ARCHIVED REPORTS_XR0007459 CASE 1

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SITE CLOSURE REPORT General Mills, Inc 2000 West Turner Road Lodi, California Delta Project No D042-708 Page 9 1 Section 9 0) that soil cleanup levels are to be based on background concentrations of the individual ' constituents unless background levels are technologically or economically infeasible It further states that where background concentrations are infeasible to achieve, soil cleanup levels are to be established to ' ensure that remaining constituents of concern will not cause ground water to exceed the applicable ground water cleanup standards or pose a threat to human health or the environment General Mills removed the tanks and excavated soil in the vicinity of the tanks Excavation is the best available technique of remediation for fuel oil impacted soil due to the low volatility of the hydrocarbons Vapor extraction and bioremediation have generally been Iess successful in remediating soil impacted with these compounds It is Delta's understanding that due to the proximity of the former tanks to existing structures, additional excavation vertically or east of the tanks, may have potentially jeopardized the adjacent building Based on the analytical data and the provided assumptions, it appears that less than 53 gallons of fuel oil may have been released Following the removal of the tanks and the excavation of soil, approximately 0 75 gallons of fuel oil may remain in soil between 15 and 18 feet bsg Additional excavation and providing ' the necessary shoring to perform the excavation to remove the estimated approximately 0 75 gallons of fuel oil contained in soil is not economically feasible General Mills initially requested site closure in September 1993 Delta prepared a Request for Site Closure Report, dated September 3, 1993 in which a General Risk Appraisal was performed for toluene, ethylbenzene, and xylenes It was assessed that the reported concentrations of these compounds in the ' analyzed soil samples do not pose a threat to ground water quality A copy of this report is included in Appendix C The Porter-Cologne Water Quality Control Act in Section 13267(b) provides that the CRWQCB may require dischargers to submit technical or monitoring reports "provided that the burden, including costs, of these reports, shall bear a reasonable relationship to the need for the reports and the benefits to be obtained from the reports " In Delta's opinion, this site should receive regulatory closure since RPT 137 S!S