SITE INFORMATION AND CORRESPONDENCE

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Kennedy/Jenks Consultants 2.0 FIELD INVESTIGATION 2.1 Scope Of Work This subsurface investigation was undertaken to ascertain if soil or groundwater at the Site have been impacted by the former ASTs. Investigation activities included: • Reviewing available regulatory files on properties in the vicinity of the Site with possible petroleum hydrocarbon contamination (Section 1.2). • Drilling four soil borings (K13-1 through KB-4) in the vicinity of the former ASTs. • Collecting seven soil samples and three reconnaissance groundwater samples for chemical analysis. • Analyzing the soil and groundwater samples for: TPH as: Gasoline; Kerosene; Diesel; and Motor Oil. 2.2 Drilling Of Soil Borings And Collection Of Samples Drilling and sampling were performed on 16 November 1995. Prior to drilling, a permit to 6, drill the borings was obtained from the San Joaquin County Public Health Services Department. A copy of the permit is included in Appendix A. All field activities were performed using procedures described in the Work Plan for Subsurface Investigation (Kennedy/Jenks, 1995). The Work Plan was approved by San Joaquin County prior to initiating field work at the Site. V The soil borings were drilled by Precision Sampling, Inc. of San Rafael, California (C-57 License No. 636387) under the observation of Kennedy/Jenks using hydraulic push and percussion hammer soil sampling techniques. As a precaution, the initial two feet of each boring were hand augered in the event that all underground utilities may not have been identified by the utility locator contractor. Three soil borings (KB-1, KB-2 and KB-4) were drilled to the first-encountered groundwater at the Site (between depths of approximately 19 and 22 feet bgs. Soil Boring KB-2 was terminated at a depth of approximately six feet bgs due to refusal. Pieces of concrete were observed in the shoe of the sampler at this depth. The locations of the soil borings are �+ shown on Figure 2. Subsurface soil samples were collected for lithologic descriptions and potential laboratory �.• analysis. Soil samples were continuously collected at 3-foot intervals using stainless steel sampling rods from the ground surface to the final depth of the boring. Lithologic logging was performed using the Unified Soil Classification System (USCS) Visual-Manual V Procedure. Soil conditions in each borehole were recorded on a boring log (Appendix B). Headspace measurements of soil from each sample interval were made in the field using a 16W Thermo Environmental Instruments Model 580A portable photoionization detector (PID). The response factor was set so that the instrument would read in parts per million by volume (ppm/v) as isobutylene. To prepare the soil for headspace measurement, the soil i:V ob1951950073.005rpftubsurfttext doc 3