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' Geulogical7ecknicrInc. • Page 2 <br /> Work Plan <br /> ' George's Service <br /> Project No.425.2 <br /> September 26,2007 <br /> On July 10, 2002, Nuel Henderson of San Joaquin County Environmental Health Division <br /> issued a letter requesting the following. This work plan addresses the requests of SCDER. <br /> ' • Analysis for natural attenuation parameters. <br /> • Further definition of the vertical extent of contamination in a down gradient direction. <br /> • Further vertical definition of contamination near the former pump island. <br /> This work plan is provided to address the requirements of July 9, 2007 correspondence form <br /> Nuel Henderson of San Joaquin County Environmental Health Division and proposes the <br /> 1 installation of two sentinel wells near the domestic well at the properties of 31488 Hwy 33 <br /> and 1600 Durham Ferry Road. <br /> 1 2.0 PROPOSED INVESTIGATION <br /> To further investigate the vertical extent of soil and groundwater impacted with gasoline <br /> range petroleum hydrocarbons, Geological Technics Inc. proposes the following work. <br /> 1. Install one (1) sentinel well near the 31488 Hwy 33 domestic well screened in the sand <br /> unit monitored by MW-106. <br /> 2. Install one (1) sentinel well between the source area and the 1600 Durham Ferry Road <br /> domestic well. Also to be monitored in the same sand unit. <br /> ' 2.1 Sentinel Monitoring Well Installation <br /> GTI proposes to install two, discretely screened, sentinel monitoring wells (SW) to a depth of <br /> approximately 35-feet bgs. These wells will target the sand and gravel layer encountered at <br /> approximately 30-35 feet bgs. One of the wells, SW-101, will be installed between MW-106 <br /> and domestic well 31448 Hwy 33. The second well, SW-102, will be installed between the <br /> source area and the 1600 Durham Ferry Road domestic well. <br /> The well borings will be drilled using an 8-inch outside diameter continuous flight hollow <br /> stem auger owned and operated by owned and operated by a licensed well driller. <br /> ' 2.1.1 Soil Sampling Procedure <br /> Soil samples will be collected at 5 foot intervals down to 20 ft bgs and then continuously <br /> from 20 to 35 ft bgs for geological and analytical evaluation. A boring log providing <br /> sediment description using the USCS and field observations will be maintained by a trained <br /> geologist working under the supervision of a registered professional geologist. <br /> ' Soil samples laboratory analysis will be collected in 6.0-inch brass liners using a 2.0-inch <br /> modified California split spoon sampler. These soil samples will be sealed with Teflon, <br /> capped with end caps, labeled and placed in a chilled cooler for transport to the laboratory <br /> 1 following Chain-of-Custody protocol. <br /> i <br /> 1 <br />