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GROUND WATER MONITORING AND SAMPLING: MULTI-LEVEL VERSUS TRADITIONAL METHODS – WHAT’S WHAT?
Citation:
PAUL, C. J. GROUND WATER MONITORING AND SAMPLING: MULTI-LEVEL VERSUS TRADITIONAL METHODS – WHAT’S WHAT? Presented at 2006 North American Environmental Field Conference and Exposition, Tampa, FL, January 10 - 12, 2006.
Impact/Purpose:
To evaluate different sampling techniques for determining VOC concentrations in groundwater.
Description:
Recent studies have been conducted to evaluate different sampling techniques for determining VOC concentrations in groundwater. Samples were obtained using multi-level and traditional sampling techniques in three monitoring wells at the Raymark Superfund site in Stratford, CT. Vertical profile devices evaluated include polyethylene passive diffusion bags (PDBs) and a discrete multi-level sampler (DMLS®). Traditional sampling devices include bladder, peristaltic, and submersible pumps. Low-flow purging and sampling techniques were used with these devices. Direct-push technology (Geoprobe®) was used adjacent to monitoring wells for comparison purposes. Samples were analyzed for 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,1-dichloroethene (DCE). Similar results were obtained with all three vertical profile methods. However, comparison between vertical profile sampling and traditional sampling with pumps showed values obtained with traditional techniques tend to provide an average concentration over the entire screened interval or water column within the screened interval. Results of the three discrete interval samplers showed distinct concentration gradients with depth, although concentrations varied between sampling devices.
