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Additional Vapor aflY.undwater Monitoring Well Work Plan Raymond Investment Corporation August 4,2009 Page 7 measurements will be marked on the well collar. Well survey data will be submitted in the required electronic deliverable format to the State Water Resources Control Board UST site database (GeoTracker). 4.4 GROUNDWATER MONITORING WELL DEVELOPMENT,AND SAMPLING At least 48 hours following construction, the monitoring well will be developed by surging and bailing the groundwater in the well until the discharge water is relatively free of sediment (clear to the unaided eye). The monitoring well will be purged until the temperature, electrical conductivity, and pH of the water have stabilized. All well-development equipment will be cleaned prior to use by washing in a solution of laboratory-grade, non-phosphate detergent and deionized water, and by double rinsing with deionized water. The purge water discharged from the well during development will be containerized in 55-gallon drums, sealed, labeled, and left on Site to await disposal pending results of laboratory analyses. A groundwater sample will be collected at least 48 hours following development of each monitoring well. Prior to sample collection, the static water level in the well will be measured to the nearest 0.01- foot with a battery-operated, water level meter. A disposable bailer will be lowered into the well to check for floating product, petroleum odor, and/or sheen. If floating product is encountered, the thickness of the product will be measured,but no laboratory sample will be collected. The monitoring well will be purged using a clean, disposable bailer until the temperature, electrical conductivity, and pH of the water have stabilized. At least three casing volumes of water will be purged from the monitoring well. The water purged from the well will be containerized in 55-gallon drums and left on Site pending analytical results of the groundwater samples. The groundwater samples will be collected with a clean, disposable bailer and transferred to laboratory-supplied containers. Each container will be labeled for sample identification and placed in a cooler chilled with ice. Upon completion of the fieldwork, the groundwater samples will be delivered under chain-of-custody procedures to a California-certified laboratory for analyses. 4.5 SOIL VAPOR SAMPLING PROCEDURES Soil vapor sampling will be conducted in general accordance with the Department of Toxic Substances Control (DTSC) Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air dated February 7, 2005. Purging of the tubing will be conducted a minimum of 48 hours following installation of the probe to allow time for subsurface conditions to equilibrate. ' A soil vapor sample will be collected from the boring in a 6,000 milliliter (ml) Summa canister. The Summa canister will be individual) certified b the laboratory to be clean for the target compounds Y Y rY g p (100% canister cleaning certification). The Summa canister will be checked for vacuum seal integrity by connecting a gauge to the canister and confirming that vacuum pressure is greater than 25 inches of _p mercury. Three to five tubing volumes will be purged from the tubing. The purge volume for '/4-inch V� tubing is 4 cubic centimeters (cc) per foot o toing. Th length of the vapor probe tubing will be approximately 7.5 feet. Each purge volume will therefore be approximately 30 cc. A laboratory-supplied manifold will be used for connections during sampling, if available. A Summa canister will be used for purging if a manifold is used, or a syringe will be used if direct connections are made. Compression fittings will be used for all connections. r After the tubing has been purged, a Summa canister will be connected to the tubing and a soil vapor sample will be extracted from the boring. A flow controller will be used, in conjunction with an integrated filter and pressure gauge, for the collection of the sample to limit the flow to approximately 167 ml/minute. During sample collection, a leak-detection compound (1,1-difluoroethane)will be applied N4�.� ilk CONDOR