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M SITE INVESTIGATION I 3.1 Soil Sampling - Seven six-inch soil borings were installed by LH on Navemher l6-21, 1989. Two E of the borings,drilled to depths oft"and"feet,were reamzd with a ten-Inch hollaw-stem auger and c verted into 63-foot deep monitoring walls �Hwd to q and Hwy1(zee Sec Hon 3.2 Nonitoring9round)surf cae(BS h 736 eland TB p)dr Th. M I depth of 46 feet helow the Yemafn ing horings, TOO and TBS.ed It Iwer.drilled to a depth of 3O feat. ❑i SCre to bottamaaflas each boring.re ist Proclse 6oring log tick as re shcwnoot an.figure 2'la the - OrilllnAA was conducted dry with no fluids added to the borehole or lubrication - thehenterlo£9 thelhollow-st¢m mpler at was Bused to collectgthe ssampj esPd dThe a gars poo,sampler sampler was a California modified i2,5-inch outside diameter)s011t-s equipped with clean brass tutees. The sampler was driven IA Inches Into Lhe undisturbed ground beyond the tip of the auger by a]4O-pound hamper having a 30-loch drop. The aa.Dle was then withdrawn from the auger and the tubes removed. This sampling technique was used for all horings except TH6,which was drllled usl ng continuous sampling method. The sam0ler was attached to the hollow-stem auger and advanced as part f the auger unit creating an ! holloxlmatBly 70-1mch long cele-'a ampl8. Samples were remove d unfit the Sampler { and c,.sifled u';ng the Unified Soil Classification System. A Sample.was - collected every five feet and placed In a clean glass Sar far la6aratory analysis. The split-spoon sampler was hrushad and washed with distilled water h',Zet'each _ sampling Interval. All sample tube Inserts'and drilling equipment were thoroughly cleaned with high pressure,.hot water prior to use to prevent ppotent lel cross-contamination hetwoen borings. The test horings were completely t hackfilled With a sand-cement grout miat,r IomediatelY after the samples were obtained, Groundwater was not encountered in any of the horings, with the exception of ww4 and HWS. Once removed,all samples ware wrapped,f carefully marked, a d Sdentl fl ed. The sa pl es were[hen carefully pros¢rued far analysis In accardan[e with EPA and California Department of Health Servtces(OOHS)protocol. Be Fore transport to the laboratory, samples were cooled to q degrees tel5ius'atthe slier lie and maintained at that temperature until they were recolved at the laboratory.Prior. - to'transport, the samples were logged onto a.chain•oF•custody form identifying the pralect number,sample type,container type,sample Sde,tlflcaHon,Wampler - nd data. The samples were picked up by Supperior Analytteai, Inc., here a .laboratory repreSentatlee signed the chain-of•custody farm. The samplos ware then placed Ina refrigerator until they were extracted and analyzed prior to 1 '.:•j their explratlon date. lk 3•� . A rc,.r,.nzatlan detector was used to field monitor the instrumentation petroleum hydrocarbon vapors emitted from each soil sample. The field tnstrumentat len did not replacis the analytical laboratoi;v,,testing. - - `1