made. One copy should be kept in a separate file or logbook, and a second copy should be

shipped with the samples to the laboratory.

7.6.2

Sample Custody Seal

In cases where samples leave the owner/operator's immediate control (e.g., shipment

to laboratory), a custody seal should be placed on the shipping container or on the individual

sample bottles. Custody seals provide prevention or easy detection of sample tampering. The

custody seal should bear the signature of the collector and the date signed. The custody seal

can be placed on the front and back of a cooler, around the opening of a polyethylene

overpack bag or on the lid of each sample container. Caution should be exercised in doing

any of the above. Experience has shown that the seal may not always adhere to plastic

coolers, and that the coolers may arrive at the destination without the appropriate seal.

Sometimes the sample containers become wet from melting ice or condensation; thus, while

their labels will stick, their custody seals may not. Taping over the seal with a transparent

tape generally solves this problem. A similar solution can be applied to the cooler lids.

7.6.3

Field Logbook

If a sample analysis produces an unexpected or unexplainable result, it will be

necessary to determine if the circumstances of sample collection, rather than a change in the

ground water quality, are responsible. Examination of the field logbook is critical in this

process. A field log should be kept each time ground water monitoring activities are

conducted in the field. The field logbook should document the following:

Well identification;

Well depth;

Static water level depth and measurement technique;

Presence and thickness of immiscible layers and detection method;

Well yield (high or low) and well recovery after purging (slow, fast);

Well purging procedure and equipment;

Purge volume and pumping rate;

Time well purged;

Collection method for immiscible layers;

November 1992

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