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U <br /> Ms.. Margaret Lagorio, Supervising REHS Page 5 <br /> San Joaquin County Environmental Health Department <br /> October 11, 2004 <br /> i1 <br /> groundwater samples will be collected from the other.The third boring will be advanced on site to <br /> approximately 100 feet bgs for the purpose of constructing a 2-inch-diameter groundwater monitoring <br /> well.First groundwater at the site is expected between approximately 56 to 65 feet bgs.Proposed boring <br /> locations are presented on Figure 2. <br /> During the drilling of each boring,a URS geologist will collect samples of the subsurface soils at 10 <br /> foot intervals beginning at 10 feet bgs.A portion of each sample will be used for lithologic logging and <br /> for headspace screening with a PID. A portion of each sample will also be retained and submitted to the <br /> laboratory for possible analysis. Subsurface lithology will be logged by the geologist according to the <br /> Unified Soil Classification System. <br /> Each soil sample retained for possible chemical analysis will be collected in brass liners,capped with <br /> Teflon tape and plastic end caps, labeled,and placed in a cooler on ice for delivery to a California <br /> certified laboratory under chain of custody. Soil samples showing visible staining or elevated PID <br /> readings will be selected for laboratory analysis.If staining or elevated PID readings are not <br /> encountered, the sample collected in the capillary fringe will be analyzed. All selected samples will be <br /> analyzed for GRO by EPA Method 8015B (preparation EPA Method 5030); and BTEX,MtBE,TBA, <br /> DIPE,ETBE,TAME, 1,2-DCA, and EDB by EPA Method 8260B (preparation EPA Method 5030). <br /> l.. Groundwater Grab Sampling <br /> A groundwater grab sample will be collected from first encountered groundwater in the soil boring <br /> advanced on Lodi Avenue using a new disposable bailer.The sample will be analyzed for GRO by EPA <br /> Method 801513; and BTEX,MtBE,TBA,TAME,DIPE,EtBE, 1,2-DCA, and EDB by EPA Method <br /> 8260B. Analytical data will be uploaded into GeoTracker. <br /> Shallow and Deep Monitoring Well Installation <br /> Both monitoring wells will be constructed from 2-inch-inside-diameter, Schedule 40, flush-threaded <br /> PVC well casing. A Monterey No. 3 silica sand filter pack will be installed from the bottom of each <br /> boring to 2 feet above the each screen.A 3-foot bentonite seal will be placed above the sand packs and <br /> neat cement will be used to seal the remaining annular space to the surface. A locking well cap will be <br /> placed on the top of each casing and the surface will be completed with a traffic-rated,flush-mounted <br /> well box. A URS geologist will direct completion of the wells and completion details will be presented <br /> on boring logs. <br /> The shallow monitoring well will be constructed in the borehole advanced on the east side of Cherokee <br /> Lane.Fifteen feet of 0.020-inch machine-slotted well screen will be set from 5 feet above to 10 feet <br /> below first encountered groundwater. <br /> The deep groundwater monitoring well will be constructed in the on-site deep borehole.Five feet of <br /> 0.020-inch machine-slotted well screen will be set from approximately 95 to 100 feet bgs The exact <br /> L screen interval will be determined in the field by a URS geologist. <br /> K:\Wprocess\15 BP ARCO\00760\2004 Assessment\760 site assessment report with workplan V2 04.doc <br />