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R&B Trucking Preliminary Site Assessment Page: 8 _. 5.8 Monitoring Well Design Monitoring wells will extend to the bottom of the first saturated zone and will terminate in its lower bounding aquitard. The well will be constructed of 2-inch threaded-joint PVC pipe (schedule 40) that is perforated from the bottom of the well to about 2 feet above the water table. Number 3 sand will be used to create a filter pack that extends from the bottom of the well to 2 feet above the perforated zone. A bentonite grout(Quik Gel/Benseal mix)will be emplaced in the annular space above the filter pack by using the tremie method while the annular space above the bentonite seal will be filled with cement. The monitoring well will be secured and a surface seal obtained by cementing in a water tight well box and a locking cap. Construction of a typical monitoring well is shown in Figure 4. 5.9 Monitoring Well Development Each monitoring well will be developed before a water sample is collected. This will be accomplished by pumping with a jet pump until clear ground water is obtained and then removing an additional 5 well volumes. One well volume is equivalent to the water contained in the well casing plus that contained in the pore spaces of the filter pack. The filter pack is assumed to have 25% porosity. The extracted ground water will be stored in 55-gallon drums until it is determined if the water is contaminated. Contaminated water will be treated at a later date. 5.10 Ground Water Sampling If it has been over 24 hours since the monitoring well was developed,5 well volumes will be removed before sampling the ground water. A travel blank will be provided by the laboratory and blanks will be collected before sampling to insure bailer or pump cleanliness. Water samples will be collected by using either a polyethylene disposable bailer or a ground water pump(bladder pump). 5.11 Sample Analysis All samples will be sent to ChromaLab at the end of each sampling day. ChromaLab is a State certified laboratory for hazardous waste analysis and is located in San Ramon, California. Soil samples will be analyzed for TPH as diesel by DHS method GC/FID, BTX&E by EPA method 8020/602.