The sewer lift station of the municipality is old. The pumps are at the end of their useful life, the controls need modernization, as well as the access hatch has degraded. Although the concrete wetwell is structurally sound, it needs to be updated.
Should the entire station be demolished and rebuilt? Not necessarily. The more important issue is whether the infrastructure in place will be able to accommodate a modern pumping system without compromising reliability, maintenance access or future capacity.
Image credit: romtecutilities.com
The retrofitting of a pumping station that is well-designed can help save precious infrastructure, while also replacing components that are no longer meeting operating requirements.
Begin with the structure that nobody wants to replace.
Wet wells can be the most costly and disruptive part to replace, since they are constructed underground and attached to existing pipes and are vital to wastewater collection.
If the concrete structure remains functional, it is possible to minimize excavation and construction work.
However, deterioration around the access hatch could complicate the process. Romtec Utilities identifies wet well hatch replacement as a standard retrofit requirement. It might be more reliable to repair the top slab rather than attach a new hatch on concrete that has deteriorated. This will allow for greater access to the structure and extend its utility, without having to rebuild the entire wet well.
An improved pump can alter the way engineers work.
Suppose a residential neighborhood has seen a significant increase in population since the original lift station was installed. The existing pumps may not be able to handle the demand to handle the increased flow of wastewater.
A pumping station upgrade could involve higher-horsepower pumps, but equipment selection cannot happen independently of the surrounding system.
Engineers must also think about the hydraulic requirements of the system. This is a consideration for flow as well as total dynamic pressure. The installation of a bigger pump without studying these factors can lead to problems in operation instead of resolving the issues. Planning future capacity at the time of initial design can make future expansion considerably easier.
Make sure that the Wastewater is moved during Construction
Retrofitting a wastewater pumping station is a particular challenge which is not faced by other construction projects. The station may have to be operational during construction.
Even when contractors are busy and preparing for the next project, wastewater is still arriving. Depending on the scope of the project, temporary bypass pumps may be required in order to maintain services during removal and the installation of the existing equipment.
Romtec Utilities faced this kind of problem in the Federal Law Enforcement Training Center located in Brunswick, Georgia.
The project involved replacing two older wastewater lift stations as well as maintaining the operation at the facility. The site-specific engineering as well as packaged systems and bypass pumping techniques made it possible to meet existing station footprints and operational requirements. This example shows why construction sequencing deserves attention prior to the installation process begins.
If you think replacement is the better alternative, then replacement is the best
Some stations may not be suited to be renovated. If the sewer lift station requires replacement because of a damaged well, structural constraints or significant changes to hydraulic requirements, it might be better to replace instead of modify.
When making a choice, it is important to consider the structural integrity of the building, its compatibility equipment, accessibility to construction, service continuity and long-term needs. Romtec Utilities begins retrofit and replacement projects by determining what components will remain and which require replacement.
From there, the firm develops site-specific engineering solutions, preliminary designs, and budgetary estimates. Prefabricated components can assist in organize installation, and reduce on-site construction.
The work isn’t over when the pumps begin to run.
Modern lift stations should function as a complete system. Before returning the lift station to service, testing the startup and commissioning will help ensure that the pumps and control equipment and other components are performing according to established specifications.
Maintenance and operation manuals, as well as training for operators, are crucial. Maintenance personnel must be familiar with the new equipment and operating procedures, in addition to the documentation before they take charge of the station.
A successful retrofit preserves the infrastructure while also addressing the shortcomings that forced modernization.
For facility owners and municipalities it is important to look beyond the immediate repair. The most successful projects integrate new equipment into existing structures and keep essential services running while construction is underway. They also make preparations for the pumping system so that it can continue in operation for a number of years.