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® Wright ® Environmental Services, Inc. Contingency Excavation of Contaminated Soil ..e 2395 East Pescadero Avenue Tracy CA 95304 209-833-0758 Fax 209-832-5152 Soil excavation would be performed in the areas shown on Figure 1, removing discovered and apparent residual contaminants interpreted to be from the subject UST's that were located in the former UST pit. The contaminated soil would be excavated and where practicable kept separate from apparently clean soil creating two soil stockpiles. The contaminant soil will be properly disposed off-site at Forward Landfill, as indicated in the Closure Permit. Soil would be removed to a depth of 5 -feet below the UST's, or as deep as practicable with the backhoe and if warranted up to the western property line and north, south and east of the UST's. The site would need to be fenced with 24-hour security during the period where excavations are open. Soil samples will be collected at 20 -foot horizontal intervals and along the sidewalls at each 5 - foot interval of vertical depth to ascertain presence or absence of contaminants. Soil samples will be collected from excavation bottom at the rate of 1 -sample per 50 square feet in addition to the four samples below the former UST location as required by the Closure Permit. Lghn. ,fnry A, nlugeg nn alLe_,,�IP_, r._,Ile,tP l isid] befit theca t� &en9l.M- li ctecl_fnc n4nmv, J fuels in the "Table #2 Minimum Verification Analyses For Underground Storage Tank Agamm witkit is. o�mt tit ft.c: ramt� As noted above, there are some limitations of using this contingency excavation approach. The presence of the aforementioned constraints and the possibility of unstable soil and subsurface utilities will limit the ultimate size of the excavation. Utilities if discovered will have to be temporarily disconnected and relocated, and the excavation will be limited in the near vicinity of the property line. Should unstable soil be discovered then sloping of the excavation side walls and limiting digging depth will have to be initiated It is Wright's opinion that the immediate removal of suspected residual contaminated soil source in the vicinity of former UST pit could result in little or no formal site assessment work being required by EHD and allow this property which is escrow to close and be inhabited. A report of the soil excavation including the quantity of soil removed chemical analysis and chain -of -custody forms and narrative of UST Closure will be prepared. Sincerely, Wright Environmental Services, Inc. c ul , / ft John Lynch' t President Cc Ms. Michelle Henry, UST Unit Christopher M. Palmer C.E.G. 1262; H.G. 246