Water Well Restoration
What You Need to Know
- It is common for water wells to experience lost capacity and a variety of water quality issues over time.
- Fouling material deposited on rock, gravel pack, and the well screen will reduce optimum flow.
- It may take years for optimum flow to be reduced, but once it happens it will occur more frequently.
- Reliable “unplugging” efforts must be instituted for best results.
- The main goal of water well rehabilitation is to reinstate original water volumes.
Effective water well rehabilitation requires the removal of all deposited material, thereby allowing the specific capacity and pore volume to be restored. There are many different strategies and methods used in water well rehabilitation, some successful, others less successful.
The success in using many of the physical and chemical methods is dependent on the user being able to fully identify the plugging material. This becomes a daunting task due to the variability of the complex geochemical and microbiological underground environment, and the reliance of the user to perfectly design a specific chemical combination required to fully remove the plugging–while not effecting well construction.
Well Rehabilitation and Maintenance with Aqua Freed® and Aqua Gard®
Since 1988, the Aqua Freed® water well rehabilitation process has been used on thousands of wells worldwide with excellent results.
The Aqua Freed process uses gaseous and liquid carbon dioxide to restore water wells. Aqua Freed is broad ranging in its ability to effectively disrupt and remove a wide variety of plugging deposits, in many different types of wells. It offers superior deposit removal and more complete pore volume recovery, with adversely effecting well construction.
The process has been used on a wide variety of wells including vertical wells, horizontal well, extraction wells, from shallow to very deep wells, from small diameter to large diameter, screened and open hole. Many of the wells treated have been rock open-hole wells that do not have a well screen, but are completed in fractured formations of limestone, dolomite, granite, and sandstone.
The Aqua Freed process is more effective at removing both deposits from inside the well screen and the formation surrounding the well. One of the active components from the injected gas is carbonic acid, a mild acid, which under atmospheric conditions produces a pH of +/-6.0. However, there is pressure in an aquifer or a sealed well, allowing the pH values to become reduced to as low as 5.0. (still relatively mild). When the pressure is released, the pH will return above pH 6.0; therefore it does not become a neutralization or disposal concern. There is also the effect of localized freezing, and more importantly, agitation, as the liquid carbon dioxide is injected at approximately 0°F.
Aqua Freed’s success is achieved from a combination of carbonic acid, agitation, and localized freezing, which results in superior disruption and detachment of the encrusted and plugging material. The bulk of the activity is due to phase changes. The expansion rate from a liquid to a gaseous state of the carbon dioxide is 570 times in volume. The agitation achieved with liquid carbon dioxide is the same action as when dry ice is placed in water. There is agitation as the carbon dioxide changes, in this case, from a solid to a gaseous state.
The Aqua Freed process is the controlled injection of carbon dioxide. The rate and volume of carbon dioxide injected is regulated to assure that the pressures (and energy) going down the well can dissipate into the surrounding formations. Gaseous and liquid carbon dioxide contain tremendous energy, described as energy of dissolution, energy of detachment and energy of agitation. This energy results in the detachment, dissolution and removal of sediments and encrustation from the surfaces within the well screen and the surrounding aquifer.
The Aqua Freed process is not an overly aggressive process, yet is capable of delivering the necessary energy required to be effective in wells constructed using PVC or HDPE, without problems.
It is far better to maintain yield and water flow efficiencies than to try to recover them.
The Aqua Gard® preventive Well Maintenance Systems is a proactive approach to well cleaning, rather than a reactive cleaning process.
Aqua Gard has proved to be more efficient and much more economical for the client, and because well and geological formation surfaces are kept clean, raw water quality is improved.
The Aqua Gard system includes the placement of energy injection equipment permanently installed with the pump in place, allowing for the regularly scheduled, routine, preventive service to the well without removing the pump.
The system can be installed in wells that are equipped with both submersible and vertical line shaft turbine pumps.
Local raw water quality, specific well operation, and historical rate of well plugging will determine the intervals between services. Aqua Gard is ideal for new well installation or for installation following a major well rehabilitation effort.
Wells that experience severe and rapid fouling recognize a financial and efficiency benefit from the onset.
WRS Inc. offers the following types of mechanical well rehabilitation:
- Wire Brushing
- Simultaneous airlift swabbing
In addition to the Aqua Freed process, WRS Inc. offers chemical well rehabilitation using chemicals commonly used by the industry. However, chemical treatments are generally less effective than Aqua Freed in the removal of deposited plugging material, and therefore only partial deposit removal is often achieved.
Chemicals commonly used include:
- Acids: Hydrochloric, Sulfamic, Hydroxyacetic, Citric, and Phosphoric.
- Disinfectants: Sodium Hypochlorite, Calcium, Hypochlorite, and Sterelene.