ARCHIVED REPORTS_XR0005851 CASE 2

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LGround Water Sampling • There are certain circumstances where it is necessary to filter or centrifuge the sample under controlled laboratory conditions prior to analysis to prevent instrument damage Sample filtration in the laboratory is permissible if insoluble materials that could damage laboratory equipment(e g , silicates)remain after acid digestion of the sample If this step is necessary, the filter and the filtering apparatus should be thoroughly cleaned and pre-rinsed with dilute nitric acrd Laboratory personnel should refer to SW-846 (U.S EPA, 1986) for information concerning these procedures Samples should not be transferred from one sample container to another Transfemng samples between containers may result in losses of organic material onto the walls of the container or sample aeration To minimize the possibility of volatilization of organics, no headspace should exist in the containers of samples containing volatile organics Field logs and laboratory analysis reports should note the headspace, if present, in the sample container(s) at the time of receipt by the laboratory, as well as at the time the sample was first transferred to the sample container at the wellhead 26 Cham-of-Custody and Records Management ' A cham-of-custody procedure should be designed to allow the RP to reconstruct how and under what circumstances a sample was collected, including any problems encountered lie U.S.EPA (1986) provides a complete description of chain-of-custody and records management The chain-of-custody procedure is intended to prevent misidentification of the samples,to prevent tampering with the samples during shipping and storage, to allow easy identification of any tampering, and to allow for the easy tracking of possession 26.1 Sample Labels To prevent sample misidentification,the RP should affix labels to each sample container The labels should be sufficiently durable to remain legible even when wet and should contain, at a minimum, the following information to Sample identification number, o Name and signature of collector, o Date and time of collection, ' o Place of collection,and o Parameters requested (if space permits) The samples can be labeled by recording the above information directly on the sample containers Alternatively,the RP may use multiple-part labels consisting of a unique identification number that is placed on the container, and at least two copies of the descriptive information for the samples (referenced to the identification number) One copy should be kept in a separate file or logbook, and a second copy is shipped inside the cooler with the samples to the laboratory 24