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{ Work Plan-Soil and Groundwater Reniediation CSUS Multi-Campus Regional Center,Stockton,CA j March 3,2003 Page 2 of 8 ' 1 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, Candor subsequently prepared and submitted the Work Plan for Soil and Groundwater Sampling by Direct Push (Geoprobe), 1 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. On December 28 and 29, 2000 Condor conducted a limited soil and groundwater investigation utilizing Geoprobe® direct push technology at the site. Condor prepared the Preliminary Investigation and Evaluation Report (PIER), dated February 7, 2001, describing the results of the work. Laboratory analytical results of the soil and groundwater samples and field observations indicated that petroleum t 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 investigation, Condor recommended the installation of three 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. The purpose of the borings was to continue with evaluation of the vertical and horizontal distribution of petroleum hydrocarbon impacted soil and groundwater at the site. Condor also recommended the installation of three groundwater monitor wells to establish the groundwater gradient and to monitor the concentrations of petroleum hydrocarbons in site groundwater. In addition, Condor recommended the completion of a sensitive receptor survey within a radius of 2,000 feet of the site to investigate the potential for receptors that may be impacted by petroleum hydrocarbons `in the groundwater. j In a letter dated April 4, 2001 to Mr. Cliff Bailey of CSUS, Ms. Dot Lofstrom of the SJCEHD concurred with the recommendations contained in the PIER. At the request of Mr. David Rosso for the Trustees of the California State University, Condor prepared the Work Plan - Additional Soil and Groundwater Investigation, dated October 5, 2001. The proposed work included the installation of.CPT borings,'direct push borings, and monitor wells and the completion of a sensitive receptor survey to identify, otential f P g � P P y . fYP ; sensitive receptors within a 2,000-foot radius of the site. The work plan was approved by Ms. Rebecca Setliff of the SJCEHD in a letter dated November 14, 2001 to Mr. Cliff Bailey of CSUS. The approved work was conducted in November and December 2001. Findings of the work were described in the Additional Soil and Groundwater Investigation and Monitor Well'Installation Report, I ated January 11, 2002, prepared by Condor. Results of the work indicated that site soil contamination was fully investigated but that groundwater contamination was not. Laboratory analytical results from soil investigations conducted by Condor at the site from December 2000 through December 2001 are shown in Figure 3, Appendix A. Groundwater contamination was present down to the total depth"of the investigation (approximately 81 feet below the ground surface) and was present at the lateral bounds of -- the area investigated, particularly to the east,in the direction of the groundwater gradient indicated by the ,initial monitoring event. The sensitive receptor survey indicated the presence of several potential ` receptors,but no wells within close proximity to the site that had not been previously destroyed. E 4M� CONDOR