Ground water sampling bias observed in shallow conventional wells. Hutchins and Acree, 2000.
EPAs Hutchins and Acree present the results of their field research showing the misleading data that are often generated using samples collected from conventional monitoring wells. They conclude that These data provide an additional example where cluster well points or other methods of obtaining depth-discrete samples would be required to provide an accurate assessment of either the extent of contamination or the rate of remediation.
Complete citation: Hutchins, S.R. and S.D. Acree. 2000. Ground water sampling bias observed in shallow conventional wells. Ground Water Monitoring and Remediation 20, no. 1: 86-93.
Plume distortion and apparent attenuation due to concentration averaging in monitoring wells. Martin-Hayden and Robbins, 1997.
This paper, authored by University of Connecticut researchers who performed much of the early work on this topic, describe the various processes that bias groundwater samples collected from conventional monitoring wells. In particular, they discuss the dilution of contaminants that occurs when clean water is simultaneously drawn into monitoring wells pumped to produce groundwater samples.
Complete citation: Martin-Hayden, J.M. and G.A. Robbins. 1997. Plume distortion and apparent attenuation due to concentration averaging in monitoring wells. Ground Water 35, no. 2: 339-346.
Supplementary material to accompany ES&T Feature Article "Estimating Future Impacts of Groundwater Contamination on Water Supply Wells" February 1, 2001
"Estimating Future Impacts of Groundwater Contamination on Water Supply Wells" February 1, 2001
Sampling trace-level organic solutes with polymeric tubing. Part 2. Dynamic studies. Parker and Ranney, 1998.
Parker and Ranney present the results of laboratory tests focused on investigation the potential positive or negative biases associated with using polymetric tubing to collect groundwater samples. This paper, the second in a series, focuses on the effects under dynamic (i.e., pumping) conditions. They show that negative biases are a function of the plymer material, the hydrophobicity of the contaminant, and the contact time between the sample and the polymer tubing. They also note that potential positive biases can occur due to desorption or reverse-diffusion of contaminants from the tubing into subsequent groundwater samples and therefore recommend the use of dedicated sampling tubing.
Complete citation: Parker, L.V. and T.A. Ranney. 1998. Sampling trace-level organic solutes with polymetric tubing. Part 2. Dynamic studies. Ground Water Monitoring and Remediation 18, no. 1: 148-155.