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I7l��'MA <br /> September 15, 1993 Working To Restore Nature <br /> a <br /> Ruiz Grocery, Tracy, California <br /> bailer through the interface The bailer is retrieved and the water sample examined for <br /> floating product, sheen, or other subjective evidence of hydrocarbons <br />► <br /> Measurement of the Depth to Groundwater in_Monitoring Wells <br /> The depth of the groundwater surface in a monitoring well is measured from the top of the <br /> well casing to the nearest 0 01 foot with a Solinst or similar electric water-level indicator <br /> The well will be vented to the atmosphere before obtaining depth-to-water measurements <br />> denting is conducted to allow the groundwater to equilibrate to barometric pressure These <br /> measurements will be combined to evaluate the elevation of the groundwater surface in each <br /> well and the slope of the groundwater surface across the <br /> site <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 /> deiomzed 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 electncal 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 SO 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 Handlin,_g <br /> Sample containers are labeled in the field with the.job 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 /> 123020-IW <br />