SITE INFORMATION AND CORRESPONDENCE

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DDJC-Tracy East Annex CPT Groundwater Quality Assurance (Field Laboratory,October 2001) A total of 22 field samples and four duplicate field groundwater samples were collected from CPT borings drilled at DDJC-Tracy from October 16 through 19, 2001.This field investigation included both the east Annex CPT sampling and the on-depot SWMU 68 (Area 3)proposed groundwater extraction well effort(results of the SWMU 68 effort are documented in a separate letter report).All samples were analyzed by an on-site laboratory using Method SW8260B.The data and associated quality control samples were assessed and validated according to the guidance set forth in the DDJC Comprehensive Field Work Plan, Volume 2 of 2- Quality Assurance Project Plan,February 2001. Holding times were met for all samples.The data are valid and can be used to characterize the groundwater; however,any data results that are flagged should be used with an understanding that the data may have limitations.Data results qualified with a"UJ"should be interpreted as having an estimated reporting limit, and results flagged with a"P'or"J+"should be interpreted as an estimated concentration. From a total of 1,248 results, 100 individual results are qualified as having estimated reporting limits or concentrations because the associated quality control did not meet the QAPP criteria. The following sample results are qualified: fifty-eight(not detected)results are qualified because of low laboratory control sample recoveries and/or low matrix spike recoveries;nineteen(not detected)results are qualified because of low continuing calibration verification recoveries; twenty-one detected results are qualified for potential high bias because the associated surrogate spikes were recovered above the QAPP limits;and two detected results are qualified because the concentration exceeded the calibration range of the instrument.The attached table lists all qualified results.