Critical components to earthen dams and levee systems are the relief wells that offer a line of defense to cracking and potential failure caused by rising water levels. But those relief wells, dug 50 or more feet into the dam or levee to relieve hydrostatic pressure, require cleaning and maintenance that is costly, risky and not very effective.
A system developed by the U.S. Army Engineer Research and Development Center (ERDC) could soon provide an inexpensive option to the U.S. Army Corps of Engineers (USACE) and its districts to better clean and maintain those wells and do so with fewer people and less risk.
Currently, relief wells are cleaned on a cycle of every 20 years at an estimated cost of $10,000 per well.
According to Taylor Rycroft, an environmental engineer with the ERDC Environmental Laboratory, current methods of using bleach and acid to deal with the growth of microorganisms and corrosion in the wells, provides just a 3-to-5 percent improvement in the well’s capacity.
“The microorganisms just grow back, and we are cleaning a well every 20 years for just a 3-to-5 percent improvement,” he said, adding traditional methods come with some hazards because of the chemicals used and equipment needed to deploy those treatments. “What we are doing right now is not very effective. It’s not great a return on the investment.”
Created by Rycroft and Zach Tomberg, an electronics engineer with the ERDC Cold Regions Research and Engineering Laboratory, Wellbot is an autonomous device that blends the power of UVC-emitting lamps with powerful brushes to address the fouling and corrosion that limits a well’s capacity.
At an estimated cost of just $5,000, and its ability to be deployed quickly and repeatedly, Wellbot provides districts with a cost-effective alternative without the potential risk from using chemicals, or the need for significant equipment and manpower to deploy.
USACE has around 20,000 relief wells in its inventory. According to Rycroft, USACE spent more than $10 million last year to maintain and clean roughly 1,000 wells.
“With Wellbot, you can use it reactively if you know you have a well that is fouled, or you can use it proactively and just keep rotating it through your wells and prevent fouling from happening,” Rycroft said. “Cost wise, Wellbot is very inexpensive. It has minimal power requirements and maintenance requirements.”
The Wellbot package includes the needed ruggedized cart, solar panels, batteries and autonomous systems. However, Wellbot could also be plugged in to an electrical grid if there was a power source near the relief wells.
Programmed to run over several days – or weeks if needed – on its own, Wellbot is a “set it and forget it” system capable of being deployed by just one person in as little as one hour, Rycroft said.
“Once the district user sets it, they forget it,” he said. “They can walk away, and it runs on its own.”
A recent field test in Vermont demonstrated the effectiveness of the Wellbot system.
Throughout the 14-day field trial, the system operated each day from 5 a.m. to 8 p.m. and retained full battery power from solar charging. There were no technical issues discovered, and visual results demonstrated Wellbot was effective at removing biofilm and chemical scale on the interior screen of a relief well without using any chemicals or heavy machinery.
“I was worried about leaving it out in Vermont weather for 14 days. The system does have a lot of electrical components,” Rycroft said, adding he lives a few hours from the Vermont test site. “I would worry something can go wrong. If there was rain, I would wonder, ‘Did we waterproof it enough?’
“But it worked. It went well. Throughout the entire process, Wellbot has exceeded expectations for sure.”
Future testing of the system will document such things as how much the use of Wellbot increased a well’s capacity, hoping and expecting it exceeds the current treatment’s results of a 3-to-5 percent improvement. That testing, Rycroft said, will also determine the best length of time Wellbot should be used in a well.
With increased interest from some USACE districts, Rycroft said Wellbot – which has been submitted to the U.S. Patent Office for patent approval – could see some future improvements, such as the ability for remote access and control.