WELL INTERFERENCE: PAYING MORE FOR LESS
The idea of paying more for less runs contrary to our capitalistic common sense and yet there are golf courses in America doing just that whenever they turn on the pumps to irrigate the greens. Why? Through well interference of course. Well interference is a condition where two or more production wells pumping in close proximity to each other steal water from each other. This condition invariably causes reduced production in the competing wells and leads to increased operating costs and excessive wear and tear on the well equipment.
As illustrated below, two wells in close proximity to each other excessively lower or depress the water table between each other which invariably lowers the yield of each well. For example, well producing 200 gallons per minute sustained) by itself may only produce 125 gallons per minute (sustained) when a neighboring well is pumping at the same time.
Though two or more wells can remain productive despite well interference, problems that may arise as a result of well interference include the following:
- Drilling of unnecessarily deep, or extraneous wells.
- Reduced yields to individual wells.
- Dry wells (especially during dry seasons).
- Conflicts with neighboring residential, industrial or municipal wells,
- Increased pumping effort (and increased operational costs).
- Excessive bio-fouling or encrustation of the well screen (or rock formation).
Methods or techniques to reduce or eliminate well interference vary from case to case, but may include eliminating or moving one or more wells, reducing pumping rates in the wells, and vertically spacing the well screens into different water-bearing zones. The best method for eliminating the problem is planning the size and layout of the well field in advance of drilling the first production well. A preliminary evaluation of all prospective water resources during the design and planning stages of the project will aid in identifying natural limitations that can lead to pumping interference.