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r <br /> 7 <br /> page 2 <br /> CSU Stanilslaus <br /> Analytical results showed dissolved contaminant concentrations in MW3 to,be the <br /> highest among the monitoring well samples, at 210 µg/I TPHg, 2.8 µg/I benzene, and 1.4 <br /> µg/I toluene. Water samples from the direct push borings contained the highest <br /> contaminant concentrations in SP2.and SP3. SP2 had 2,100 µg/I TPHg, 92 µg/I <br /> benzene, 24 µg/I toluene, 320 }zg/I ethylbenzene, 170 µg/I total xylenes, and 700 µg/I <br /> total petroleum hydrocarbon as kerosene (TPHk). SP3 had the highest concentration of <br /> total petroleum hydrocarbon as motor oil (TPHmo) at 1,200 pg/I. <br /> The report recommends continued sampling and analysis of groundwater from monitor <br /> wells MW-1, MW-2, and MW-3 on a quarterly schedule. Secondly, the report <br /> recommends additional shallow and deep groundwater investigation in the down <br /> gradient direction (east)from the source area to further delineate the lateral and vertical <br /> extent of the plume. EHD agrees with these recommendations and adds that impacted <br /> groundwater must be delineated in all directions. The report also recommends over- <br /> excavating approximately 1800 cubic yards of impacted soil from the former tank site <br /> down to the saturated zone. EHD does not agree with this recommendation. According <br /> to CCR, Title 23, Division 3, Chapter 16, Underground Storage Tank Regulations the <br /> contractor shall evaluate at least two feasible remedial alternatives for cleaning up the <br /> site. A Work Plan to investigate the vertical and lateral extent of impacted groundwater <br /> and to compare at least two different, but feasible, remediation alternatives for mitigating <br /> contamination in the soil and groundwater at this site should be submitted to EHD by <br /> June 10, 2002. <br /> If you have any questions or comments please call Rebecca E. Setliff at (209) 468-3440. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> lop <br /> �a . ' HS Nuel Henderson Jr. <br /> LOP/Site Mitigatierf Unit IV Registered Geologist, Unit IV <br /> cc: Marty Hartzell, CVRWQCB <br /> Donald F. Kresse, CONDOR <br /> f.- <br />