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1 r <br /> 612 N. Buena Vista, Stockton <br /> Page 2 <br /> EHD has reviewed the Site Characterization- Second Event Report dated 22 March 2007 <br /> prepared by GeoPhase that contains the analytical results of soil and groundwater samples from <br /> five borings that were completed in March 2007 and has the following comments: <br /> 1. Four geoprobe borings were completed within 10 feet of the former 550-gallon UST <br /> - location. The fifth geoprobe boring was completed 20 feet from the former UST in a <br /> down-gradient direction, as requested by EHD. <br /> 2. The results of the 12 soil samples and the five groundwater samples collected were <br /> below detection limits for all gasoline constituents analyzed. <br /> 3. The soil and groundwater investigation appears to hav6defined the limits of the <br /> contamination to the immediate area of the former UST: <br /> 4. EHD approves the proposal to remove approximately 40 cubic yards of contaminated soil <br /> and approximately 1500 gallons of contaminated water: Soil that is not contaminated <br /> should be separated from contaminated soil and placed back in the excavation. EHD <br /> approves the off-site disposal of contaminated soil and water to an approved permitted <br /> facility. <br /> Monitoring well MW-1 located in the UST area will be destroyed/removed during soil excavation. <br /> A replacement monitoring well (MW-1 R) is proposed in the former UST location after filling the <br /> excavation with clean material/soil and proper compaction. The installation of MW-1 R in the <br /> former UST area is approved. <br /> Continued quarterly groundwater monitoring will be required until a no further action required <br /> (NFAR) letter is issued and site closure is granted. The groundwater monitoring and sampling <br /> data will be used to evaluate the effectiveness of the corrective action performed. <br /> Groundwater samples havebeen analyzed for 1,2-DCA, EDB, MTBE, TBA, DIPS, TAME, and <br /> ETBE only once. Another analysis for these contaminants to confirm the initial non-detect results <br /> must be performed. <br /> If you have any further questions regarding this matter, contact Harlin Knoll at(209)468-3442. <br /> Donna Heran, REHS, Director <br /> Environmental m ntal Health Department <br /> Harlin Knoll, Senior REHS Y Margare La orio, REKS <br /> g <br /> LOP/Site Mitigation Unit IV Program Coordinator Unit IV <br /> c: CVRWQCB—Jim Barton <br /> SWRCB, Cleanup Fund <br /> GeoPhase <br /> Donald Brand <br /> II <br />