Revisiting the Radial Collector Well: Applying New Technologies To Enhance Value

Ranney collector wells have a time-proven history in the development of groundwater from connected surface water bodies. The general design and configuration of a Ranney well would be adaptable to other situations, however the cost and technological barriers to placing these wells limits their use typically to large municipal or industrial users.

Ranney collector wells entail extensive engineering and construction. A large caisson is constructed, then operators and equipment enter the caisson to work at depth to extend the radial segments from the caisson into the surround formation. The caisson itself must be constructed with a large enough diameter to permit down-hole work, and the extended laterals are limited in length and are not guided or steered in their construction.

In contrast, a Horizontal Directional Drilling (HDD) enhanced radial collector well may be scaled down considerably in construction and cost, while increasing flexibility in installation.

In practice, the HDD-enhanced collector is installed by first drilling a large diameter vertical well or installing a small-diameter caisson, with a maximum diameter of three feet. Then horizontal directional drilling is used to stand off remotely from the central caisson and extend the laterals to it, either terminating the laterals in the central well, or continuing through it to terminate either at the surface or at depth some distance away. Many configurations of this well are possible, depending on the water source and location, and the capture area desired.

Collector wells constructed in this manner may be considerably less expensive and of smaller construction and infrastructure footprint than larger Ranney collectors. This opens the technology for applications with fewer financial resources, as well as for locations with more limited groundwater availability.