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*4010, *-8104 Mr. Howard Hold October 6, 2004 Page 2 pressure,resistivity, and ultra violet induced fluorescence)to interpret the stratigraphic profile of each boring. When target sample depths are reached (based on the interpretation of the stratigraphic profile)below the depth of the water table, a push-type ground-water sampler with a sealed stainless steel screen section is pushed to the desired sampling interval. The sampler push rod is then retracted to expose the screen, allowing ground water to hydrostatically flow from the formation into the sampler(Gregg In-Situ, Inc.). When sampling is completed,the sampler is retrieved and the borehole continues to be advanced. The CPT technology encounters difficultly in advancing when gravel and cementation or hardpan are encountered. These conditions can bend and damage the CPT system. Water may be used to assist in the advancement of the borehole. Any fluids generated from the borehole advancement will be spread on the ground away from the drill site. Proposed CPT Locations Based on the historical record for ground-water flow directions and the estimated extent of ground-water quality impacts in the shallow and deep zones (LSCE, 2003), areas were identified for CPT locations in both the shallow and deep zones to characterize the lateral and vertical extent of chloride-impacted ground water. Each CPT boring will be advanced until field measurements of total dissolved solids (TDS) (field measurement of electrical conductivity (EC) will be multiplied by 0.66 to convert to an equivalent total dissolved solids concentration) approach the water quality protection standards(WQPS) for TDS. The WQPS for the shallow zone is 600 mg/L, and the WQPS for the deep zone is 460 mg/L. Historical plume boundary comparisons between TDS and chloride have been similar, therefore, field calculations of TDS concentrations which approach TDS WQPS will also be representative of chloride concentrations approaching WQPS. The proposed locations along with estimated depths for the CPT borings are presented below. While the CPT boring is being advanced, water quality samples will begin to be collected once the water table (approximately 110 to 115 feet below ground surface) is encountered. As the CPT boring is advanced to greater depths, ground water will be monitored for EC to estimate the extent of contamination. The target depths associated with each proposed boring below are only estimates and may change depending on the water quality measurements collected during the field investigation. Shallow CPT Locations • A minimum of two CPT borings located approximately 500 to 1,000 feet north to northwest of the north pond to depths of up to approximately 160 to 180 feet; • A minimum of two CPT borings located approximately 400 to 800 feet east to northeast of the northeastern corner of the north pond to depths of up to approximately 160 to 180 feet;