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PRELIMINARY INVESTIGATION AND EVALUATION REPORT California State University Stanislaus Multi-Campus Regional Center 1.0 INTRODUCTION This report was prepared by Condor Earth Technologies, Inc. (Condor) to describe soil and groundwater investigation utilizing Geoprobe® direct push technology conducted at the California State University Stanislaus (CSUS), Multi-Campus Regional Center in Stockton, California, on December 28 and 29, 2000. The site is located at the intersection of Aurora Street and Flora Street in the southeast portion of the campus (Figures I and 2, Appendix A). The purpose of the limited subsurface investigation was to evaluate the potential for petroleum hydrocarbon contamination in soil and/or groundwater related to an underground storage tank(UST) formerly located at the site. All work conducted by Condor was under the supervision of a California Registered Geologist. This report includes project background information, a description of the fieldwork and laboratory analytical results, conclusions, and recommendations. This report was prepared under contract with Trustees of the California State University. 2.0 PROJECT BACKGROUND The site contained three USTs associated with past uses of the site. On July 22, 1998, Henderson Construction of Stockton, California removed the three USTs from the site, each from a separate L. excavation. Tank 6 (TK6) reportedly contained fuel oil for a generator room. Tank 10 (TK10) was reportedly a 10,000-gallon capacity UST formerly containing diesel fuel. Tank 11 (TK1I) was reportedly a 1,000-gallon capacity UST formerly containing gasoline. TK10 and TK1 I were located adjacent to the north and south end, respectively, of a fuel dispenser island. TK6 was located approximately 100 feet i' southeast of TK10 and TKI1. On July 23, 1998, a Condor representative was on site to collect soil samples under the direction of Ms. Letitia Briggs of the San Joaquin County Public Health Services Environmental Health Department (PHS/EHD). The soil samples were analyzed by APCL of Chico, rV California. Henderson Construction prepared a brief letter report, dated August 31, 1.998, describing the UST removal activities, soil sampling activities; and laboratory analytical results of the soil samples. L, Field observations and the laboratory analytical results of the soil samples indicated that further subsurface investigation of the TK6 and TK1 1 excavations was not necessary. Field observations and the laboratory analytical results of the soil samples collected from beneath the former location of TKIO, however, indicated the presence of diesel range petroleum hydrocarbons_ In a letter dated April 28, 2000, the San Joaquin County PHS/EHD requested the submittal of a work plan to investigate the lateral and vertical extent of contamination at the site. Condor prepared and submitted the Work Plan for Soil and Groundwater Sampling by Direct Push (Geoprobe), dated June 21, 2000. Ms. Carol Oz of the San Joaquin County PHS/EHD approved the workplan in a letter to CSUS dated July 7, 2000, with the following comments and conditions: A boring permit would be obtained prior to scheduling work. Work must be completed within 90 days of the work plan approval. F A report of findings must be submitted within 60 days of work completion. Soil and groundwater samples should be analyzed for TPH-G in addition to the other analytes ++ proposed. A detection level of 0.5 ppb should be used for MTBE. Soil samples should be collected every 5 feet and every significant lithologic change. W L t� CONDOR