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Page last updated on September 7, 2021 at 2:37 pm

For more information, please contact

Travis Zimmerman, Assistant GIS Coordinator, 812-349-3622, zimmermant@bloomington.in.gov

 

The Challenge 

The purpose of a water lift is to move wastewater from a low spot in a neighborhood, uphill and down the line into the next lift station, continuing through the pipe system all the way to a wastewater treatment plant. Without water lifts, wastewater would continually back up an area's sewer system. The city of Bloomington Utilities (CBU) has two older water lift stations built in the 1950s/1960s located in the Park Ridge East neighborhood that use air compressors to move wastewater. The old lift stations have three parts that control the pumps: a sensor, a timer, and a sequencer. The process is complex but, simply speaking, a check valve allows fluid in until it reaches a probe, waiting for that tank to fill up, then the air compressor kicks on and pumps the water out. The first tank is clear for a few seconds and then the process repeats again with a second pump and a secondary tank. Due to age and design, CBU found these mechanisms failed too often Over the years, the timer would go out a few times and need replacement. The sequencer would fail nearly once a year and need replacement. The sensor was the most expensive part, but CBU had a stockpile to replace them with when they failed. The real problem came when CBU ran out of these replacement parts. Then, CBU needed to innovate a solution that would effectively fix the flaws in these older lift stations while also not breaking the bank.

 

The Idea 

The parts needed to operate the air compressor lift stations either cost a lot of money to replace or are no longer manufactured at all! When CBU looked into purchasing new components, the estimate amounted to $1,000 and would have required an entirely new system to wire it up. They also tried ordering a custom built part, but that did not work either. Due to a large oversight by the company that made the parts, this custom build ended up only replacing two of the three lift components (the sensor and timer), but used the original sequencer to alternate between pumps. This partial fix functioned for a few months, but eventually the lifts began to fail again and reached a point of needing to be pumped out manually everyday by CBU crews. One engineer, Travis Zimmerman, became dissatisfied with this unsustainable solution to the problem and had the idea to create a computer board to do the job. He went to his own collection of computer parts (relay boards, sensors, etc.) and created a prototype that would automate the lift station without relying on solely the air compressor's old parts. 

When the prototype indicated strong possibilities of results, CBU invested in more parts and Travis made a better version which now operates in the two lifts, helping alternate the pumps and keeping water levels in check. Essentially, he wrote a program that's only job is to wait and block electricity, and it lives inside a small computer chip. When the water level in the tank fills up, a sensor in the tanks asks if the water can get pumped out. The program will say yes, and allow electricity to flow, but the program sets a timer so that water can't flow for too long.  When the timer is up, the program blocks the electricity and goes back to waiting. It simplifies and modernizes the function of a water lift, minimizing opportunity for failure.

While Travis created the prototype computer system, Tony Eads, Assistant Superintendent at T&D, believed in the project and ordered the necessary computer parts. Travis then taught Eric and Jeremy, lift station mechanics, how to install the computer boards so they could carry out future upgrades as needed. A team effort to say the least! 

Prototype computer boards
Prototype computer board used to model lift station fix.

The Cost 

The custom rebuilds and new parts would have cost $750-$1,000, but because they did not work for Bloomington’s lifts in question, CBU did not end up paying this amount. Instead, these computer boards that did end up working cost only $40 each, saving CBU a tremendous amount of funds they can now allocate elsewhere. No additional modifications have been needed since.

 

The Benefit

With installation of the computer boards, CBU has more control over the lifts and can essentially code which pumps they want pumping to which tank. The computer boards automate the two lift stations without relying on solely the air compressor's old parts. In establishing safer and more effective technology, this innovation has significantly decreased the chance that the older lifts fail to fulfil their functions.

 

Metadata

City Department(s): City of Bloomington Utilities Engineering and T&D; Information and Technology Services Department 

City Point of Contact: Travis Zimmerman

Partner(s): N/A

Partner(s) Point(s) of Contact: N/A

Type of Innovation: Mechanical

Date Implemented: August-October 2019