Economic Aspects of Water Well Stimulation

Abstract

From the analysis of technical and economic data of the survey reported in this and the preceding article, it may be concluded that water well stimulation has shown highly favorable results, not only in its technical performance, but also by the economic criterion chosen. In the majority of instances, stimulation has added specific capacity at a unit cost less than the unit cost of the specific capacity produced by the original well. The median cost of improvement of even the least favorable method by this economic criterion occurs at a unit cost less than half the unit cost of the original specific capacity. This is not only important in regions of existing groundwater exploitation; it is equally applicable and possibly much more important to the large areas in which there are adequate quantities of groundwater contained in aquifers of such low permeability that groundwater production from wells has not been economical. Wider knowledge and application of water well stimulation can potentially bring about a greater utilization of this segment of groundwater resources. Based on these analyses and results, the author recommends that water well stimulation be much more widely considered as a technique for developing groundwater supplies. Such recommendations should not, however, be made without a simultaneous mention of a number of quite legitimate limitations to the benefits of water well stimulation. The well production may not always be limited by the specific capacity and available drawdown, but, instead, by extraneous factors, such as avoidance of interference with other wells on adjacent properties, avoidance of intrusion of undesirable waters, or legal restrictions. Once such limits are reached, water well stimulation can be of no further influence in reducing investment cost per unit of production, although it can still function to reduce operating costs. The latter possibility will be described in a later paper. Considerations of flexibility and standby facilities also enter in. If a well supply consists of only one well, then the choice between stimulation and construction of an additional well should be influenced not only by considerations of investment cost but also by the general desirability of having alternative facilities for flexibility and emergency. In bringing this restriction to bear in connection with the survey data, it should be recalled that the investment cost for the original well in the present study does not include the pump and a large number of additional facilities that are necessary before a well can become a water supply. To that extent, the comparisons, specifically those of unit cost ratios, are very conservative. If an additional well is contemplated, the actual economic advantage of stimulation of an existing well will be found to be much greater.