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Project No. 58080-06-02 <br /> September 30, 1994 i <br />` Page 4 <br /> proposed locations shown on Figure 2. Thel borings will be advanced utilizing a <br /> truck mounted drill rig equipped with a minimum of 10-inch diameter hollow stem <br /> augers. Barings GB-8 and GB-9 will be advanced using angle. drilling.techniques <br /> benea* the existing structure.., Borings GB-6 through GB 11 will be drilled to.: <br /> c maximum depth of approximately 55 feet bgs. Borings 1ti1W 4 and MW-5 wiEl be <br /> I drilled to a maximum depth of approximately 10 feet bgs for subsequent monitoring <br /> well installations: <br /> 64eat celativeiy undisturbed soil samples at five foot intervals tYsing a split�spaon. <br /> I sampler equipped with three 6-inch-long by 2-inch diameter brass.sample.tubes. ' e <br /> •` 47k1a lJs • . s ..... <br /> gs' ill be logged under the supervision,of A:104: <br /> fornta registered engineer <br /> and/ar geologist utilizing the Unified Sail Classification System: The sample:tubes <br /> E wll be capped, labeled; chilled, :and transported to a Califirnia-certified <br /> environmental laboratory utilizing standard cli-ain-of-custody procedures: <br /> I Perform headspace isurvey&on the soil samplas collected usingg a portable organic <br /> vapor analyzer(OVA},equipped with a photo ionization detector{PIIS}. Headspace <br /> readings represent qualitative indicators of & presence of organic vapors in the <br /> pore space of the soil samples collected. The beadspace;readings will be recorded <br /> an the boring logs submitted with the;final re0ort. <br /> ^, <br /> Submit up to,four soil samiples per sail boring toi the analytical laboratory for testing. <br /> for TPHg and TPHd using EPA Test Method?8015 modified and BTEX following <br /> EPA Test Method 8020. Approximately ten sail samples will also be analyzed for <br /> tvMTBEfollowing EPA Test Mtho8020. <br /> 4 ed ,;i <br /> • Quality assurance/quality control procedures will be provided during the field <br /> exploration activities. These procedures included cleansing/rinsing of the sampling <br /> equipment,steam cleaning augers prior to and between borings,and providing chain- <br /> of-custody <br /> harof-custody documentation for each soil sample transferred to the laboratory. ; <br /> trieansing/rinsing of the sampling equipmer t will be performed prior to the f <br /> collection of each soil sample by washing the equipment with a trisodium phosphate <br /> solution followed by subsequent tap water and!deionized water rinses. <br /> ij r,, M1 <br /> • Soils generated 4u6ng the excavation activities with be stored onsite;in 55 galloh <br /> drurrms pending the results of the laboratory; analyses and subsequent disposal I <br /> fallowing regulatory protocol. si � <br /> I� f <br /> Task IV- Znstaitatign o %Wr 1✓xtraction. Wells <br /> Install vapor extraction wells within three to five of the onsite borings with I <br /> detectable petroleum hydrocarbon impacts based on field screening: `The vapor <br /> extraction wells will lie constructed using 4-inch diameter polyvinyl chEoride�p`Vic. <br /> Ca. sing: The vapor wells will be constructed using approximately 30 feet of 0.040=inch <br /> slotted screen PVC casing between approximately 15 and. 45 bgs: A filter pack <br /> consisting of No. 3 Monterey<sand will be trimmed around the screen from the <br /> ma <br /> 1� <br />