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QualltX-&Lurance.procedures <br /> To prevent contamination of the samples, CGI personnel adhere to the following procedures in the field <br /> �j A new, clean pair of latex gloves are put on prior to sampling each well <br /> I Wells are gauged, purged and groundwater samples are collected in the expected order of increasmg degree of <br /> contamination based on histoncal analytical results <br /> • All purging equipment will be thoroughly decontaminated between each well, using the procedures previously <br /> described at the beginning of this section <br /> • During sample collection for volatile organic analysts, the amount of air passing through the sample is <br />' minimized This helps prevent the air from stripping the volatiles from the water Sample bottles are filled by <br /> slowly running the sample down the side of the bottle until there is a convex meniscus over the mouth of the <br /> bottle The hd is carefully screwed onto the bottle such that no air bubbles are present within the bottle If a <br /> bubble is present, the cap is removed and additional water is added to the sample container After resealing the <br /> sample container, if bubbles still are present inside, the sample container is discarded and the procedure is <br /> repeated with a new container <br /> Laboratory and field handling procedures may be monitored, of required by the client or regulators, by including <br /> quality control(QC)samples for analysis with the groundwater samples Examples of different types of QC samples <br /> are as follows <br />' Trip blanks are prepared at the analytical laboratory by laboratory personnel to check field handling procedures <br /> Trip blanks are transported to the project site in the same manner as the laboratory-supplied sample containers to <br /> be filled They are not opened, and are returned to the laboratory with the samples collected Trip blanks are <br />' analyzed for purgable organic compounds <br /> • Equipment blanks are prepared in the field to determine if decontamination of field sampling equipment has been <br /> effective The samphng equipment used to collect the groundwater samples is rinsed with distilled water which <br /> is then decanted into laboratory-supplied containers The equipment blanks are transported to the laboratory, and <br /> are analyzed for the same chemical constituents as the samples collected at the site <br />' Duplicates are collected at the same time that the standard groundwater samples are being collected and are <br /> analyzed for the same compounds in order to check the reproducibility of laboratory data They are typically <br /> only collected from one well per sampling event The duphcate is assigned an identification number that will <br /> not associate it with the source well <br />' Generally, trip blanks and field blanks check field handling and transportation procedures Duplicates check <br /> laboratory procedures The configuration of QC samples is determined by CGI depending on site conditions and <br />' regulatory requirements <br />' t <br /> 1 <br /> CLEARWATERGROUP,INC ("GWS) 4 revised February 2, 1998 <br />