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GeolvgicalTedmics Inc. Page 2 Valentine(Eldorado St.) Work Plan Project No.723.2 October 29,.1998 . borings indicate the presence of low to moderate levels of TPH-G to a depth of 60 feet bgs 3.4 SOIL BORING INSTALLATION Rather then-install a deep, discretely screened, monitoring well.we are proposing to install a deep soil boring, SB-101, in which SimulProbe samples will be collected. This approach is proposed because at this time the deep geology and the vertical extent of contamination,are unknown at the site. 3.1 Borehole Drilling i The borehole, SB-101 will'be located adjacent to the previous soil boring "B' The soil boring will be drilled using an 8-inch outside,,diameter, hollow stem auger, owned and operated by V&W drilling. The drilling method will be hollow-stem auger and coring will be with a modified California split spoon sampler. Soil coring will be continuously.starting at a depth of 5 feet and extending to the total depth'of the borehole. Samples for laboratory analysis will be collected using the SimulProbe sampling tool. It is proposed to drill the soil-boring approximately 10 feet beyond the last contamination observable.by field methods. Soil and pore-water samples will be collected by use of a SimulProbe sampling tool at geologically different units. '.See Section 3.2 for'SimulProbe procedure. a Upon completion of the borehole and collection of the last sample the borehole will be closed by neat cement grout containing less the 4% bentonite. The grout will be pumped, via a tremie tube, to the bottom of the hole to displace water that has collected in the hole. The surface will be capped with a concrete plug finished flush to grade. x 3.2 , Sample Collection with the SimulProbe j The SimulProbe allows a soil sample to be collected at the exact interval from which the water or soil gas sample is collected thus providing correlative information on the sorbed portion of the contaminated :zone. Furthermore the SimulProbe's design reduces the r possibility of cross contamination from shallower borehole waters. After the SimulProbe groundwater sampling tool is advanced into the saturated zone the tool is retracted to expose the screen: .The sample collection chamber is allowed to fill under ambient hydrostatic pressure. Once full the chamber'is sealed with a pneumatically actuated ` (Nz gas) solenoid valve and the apparatus is brought to the surface. The sample chamber is carefully emptied using a bottom-emptying device thus reducing the possibility of sample agitation and volatilization. Once the sample container (40-m1 VOA) is filled and capped, the bottle will be inverted, tapped, and checked for headspace bubbles. The sample container is identified and labeled with a unique designation, inserted into foam holders and placed in 1 an ice chest cooled to 4°C for transport to the laboratory. Once the borehole has extended below groundwater, pore water and soil samples will be collected at geologically significant different units using the SimulProbe. It should be noted that collection of pore water samples might not be successful in clay units'.