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'�,W/ \"NW ADDITIONAL GROUNDWATER INVESTIGATION AND REMEDIATION FEASIBILITY EVALUATION WORK PLAN University Park 1252 N. Stanislaus Street Stockton, California January 25,2005 1.0 INTRODUCTION This work plan was prepared by Condor Earth Technologies, Inc. (Condor) to describe proposed field and laboratory techniques to further investigate the lateral and vertical extent of groundwater contamination and to evaluate potential remediation technologies at the University Park Underground Storage Tank (UST) project location (site) located at 1252 N. Stanislaus Street, Stockton, California, at the intersection of Flora and Aurora Streets (Figures 1 and 2, Appendix A). The site is currently under commercial development by Grupe (current property owner). The purpose of the proposed field and laboratory procedures is to further evaluate the distribution and flow pathways of groundwater contamination and to evaluate the subsurface physical and chemical characteristics for feasibility of using ozone injection, oxygen infusion (enhanced natural attenuation), and perhaps other technologies at the site. Condor prepared this work plan at the request of Mr. David Rosso, representative for the Stockton Center Site Authority(SCSA, the former property owner). The proposed work includes the installation of three shallow monitoring wells, three deep monitoring wells, discrete depth soil sampling from the monitoring well boreholes, bench scale testing for ozone injection and enhanced bioremediation (oxygen infusion, etc.), and analyses of soil samples collected during the work for laboratory chemical and physical properties. All work conducted by Condor will be performed under the supervision of a California Certified Hydrogeologist and/or Professional Engineer. 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, bench scale testing, and laboratory analyses proposed for the groundwater investigation and remediation feasibility evaluation work, and a project schedule. 2.0 SITE BACKGROUND On July 22, 1998 Henderson Construction of Stockton,California removed 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 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