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Two small-diameter (≤0.5-inch/13-mm O.D.) bladder pumps were evaluated under the U.S. EPA Environmental Technology Verification Program to assess their ability to provide representative water quality samples for several volatile organic compounds (VOCs) and major element cations. Both a pneumatic bladder pump (PnBP) and a newly designed mechanical bladder pump (MBP) were evaluated. Since the MBP does not require compressed air to operate, the field logistics are simplified and cost of conducting low-flow sampling can be reduced. Replicate samples were collected from an above-ground standpipe spiked with selected VOCs and cations. Low-flow sampling protocol was followed during collection of replicate samples from six direct push (DP)–installed monitoring wells at Tyndall Air Force Base, Florida. Simple statistical methods are used to evaluate the sample quality provided by the pumps as compared to reference samples. F-tests are used to evaluate pump sample precision, and t-tests are applied to evaluate comparability of the pump sample results to the colocated reference or port sample results. Statistical analysis reveals that the samples collected with the pumps provide precision comparable to that observed in the reference samples. Significantly greater variability was observed between the pump and reference samples collected from the DP wells than was observed during the standpipe trials. The results and statistics from the trials at the standpipe indicate that both the PnBP and MBP provide water quality samples that are comparable to the reference samples, for the analytes investigated. |
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