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//]M"e GEOMATRIX (Geomatrix, 2003). The proposed concentration limits are presented in Table 2. These concentration limits form the objectives for the EMP and CAP. The following EMP, engineering feasibility study(EFS), and CAP comprise Simplot's corrective action work plan for the Lathrop facility. Prior to field work, a site-specific health and safety plan for the planned fieldwork will be prepared and approved by a Certified Industrial Hygienist. 5.1 EVALUATION MONITORING WORK PLAN The existing groundwater monitoring data indicate that detection monitoring wells (LP-4 through LP-6) exceed the concentration limits established for dissolved solids in the background monitoring well(LP-7). Additional groundwater characterization is necessary to assess the nature and extent of the release further downgradient(north) of the detection monitoring wells. To complete the additional groundwater characterization, Geomatrix has prepared the following EMP work plan. The first phase of the EMP consists of exploratory borings and depth-discrete sampling of groundwater from the water table, shallow zone, and intermediate zone at locations north and west of the lined ponds to evaluate dissolved solids concentrations (Phase I EMP). If these depth-discrete samples characterize the nature and extent of the dissolved solids release(s), the second phase of the EMP will be unnecessary (Phase II EMP). However, if the depth-discrete samples do not fully characterize the nature and extent of the dissolved solids release(s), Simplot will propose a second phase of the EMP expected to consist of sampling some of Occidental's monitoring and extraction wells in the shallow, intermediate, and deep zones for dissolved solids analyses. The proposed EMP will consist of the following: • Advancing nine exploratory borings at locations shown on Figure 2 and collecting depth-discrete groundwater samples from the water table, shallow zone, and intermediate zone for dissolved solids analysis. • Concurrent monitoring of the existing monitoring wells (LP-I through LP-7 and PWl-48) for depth to groundwater and sampling for dissolved solids analysis. For purposes of corrective action design, samples from the existing monitoring wells will also be analyzed for organic COCs. • Concurrent sampling of Simplot's supply wells (production well and backup well) for dissolved solids analysis. 1:\6000s\6741.000\Archive\6741-13.doc 6