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Apr , 4- 2000 5 : 04AM No - 1112 P. 5/11 Preliminary P,tldm8ement Assessment work PIAL] Proposed Joe Widmer Elementary School January 11,2000(Revised March 24,2000) Page-2- photorevised 1987. The site is generally bounded by Stonebridge Lane to the south and undeveloped land to the north,east and west. The site is undeveloped and is generally void of vegetative cover_ An ,Environmental .Site Assessment and Geological Hazards ,Report, dated September 3, 1999, was prepared for the site by Condor. According to information contained in the above referenced document, the site has primarily been used for agricultural purposes since at least 1937. Mr. Curtis Lewis (deceased) of Middle K Farms historically conducted farming activities at the site. According to information obtained from the San Joaquin County Agricultural Commissioner's Office, oats appear to be the primary crop cultivated at the site. A representative of the San Joaquin County Agricultural Commissioner's Office indicated that the office did not have pesticide use reports for Section 23. However, pesticide use reports and restricted materials permits submitted by Mr. Lewis for Section 1.4 (this is the Section in which Mr.Lewis resided)were obtained from the San Joaquin County Agricultural Commissioner's Office. The biformation submitted by Mr_ Lewis indicates that he cultivated oats in both Sections 14 and 23 and likely applied the same pesticides and herbicides to crops in both Sections. Sketches included in the restricted materials permits obtained from the San Joaquin County Agricultural Commissioner's Office indicate the intent to apply chemicals in the northern portion of Section 23 (the area containing the site). The information obtained from the San Joaquin County Agricultural Commissioner's Office is included in Appendix B and contains information pertaining to adjacent and nearby properties. The majority of the site has been raised and graded to its present condition by mechanically placing and compacting fill soil from adjacent properties. Condor observed grading at the site as recently as July 7, 1999. Historical use of adjacent properties, as reported by Mr. Doug Bower of Lathrop Investment LP and from review of historical aerial photographs was similar to that of the site. 2.2 SHARPE DEPOT BACKGROUND The Sharpe Depot is listed on the U-S. EPA National Priorities hist and is located approximately one- quarter mile east of the site (Figure 1, Appendix A). Remediation of groundwater containing Trichloroethylene(TCE) is currently being conducted by Radian International(Radian) in the vicinity of the Sharpe Depot. Data obtained from Radian indicate a northwesterly movement of TCE in groundwater from the southern and central areas of the Sharpe Depot towards the site. As part of the monitoring activities associated with the Sharpe )Depot, a nested set of four monitoring wells was installed at the proposed Joe Widmer site in October of 1985 to monitor groundwater quality in four distinct aquifer zones. Monitoring wells 506A, 506B, 506C, and 506D were screened from 8 to 18 feet below ground surface(bgs),40 to 50 feet bgs, 133 to 148 feet bgs, and 215 to 235 feet bgs, respectively. Arsenic was detected above the maximum contaminant level (MCL) of 0.005 milligrams per liter (mg/1) in groundwater samples collected from monitoring well 506A during quarterly sampling events conducted in 1996 at concentrations ranging from 0.256 to 0.764 mg/l. According to Radian, concentrations of arsenic and selenium are routinely detected in samples collected from monitoring wells in. the vicinity of the site at concentrations exceeding MCLS. According to the Remedial ,investigation/Feasibility Study at Sharpe Site Well Sampling Frequency ,Recommendations, prepared by Environmental Science & Engineering, Inc. and dated December 1990, monitoring well 506A was sampled 1.5 times from November 14, 1985 to June 5, 1990. TCE was detected in samples collected from this well in 10 of the 15 sampling events ranging in concentrations of 2.1 to 0.5 micrograms per liter (µg/1). According to the FFA Annual Progress Report: October 1997 through September 1998,