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Georogica! Page 3 Additional Site Characterization Work Plan Project No.724.2 July 7,20M to hydrate approximately one half-hour. A surface seal will be achieved by pumping a neat cement grout (augmented with < 4% bentonite) via a tremie tube. The well will be secured with a locking watertight cap encased in flush mounted traffic rated well box. (See Figure 3 t for a schematic of monitoring well construction) L After the well sealing materials have set (>24 hours) the wells will be developed (using L mechanical surging and pumping methods) until a clear stream of water is obtained. The well will be purged and groundwater samples collected no sooner than 48 hours after well development. All development and purge water will be containerized in 55-gallon DOT Lapproved containers and stored on site until their disposition can be arranged. L A licensed surveyor will survey the top of casing measuring point for the new well into the common elevation plane of the existing monitoring wells. 2.2 Soil Sampling Procedure L Soil samples will be collected for geological and analytical evaluation at five-foot intervals. L A boring log providing sediment description using the USCS and field observations will be maintained by a professional geologist working under the supervision of a registered geologist. Soil samples will be collected in 6.0-inch brass liners using a 2.0-inch modified L California split spoon sampler. All soil samples will be sealed with Teflon, capped with Teflon end caps, labeled and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. LBecause every soil sample collected will not be submitted for laboratory analysis, a screening process will be used to gather additional information through field observation noting Lsediment 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 L and other pollutants,and the readings above background on an organic vapor meter (OVM). The OVM is a field portable photo ionization detector that uses a 10.0 eV lamp to detect compounds with ionization potential below 10.0 eV(hydrocarbon range). 2.2.1 Laboratory Analyses- Soil Based on field screening observations, up to two soil samples from the borehole will be submitted to Sherwood Laboratories of Hilmar (State Certified Laboratory #1400) for L analysis for: • Benzene,toluene,ethylbenzene and xylene(BTEX)by EPA method 8020 L • Gasoline range petroleum hydrocarbons (TPH-Gasoline)by EPA method 5030/8015(m) • Methyl Tertiary Butyl Ether(MTBE)by EPA method 8020 with confirmation by 8260 LThe detection limits for these compounds are listed below. A Chain of Custody will be completed for all samples collected and tracked to ensure sample integrity. L