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I I„ SOIL VAPOR EXTRACTION AND AIR SPARGE FEASIBILITY EVALUATION WORK PLAN ! University Park 1252 N. Stanislaus Street Stockton, California September 15,2004 ± 1.0 INTRODUCTION This work plan was prepared by Condor Earth Technologies, Inc. (Condor) to describe the installation of soil vapor extraction (SVE) and air sparge (AS) wells at the former California State University Stanislaus Multi-Campus Regional Center (now University Park) located.at 1252 N. Stanislaus Street, Stockton, ` California (Figures 1 and 2, Appendix A). The purpose of the work is to evaluate the feasibility of using r SVE and AS methods to remove petroleum hydrocarbon contaminants from soil and groundwater'at the site. Condor prepared this work plan at the request of Mr. David Rosso, representative for the Stockton Center Site Authority(property owner). The proposed work includes the installation of three SVE wells and one AS well, performing pilot testing _ on the SVE and AS wells, and summarizing the field activities, findings, and recommendations in a 4 report. All work conducted by Condor will be performed under the supervision of a California registered w geologist. The fieldwork and reporting will be conducted in accordance with San Joaquin County Environmental Health Department (SJCEHD) and'California Regional Water Quality Control Board (CRWQCB) guidelines and requirements. This work plan includes project background information, a description of the fieldwork and laboratory analyses proposed for the SVE and AS well installations and pilot tests, and a project schedule. 2.0 SITE BACKGROUND On July 22, 1998 Henderson Construction of Stockton, California removed three underground storage f tanks (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 l I (TK 11) was reportedly a i,000- gallon capacity UST formerly containing gasoline. TKIO 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 TK 10, TK 11, 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 SJCEHD. Field observations and the laboratory analytical results of the soil samples collected from beneath the former location of TK10 indicated the presence of diesel range petroleum hydrocarbons and { the need for further subsurface investigation. On December 28 and 29, 2000 Condor conducted a limited soil and groundwater investigation utilizing { Geoprobe® direct push technology at the site. Laboratory analytical results of the soil and groundwater samples and field observations indicated that petroleum hydrocarbons were present in site soil and groundwater down to the approximate total depth of the investigation (36 feet below grade). Based on the. results of the Geoprobe investigation, Condor recommended the installation of three Cone Penetrometer (CPT) borings to investigate the site geology, three direct push borings to collect soil samples, and three Hydropunch borings to collect discrete groundwater samples at depths to be determined by the results of the CPT borings. Condor also recommended the installation of three groundwater monitoring wells to J ,ti �r 1� CONDOR