The sewer lift station in a municipality is old. The pumps are at the end of their service lifespan, the controls require modernization as well as the access hatch has become damaged. But the concrete wet well is structurally sound.
Should the station be removed? Not necessarily. The best question to ask is whether the existing infrastructure can accommodate a pumping system that meets modern standards without compromising reliability and future capacity.
Image credit: romtecutilities.com
Retrofitting a pump station can be an excellent way to preserve infrastructure and replace parts which are no longer in use.
Begin with the structure that nobody would like to replace.
The wet well is often one of the most costly and disruptive components to replace as it is buried, connected to existing piping and is essential to the collection of wastewater.
If the concrete structure remains serviceable, retaining it may minimize excavation and construction work.
However, the deterioration of the access hatch could complicate the process. Romtec Utilities identifies wet well hatch replacement as a typical retrofit requirement. It might be more reliable to replace the top layer instead of installing a brand new hatch to a deteriorated concrete. This method can be used to increase accessibility and the usability of the structure without having to rebuild the entire wet well.
The development of pumps that are more powerful is different
Imagine a place that has grown significantly from the time of the first lift station installation. The existing pumps may not be able to handle the demand for increased wastewater flows.
Pumps with more horsepower may be used to upgrade the pumping station, however the equipment needs to fit into the system. Pumps with greater power may require modifications to discharge elbows, piping valves, electrical control and other parts.
The engineers should also take into consideration the requirements for hydraulics of the system. This includes flow rate and dynamic head total. In the event of installing a larger pump, not taking a look at these requirements could cause operational problems rather than solving these. Planning future capacity prior to initial design makes future expansion easy.
Keep the water moving during construction
A wastewater pump station retrofit poses a challenge which normal project for replacement of equipment may not have to face: the pump station could require a continuous operation during construction.
Contractors continue to work, and wastewater continues to come in. Depending on the scope of the project, temporary bypass pumps may be required to keep operation during the removal and installation of existing equipment.
Romtec Utilities faced this kind of challenge in the Federal Law Enforcement Training Center in Brunswick, Georgia.
The work involved replacing two older wastewater lift stations and ensuring the operation at the facility. The project was able accommodate existing station footprints as well the operational needs by utilizing site-specific engineering and packaged replacement systems. This is a good example of why it is important to look at the construction process prior to installing.
If replacing is the only alternative
There are many stations that can be repaired. A severely deteriorated wet well, inadequate structural capacity, or major changes in hydraulic requirements may make sewer lift station replacement more appropriate than modifying the existing installation.
Before making a decision it is essential to think about the structural health of the building, its compatibility with equipment, accessibility to construction, the continuity of services and the long-term requirements. Romtec Utilities begins retrofit and replacement projects by identifying which elements will remain and which ones require replacement.
The company develops engineering solutions tailored to the location, initial plans and budget estimates. Prefabricated components can be useful for organizing installation and reducing certain on-site demands.
The work isn’t over when the pumps begin to run.
The modernized lift station should operate as a system. Prior to returning a lift station to normal operation, initial tests, commissioning and verification of equipment are required to make sure that all pumps, controls and the related equipment function as designed.
Both manuals and training for operators are equally crucial. Maintenance workers must be aware of the new equipment, operating procedures, and other documentation before they take over responsibility for the station.
A successful retrofit helps preserve the infrastructure and addresses the limitations which made modernization necessary.
Municipalities and owners of facilities need to take a look beyond the immediate fixes. The most successful projects integrate new equipment into existing structures to maintain essential service during construction. They also prepare the pumping system so that it can continue in operation for a number of years.