Kleinfelder is the sole licensee of Hydropuls in North America.

With increased emphasis on sustainability and brownfield redevelopment, well owners increasingly look to more cost-effective, long-term well development and maintenance solutions. Underperforming wells limit removal rates, shorten pump life, and increase remediation time and costs.

The performance of recovery wells is largely dictated by the effectiveness of a groundwater remediation system. Conventional well maintenance or rehabilitation methods often call for chemical processes, such as acids and dispersants, and/or mechanical processes such as brushing and jetting. More recently, owners and well operators are looking to impulse generation technology—used independently or in combination with chemical and mechanical processes—to rehabilitate groundwater recovery wells that are not performing due to mechanical or biological plugging.

Impulse Incentive
Impulse-generation techniques, involving the rapid expansion of a highly compressed gas or liquid, were first developed for the oil and gas industries. Beginning in the 1950s, the technology was used for seismic exploration and enhancing oil production. Starting in the early 1990s, the technology was modified for use with water well development and rehabilitation efforts.

One impulse-generation method, the U.S. and European-patented Hydropuls® system, involves releasing a compressed gas into the well screen interval in quick, short bursts, which causes vibrations that loosen sediment and biological deposits on the well screen and surrounding formation. This process has proven to be more effective in treating a variety of well types and blockages than conventional methods alone.

The expansion of compressed gas creates an air lift effect and vibrates and loosens mechanically plugged sediment and biological deposits from the screens and surrounding aquifer. Typically, the impulse generator is used simultaneously with other mechanical methods (surging and isolation pumping) operated by a drilling/pump contractor to remove the sediment and biological deposits loosened by the impulse generator.

Hydropuls impulse technology can be used in wells up to 6,000 feet deep and within a variety of well types, including vertical and horizontal screened wells, perforated or slotted steel casing, open-rock boreholes, and PVC-lined wells with diameters from 2 inches to more than 24 inches.

Operational edge
In one case, an owner looking to remediate a former manufacturing site needed help rehabilitating a groundwater recovery well that had significant chemical precipitation, biofouling and mechanical plugging from migration of fine sediment.

The 45-foot-deep well was constructed of 6-inch stainless steel casing and screen. The Engineers relied on a combination of mechanical surging and pumping, the use of Hydropuls impulse-generation technology and acid shock treatment. The rehabilitation process consisted of an initial brushing of the well screen, impulse generation/pumping, isolation pumping/surging, and finally chemical injection while treating with Hydropuls technology.

After the initial Hydropuls step was completed, the well was treated with a strong granular acid to further assist with the removal of any remaining bacteriological material. Oxalic acid was used because of its excellent ability to remove oxide deposits of iron and manganese which are the common by-products of bacteriological reduction processes in groundwater.

The rehabilitation work significantly increased the well’s pumping capacity and a post rehabilitation video showed the well screen slots were unobstructed. The recovery well currently yields 9 gpm with pumping water level 60 inches above the pump.

It’s worth noting that a successful rehabilitation project is typically not related to one particular rehabilitation method, whether chemical, mechanical or impulse generation. Instead, a successful and long-term rehabilitation requires well owners and drilling/pump contractors to constantly monitor the results from each rehabilitation method used on the well and be willing to adjust the rehabilitation program to utilize those methods deemed most effective.

Chris Allen, L.G., is a senior water resources specialist at Kleinfelder, responsible for planning and overseeing all types of well development and rehabilitation projects throughout North America. Jim Bailey is the well services director for Kleinfelder.