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Invitation to Bid. Hartmann do Setness • Stockton Platiag, Incorporated 632 South EI Dorado Strut siockton,CA 95203-3407 Page 4 • total lead analyses have a sensitivity 1,000 times greater than the TEL test method, and so this provides a slightly less valuable but far more sensitive backup h analysis TEL method should thet tetraethyl lead prove to be present but below the lirrut of detection by t also provides good data on background lead concentrations in theld native cr soils as ial the Sitcontrasted with TEL impacted soils Background lead concentrations metals plating site and is near to where local studies d �ha��e d�countpthe presence of TEL of heavy metals from past activities Such an argument data in the absence of total lead data, therefore we have included it as a target analyte Assuming that only one of these tanks has leaked, this relatively simple sampling regime should serve to categorically eliminate one tank or the other as a source candidate ,�..... The existing data supports the conclusion ----_-_-_----„-----�-_ - . that an on-site source exists for the = __-�__ ' c = -- - - - - - - observed groundwater impact Therefore a _ _ _ Q zone of soil impact exists through .-hich --�-_ ___-_ _ ---—- - - —- --- the gasoline fuel hydrocarbons moved in7-- order _ ro ° yin sY .. — — — c v — _ �o+r�_— ____ order to reach the aquifer surface It is =_-__ --__- ° _` _ _-_--___-_^__ necessary to know the size and shape of _-_—=__ -_- ° °° Q 4 - - - - - _ _ _ _ . _ this soil-bound plume in order to assess the1]1 . ------------------- W________ need for pneumatic conductivity feasibility --------------------------- testing, and to provide for confidence in the reliability of the eventual remedial ------- ------�- design Figure 2. Soil-Vapor Vertical Intercept Profiling It is believed that on or about October 23, 1990, when TKI-90 uas being tested, that a release of approximately 700 gallons of unle.adead gasoline occurred Soil vapor sampling penetrations %vill be made at locations chosen moving away from the TKI-90 location (see Figure 1) At each of these locations, soil vapor samples will be withdrawn into Tedlar sampling bags at discreet depths and tested with a photoionization detector (PID) for ionizable gases The point at which the soil vapor plume Is encountered will be registered in each penetration Within the boundaries represented by the soil vapor intercepts will be the actual soil-bound fuel saturation (Figure 2) Soil samples will be selected from either side of these intercepts for laboratory analysis with the objective being to provide analytical proof of the dimensions of the vertical soil saturation plume . Therefore, for the Source Disenmination and Soil Impact Delineation tasks, your bid should include the following