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Ll <br /> L11 September 2002 <br /> Dennis H. Catanyag <br /> San Joaquin County <br /> L <br /> Environmental Health Department <br /> Page 3 <br /> L <br /> results of samples obtained by Wright corroborate the integrity testing finding that no <br /> Lsignificant releases from the used oil tank occurred. <br /> PROPOSED ANGLE BORING LOCATIONS <br /> LPHS/EHD is requiring that samples of native soil beneath each end of the used oil tank be <br /> collected from angle borings despite the fact that integrity testing and investigations <br /> L performed by Wright do not indicate that a significant release of oil from the tank <br /> occurred. As shown on Figure 3, the used oil tank is located within a berm that is <br /> L congested with aboveground piping. POSDEF must disassemble process piping to create <br /> space to maneuver drilling equipment near the tank to satisfy PHS/EHD's requirement <br /> for more sampling. Further, the limited space available necessitates that the drilling <br /> equipment be specially modified so the equipment can operate in these tight confines and <br /> L <br /> that the equipment be lifted in and out of place by a crane. Plan and cross-section views <br /> of the proposed locations of angle borings S13-3 and S13-4 are shown on Figures 4 and 5, <br /> Lrespectively. <br /> PROPOSED SAMPLING PROTOCOL <br /> LA minimum of two samples of native soil below the tank's invert will be collected from <br /> each boring. As depicted on Figure 5, the two soil samples from each boring are planned <br /> to be collected at vertical depths of 7 and 8 feet bgs. However, actual soil sampling <br /> depths may vary based upon encountered field conditions. A water sample will also be <br /> obtained from one of the borings if groundwater is present during drilling. <br /> LEquipment Decontamination <br /> LDownhole equipment, including drilling and sampling equipment, will be <br /> decontaminated prior to completing each angle boring to reduce the potential for <br /> cross-contamination. Decontamination may be accomplished by either (1) steam <br /> L <br /> cleaning or(2) washing in a solution of Alconox® or equivalent non-phosphate detergent, <br /> followed by rinsing with clean water, then rinsing with distilled water. Alternatively, <br /> L unused, pre-cleaned equipment may be utilized (e.g., disposable polyethylene or Teflon <br /> bailers). <br /> LSoil Sampling and Handling <br /> Soil samples will be obtained by using a direct-push rig (e.g., Geoprobe) to drive a clean <br /> Lsplit-spoon sampler containing stainless steel or brass liners into the undisturbed native <br /> L <br />