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jet l .Y' iad Ms. Carol Oz April 20, 1999 Page 2 SCOPE OF WORK Ground Zero will supervise the drilling and sampling of three soil borings in the vicinity of the former UST. One boring will be placed in the center of the former UST excavation, one boring will be placed approximately 25 feet north of the former UST, and one boring will be placed approximately 25 feet south-southeast of the former UST. The proposed boring locations are shown on Figure 3. The borings will b'e advanced to a depth of approximately 15 feet bgs or until the vertical extent of soil contaminationF has been determined, based on field observations. A drilling company licensed in the State of California will advance the borings using a truck mounted Geoprobe 5400 direct push rig. Soil samples will be collected for logging and identification purposes at 5-foot depth intervals. Samples will be collected using a 1-inch diameter core sampler lined with clear acetate sleeves. The portion of the sample to be analyzed will be immediately capped and preserved in an iced cooler at a temperature of approximately 4° Centigrade. No cuttings requiring disposal will be produced using the direct push drilling method. Borings will be backfilled to the ground surface with neat cement grout Up to four soil samples (two'.from the center boring and one from each of the perimeter borings) will be submitted for analysis of total petroleum hydrocarbons as gasoline (TPHg) using EPA method 8015 modified;-benzene, toluene, ethylbenzene, xylenes (BTEX) using EPA method 8020. In addition, one soil sample will be analyzed for gasoline oxygenate additives and tetra ethyl lead using EPA method 8260 and the'.LUFT method, respectively. Selection of soil samples for laboratory analysis will be `based on. field evidence of petroleum hydrocarbon contamination such as discoloration, odors, and FID readings, as• well as lithologic changes. If no evidence of contamination is noted in the field, samples from the capillary fringe and/or the bottom of the boring(s)will be submitted for analysis. One discrete groundwater sample will also be collected from the center boring and analyzed for the constituents listedi above. The sample will be collected by driving the sampler to the desired depth and exposing the screen to the formation. The groundwater sample will be collected using a length of polytetrafloroethylene (PTFE) tubing equipped with a stainless steel bottom check valve. The tubing will be inserted into the probe rods and pushed to the bottom of the sampler at the desired depth. The groundwater sample will be brought to the surface by gripping the top of the tubing and rapidly moving the tubing up and down creating a positive displacement effect, thereby forcing the water sample to the surface where it will be collected directly into the sample containers. All sampling and drilling equipment will be washed thoroughly with laboratory-grade detergent and E water between uses to minimize the potential for cross contamination. All fieldwork will be conducted in accordance with the Site Safety Plan included in Attachment A. e A technical report describing'field activities, analytical results, conclusions and recommendations will be submitted to Haley Flying Service Inc., Ms. Carol Oz of PHS/EHD and Mr. Mark List of the California Regional Water Quality Control Board (CRWQCB). data/groundze/ha1cy/wp0399.doc 4 i r