SITE INFORMATION AND CORRESPONDENCE

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Healy Property 9172 Thornton Road, Stockton, CA Project No. W0628.00 Page 2 Total petroleum hydrocarbons were detected at 15 parts per million (ppm) and at 3.1 ppm beneath the unleaded gasoline and leaded gasoline tanks, respectively (Table 1). No other petroleum hydrocarbon analytes were detected in these or any other sample. SITE ASSESSMENT ACTIVITIES On January 7, 1993, upon request from San Joaquin County Public Health Services, Environmental Health Division, RESNA supervised the installation of one soil boring between the former tank location and the pump island in the estimated former product line location. The boring was drilled to a depth of 35 feet below grade by Spectrum Exploration, C57 license #512268, with a six inch hollow stem auger rig (Figure 2). Soil samples were collected at five foot intervals from the surface to 35 feet deep with a 2 inch California modified split spoon sampler. Five samples were submitted for analysis to RESNA Environmental Laboratory in Fremont, California (State certificate # 1210). Samples were analyzed for benzene, toluene, ethylbenzene, xylenes(BTEX), and total petroleum hydrocarbons as gasoline (TPHG) by EPA methods 8020 and 8015, respectively. Soil samples were logged by a field geologist for soil lithology. Soil boring log SBI is included in Attachment 1. Soil samples were screened for volatile organics with a photoionization detector (OVM 580B) calibrated to the isobutylene molecule. Drill cuttings were stored on site and covered with visqueen until an appropriate disposal plan can be developed. After the completion of the boring, the boring was abandoned with neat cement by the tremmie method. During site activities the former product lines were located and removed by the site owner under the direct supervision of San Joaquin County Public Health Services, Environmental Health Division. All site activities were conducted in accordance with RESNA's Quality Assurance/Quality Control Plan and under the site specific health and safety plan ("Workscope to Assess Possible Petroleum Hydrocarbon Contamination, " December 21, 1992). RESULTS OF THE INVESTIGATION Soils encountered were well graded sands with silt from the surface to approximately 20 feet below grade, silt from 20 to 31.2 feet below grade, lean clay from 31.2 to 35 feet below grade and well graded sand from 35 to 36.5 feet. No field evidence of contamination (olfactory, visual, or photoionization detector readings) was noted during site activities. L-012293.FNL