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Preliminary Site Assessment Report ' LOPEZ PROPERTY 1601 Turnpike Road, Stockton, California ' 1.0. INTRODUCTION ' At the request of Mr. Steve Dunn, Advanced GeoEnvironmental, Inc. (AGE) has prepared the enclosed Preliminary Site Assessment Report for the property located at 1601 Turnpike Road, Stockton, California. The scope of work included advancement of three, soil probe borings and ' preparation of this report. The location of the site is illustrated on Figure 1 and a plan of the site is illustrated on Figure 2. ' This report has been prepared in accordance with guidelines established by the Central Valley Regional Water Quality Control Board (CVRWQCB) for the subsurface investigation of underground storage tank (UST) sites. Site background information is provided in Appendix A. One 1,000-gallon leaded gasoline UST was removed in October 1987; the SJCEHD noted hydrocarbon odor and soil discoloration at the time of removal. Soil samples were collected at 15 ' feet below surface grade (bsg) and analyzed for gasoline, diesel, kerosene, motor oil, benzene, toluene, ethyl benzene, xylene (BTEX) and lead; the analytical results showed non-detect for all ' analytes except lead (5.5 milligrams per kilogram: mg/kg). The chain of custody was never submitted, and because of the missing documentation and the discrepancy between the SJCEHD evaluation and the analytical results the case was not closed. An Unauthorized Release Report ' (UAR)was issued by the SJCEHD in March 1994 to facilitate further site assessment. One soil boring was advanced through the former tank excavation to a depth of 15 feet bsg on ' 04 June 1996.However,the SJCEHD was notified that the sample had been lost and the site was re- sampled on 20 June 1996 at a depth of 16 feet bsg.The analytical data for the 20 June 1996 sampling indicated non-detect for gasoline, BTEX and the fuel oxygenate MTBE. The laboratory quality ' assurance procedures were questioned by the SJCEHD and resolved in December 1996.The property was given a"no further action" letter and"closed by the SJCEHD in May 1997. 2.0 PROCEDURES ' Field work was conducted in accordance with guidelines established by the CVRWQCB for the investigation of UST sites. Soil boring installation and sampling procedures for the site were outlined in Site Assessment Work Plan dated 15 December 2000, prepared by AGE and approved by the EHD by letter dated 29 December 2002.