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The leodville Mill Environmental Sampling Procedures <br />Water Sample Collection <br />Page 2 -16 <br />Wells will be presumed to be adequately flushed for a representative sample when <br />indicator parameters such as pH, temperature and specific conductance are observed <br />to vary less than ±10 %. Measurement of the field indicators will be recorded at a <br />minimum frequency of once per casing volume removed. Evacuation of 3 to 6 well <br />volumes may be necessary to meet the indicator parameter criterion, however, in <br />wells with very low recoveries this amount may not be practical. In these instances, <br />the well may be evacuated to near dryness and allowed to recover prior to sampling. <br />Evacuation rates should be kept well below 10 gallons /minute and in most cases <br />should be below 5 gallons /minute. <br />EVACUATION METHODS <br />The evacuation of monitoring wells prior to sampling will be accomplished using a <br />bailer, hand -lift pump, a submersible pump, or other appropriate methods that will <br />not impact the integrity of the sample. Prior to beginning evacuation, non - disposable <br />equipment should be decontaminated according to pertinent decontamination <br />procedures. <br />The selection of an evacuation method most often relies on the expected recharge. <br />If the recharge is anticipated to be rapid, a submersible pump may be used. Care <br />should be utilized to ensure this does not act as a route of cross contamination. <br />Hand - bailing may be utilized in any case, but in general is more efficient in wells with <br />a low recharge rate. A new length of either nylon or PVC cord should be used for <br />each well and for each evacuation event. <br />SAMPLE COLLECTION <br />Sampling can begin after evacuation of the required volume of water from the well. <br />Sampling of the monitor well should occur as soon as possible after evacuation, <br />preferably immediately. In most cases, the time lapse between evacuation and <br />sampling should not exceed two hours. <br />The collected groundwater samples will be placed in the appropriate types of <br />containers. Following collection, the samples should be prepared for shipping and <br />necessary documentation completed. <br />April 2013 <br />