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Harding Lawson Associates <br /> February 6, 1997 <br /> Ms. Margaret Lagorio <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> Page 2 <br /> PG&E GGS PEA- Field Procedures <br /> INTRODUCTION: In coordination with the RWQCB, the goal of this Preliminary Environmental <br /> Assessment(PEA)is to establish the presence or absence impacted conditions at the PG&E Gas Gathering <br /> Facilities, (re.,the presence or absence of impacted soil, impacted sail and groundwater, or impacted <br /> groundwater only at each of the sites). The definition of the vertical and lateral extent of impacted soil or <br /> groundwater is not an objective of this PEA; even at those sites with preliminary analytical data. These <br /> issues will be addressed in subsequent investigations. <br /> SOIL SAMPLING: Three to six borings at each site will be advanced to the groundwater table. The <br /> borings will be advanced with a Geoprobe direct push technique (2-inch diameter) or hollow stem auger <br /> (6-inch diameter)methods depending on local conditions. The borings will be continuously cored and <br /> samples collected at a minimum of five foot intervals. The core and soil samples will be logged under the <br /> supervision of a California registered geologist. The lithologies will be described using the Uniform Soil <br /> Classification System (USCS)and recorded along with other subjective criteria (eg., discoloration, odor, <br /> and readings from a photoionization detector(PID)) on the boring logs. Selected soil samples will be <br /> analyzed following the methods and procedures listed in the Analytical Program Section below. <br /> GROUNDWATER SAMPLING: One hydropunch-style groundwater sample will be collected from each <br /> boring. The borings will be advanced to just above groundwater, and the sampling tool will be pushed <br /> into the groundwater table approximately 5 feet. The sampling tool will then be retracted exposing about <br /> five feet of screen and the attached casing which extends to the surface. Groundwater samples will be <br /> collected using a bailer lowered into the casing to collect adequate sample volume and then carefully <br /> decanted into the appropriate sample containers. Sample containers will be checked to insure that no <br /> headspace or bubbles are present. Samples will be submitted to a state certified analytical laboratory <br /> under appropriate Chain-of Custody protocal in an iced-cooler. <br /> GROUTING BOREHOLES: Each borehole will tremie grouted to grade upon completion of groundwater <br /> sampling using a neat cement slurry. Grout will be pumped through the casing that is attached to the <br /> hydropunch drive point forcing the tip off of the casing and filling the boring from the bottom up. <br /> ANALYTICAL PROGRAM: Selected soil samples and each groundwater sample will be submitted for the <br /> following analyses: <br /> • Total Petroleum Hydrocarbons as gasoline (TPHg)using EPA Method 8015M <br /> • Benzene,Toluene, Ethylbenzene, and Total xylenes (BTEX) using EPA Method 8020 <br /> • Total Extractable Petroleum Hydrocarbons(TEPH) quantified as motor oil, diesel, and kerosene, using <br /> EPA Method 8015M <br /> • Glycols; quantified as ethylene, diethylene,triethylene, and tetraethylene using EPA Method 8015M <br /> DECONTAMINATION OF DRILLING AND SAMPLING EQUIPMENT: Drilling equipment will be steam <br /> cleaned prior to each use. Groundwater sampling equipment and soil sampling equipment will be washed <br />