SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

GMOMATRIX in an ice-cooled chest for subsequent delivery to the analytical laboratory, Friedman and Bruva. Inc. (F&B), of Seattle, Washington (a State-of-California certified laboratory), under Geomatrix chain-of-custody procedures. Following sampling, cement grout was placed in the boreholes from the bottom to the ground surface with a tremie pipe. Grouting was performed under the supervision of a SJC-PHS inspector. Soil cuttings are stored on-site in labeled 55-gallon steel drums pending proper disposal. 4.2 GRAB GROUNDWATER SAMPLING A grab groundwater sample was collected from boring SB—13 to assess groundwater condi- tions down-gradient (east)of the area where petroleum hydrocarbon-affected soil was ob- served. Grab groundwater samples from SB-13 were collected by lowering through the hollow stem augers a 1-inch diameter Schedule 40 polyvinyl chloride (PVC) piping consisting of blank casing and 10 feet of slotted well screen. The augers were then retracted to approximately 35 feet bgs to expose the water bearing units while maintaining a surface seal. A small-diameter bailer was lowered into the PVC piping and groundwater was decanted from the bailer into acidified 40-milliliter volatile organic analysis(VOA)vials and 1-liter amber bottles provided by the laboratory. Sample containers were labeled, sealed in plastic bags, and stored in an ice- cooled chest pending delivery to F&B under Geomatrix chain-of-custody procedures. Geomatrix had proposed to collect a grab groundwater sample from boring SB-14, as part of the Amendment, in order to assess groundwater conditions downgradient to the northeast of the area where petroleum hydrocarbon-affected soil was observed. During drilling at SB-14 residual petroleum was encountered in the sail core and a grab groundwater sample was not collected. 4.3 MONITORING WELL SAMPLING On May 20, 2002, groundwater samples were collected from previously installed on-site monitoring wells MW-2,MW-3, and MW4. Prior to sampling the wells, water levels were measured and the presence of separate-phase petroleum was evaluated using a hydrocarbon- water interface probe. Wells MW-2, MW-3, and MW-4 were sampled by a Geomatrix field technician, after a mini- mum of four casing volumes of water had been removed from each well. Water-quality parameters measured and recorded during purging included pH, specific electrical conductance, I:'Dc�c Sttfe 5U00s 5Q 11.E I IRrpc�rtl5aii and fi W RcWmdoc 6