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Geological Technics Inc. • Page e 2 Sinclair Trucking Report-Subsurface Investigation Project No.320.2 July 21,1999 r 1.2 Monitoring Well Installation ' The monitoring well was constructed of 2-inch diameter, flush threaded, schedule 40 PVC casing, with 15 feet of 0.010-inch perforations from 10 feet down to 25 feet. A #3 Monterey Sand surrounded and extended two feet above the perforations. The well was surged using a surge block to settle the filter pack before the granular bentonite transition seal was installed and hydrated. The annulus was sealed using a neat cement grout installed with a slurry pump and tremie pipe. The wells were completed with a locking watertight cap enclosed in a flush ' mounted watertight traffic box. The annular seal was completed integral with the installation of the well box. An as-built monitoring well construction schematic is given in the boring log. After the well sealing materials had set (for a period greater than 24 hours), the well was developed (using mechanical surging and pumping methods) until a clear stream of water was obtained. All development water was containerized in 55-gallon DOT approved ' containers and stored on site. On February 19, 1999, a monitoring event was performed and samples were collected for ' analysis. Depth to groundwater averaged approximately I 1 feet below ground surface (bgs). 1.3 Soil Sampling, Geologic Logging, and Field Observation Soil samples were collected for geological and analytical evaluation at continuous coring intervals. A boring log providing sediment description using the USCS and field observations, and well construction was prepared. Soil samples were collected in 6.0-inch ' brass liners using a 2.0 inch modified California split spoon sampler. All soil samples were sealed with Teflon or aluminum foil, capped, labeled and placed in a cooler with crushed ice at 4° Celsius for transport to the laboratory following Chain of Custody protocol. ' Since only selected soil samples collected were submitted for laboratory analysis, a screening process was used to gather additional information. This screening includes field observation noting: ' ■ sediment type, especially grain size and clay content ■ moisture content ■ visible evidence of contamination, i.e., color change due to reduction of iron or ' discoloration from hydrocarbons and other pollutants ■ readings above background on a organic vapor meter(OVM) ' The OVM is a portable photo ionization detector that uses a 10.0 eV lamp to detect compounds with ionization potential below 10.0 eV (hydrocarbon range). The OVM is calibrated daily using a 100 part per million-concentration isobutylene gas standard. 1