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1 Problem Assessment Work Plan CSUS-Multi-Campus R46nal Center January 23,2043 Page-5• { f :0.01 foot and horizontal accuracy of 1.0 foot. The measuring point for water-level measurements will be 'marked on each well collar. IAt least 48 hours following construction, the monitor wells will be developed by surging and bailing the groundwater in each well until the discharge water is relatively free of sediment (clear to the unaided eye). i The monitor wells will be purged until the temperature, electrical conductivity, and pH of the water has a 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 de-ionized water, and double rinsing with de- .ionized water. The purge water discharged from the wells during development will be placed in 55,`gallon -drums, sealed, labeled, and left on-site pending results of laboratory analyses. ..Groundwater samples will be collected at least 48 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 l 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 measured. Laboratory samples will not be collected from wells that contain floating product. The monitor wells will be purged using a clean, disposable bailer or a Teflon® and stainless steel submersible pump until the temperature, electrical conductivity, and pH of the water has stabilized At least ".three casing volumes of water will be purged from each monitor well. The purged water,from each well will � °be placed in 55-gallon drums, sealed, labeled, and left on-site pending results of laboratory analyses.'` Each well will be allowed to recover to at least 80% of its pre-purge water level before sampling. However, if any of the monitor wells does not recover to at least 80% of its pre-purge water level by the end of the slay of the purge (standard workday), the monitor well will be sampled at that time and the percent recovery ;noted The groundwater samples will be collected with clean, disposable bailers or a Teflon® and stainless ' ,steel submersible pump. Each water sample will be gently drained from the bailer or filled from the pump ' discharge line at very low flow into the appropriate laboratory supplied containers. The sample containers t will be sealed, labeled, placed in a cooler chilled with ice, and delivered under chain-of-custody procedures ij to a California certified laboratory for analyses. I ,5.0 LABORATORY ANALYSES The groundwater samples collected from the borings and monitor wells will be analyzed for total petroleum 1 - hydrocarbons quantified as gasoline (TPH-G) and for total petroleum hydrocarbons:(TPH) quantified as } kerosene, diesel, and motor oil by EPA Method 8015M; for benzene, toluene, ethyl benzene, and total xylenes (BTEX) by EPA Method 8020; and for gasoline oxygenates/additives by EPA Method 8260. The gasoline oxygenates/additives include Methyl tertiary-Butyl Ether (MTBE), ethanol, tertiary-Butanol, Di- isopropyl ether (D1PE), Ethyl tertiary-Butyl Ether (ETBE), tertiary-amyl Methyl Ether (TAME), 1,2- Dibromoethane, and 1,2-Dichloroethane (1,2-DCA). The samples will be delivered under chain-of-custody i procedures to a California certified laboratory for analysis. The analytical methods and analytical detection „limits arep resented in Table 1. � � t Cw 4 t�• A CONDOR