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K L E I N F E L D E R 3) From correlation of cross-sections from the well logs with field test kit groundwater sampling results of the newer wells, it appears that a silty clay/clay aquitard at the approximate interval from 50 to 60 feet has limited vertical migration of selected constituents beneath the newer wells. 4) A comparison was made of analytical laboratory results between the highest concentrations of ' selected constituents in groundwater from background well MW-5 and the four newer wells (see Table 5.3.1). Based upon this comparison, most of the selected constituents in groundwater from the newer wells were below these background levels of well MW-5. The constituents which exceeded the background levels in the newer wells was not significantly ' elevated (order of magnitude increase). 5) Three of four isocontour maps of selected constituents in groundwater from the wells in the vicinity of the lime pond area show a significant decrease of selected constituents over distance in the cross-gradient and upgradient directions. A decrease in constituent levels in the downgradient direction to the northwest was less significant. 6) Although several aquitards were noted in the newer wells, no corresponding aquitards were noted from review of wells logs of older wells (MW-1, MW-2, MW-3 and MW-5). It is unknown if this may be the result of the degree of care and precision taken in said logging. 7) Kleinfelder understands that as of the date of this report approximately 100 percent of the spent lime have been reused in the engineered fill for the proposed industrial/commercial areas of the site. According to an October 7, 1998 letter from the Regional Water Quality Control Board, the reuse of lime material as engineered fill complies with the current WDRs. ' It is Kleinfelder's opinion that after closure of the lime ponds, that groundwater concentrations of the constituents of concern in the vicinity of the former lime ponds will decrease over time. Additionally, further development over the lime pond area will help to inhibit infiltration of an constituents of concern still present in the soil. 8) Kleinfelder recommends further monitoring in the vicinity of the lime pond area to assess if pond closure and redevelopment will lead to a further decrease of constituents of concern in groundwater. On behalf of Bing Kirk of Atherton Kirk Development Company, Kleinfelder respectfully requests that the monitoring frequency be decreased from a quarterly to a semi- annual basis. 9) A copy of this report should be submitted to the San Joaquin County Public Health Services Department Environmental Health Division (PHS/EHD) and the Central Valley Office of the State of California Regional Water Quality Control Board by Atherton-Kirk for their review and consideration. On October 8th, 13th, and 28th, 1999 and May 12, 2000, Kleinfelder collected soil ' confirmation samples beneath the former lime ponds, and collected soil confirmation samples of the in-place mix (October 28th, 1999), respectively at the former Spreckels site in Manteca, California. Based on the results of the chemical analyses conducted on the ' samples analyzed, the following conclusions were detailed in Kleinfelder's report titled "Confirmation Sampling, Removal of Spent Lime Ponds, Former Spreckels Sugar Plant No. 2...." dated September 26, 2000: 1) As evidenced by the confirmation samples' concentrations, the former lime ponds have been excavated to concentrations, which are generally at or below the concentrations of the approved ' "mix." Therefore, the ponds appear adequately excavated. 2) The lime ponds have been excavated, and the spent lime primarily reused on site in the manner approved by the RWQCB. ' 20-3978-03.MN7/ST08R117 February 1,2008 0 2008 Kleinfelder Page 9 of 19