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Margrave Property , Report-Soil Boring Installation Project No.148.2 January 7, 1994 Page 2 it On September 17, 1993 Mrs. Margrave authorized Geological Technics Inc. to prepare a work plan to further investigate the suspected release of petroleum hydrocarbons from the former UST. i On October 29, 1993 GTI submitted the Soil Boring. Installation Work Plan. ' accompanied by a soil boring permit ,application and appropriate fee to the SJCPHS. On December 6, 1993 Mr. Steve Sasson of.SJCPHS approved the Work r Plan as written and issued the soil boring permit. On December 16, 1993 GTI-mobilized to the site and conducted the proposed subsurface investigation. 2.0 SUBSURFACE INVESTIGATION The purpose of drilling the soil borings was to provide a better understanding of the site's vadose zone environment and how its geology may have affected the transport of petroleum hydrocarbons and its attenuation processes. More specifically it has defined the lateral and confirmed the vertical extent of soil t, contamination. 2.1 Soil Boring Installation On December 16, 1993, GTI and well drillers Osterberg and Stewart Inc. mobilized drilling equipment to the site. Hollow stem auger drilling methods with wire line coring equipment were utilized for .this investigation. Four soil borings, SB- 1, SB-2, SB-3, & SB-4, were drilled adjacent to the former UST excavation (Figure r 2). Mr. Steve Sasson of the SJCPHS was on site to observe the drilling activity. L` During drilling, soil samples were collected for geological and analytical evaluation at 5 foot intervals starting at eight feet'below ground surface to the L, total depth of 30-35 feet. Soil samples for laboratory analyses were collected in brass liners using a 2.5 inch. modified California split spoon sampler. All soil samples were sealed with aluminum foil, capped, labeled and placed in a cooler at 4° Celsius for. transport to the laboratory following Chain of Custody protocol. 2.2 Field Screening Methods C Because every soil sample collected was not submitted for laboratory analysis, a screening process was used to gather additional information through field observation noting sediment type, especially grain size and clay content, moisture content, visible evidence of contamination, i.e., color change due to 4�