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2 . The memo notes slight variations in analytical results of <br /> split groundwater samples from MW1 which were analyzed for <br /> halogenated volatile organic constituents by the Board and <br /> by Kleinfelder. A single sampling event is insufficient to <br /> identify and characterize all consituents which may or may <br /> not be present and additional monitoring and sampling is <br /> required. <br /> Four priority pollutant metals were detected in the water <br /> sample collected by Board staff . However, all constituent <br /> concentrations detected were below Maximum Contaminant <br /> Levels for Drinking Water. <br /> Through future sampling events, groundwater chemical charac- <br /> teristics will be more accurately determined. It is likely <br /> that mineral constituent presence has little or no relation <br /> to the operation of the former surface impoundment. The <br /> source of contaminants will be addressed as additional <br /> groundwater characterization is performed. <br /> 3 . Groundwater monitoring will be conducted monthly to deter- <br /> mine groundwater level , direction and gradient. Samples <br /> will be collected for analysis on a quarterly basis for the <br /> following constituents : General Minerals, Priority Pollu- <br /> tant Metals , Total Extractable Petroleum Hydrocarbons <br /> ( 3510/8015 ) , Halogenated and Aromatic Volatile Organics <br /> ( 601/602 ) and Phenols ( 604 ) . The monitoring program will be <br /> initiated immediately and continue for twelve consecutive <br /> months. <br /> 4 . TPCA requires determination of permeability, transmissivity <br /> and storage coefficient for the water bearing zone beneath <br /> the surface impoundment . Permeability was determined by <br /> laboratory analysis of samples collected during drilling of <br /> each monitoring well. Transmissivity can be calculated <br /> using the k values obtained. Storativity can be determined <br /> for unconfined zones by determining the specific yield for <br /> the saturated zone. Specific yield can only be determined <br /> accurately by conducting a pumping test or slug test on the <br /> wells. This information will be included in an addendum to <br /> the report to be submitted before June 1, 1991. <br /> 5 . Background water quality characteristics will be addressed <br /> after additional monitoring and sampling is conducted. <br /> Although MW3 may be influenced by an offsite source result- <br /> ing in high TDS, it may be adequate to establish background <br /> concentrations for other constituents. Depending on whether <br /> sources can be documented, it may be possible to establish <br /> "background" concentrations for different constituents in <br /> different wells. <br /> 6 . Additional samples have been collected and analyzed to <br /> determine an acceptable concentration for ambient lead in <br /> the vicinity of the facility. Results will be statistically <br /> analyzed using the Average Replicate t-test, recommended in <br /> 2 <br />