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Kennedy/Jenks Consultants Ms. Jo Anne Kipps, P.E. Central Valley Region California Regional Water Quality Control Board 18 March 2004 Page 2 location. First,the CPT probe is advanced to depths below ground surface (bgs) of 100 to 150 feet to record stratigraphy based on measurements of cone bearing, sleeve friction, and dynamic pore water pressure during penetration to provide a nearly continuous hydrogeologic log.The CPT data are interpreted in real time, allowing evaluation and modification of planned sampling. The CPT borings will be grouted as the CPT is advanced (using a grout collar),or pressure-grouted through tremmie pipe after the CPT is completed. Strata from which to collect groundwater samples will be selected based on the CPT results at each location, indicating coarse-grained material and coarse-grained layers. Based on well logs for nearby wells and depth to groundwater data from the California Department of Water Resources website, groundwater is expected at approximately 120 feet bgs. Perched groundwater may be encountered at shallower depths. Groundwater samples will be collected using a HydropunchTM or equivalent sampler at a location near the CPT boring. A groundwater sample is acquired at the desired sampling interval by advancing end-to-end connections of 1%inch diameter hollow push rods with a finer mounted at the tip. Once at the desired sample depth,the push rods are retracted, exposing the encased filter screen and allowing groundwater to infiltrate hydrostatically from the formation into the inlet screen. A small diameter bailer(approximately 1/2 or 3/. inch) is lowered through the push rods into the screened section for sample collection.The HydropunchTM openings will be grouted through the riser pipe on completion. No more than two samples will be collected from each location. Sample Locations The potential irrigation area under investigation first is approximately one-half square mile on relatively flat terrain in the Jepsen Webb Ranch LLC property. The 10 anticipated sampling locations are shown on the attached Figure 1. Sample locations have been based on a grid pattern to assess the groundwater characteristics across the potential Irrigation area(s)and the downgradient area. Existing information suggests that the groundwater gradient direction is west to northwest,so the proposed CPT west of the application area, if this location can be accessed, is expected to provide downgradient groundwater quality. CPT and groundwater sampling may be conducted in additional areas if warranted based on the results of the initial investigation. Sampling from locations with larger spacing will be conducted first,followed by sampling from locations spaoed closer to each other, allowing eliminations or relocation of CPT borings and sampling points during the field investigation as data is collected. Specifically, sample locations may be eliminated if the initial results are spatially and hydrogeolgically consistent or if the subsurface is too hard for the CPT probe to penetrate to groundwater. G'vs9Awtad��WAO'Ato1,WJacaoAaNGcmOertwA Wn dhAeu�laMutl�F.da .. . -----b 'd-6M 'ON SAViUSNOO S>IN3I'MAND W'd9l Ol M6 'WPA