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�s �•._-�-'�- _ ,� z�� .r,a . `, �� '�� ` �; � ��.5�° .,;.yam t: STI. I'tN c� t. ctctcRES L' itc: VS NC , I STANDARD OPERATING PROCEDURES RE:GROUNDWATER PURGING AND SAMPLING SOP--! Prior to water sampling,each well is purged by evacuating a minimum of three well-casing volumes of groundwater or until the discharge water temperature,conductivity,and pH stabilize. The groundwater sample - should be taken when the water Icvcl in the well recovers to 80:7.,of its static level. c The sampling equipment used consists of either a teflon bailer or a stainless steel bladder pump with a ' teflon bladder. If the sampling system is dedicated to the well,then the bailer is made of teflon,but the bladder „ pump is PVC with a polypropylene bladder 'Forty milliliter(ml)glass volatile-organic-analysis(VOA)vials,with I-_ teflon septa,are used as sample containers. The groundwater sample is deca::lt into each VOA vial in such a manner that there is a meniscus at the tcp of the vial. The cap is quickly placed over the top of the,&I and securely tightened. The VOA vial is then inverted and lapped to see if air bubbles arc present. If none are present,the sample is labeled and refrigerated !.7 ' for delivery under chain-of-custody to the laboratory. Label information should include a sample identification number,job identification number,date,time,type of analysis requested,and the samp:er's name. For quality control purposes,a duplicate water sample is collected for each well. This sample is held at the laboratory unless needed. A trip blank is prepared at the hboratory and placed in the transport cooler. It remains with the cooler and is analyzed by the laboratory a[cng with the groundwater samples. A field blank is prepared in the field when sampling equipment is not dedicated.The field blank is prepared after a pump or bailer , has burn steam-cleaned,prior to use in a second welt,and is analyzed along with the othzr samples.The field blank �1 .,yam - demonstrates the quality of in-field cleaning procedures to prevent cross-contamination. To minimize the potential for cross-contamination between wells,all the well-development and water- sampling equipment that is not dedicated to a well is steam-cleaned between each well, As a second precautionary measure,wells will be sampled in order of least to highest concentrations as established by previous analyses. •t "V 1 4 - 1 y k' V y