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Sampling Plan- 152 East 11th Street, Tracy, CA �,� F::U lPage 9 <br /> ' <br /> p <br /> MAY 14 1993 <br /> ENVIRONMENTAL HCALTH <br /> Procedures PERMIT/SERVICES <br /> Determination of Groundwater Elevations <br /> During investigations of groundwater quality at the Beacon Station at 153 East 11th Street, <br /> a local topographic elevation datum was established by others at Monitoring Well ULT 7 <br /> (Refer to Figure 2) and has been assigned an elevation of 50 00 ft Following installation of <br /> Monitoring Wells NAV 5 through NAV S, the elevations of the tops of the casings of <br /> these four wells and each existing well m the combined Navarra and Ultramar array will be <br /> surveyed relative to that datum so that groundwater depth measurements can be used to <br /> compute groundwater elevations <br /> Prior to sampling of any well, the depth from the top of the casing to the water table will be <br /> measured in all wells in the combined Navarra and Ultramar monitoring well array using a <br /> conductivity meter equipped with a graduated tape and sound alarm These data will be <br /> used to compute the groundwater table elevations relative to the local datum and to <br /> produce a map of groundwater elevation contours <br /> Smphng Procedure <br /> Prior to each round of sampling, each monitoring well will be purged The purge water be <br /> stored on the 152, East 11th Street site When full, the contents of the tank will be <br /> siphoned into a vacuum truck operated by a permitted hauler and transported of site for <br /> disposal at a licensed waste-oil recycling facility <br /> Samples will be recovered from each well using a dedicated bailer which will be suspended <br /> in the well casing when not m use Water brought to the surface in the bailers will be <br /> decanted so as to completely fill clean glassware supplied by the laboratory The sample <br /> vials will then be tightly closed, labeled for identification, entered into chain-of-custody <br /> control and packed on chemical ice for transport to the laboratory within 24 hours <br /> Following completion of sampling, the depth to groundwater will be re-measured m each <br /> sampled well and checked against the depth measured prior to the start of well purging <br /> This will provide information on well-recovery rates and indicate whether or not <br /> representative samples of groundwater are being recovered <br /> Sample Analyses <br /> Each groundwater water sample will be analyzed for the following suite of analytes <br />