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w ADDITIONAL SOIL AND GROUNDWATER INVESTIGATION AND MONITOR WELL Lo INSTALLATION REPORT California State University Stanislaus a., Multi-Campus Regional Center 1.0 INTRODUCTION LM This report was prepared by Condor Earth Technologies, Inc. (Condor) to describe additional soil and groundwater investigation and groundwater monitor well installations conducted between November 19 and December 18, 2001 at the California State University Stanislaus (CSUS), Multi-Campus Regional Center (site) in Stockton, California. The site is located at the intersection of Aurora Street and Flora Street in the southeast portion of the campus(Figures 1 and 2,Appendix A). The purpose of the work was to further investigate the lateral and vertical extent of petroleum hydrocarbon contamination at the site. The work included advancement of four cone penetrometer (CPT) borings and four direct push borings, and the installation, development, and sampling of three shallow groundwater monitor wells. The work also included a sensitive receptor survey (SRS) to identify potential sensitive receptors within a 2,000- foot radius of the site. This report was prepared at the request of Mr. David Rosso for the Trustees of the +— California State University. All work conducted by Condor was under the supervision of a California Registered Geologist. This 4� report includes project background information, a description of the fieldwork and laboratory analytical results, conclusions, and recommendations. 40 Now, 2.0 PROJECT BACKGROUND The site contained three underground storage tanks (USTs) associated with past uses of the site. On July 22, 1998, Henderson Construction of Stockton, California removed all three USTs from the site, each from a separate excavation. A fuel dispenser island was also removed. 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 (TKI1) was reportedly a 1,000-gallon capacity UST formerly containing gasoline. TK10 and TK11 were located adjacent to the north and south end, respectively, of the former fuel dispenser island. TK6 was located approximately 100 feet southeast of TK10, TKl1, and the fuel w dispenser island. On July 23, 1998, a Condor representative was on-site to collect soil samples from the excavations under the direction of Ms. Letitia Briggs of the San Joaquin County Public Health Service/Environmental Health Department (PHS/EHD). The soil samples were analyzed by APCL of Chico, California. Henderson Construction prepared a brief letter report, dated August 31, 1998, describing the UST r removal activities, soil sampling activities, and laboratory analytical results of the soil samples. Field observations and the laboratory analytical results of the soil samples indicated that further subsurface investigation of the TK6 and TKI I excavations was not necessary. Field observations and the laboratory analytical results of the soil samples collected from beneath the former location of TK10, however, indicated the presence of diesel range petroleum hydrocarbons. In a letter dated April 28, 2000, the PHS/EHD requested the submittal of a work plan to investigate the lateral and vertical extent of contamination at the site. At the request of CSUS, Condor subsequently prepared and submitted the Work Plan for Soil and Groundwater Sampling by Direct Push (Geoprobe), > dated June 21, 2000. In a letter dated July 7, 2000,Ms. Carol Oz of the PHS/EHD approved the work pl 4M i CONDOR L