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r YID `r WORK PLAN ADDITIONAL SOIL AND GROUNDWATER INVESTIGATION California State University Stanislaus Multi-Campus Regional Center `r October 5,2001 1.0 INTRODUCTION This work plan was prepared by Condor Earth Technologies, Inc. (Condor) to describe additional soil and groundwater investigation 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 is to further investigate the lateral and vertical extent of petroleum hydrocarbon contamination at the site and to identify potential sensitive receptors within a 2,000-foot radius of the site. The proposed work will include installation of cone penetrometer (CPT) borings, direct push borings, and monitor wells. The work will also include a sensitive receptor survey. This work plan was prepared at the request of Mr. David Rosso for the Trustees of the California State University. All work conducted by Condor will be under the supervision of a California Registered Geologist. This work plan includes project background information, a description of the field, laboratory and reporting y procedures proposed to conduct the work, and a project schedule. 2.0 PROJECT BACKGROUND V 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 (TK11) 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, TK11, and the fuel 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 ,r Health Department (PHS/EHD). The soil samples were analyzed by APCL of Chico, California. Henderson Construction prepared a brief letter repor, dated August 31, 1998, describing the UST 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 1 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 y 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), V L4 CONDOR V