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_ _�■rAM <br /> December 8, 1993 Working to Restore Nature <br /> ARCO Station No 760, Lodi, California <br /> Groundwater Sampling <br /> The static water level in each well is measured to the nearest 0 01 foot with a Solinst or <br /> similar electric water-level indicator cleaned with a laboratory-grade detergent and <br /> de;oruzed water before use in each well A clean bailer is used to obtain a sample from the <br /> surface of the water in the well for subjective analysis of hydrocarbons The sample is <br /> retrieved and examined for floating product, sheen, color, and clarity. <br /> Approximately 3 to 5 well volumes are purged from each well with a stainless-steel electrical <br /> submersible pump to allow sampling of representative formation water The pump, cables, <br /> and hoses are cleaned with a laboratory-grade non-phosphatic detergent and water before <br /> use in each well The wells are purged until Ph, temperature, and electrical conductivity of <br /> the water stabilized, as measured by portable meters calibrated to a standard buffer and <br /> conductivity standard The water level is allowed to recover to at least 80 percent of the <br /> initial water level <br /> A sample of the formation water then is collected from the surface of the water in each of <br /> the wells with a Teflon bailer and slowly transferred to laboratory-cleaned sample <br /> containers The recovered fluids from sampling in each well are directed into type 17-E, <br /> steel, 55-gallon liquid waste drums approved for this use by the Department of <br /> Transportation until suitable disposal options are selected based on analytical results <br /> Disposal of water at an appropriate disposal facility is the responsibility of the client <br /> Water Sample Labeling and Handling <br /> Sample containers are labeled in the field with the fob number, sample location and depth, <br /> and date and promptly placed in iced storage for transport to the laboratory A Chain of <br /> Custody Record is initiated by the geologist and updated throughout handling of the samples <br /> and accompanies the samples to a laboratory certified by the State of California Samples <br /> are transported to the laboratory promptly to help ensure that recommended sample holding <br /> times will not be exceeded. Samples in our custody will be properly disposed of after their <br /> useful life has expired <br /> Is 0913ccar <br /> 38048-10 <br />