Pumping tests for construction dewatering in chalk

Well pumping tests, where one or more wells are pumped at a controlled rate for an extended period of time (usually several days), can be an effective method of obtaining data for the design of construction dewatering systems. Pumping tests in chalk present particular challenges, and the design of the test well and monitoring well array should take account of the hydrogeological setting of the chalk, which can include unconfined or confined aquifers, with or without overlying granular water-bearing deposits. Data from the pumping tests can be used to derive hydrogeological parameters, or can be used directly in dewatering design by the superposition of drawdown method. Where there is concern about potential impacts from groundwater lowering (e.g. settlement, changes in water chemistry, depletion of groundwater-dependent features) then relevant data from constant rate pumping phases can be useful in the assessment of the magnitude and distribution of impacts that might result from the dewatering system.