A municipality has an outdated wastewater lift station. The pumps are at the limit of their lifespan and the controls are dated, as well as the access hatch has deteriorated. The concrete wet well is sturdy and solid.
Should the entire station be destroyed and rebuilt? Not necessarily. One of the most important questions to ask is whether the current infrastructure will support an efficient pumping system that is in line with current standards without compromising reliability or future capacity.
Image credit: romtecutilities.com
A thoughtfully designed retrofit to a pump station will help protect vital infrastructure while replacing components that are no longer in compliance with operational requirements.
Begin with the Structure that nobody wants to replace.
The wet well is typically one of the more expensive and challenging components to replace because it is hidden, connected to the existing pipes, and crucial to the collection of wastewater.
Intentionally retaining the concrete structure could make it easier to dig and build.
However, damage to the access hatch may complicate the decision. Romtec Utilities says that wet well hatches are often replaced in retrofits. It may be more durable to replace the top slab instead of constructing a new hatch on concrete that has deteriorated. This can make it easier to access and increase the usefulness of the structure without the need to replace the entire wet well.
An improved pump changes the design
Imagine a neighborhood which has seen significant increase in population since the construction of a lift station. The current pumps may not be able with the increasing flow of wastewater.
A change to the pumping station may be accompanied by higher horsepower pumps. However, equipment selection isn’t a part from the rest of the system. Pumps that have higher horsepower might require adjustments to the elbows for discharge and piping, as well as electric controls, valves and other components.
Engineers also need to evaluate the requirements of the hydraulic system, including flow and total dynamic head. If you decide to install a larger pump without considering these factors, it can cause problems with operation rather than addressing these. The planning for future expansions at the time of your initial design process will allow for a much simpler process to build later on.
Keep the water moving during construction
Retrofitting an existing pump station could be a new challenge. Contrary to other equipment replacement projects, the station must continue to operate for the duration of construction.
Even when contractors are working, wastewater continues to arrive. In the case of the project the temporary bypass pumps could be required to keep services during removal and the installation of existing equipment.
Romtec Utilities was able to take on this task in the Federal Law Enforcement Training Center, Brunswick, Georgia.
The project consisted of replacing two older wastewater lift stations while also maintaining the operation of the facility. Specialized engineering on site as well as packaged systems and bypass pumping techniques made it possible to meet existing station footprints and operational needs. The scenario illustrates why construction sequencing deserves attention before the construction process starts.
In the event that replacing becomes the best option
Not all stations are suitable for rehabilitation. 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.
It is crucial that the decision made takes into consideration structural conditions along with equipment compatibility, construction accessibility, as well in the long-term requirements for operation. Romtec Utilities starts retrofitting and replacing projects by identifying the components to be kept as well as those that require to be replaced.
The company then develops engineering solutions specific to the site, as well as preliminary plans and budget estimates. Prefabricated components are also useful in arranging installation and decreasing certain on-site demands.
The Project Isn’t Complete until the Pumps are In Place
A modernized lift station must function as a system in one. Before returning the lift station to service, tests of startup and commissioning are a way to make sure that the pumps, control equipment and other components work in accordance with an approved design.
Both manuals and training for operators are equally essential. Maintenance personnel should be knowledgeable with the new equipment and operating procedures, in addition to the manuals before they assume responsibility for the station.
A successful retrofit will preserve the infrastructure, while addressing the limitations which required modernization.
Municipalities and facilities owners need to consider more than immediate repairs. The most successful projects are those that integrate new equipment into existing structures, and continue to provide essential services while construction is underway. They also plan the pumping system to continue operation for many years.