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the brass tube and stored at approximately 4(--]C for transport to the laboratory After the <br /> soil sample is placed in the plastic bag, it will be allowed to warm, inducing volatilization of <br /> petroleum hydrocarbon vapors The headspace vapors will be screened with the OVM <br /> The highest observed reading will be recorded on the boring logs <br /> 4 4 GROUNDWATER DEPTH EVALUATION <br /> Depth to groundwater will be measured to the nearest 0 01 foot using an electronic hand <br /> held water level indicator The tip of the probe will be examined to evaluate whether a <br /> product sheen is present <br /> 5 0 MONITORING WELL. DEVELOPMENT/PURGING AND SAMPLING <br /> Following installation, the wells will be surged with a surge block to remove fines from the <br /> sand pack After surging, ten casing volumes of ground water will be purged from each <br /> well using a bailer or centrifugal pump to remove sediment and enhance representative <br /> sample quality <br /> Groundwater sampling events conducted after the initial well development and sampling <br /> event will be preceded by purging three well volumes as described above Purge water will <br /> be monitored for the parameters temperature, pH, and conductivity until stabilized Wells <br /> will recharge to 80% before sampling If wells dewater they will be allowed to recharge for <br /> a minimum of one hour prior to sampling <br /> After the water levels within the wells stabilize, a sample will be collected with a dedicated, <br /> clean, disposable plastic bailer Samples will be contained in air-tight vials and then <br /> packed on ice and sent to the laboratory for analysis Groundwater samples will be <br /> transported to the laboratory and analyzed within the EPA-specified holding time for <br /> requested analysis <br /> Each sample container submitted for analysis will have a label affixed to identify the fob <br /> number, sample date, time of sample collection, and a sample number unique to that <br /> sample Samples will be analyzed by a California-certified laboratory <br /> A chain-of-custody form will be used to record possession of the sample from time of <br /> collection to its arrival at the laboratory When the samples will be shipped, the person in <br /> custody of them relinquishes the samples by signing the chain-of-custody form and noting <br /> the time The sample control officer at the laboratory will verify sample integrity and <br /> confirm that it was collected in the proper container, preserved correctly, and that there is <br /> an adequate volume for analysis <br /> 6 0 Wellhead Top of Casing Measurement <br /> The top of each new well riser will be measured to allow correlation of the groundwater <br /> levels at the site The measured point on each well riser will be marked to help insure <br /> future groundwater level measurements are taken from the same location All <br /> measurements will be measured relative to an arbitrary datum to the nearest 0 01-foot <br /> using a surveyor level and graduated stadia rod One well riser will be assigned the <br /> arbitrary datum and the other well riser will be measured relative to it higher or lower <br /> . 1419 11-RPT HORIZON ENVIRONMENTAL INC <br />