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Margrave Property S40/ <br /> Work Plan <br /> Project No. 148.2 <br /> October 29, 1993 <br /> Page 2 <br /> On March 24, 1993 Ms. Donna Heran of the SJCPHS in correspondence <br /> recognized that the test data showed that further investigation may be <br /> required before site closure. <br /> On September 17, 1993 Mrs. Margrave authorized Geological Technics Inc. to <br /> prepare a work pian to further investigate the suspected release of petroleum <br /> hydrocarbons from the former UST. <br /> 2.0 PROPOSED INVESTIGATION <br /> 2.1 Soil Boring Installation <br /> Geological Technics Inc. proposes to install four soil borings (SB-1, 2, 3, & 4) <br /> surrounding the former UST excavation, (Figure 2). The soil boring will be <br /> drilled using a 7.25 outside diameter continuous flight hollow stem auger to a <br /> total depth to be determined but not to intercept the groundwater. Soil <br /> cuttings will be stockpiled on site and underlain and covered with 6 mil <br /> plastic sheeting. Soil samples will be collected for geological and analytical <br /> evaluation at five foot intervals. Soil samples will be collected in 6.0 inch <br /> brass liners using a 2.0 inch modified California split spoon sampler. All soil <br /> samples will be sealed with aluminum foil, capped, labeled and placed in a <br /> cooler at 4° Celsius for transport to the laboratory following Chain of Custody <br /> protocol. <br /> Because every soil sample collected will not be submitted for laboratory <br /> analysis, a screening process will be used to gather additional information <br /> through field observation noting sediment type, especially grain size and clay <br /> content; moisture content; visible evidence of contamination, i.e., color <br /> change due to reduction of iron or discoloration from hydrocarbons and other <br /> pollutants, and the readings above background on a organic vapor meter <br /> (OVM). The OVM is a field portable photo ionization detector that uses a 10.2 <br /> eV lamp to detect compounds with ionization potential below 10.2 eV <br /> (hydrocarbon range). <br /> The soil borings will be closed as follows: after the last soil sample has been <br /> collected the augers will be lifted 3 feet and 50 pounds of bentonite will be <br /> poured through the hollow stem of the augers and hydrated with clean tap <br /> water. A tremie pipe of sufficient length to reach the total depth of the boring <br /> will be installed through the center of the hollow stem augers and then the <br /> augers will be withdrawn from the hole. The borehole annulus will be closed <br />