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JOB HAZARD ANALYSIS <br /> SOIL VAPOR CONTAMINANT ASSESSMENT (SVCA) SURVEY <br /> PETROLEUM HYDROCARBON CONTAMINATED SITES <br /> DESCRIPTION OF OPERATIONS <br /> SVCA surveys are conducted at gasoline or other sitesof potential <br /> petroleum hydrocarbon contamination. The objectives are to <br /> assess the nature and extent of subsurface hydrocarbon <br /> contamination at a site, to determine the location (s) of a <br /> potential source (s) , and to develop information which will aid in <br /> the development of remedial options. <br /> An SVCA is initiated by developing a sampling scheme, either the <br /> most likely locations of petroleum losses are identified or a <br /> sampling grid is established using a tape and visual sightings . <br /> The locations of underground utilities are located visually, with <br /> the assistance of the local utility locator service, and with <br /> site blueprints. In areas covered with asphalt or concrete, a <br /> 1-inch hole is drilled through the pavement to allow access to <br /> the subsurface. A soil vapor sample is collected through a <br /> small diameter stainless steel probe which is driven to the <br /> sampling depth (typically 0 .5 to 15 feet below ground surface) <br /> with an electric hammer drill. After the probe is firmly seated, <br /> a vacuum pump is connected to the above-ground end and the system <br /> is pumped until a near-steady state is attained, generally 0 . 5 to <br /> 4 minutes . A clean, gas-tight syringe is used to collect a soil <br /> vapor sample through a teflon septum attached to the probe. Gas <br /> identification and quantification is made by a portable gas <br /> chromatograph. After sample analysis, the probe is removed with <br /> a hydraulic jack and the hole in the pavement is backfilled with <br /> soil and grout. <br /> 2 <br />