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0 Mr. Christopher Cochrane California Regional Water Quality Control Board March 12, 2001. Page 2 The borings for the soil sampling will be advanced to a depth of approximately 10 feet below ground surface. Soil samples will be collected at the ground surface and at depths of 2, 5, and 10 feet below ground surface. The soil samples will be logged using the Unified Soil Classification System visual-manual procedure (American Society for Testing and Materials Method D 2488). Samples of the soil underlying the ponds will be obtained and analyzed for brine constituents at a minimum of six locations as shown on Figure 2. Depth discrete samples will be obtained from the soil at the base of the ponds and at depths of 2, 5, and 10 feet below the base of the ponds by driving a 6-inch long, 2%a-inch diameter brass sampling tube into the soil. A portion of the soil sample will be analyzed for electrical conductivity(EC)in the field using a 10 to 1 saturation extract. The field EC will be used to establish a correlation to laboratory analyses of brine constituents in the soils. The brass tube and all sampling equipment will be decontaminated prior to each use by scrubbing with non-ionic detergent, and rinsed with potable water, followed by a deionized water rinse. After completion of the sampling,the boreholes will be backfilled with hydrated bentonite chips or grout. Soil cuttings and equipment decontamination water generated from the field sampling activities will be left in the bottom of the ponds. After each sample is collected, the ends of the brass tube will be covered with Teflon®film, capped with polypropylene end caps, and sealed with plastic tape. Each sample will labeled with project number, date of collection, and a sample control number. Samples will be placed in an ice-cooled chest for transport under chain-of-custody procedures to a California-certified hazardous waste laboratory. ANALYTICAL METHODS The soil samples will be analyzed by a California-certified hazardous waste laboratory for the following parameters: EC, pH, sulfate, chloride, nitrate, soluble cations (sodium, calcium and magnesium),boron, and exchangeable sodium percentage. Analyses of the constituents of concern will be performed on laboratory-prepared extracts from the soil sample using deionized water and will follow appropriate EPA methods. A laboratory familiar with agronomic soil analysis methods will test for exchangeable sodium percentage. REPORTING After receiving the analytical results of the soil samples from the laboratory, a letter-report will be prepared for submittal to the California Regional Water Quality Control Board (RWQCB). The letter will include a summary of the soil sampling field observations, laboratory data, an evaluation of the findings, and recommendations for appropriate closure of the ponds.