Equal Depth to Water in Wells. The boreholes will be closed by installing a granular bentonite plug approximately 2 feet thick. This will be hydrated with tap water. A neat cement grout containing <4% bentonite by weight will be pumped to grade, using a grout pump and tremie pipe. Clean soil cutting will be added to the existing stockpile and obviously contaminated soil cuttings may be underlain and covered with plastic and segregated from the existing stockpile or containerized in D.O.T. approved 55 gallon steel drums.