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Work Plan for Geotech.and Envtl.Analysis PO4-7204 SMS Briners -2- October 2004 environmental and geotechnical analysis within both ponds and sample collection for geotechnical analysis around the perimeter of both ponds(Figure 1). The proposed tasks to accomplish these goals are described in the following sections. Field Exploration We propose to use a combination of conventional drilling and an electric cone penetration testing(CPT) rig. The use of the CPT results in greater field productivity, a better representation of subsurface conditions using the CPT's continuous profile and reduced scope in the laboratory testing program as a result of the quality of the field CPT data. The CPT work will allow us to obtain good data for estimating the in-situ strength and compressibility of the native soils,and to supplement the boring data, We propose to drill a total of five(5)hollow-stem-auger borings to depths ranging from 50 to 100 feet bgs. Four (4) borings will be drilled at locations within the pond bottoms and one (1) boring will be drilled at a location within one of the existing berms. Because of access concerns in the pond bottoms, we plan to use a drill rig equipped with balloon tires to decrease ground contact pressures relative to a conventional drill rig. Three of the borings in the pond bottoms will be advanced to a depth of 50 feet bgs. The remaining two borings will be advanced to depths of 100 feet bgs. We plan to advance a total of three(3)CPT soundings to depths ranging from 50 to 60 feet bgs. All three CPTs will be advanced at locations on existing berms around the evaporation ponds. One CPT will be advanced adjacent to one of the borings to provide a site-specific correlation between boring and CPT data. A Golder field engineer/geologist will maintain a log of the soil encountered in each borehole and will visually classify the materials under the direct supervision of a California Professional Engineer or Registered Geologist. The materials will be classified according to the Unified Soil Classification System. Selected bulk, disturbed and intact samples will be retrieved, sealed and transported to our laboratory for further evaluation. Samples will generally be obtained at every 5 feet or significant change of strata. The number of blows necessary to drive both a Standard Penetration Test(SPT)sampler and a California-type sampler will be recorded. The depth to groundwater,if encountered,will be measured. Samples will be collected using a thin-wall tube sampler pressed or driven inside a hollow-stem-auger to depths listed in Table 1. Disturbed soil will be removed from either end of the tube sampler, and the tube will be capped with a non-reactive material, labeled,and submitted for laboratory analysis as listed in Table 1 and discussed in the Sample Analysis section below. Upon completion of drilling activities, all borings will be grouted with bentonite and leveled to match the existing ground. The investigation-derived wastes (IDW) generated during the drilling activities will be disposed by spreading the IDW into the adjacent stabilization pond before each borehole is backfilled with bentonite. We have assumed that the drilling can be completed in 4 work days. Golder will also coordinate with San Joaquin Comity and the RWQCB to develop a required work plan and obtain a permit for drilling activities. Sample Analysis Selected samples will be analyzed for the geotechnical properties and chemical concentrations as listed in Table 1. Geotechnical analysis will consist of in-situ moisture content and dry density, grain size distribution, Atterberg limits, maximum density, consolidation, matrix suction, R-value, and unconfined triaxial testing. Environmental analysis will consist of Total Chloride and DI-WET Golder Associates N:VroponMP04'/ (SMSBdnm-Gdd rapbmlbn)\workplan rorcwnty lali-09.doc