ARCHIVED REPORTS XR0007842 - Laserfiche WebLink

Home Browse Search

�5 Ms Lori Duncan Page 3 of 3 . Groundwater analytical results are sunuiiarized on Table 3 Attachment 3 contains laboratory reports and chain of custody documentation 4 0 SUMMARY Groundwater levels and the direction of gioundwater flow beneath the site were generally consistent with historical measurements An average of 0 13 feet of free product was measured in well MW3 during the reporting period A passive skimmer was installed in well MW3 on April 28, 2003 to remove free product Several VOCs were present in groundwater at levels exceeding their primary Maximum Contaminant Levels (MCLs) Benzene, 1,4-dichlorobenzene, and cis-1,2-DCE were present at levels exceeding their respective MCLs of 1 0 ppb, 5 0 ppb,and 6 0 ppb only in well MW3 (32 ppb, 6 5 ppb, and 24 ppb,respectively) TCE was present at levels exceeding its MCL of 5 0 ppb in wells MW3 (5 6 ppb) and MW7 (6 5 ppb) PCE was present at levels exceeding its MCL of 6 0 ppb in each site well except MW3 5.0 CONCLUSIONS Petroleum hydrocarbon contamination in the form of free product (oil) in well MW3, is apparent in groundwater within close proximity to the fol mer UST The contaminant plume associated with the former UST appears to be stable as evidenced by the lack of free product and/or dissolved petroleum hydrocarbon constituents in any perimeter wells PCE exceeds its MCL of 5 ppb in each site well except well MW3, which was completed at the location of the former waste oil UST However, dissolved concentrations detected in groundwater samples collected . from wells MW1, MW2 and MW4 have generally been decreasing since first sampled in December 2000 Groundwater samples collected from newly installed wells indicate that PCE is present upgradient (well MW5), downgradient(well MW6), and cross-gradient (well MW7)from the former waste oil UST The distribution of PCE in groundwater beneath the site, with the highest concentration detected in the cross-gradient well nearest the intersection of Park and El Dorado Streets, suggests that there may be an off- site source of PCE contamination in gi oundwater Please feel free to contact John Lane of Giound Zero at (209) 838-9888 if you have any questions regarding this submittal Respectfully, `��ED CSD Ground Zero Analysis,Inc rpm .JOHN P P I_.",Nc No 6795 • John P Lane N� CA Registered Geologist No 6795 >�, < OF C AL�i`` Attachments cc Mr Gary Gabbard Mr James L L Barton, RWQCB-Central Valley Region Mr Patrick Riddle, Attorney dt Law G 1GROUNi]ZEIGABBARblreports\QMR1200313QM2003 clot.