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WORK PLAN-Monitor Well Installation ' Herman&Helen's Marina May 30, 1997 Page-7- electrical conductivity, and pH of the water have stabilized. All well-development equipment will be cleaned prior to use in each well by washing in a solution of laboratory-grade, non-phosphate detergent and hydrocarbon-free water, and double-rinsing with hydrocarbon-free water. The purge ' water discharged from the wells during development will be placed in 55-gallon drums, sealed, labeled, and left on site to await disposal pending results of laboratory analysis. 3.5 Well Collar Survey ' A survey will be conducted by a licensed professional surveyor to determine the location and relative elevation of the well collars following the installation of the monitor wells. In addition, measuring points located adjacent to the slough and irrigation canal will be surveyed in order to collect surface ' water elevation data:. The well collars and surface water measuring points will be surveyed with a vertical accuracy of 0.01 foot and horizontal accuracy of 1.0 foot. The measuring point for water- level measurements will be marked on each well collar and on a permenant structure adjacent to the ' slough and irrigation canal, respectively. The groundwater gradient and surface water elevations will be estimated using the survey information. 3.6 Groundwater Sampling ' Groundwater samples will be collected at least 24 hours following development of the monitor wells. Prior to sample collection, the static water level in each well will be measured to the nearest 0.01-foot with a battery-operated water-level meter. A disposable bailer will be lowered into each well to check ' for floating product, petroleum odors, and/or sheen. If floating product is present, the thickness will be estimated by collection of a bailer sample. Laboratory samples will not be collected from wells that contain floating product. ' The monitor wells will be purged using a clean submersible pump or bailer until the temperature, electrical conductivity, and pH of the water have stabilized. At least 3 casing volumes of water will ' be purged from each monitor well. The purged water from each well will.be containerized in a 55- gallon drum and left on site pending analytical results. Each well will be allowed to recover to at least 80% of its pre-purge water level before sampling. The groundwater samples will be collected with clean, disposable bailers. Each water sample will be gently poured from the bailer to two (2) 40-m1 glass, volatile organic analyses (VOA) vials. Each vial will be labeled for sample identification and placed in a cooler chilled with ice. Upon completion of ' the fieldwork, the water samples will be delivered under chain-of-custody procedures to GeoAnalytical Laboratories, Inc., in Modesto, California. 3.7 Chemical Analysis ' The soil and groundwater samples collected from the monitor wells will be analyzed for benzene, toluene, ethyl benzene, and total xylenes (BTEX) by EPA Method 8020 (602 for water), total petroleum hydrocarbons as gasoline (TPH-G) by Method 5030/LUFT, methyl tertiary butyl ether (MTBE) by EPA Method 8020 (602 for water), and for total extractable petroleum hydrocarbons as diesel, kerosene, and motor oil (TEPH) by Method 3550/LUFT (3510 for water). Since MTBE confirmed at the site during the previous soil and groundwater investigation, confirmation using %4i, ' s CONDOR