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AM ? 'Lc <br /> i <br /> E <br /> 1 STANDARD OPERATMG PROCMURFS <br /> RE,GROUNDWATER PURGING AND SAWUVG <br /> SOP-4 <br /> :r <br /> Prior to water sampling,each well is purged by evacuating a minimum of three well-casing volumes <br /> of groundwater or until the discharge water temperature, conductivity, and pH stabilize. The <br /> groundwater sample should be taken when the wat,-r level in the well recovers to 80%of its static <br /> level. <br /> f <br /> The sampling e:uipment used consists of either a teflon bailer or a stainless steel bladder pump <br /> with a teflon bladder. If the sampling system is dedicated to the well,then the bailer is made of <br /> teflon, but the bladder pump is PVC with a polypropylene bladder. Forty milliliter (m]) glass <br /> volatile-arganic-analysis(VOA)vials,.lith teflon septa,are used as sample containers. <br /> The groundwater sample is decanted into each VOA vial in such a manner that there is a meniscus <br /> at the top of the vial. The cap is quickly placed over the top of the vial and securely tightened. The <br /> VOA vial is then inverted and tapped to see if air bubbles are present. If none are present,the <br /> sample is labeled and refrigerated for delivery under chain-of-custody to the laboratory. label <br /> information should include a sample identification number,jou identification number, date,time, <br /> type of analysis requested,and the sampler's name. <br /> For quality control purposes,a duplicate water sample is Collected from each well. This sample is <br /> put on hold at the laboratory. A trip blank is prepared at the laboratory and placed in the trm—port <br /> cooler. It remains with the cooler and is analyzed by the laboratory along with the groundwater <br /> samples. A field'blank is prepared in the field when sampling equipment is not dedicated. The I <br /> rY,J field blank is prepared after a pump or bailer has been steam-cleaned,prior to use in a second welt, <br /> and is analyzed along with the other samples. The field blank demonstrates the quality of in-Feld <br /> cleaning procedures to prevent cross-contamination. <br /> To minimize the potential for cross-contamination between wells, all the well-development and <br /> water-sampling equipment that is not dedicated to a well is steam-cleaned between each well. As <br /> a second precautionary measure,wells will be sampled in order of least to highest concentrations <br /> z r as established by previous analyses. <br /> 4 ] <br /> r " <br /> 4 f <br /> I <br /> {{ <br /> f <br /> A <br /> � I I <br /> ROD= RAREM <br /> 2 <br /> S <br /> 4� <br /> 111 <br />