A municipality has an aging wastewater lift station. Pumps are nearing the end their useful life, while controls need to be modernized and the access hatch needs to be replaced. Yet the concrete wet well remains robust and solid.
Image credit: romtecutilities.com
Should the station be totally gone? Not necessarily. One of the most important questions to consider is whether the existing infrastructure will be able to support pumps that meet the latest standards, without compromising reliability and future capacity.
Retrofitting a pumping station can be a great way to maintain infrastructure and replace components that are no longer functional.
Start with the structure that nobody would like to replace.
Wet wells are often the most expensive and difficult part to replace, since they are buried and connected to existing pipes and are essential for wastewater collection.
Retaining the concrete structure could reduce excavation work and construction.
But, any deterioration that occurs around the access hatch can make the decision. Romtec Utilities identifies wet well hatch replacement as an usual retrofit requirement. It might be more reliable to remove the top slab instead of constructing a new hatch on concrete that has deteriorated. This option can be utilized to increase access and improve the functionality of the structure, without needing to rebuild the entire wet well.
The design of an even more powerful pump is different
Take a look at a neighborhood that has seen significant expansion since the establishment of its lift station. The existing pumps may not be able to handle the demand for increased flows of wastewater.
A change to the pumping station may require higher horsepower pumps, but the choice of equipment cannot be made independently of the surrounding system. More powerful pumps may require adjustments to elbows for discharge, piping valves, electrical controllers, and other components.
The engineers must also assess the hydraulic requirements of the system. This includes flow rate and dynamic head total. A larger pump prior to assessing the requirements could cause more problems than it resolves. Making plans for future capacity at the time of initial design can make future expansion considerably easier.
Make sure that the wastewater is moving during construction.
A wastewater pump station retrofit introduces a challenge that ordinary equipment replacement projects may not face: the station may need to remain operational throughout construction.
Even when contractors are busy the wastewater still flows in. Depending on the project, temporary bypass pumping may be necessary to keep services while existing equipment is removed, and new equipment is installed.
Romtec Utilities took on this kind of problem in the Federal Law Enforcement Training Center at Brunswick, Georgia.
The project involved replacing two wastewater lift stations that were in use and ensuring the operation of the facility. The project was able accommodate the existing footprints of stations as well as operational requirements by using site-specific engineering and system for replacement that is packaged. The example illustrates the importance of focusing on construction sequencing before installation begins.
If replacement is the best alternative
Some stations are not suitable to be renovated. Sewer lift stations might need to be replaced in the event of a badly damaged wet well, or have a low structural capacity.
Before making a decision it is important to consider the structural health of the structure, its compatibility to equipment, its accessibility to construction, the continuity of services as well as long-term requirements. Romtec Utilities begins retrofit and replacement projects by determining what components will be left and which require replacement.
The company can then design engineering solutions specifically for the location, initial designs as well as budget estimations. Prefabricated parts are a great way to make installation easier and less time-consuming, as well as reduce construction on site.
The Project Doesn’t End When the Pumps Are Running
Modern lift stations should work as a whole. Before returning the lift station to service, startup tests and commissioning tests will ensure that the pumps and controls as well as other equipment perform as per the accepted specifications.
Training for operators and operation and maintenance manuals are equally important. Prior to taking over the responsibility of a station, maintenance personnel should be familiar with the latest equipment, procedures, and documents.
Retrofitting successfully preserves the infrastructure that is still valuable and addresses the shortcomings that forced modernization.
Municipalities and facility owners must think beyond repairs that are immediate. The most effective project is one that integrates the new equipment into existing structures, keeps up with essential service throughout construction, and then prepares the pumping system for years of continued operation.