Explore proper well development using air with columnist Thomas Kwader.

Wells with smaller diameters and relatively shallow water levels usually are good candidates for developing with air. Close-up view of drilling a monitoring well. Photo courtesy of U.S. Geological Survey.
Proper well development is an important part of the installation of every type of well drilled including piezometers, monitoring wells and especially large-capacity production wells. Proper well development helps assure representative clear water at the highest flow rates possible from the given formation.

Well development methods commonly include surging, bailing, pumping and compressed air. The most effective methods of well development employ techniques which allow water to move in and out of the screen as opposed to bailing or pumping which generally only allows for movement of water in one direction into the well. The back and forth motion of the water effectively breaks the “bridges” formed by using drilling muds and natural formation clays when water is moving only in one direction into the well. Well development with compressed air can be a very effective method when the physical characteristics of the well are considered. Development with compressed air generally involves lowering a small diameter pipe or tube to near the bottom of the well. Compressed air is applied from an air compressor at a pressure and rate great enough to lift the overlying column of water to land surface.

Not all wells are suited for development by air. Compressed air will tend to form a “train” in larger diameter wells or wells where the column of water is not sufficiently “thick” enough — like bubbling water in a fish tank. In this case, the air will form a “pathway” on one side of the casing, and water will stay in a column on the other side. Generally, the well diameter should be less than six inches and the water column three times the length of the distance from the static water level to land surface in order to be effective. Another undesirable factor is if the water level is too low, the airlifted water will exit the screen or borehole if it is above the water table. Larger compressors can overcome some of these factors, however, small diameter wells with fairly shallow water levels are preferable and generally good candidates for development with air.

If the well has the suitable criteria for well development by air, the advantages of compressed air include: the aggressiveness of the air is effective for removing fine particles from the well; the equipment required — air compressor and tubing — is minimal; and the method is relatively fast.