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San Joaquin County September 16, 1996 Page 2 The island souls contain organic peat, and thus possess large carbon content. Chemical analysis and interprdation of data which discriminate between petroleum and other plant hydrocatbon must be done or further sampling work is pointless. Therefore, the samples will be sent to Friedman and Bruya, Inc., Environmental Chewsts(F&B)who specialize is expert hydrocarbon analysis and interpretation,and are recognized as a nationwide leader in this field. F&3 are certified by the State of California, Dept. of Health Services cion number 1727. PHS-E HD has required soil samples be collected and analyzed toinvestigate the full extent of ooI ,aminaticm evidenced at six feet bgs. In a telephone conversation subsequent to the August 28, 1996 PHS4M D letter it was determined that the first soil samples would be collected in a radius of six the ten feet fi+om the center of the tank pit. Also it was determined that if groundwater was encountered first it world be sampled and then soil samples be collected below the occurrence of groundwater. In our opinion and experience, this approach of ch mically analyzing soil firm below groundwater does not yield condasm data since the presence of contamijunits, if any, could be atb*Wod to dissolved flaw in the groundwater. Further, given the presence of organic soils the possibility of a`false positive" is real and does not add substance to this investigadom Considering this, all soil maples collected below groundwater will be collected as directed by PHS-EHD repnowtatives, Wright will submit all collected soil and groundwater samples to FdtB to be chemically analyzed as agreed upon with PHS-EHD des based upon field observations. If field logging evidence of vadose soil shows contaminant presence,these soils will be sampled and analyzed as well. EXPLORATORY BORINGS/RECONNAISSANCE SOIL SAMPLING Up to 10 same locations will be selected to obtain samples(of soil and ground water) using direct posh technology. Sample points will be located closest to the former tank pit(as the overhead cover allows for equipaetit access) first, (samples 1-4)then progressively outward as agreed upon with PHS-EFW reprafted in the field(samples 5-10). Tentatively samples will be collected at the locations (1.10)shown an Figure 3. Pcrndb will be secured prior to doing the field work. The site safety plan for the sampling event in March 1996 will be utilized for this sampling event. The sample pants will be located within ten(10)fed of the former sides of the tank pit,and advanced into the ippern groundwater where groundwater samples will be collected. Sincegroundwater flow is arbitrary,this approach will provide data from all around the pit The maldmum sampling depths are anticipated to be less than ten fed deep based upon previous site experience. The boreholes will be drilled with hand auger tools and or truck mounted =nWling ogaupment All drilling oquupunent and sampling tools will be cleaned prior to arriving, and before eaving lthe site. Thu: sample eft will be advanced to the desired sampling depth interval. The split spoon sampler will then be retrieved and dissembled, and the soil filled acetate linea will be sealed with td1on paper and plastic endcaps,labeled,logged onto chain-of-custody forms and placed in a chilled ice chest. The boreholes will be logged using the Unified Soil Classification System under the supervision of a regia*p FA Vologist using the attached Sampling Protocol. Additional lithologic information will be collected to desoft the subsurfim goolo ff The samples will be collected continuously from the surface to record intervals of potential contamination and stratigraphic features of interest. Upon completion.of the sampling and collection of information, the boreholes will be baciffilled with grout, placed from the bottom to top of the borehole.