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r <br /> Water Sam le Labelin and Handlln <br /> • Sample containers are labeled in the field with the fob number, sample location and depth, and <br /> date and promptly placed in iced storage for transport to the laboratory A Chain of Custody <br /> Record is initiated by the geologist and updated throughout handling of the samples and <br /> accompanies the samples to a laboratory certified by the State of California. Samples are <br /> transported to the laboratory promptly to help ensure that recommended sample holding times <br /> will not be exceeded. Samples in our custody will be properly disposed of after their useful life <br /> has expired. <br /> RQQrting Results of AnaLyses <br /> Hydrocarbon constituents in soil samples are reported in units of parts per million. Hydrocarbon <br /> constituents in groundwater samples are reported by the laboratory in units of parts per billion <br /> (pbb). The maximum contaminant levels listed in Title 22 of the California Code of Regulations <br /> for benzene, ethyibenzene, and total xylene isomers in dnnldng water are 1.0, 680, and 1,750 <br /> pbb, respectively. The action level established by the California Department of Health Services <br /> for toluene is 100 pbb. To conform with the Iaboratory reports, we report groundwater chemical <br /> data an units of ppb <br /> Evaluatin the- -Groundwater FI w Direction and Gradien <br /> The elevations and positions ("x" and "y" lateral coordinates) of the monitoring well are <br /> surveyed by a licensed land surveyor with respect to a local datum that references the elevation <br /> according to mean sea leve"-. 7-ne elevaton of the monitoring wells are measured within ^.0l <br /> foot of the Iccal datum. ie hce=ntal distances are measured to fhe near"et 0.I foot. the <br /> elevations are to be taken to dither a notch of an arrow to be marked on the tap edge of the well <br /> casing. <br /> The groundwater elevation for each monitoring well is calculated by subtracting the depth to <br /> water from the wellhead elevation. The groundwater elevation information is used to construct <br /> a potentiometric surface map, which is used to evaluate the direction of groundwater flow and <br /> the magnitude of the groundwater gradient. <br /> R-081644 FLD <br />