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a. L- ADDITIONAL GROUNDWATER INVESTIGATION REPORT California State University Stanislaus • Multi-Campus Regional Center 1.0 INTRODUCTION Condor Earth Technologies, Inc. (Condor) prepared this report to describe the additional groundwater investigation conducted April 14 through 17, 2003, 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, Attachment A). The purpose of the work was to further investigate the lateral and vertical extent of petroleum hydrocarbon contamination in groundwater at the site. The work included advancement of five deep cone L. penetrometer (CPT)/direct push boring pairs and one shallow direct push boring (Figure 2, Attachment A). This report was prepared at the request of Mr. David Rosso for the Trustees of the California State University. V 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 LM results, discussion, and recommendations. 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 (TK 11) 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 LM 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. The soil samples were analyzed by APCL of Chico, California. Henderson Construction prepared a brief letter report, dated August 31, 1998, 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 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 SJCEHD 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 (Geoprohe), dated June 21, 2000. In a letter dated July 7, 2000, Ms. Carol Oz of the SJCEHD approved the work plan (with modifications) and requested that the work be conducted within 90 days and that a report of findings be submitted within 60 days of work completion. �'a CONDOR