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' Work Plan-Soil and Groundwater Investigation Haman&Helen's Marina May 30, 1995 Page-3- ' The hydropunch boreholes will be drilled using 4-inch diameter, hollow stem auger. The augers and bit will be steam cleaned before each borehole is drilled. Two (2) of the proposed ' hydropunch boreholes will be located on the levee and will be drilled to a depth of approximately 25 feet below the top of the levee or until groundwater is encountered. The remaining hydropunch ' borehole will be located below the levee and will be drilled to a depth of approximately 10 feet below the ground surface (bgs) or until groundwater is encountered. Upon completion of the drilling and sampling, the boreholes will be grouted with a cement slurry containing 3 to 5 percent bentonite. The slurry will be tremied into the borehole to avoid bridging. There is a potential for artesian flow at the proposed borehole located below the levee. If ' artesian flow is encountered, the borehole will be backfilled immediately with bentonite chips. The backfilling procedure will consist of raising the auger approximately three (3) feet off the bottom of ' the borehole and feeding the bentonite chips into the auger flights while operating the drill in reverse. The bentonite chips will be auger fed to within two (2) feet of the ground surface and the remaining borehole will be backfilled with a cement slurry containing 3 to 5 percent bentonite. Further drilling at any location where artesian flow is encountered will be aborted. ' 3.3 Soil Sampling ' Soil samples will be collected at five (5) foot intervals using a California-modified, split-spoon sampler fitted with three clean, brass liners. The soil sampling equipment (i.e., split-spoon) will be ' cleaned prior to collecting each sample. The cleaning procedures will consist of washing the sampling spoon in a solution of laboratory-grade, non-phosphate detergent and hydrocarbon-free water, and ' double-rinsing with hydrocarbon-free water. ' During the sampling, the split-spoon sampler will be driven ahead of the auger. The uppermost liner will be discarded. One sample liner will be used for geological logging and for field ' screening using an organic vapor analyzer (OVA-FID/PID) and the bottommost liner will be prepared, as described below, for shipment to the laboratory. The soil samples will be logged according to the ' LV CONDOR