High quality groundwater sampling

Representative Samples
A project manager’s goal for groundwater sampling is to collect samples that are representative of actual in-situ conditions, and to maintain sample integrity by minimizing the changes in sample quality and chemistry during collection. Sampling has evolved from earlier techniques of bailing and high rate pumping, to techniques of minimal drawdown and low flow pumping.
Low flow pumping has been proven to provide consistent, highly representative groundwater samples. By maintaining flow rates of 500 ml/min or less, sample extraction is kept at a rate comparable to ambient groundwater flow and drawdown is minimized, thus reducing turbidity and disturbance in the well. Reduced agitation is particularly important for accurate measurement of dissolved volatile organic compound (VOC) concentrations in groundwater; too much agitation can cause degassing of VOCs to the atmosphere.