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I <br /> Groundwater sampling Yrotcccl <br /> Prior to arriving at the sampling site, all sampling equip- <br /> ment will be washed with laboratory grade detergent, and <br /> rinsed twice with tap water, once with acetone, and once with <br /> deicnized water. The sample washing procedure will be car- <br /> ried out on-site before sampling of other monitoring wells, <br /> in such cases where more than one monitoring well is to be <br /> sampled, with the sampling device. <br /> Immediately prior to sampling, the depth to water (DTW) level <br /> in the well will be recorded. The apparent thickness of <br /> product on top of the groundwater, if present, will be <br /> measured using an interface probe or clear graduated acrlyic <br /> bailer. The procedure for conducting these monitorings are <br /> presented in the Groundwater Monitoring Protocol attachment. <br /> If free product is detected, analysis of groundwater for <br /> dissolved product will not be conducted. The product will be <br /> sampled for content, if collection of a sample is possible. <br /> Before collecting at least two groundwater samples from each <br /> well, the well will be purged until indicator parameters <br /> (temperature, conductivity and pH) stabilize. This will <br /> entail the removal of at least three or more well casing <br /> volumes by bailing or pumping. The criteria for determining <br /> well casing volumes and storage of purged waste is discussed <br /> in the Well Development Protocol section. The indicator <br /> parameter measurements will be taken both before and after <br /> purging of each well casing volume. once the - well is purged <br /> and well water chemistry has stabilized, a sample will be <br /> collected after the water level approaches 8o percent of its <br /> initial elevation. Where water level recovery is slow, the <br /> sample will be collected after stabilization is achieved and <br /> enough water is present to fill sample containers. <br /> cross contamination from transferring pumps from well to well <br /> will be avoided by utilizing dedicated equipment. Where this <br /> is not feasible , thorough cleaning of equipment will be <br /> performed between sampling rounds. Sampling will proceed <br /> from the least contaminated to the most contaminated well, if <br /> information is available before sample collection, or if it <br /> is indicated by field evidence. Where several types of <br /> analysis will be performed for a given well individual sam- <br /> ples will be collected in the following order: <br /> 1. Volatile organics <br /> 2 . Purgeable organic carbon <br /> 3 . Purgeable organic halogens <br /> 4 . Total organic carbon <br /> 5. Total organic halogens <br />