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San Joaquin County Environmental Health Department <br />Site Mitigation Program <br />8 December 2021 <br />Page 2 <br />Soil and Soil Vapor Sampling <br />The Sites Phase II ESA includes the soil and soil vapor sampling as described below. The objective of this <br />sample is to evaluate whether potential subsurface impacts from the nearby underground petroleum <br />pipeline may be affecting Site. <br />Pre-field Activities <br />The following pre-field activities will be completed prior to performing the fieldwork associated with the <br />Phase II ESA: <br />Preparing a Site-Specific Health and Safety Plan (HASP) outlining the procedures to be followed <br />during the field sampling activities. <br />Marking the Site and notifying Underground Service Alert (USA) and obtaining a USA Ticket <br />Number for the field sampling activities. <br />Procuring field and sampling equipment along with sampling canisters and coordinating with the <br />laboratory. <br />Field Activities <br />The Phase II ESA field investigation will include the following activities: <br />A private utility locator will be retained to scan for underground utilities in the vicinity of the <br />proposed soil and soil vapor sampling locations. <br />Twelve 2.25-inch diameter borings will be advanced by a California C-57 licensed driller using a <br />direct-push technology drill rig to a depth of approximately 10 feet below ground surface (bgs), <br />one boring every approximate 1,000 feet of pipeline (Figure 2). <br />One soil sample will be collected at the bottom of each boring and placed in labeled laboratory- <br />provided sample containers. The collected soil samples will be stored in a cooler with ice and <br />transported under chain-of-custody documentation to a California-certified analytical laboratory <br />for the following: <br />–Total petroleum hydrocarbons as gasoline, diesel, and motor oil (TPHg, TPHd, and <br />TPHmo) using United States Environmental Protection Agency (USEPA) Method 8015; <br />and, <br />–Volatile organic compounds (VOCs) using USEPA Method 8260. <br />Each boring will be backfilled with bentonite from 5.5 to 10 feet bgs, followed by the installation <br />of a temporary soil vapor probe within each boring: <br />–Small diameter (1/4-inch) Teflon® tubing, fitted with a filter at the bottom to prevent <br />particulate infiltration, will be placed in the boring at approximately 5 feet bgs;