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1 <br /> Ms.Margaret Lagorio,SJCEHD February 2,2009 <br /> Work Plan for Collection of Soil Gas Data <br /> Joe's Travel Plaza, 15600 S.Harlan Road <br /> Lathrop,California <br /> Page 6 <br /> outer diameter steel rods. The rods, which are 4 feet in length, will be driven into the ground <br /> with the StrataprobeTm hydraulic ram. <br /> Once the rods are emplaced to a depth of 4 feet bgs at each location, the rods will be retracted <br /> thereby opening the steel drop-off tip and exposing the vapor sampling port. An inert '/s-inch <br /> tube will be threaded through the center of the probe and attached to the sampling port with a <br /> stainless steel post run fitting. The rods will be then retracted slowly until soil gas can be purged <br /> (i.e. to create a vacuum break). If no air can be purged from the subsurface at 4 feet bgs (due to <br /> presence of interstitial pore water, for instance), the rods will be emplaced 6 inches shallower <br /> (3.5, 3.0, 2.5 feet bgs, etc.) until soil gas can be purged. After rod retraction, hydrated bentonite <br /> will be placed around the collar of the drill rods to limit the potential for surface air migration <br /> down the outside of the rods. Once a twenty-minute equilibration period elapses, soil gas <br /> samples will be collected. Prior to collection of the soil gas samples, the volume of air required <br /> to completely flush the sample tubing of ambient air and to fill it with in-situ soil vapor will be <br /> calculated (based on actual tubing diameter and length used in the field at each point). Prior to <br /> sample collection, this calculated volume of air will be purged to the atmosphere using a <br /> calibrated syringe connected via an on/off valve. <br /> Following purging, soil gas at each location will be collected in one-liter SUMMA TM canisters. <br /> During filling of the canisters, the flowrate will be regulated to fill at a rate of 200 milliliters per <br /> minute (ml/min). During canister filling, a gas leak check (1,1-difluoroethane [1,1-DFA]) will <br /> be used to confirm that the sample train and probe rod were tight and leak-free. Leak detection <br /> will be achieved by spraying the outside of the sample train assembly with 1,1-DFA during <br /> sample filling. <br /> External probe parts will be cleaned of excess dirt and moisture prior to insertion. The internal <br /> inert tubing and sampling syringes will be single-use and will be discarded after each sample is <br /> collected. Following the completion of each boring, the resultant boreholes will be filled with <br /> grout and completed with an asphalt cold-patch or concrete to match the surrounding surface. <br /> Task 3: Laboratory Analyses <br /> Soil vapor samples collected during this investigation will be forwarded to AirToxics, Inc., a <br /> California state-certified analytical laboratory, and analyzed for the presence of GRO, BTEX, <br /> MTBE, 1,1-DFA, and naphthalene by EPA Modified Method TO-15 GUMS. Analyses for <br /> naphthalene (a known carcinogenic component of diesel) will be used in lieu of DRO analyses <br /> for the purposes of this screening. Additionally, the samples will be analyzed for carbon dioxide <br /> (CO2) using American Society for Testing and Materials (ASTM) Method D 1946. <br /> K:Uoe's Truck Plaza\Work Plans\Work Plan for Collection of Soil Gas Data 2-2-09.doc <br />