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December 23, /999 <br /> <br />C.3.3.1 Preparnfiorr jor Purging <br />r~Re c--r <br />Before well purging begins, the following procedures aze to be performed at each well: <br />- Note the condition of the outer well casing, concrete well pad, protective posts (if <br />present), and any other unusual conditions of the area around the well. <br />- Open the well. <br />- Note the condition of the inner well cap and size of outside diameter of casing. <br />- Measure (to nearest 0.01 foot) and record depth of static water level from the <br />measuring point on the well casing and indicate time. Record what the measuring <br />point is (i.e., notch on north side, top of PVC well casing). <br />- Calculate volume of water in the well casing in gallons based on feet of water in well <br />and casing diameter. (For micropurging, calculate the tubing volume.) <br />C.3.3.2 Purge Volume Calculations <br />The volume of water purged from the well should be adequate to remove all stored water <br />from the well casing prior to sampling. <br />Two exceptions to this approach may be encountered: wells which are very low-yield or <br />wells which are extremely deep or large diameter. Inlow-yielding wells, the casing maybe purged <br />dry. This will effectively remove all stored water in the casing, and the sample can be collected <br />when the water level recovers sufficiently to allow for sample collection. Indeep or lazge-diameter <br />wells having a volume so large as to make removal of all water impractical, micropurge techniques <br />should be employed. If micropurging techniques are employed, then a volume of water equal to two <br />times the combined volume of the tubing and pump should be purged prior to sampling. <br />C.3.4 Groundwater Sample Collection <br />Obtain samples for chemical analysis immediately after purging is completed. For slow <br />i <br />recovering wells, the sample will be collected immediately after a sufficient volume of water is <br />available. Most wells are equipped with dedicated equipment, but the water quality samples may <br />be collected using bailers or submersible downhole pumps. The following sampling procedure <br />should be used at each well: <br />- Assemble decontaminated sampling equipment. If bailers are used for sampling, a <br />bailer will be dedicated for each well. Assemble the manual filtering apparatus. <br />- Fill out the sample bottle labels and attach to the appropriate sample bottles. Write <br />in all information except the sampling time. <br />Agapito Associates, Inc. <br />