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' Soil Investigation Work Plan Pilkington North America,Inc. October 27,2010 Page 3 Ongoing monitoring and recovery operations have included quarterly groundwater monitoring and ' periodic well water level measurements, product thickness measurements, and diesel-recovery operations (bailing, passive and active skimming, and application of SoakEase Socks). The recovery operations have occurred on an approximately weekly basis during the spring and summer months when fluid columns in ' the recovery wells are at levels which support active skimming operations and, monthly during fall and winter months when fluid column levels are to low to support active recovery operations. Through August 2010, a cumulative total of approximately 214 additional gallons of diesel have been recovered. ' It should be noted that the leading edge of the on-site groundwater diesel plume has remained relatively stable since monitoring began in 1996. In addition, results of the Site's ongoing monitoring and recovery ' activities indicate that the initial extent of free product diesel on groundwater, as estimated on December 12, 1996, has decreased by approximately 40%(Figure 2,Attachment A). ' 3.0 SITE GEOLOGY AND HYDROGEOLOGY The site lies within the Great Valley Geomorphic Province of California within the East San Joaquin Groundwater Subbasin. The surface and near surface sediments are comprised primarily of unconsolidated to semiconsolidated sedimentary deposits, consisting of clay, silt, sand and gravel'. Based on the results of Site investigations, local soils consist of sand and silty sand to the depths investigated at 17 feet bgs, with a thin silty clay to clayey silt horizon often present at 12 to 15 feet bgs. Groundwater ' occurs under unconfined conditions at an average depth of approximately 11 feet bgs, and has ranged from approximately 4.7 to 15.2 feet bgs. ' 4.0 DIRECT PUSH BORING FIELD PROCEDURES This section includes a description of the site preparation, direct push boring procedures, and laboratory analyses. ' 4.1 SITE PREPARATION Condor will complete the applications and obtain the required boring permits from the SJCEHD prior to ' the fieldwork. Condor will coordinate all field activities with the SJCEHD. The proposed boring locations will be marked with white paint and Underground Service Alert(USA)will be notified at least 48 hours in advance of the fieldwork to locate and identify underground utilities in the vicinity of the ' work area. Companies contacted by USA may not identify utilities past private property lines and it is the responsibility of the property owner to identify any on-site utilities in and near the work area. 4.2 DIRECT PUSH BORING PROCEDURES Prior to commencement of fieldwork, a tailgate safety meeting will be held and a site-specific Health and Safety Plan will be discussed with, and presented to, all field personnel for their signatures. Eight direct ' push borings are proposed to investigate the soil for residual diesel contamination in utility corridors, near the current fuel dispenser, and near the current 1,000 gallon diesel AST and associated above ground piping to the standby generator (Figure 2, Attachment A). All borings will be advanced utilizing direct push technology to first encountered groundwater, anticipated to be at a depth of approximately 10 to 15 feet bgs. Department of Water Resources Bulletin 118,California's Groundwater, last updated 1/20/2006. ' �.� CONDOR