A decrepit wastewater liftstation is located in a municipality. The pumps are nearing the expiration date of their useful life, and the controls require modernization, and the access hatch is deteriorating. Although the concrete wetwell is solid in its structure, it is in need of to be updated.
Should the entire station be demolished and rebuilt? Not necessarily. The better question is whether the existing infrastructure can support a modern pumping system without compromising the reliability, accessibility to maintenance or capacity in the future.
Image credit: romtecutilities.com
A carefully engineered pump station retrofit can preserve valuable infrastructure while replacing components that no longer meet operational requirements.
Start with the structure that nobody wants to replace.
The wet well can be among the most expensive and disruptive components to replace since it is hidden, connected to the existing piping and is essential to the process of removing wastewater.
Retaining the concrete structure could help in reducing excavation work and construction.
But, any deterioration in the vicinity of the access hatch can complicate your choice. Romtec Utilities says that wet well hatches are usually replaced in retrofits. It is possible to be more durable to replace the top slab instead of attaching a new hatch on deteriorated concrete. This can make it easier to access and increase the usefulness of the structure without having to rebuild the entire wet well.
A new pump improves the way engineers work.
Let’s say a residential area has seen a significant increase in population since the first lift station was built. It is possible that the current pumps are not able to handle increased water flow.
The upgrade of a pumping system may include more horsepower, but this can’t be accomplished without considering the whole system. Higher horsepower pumps might require modifications to discharge elbows, piping, valves, electrical controls and other parts.
Engineers must also take into consideration the hydraulic needs of the system. This is a consideration for flow as well as total dynamic pressure. If you add a larger pump without evaluating these conditions, it can cause problems in operation instead of resolving them. The planning of future capacity at the initial design can simplify future expansion.
Make sure that the Wastewater is moved during Construction
A retrofit to a wastewater pump station introduces a challenge that ordinary replacement of equipment projects do not have to face: the pump station could require a continuous operation through the entire construction.
Even when contractors are working, wastewater continues to arrive. Depending on the project the temporary bypass pumping might be required to maintain the service until existing equipment is removed and new components are installed.
Romtec Utilities took on this task at the Federal Law Enforcement Training Center, Brunswick, Georgia.
The project involved replacing two old wastewater lift stations, while keeping the operation of 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. The case study illustrates why construction sequencing deserves attention before the construction process starts.
When replacing is the most efficient option
Not all stations are suitable for rehabilitation. A badly degraded wet-well or a structural weakness or major changes in hydraulic requirements may make sewer lift station replacement better than making changes to the existing installation.
It is essential that the decision taken takes into account structural factors the compatibility of equipment and construction accessibility, as well longer-term operational requirements. Romtec Utilities begins retrofits and replacements by identifying the components to be left in place and those which need replacement.
From there, the business creates engineering solutions that are specific to the site, preliminary designs, and budgetary estimates. Prefabricated parts are a great way to organize installation, and reduce the amount of construction work that is required on site.
The project won’t be finished until the pumps start
The modern lift station must operate as a system. Before returning a lift facility to normal service, startup testing, commissioning, and equipment verification are necessary to make sure that all pumps, controls and related equipment operate in accordance with their design.
Operator training, as well as operation and maintenance manuals are equally crucial. Maintenance staff must understand the new equipment, operating procedures, and other documentation before they take over responsibility for the station.
Retrofitting infrastructure effectively preserves its value while fixing the issues that caused modernization.
This means that municipalities as well as facility owners must think beyond immediate repairs. The most successful plan is one that integrates the new equipment with existing structures, provides essential services during construction, and prepares the pumping system for years to come of operation.