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' O R es r Dewberry 1611 .:• MEMORANDUM Rather than a subset of analytes , the complete set as defined in Table 3 — Unsaturated Zone Monitoring of monitoring parameters need to be sampled except for the volatile organic compounds . This includes : • Total Dissolved Solids • pH • Specific Conductivity • Chloride • Alkalinity — Carbonate/ Bicarbonate • Nitrate — Nitrogen • Sulfate • Calcium • Magnesium • Potassium • Sodium • Iron • Barium • Strontium • Aluminum • Manganese • Boron Dewberry amends Appendix C to include sample analysis or field measurement of the above referenced seventeen constituents . All clearance sampling of engineered fill and native soil will be evaluated in comparison to this constituent group . Background , Characterization , and Verification Sampling As detailed in the Closure Plan ( Page 7 , Background Sampling ) and Appendix C — Sampling and Analysis Plan of the Closure Plan , Dewberry initially recommended background concentrations of indicator parameters be determined by collecting representative samples of fill soil used to construct the outer berm of the impoundments . These background fill soil samples were to be collected , analyzed , and evaluated prior to the start of clean closure activities . ( Page 1 , Section 2 . 1 ) . In particular, background soil results will be evaluated to identify constituents that are naturally occurring in the soil or are attributable to factors not related to the release of brine waste ( i . e . , nitrate impacts due to agricultural activity ) . RWQCB indicated soil samples should be sampled in such a way as to determine the potential effects to the underlying groundwater . Performing a deionized water waste extraction test ( DI -WET) meets this criteria for the engineered fill and the native soil . Dewberry amends Appendix C to perform twelve DI -WET tests to establish background concentrations for the native soils . Twelve representative samples throughout the DVI property will be analyzed to create a background data set which will then be used to verify the native soil below the impoundment has not been compromised by the brine waste ( see Attachment 1 ) . Additionally , if necessary , engineered fill samples in the berm and under the treatment building area might be evaluated for comparison purposes if clarification is necessary based on native soil and engineered fill discrepancy . In addition , the Closure Plan originally outlined a series of soil samples to characterize the engineered fill . Each soil characterization sample will now be tested using the DI -WET procedure , and the aqueous laboratory sample results will be compared to the native soil sampling results . Whereas the native soil sample results below the impoundment will be verified clean in comparison to the site background sample results , the engineered fill sample results will be verified clean in comparison to the native soil sample