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Ms Lon Duncan • May 17,2001 San Joaquin County Page 2 Then the sampler is pushed another foot to collect the sample Stainless steel sample rings, caps and Teflon are provided " "The CPT/Hydropunch holes are grouted using a support rig The grouting procedure consists of pushing a tremie pipe to the test hole termination depth Bentonite grout is then pumped under pressure as the tremae pipe is pulled from the hole, Various Regional Water Control Boards have reviewed and approved this methodology The support ng is also capable of coring through asphalt or concrete to allow for CPT penetration " The estimated cost for 5 soil borings using CPT technology for the vertical definition at depths of 60 to 150 feet in depth, is between $14,500 and $26, 000 An alternative method, less costly and preferable to the client, is the use of Geoprobe technology as proposed in the previously submitted work plan and addendum A local drilling contractor reports having success in drilling to depths of 100 feet in San Joaquin County using Geoprobe technology The drilling contractor suggests drilling two adjacent holes per sampling location, one for soil sampling, and the other for water sample collection at the proposed sample depths This will prevent possible cross contamination between sample points This procedure is less costly, estimated at under $10,000, and will allow access to the back yard to the northeast of the former underground storage tanks The bore holes will be destroyed by grouting using a tremae • pipe in a similar manner to the boring destruction method described in the CPT technology described above MJ Kloberdanz and Associates propose the installation of 5 soil borings and 5 groundwater sampling borings to 60 feet or ten feet into a competent clay or aquitard If the lateral and vertical extent of the soil and groundwater impact remains undefined, an additional addendum to the work plan describing the additional areas and depths to be investigated and the methods proposed to gain access and conduct the investigation will be submitted Soil and water samples collected in the saturated zone below the water table will be obtained from separate direct push borings Water for laboratory analysis will be sampled at five-foot intervals below the capillary fringe in all borings Soil samples will be collected above and below the saturated zone for laboratory analysis in the immediately adjacent test borings All soil and water samples collected for laboratory analysis will be analyzed for petroleum hydrocarbons by EPA Method 8015m, volatile aromatic hydrocarbons (benzene, toluene, ethyl benzene, and xylenes) by EPA Method 8020, and fuel additives and oxygenates including 1,2 dichlorethane, ethylene dibromide, ethanol, and methanol by EPA Method 8260B Regardless of the method used, the SWRCB UST Cleanup Fund will need to approve the site investigation costs before the work can proceed While use of the CPT is a clever method for this type of investigation, equipment availability is limited to select companies in the Sacramento and San Francisco Bay area We are concerned that