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Project No.S8t113 4)6-M September 30, 1994 Page 4 proposed locations shown on Figure 2. The borings will be advanced utilizing a truck--mounted drill rig equipped with a minimum of 10-inch diameter hollow stem augers. Bongs GB-8 and 68.9 will be advanced using angle drilling techniques beneath the existing structure. 'Borings GB-6 through GB-11 will be drilled to a maximum depth of approximately 55 feet bgs. Borings MW-4 and MW-5 will be drilled to a maximum depth of approximately 70 feet-bgs for subsequent monitoring well installations. • Collect relatively undisturbed soil samples at five foot intervals using a split spoon sampler equipped with three 6-inch-long by 2-inch diameter brass sample tubes. The borings will be logged under the supervision of a California registered end and/or geologist utilizing the unified Sail Classification System. The sample tubes will be capped, labeled, chilled, and transported to a California-certified environmental labtratory utilizing standard chain-of-custody procedures. Perform headspace surveys on the soil samples collected usinga portable organic vapor analyzer(OVA),equipped with a photo ionization detector(PID). Headspace readings represent qualitative indicators of the presence of organic vapors in thei pore space of the soil samples collected. The-headspace readings will be recorded` on the boring logs submitted with the final report. Submit up to Air soil umpla lrrcr seri boring to the analytical laboratory for testing for TPHg and TPHd using EPA Test Meths d 8015 modified and BT$X following EPA Test Method 8020. Approximately ten soil samples will also be analyzed for MTBE following EPA,'Test Method 8o20. Quality assurance/quality control procedures will be provided during the field .exploration.activities. Theserocedures included cleansin rothe- g lin p 8/ in ` f equipment,steam cleaning augers prior to and between borings,and providing chain of dMody documentation for each soil sample transferred to the laboratory. `Cleansin rinsin of the sampling equipment will be performed prior to the . 8/ g P gP collection of each soil sample by washing the equipment with a trisodiwn phosphate solution.followed.try subsequent tap water and deionized water rinses. Soils generated red during the excavation activities will be Moate X55 g�tt�n drums .066 ing the results of the laboratory analyses and subsequent. disposal following regulatory protocol. Task IV - Installation of,V�r��;traction Wells • Install vapor extraction wells within three to five ;of the onsite borings with: detectable Petroleum hydrocarbon impacts'based on field screening. Ibe vapor extraction wells will be constructed using 44neh diameter polyvinyl chloride(PVC) using..The vapor wells will be constructed using approximately 30:feet of 01140-inch slotted scr.een PVC casing between approximately 5., - . A filter pack consisting of No. 3 Monterey sand will be trimmedd around the scan from the.