A municipality has an aging wastewater lift station. The pumps are nearing the maximum lifespan and the controls are inefficient as well as the access hatch has deteriorated. The concrete wet well is structurally sound.
Should the entire station demolished and rebuilt? Not necessarily. The more important question to ask is whether or not the existing infrastructure will support the pumping system of modern standards without compromising reliability or capacity.
Image credit: romtecutilities.com
A well-designed retrofit of a pump station can help preserve the infrastructure’s value while replacing parts that do not meet current operational standards.
Begin with the Structure that nobody wants to replace.
The wet well is often one of the most costly and disruptive parts to replace because it is buried, connected to existing piping and is essential to the process of removing wastewater.
Retaining the concrete structure may help in reducing excavation work and construction.
However, damage to the access hatch may complicate the decision. Romtec Utilities says that wet well hatches are often replaced as part of retrofits. It may be more durable to remove the top slab instead of attaching a new hatch onto deteriorated concrete. This method can increase accessibility and extend the structure’s usefulness without the need to replace the entire wet well.
An improved pump changes the engine
Imagine that the area of residence has grown significantly since the initial lift station installation. The existing pumps may no longer provide sufficient capacity for the increasing flow of wastewater.
Pumps that have higher horsepower can be used to improve an existing pumping station, however the equipment needs to fit into the system. Pumps with higher horsepower may require adjustments to discharge elbows, piping and pipework along with electronic controls, valves and other parts.
Engineers must also take into consideration the hydraulic requirements of the system. This is a consideration for flow as well as the total dynamic pressure. Installing a larger pump without checking these parameters can cause problems with operation rather than addressing them. Making plans for future capacity in the initial design process can simplify future expansion.
Keep the water moving during construction
Retrofitting an existing wastewater pump station could be the challenge of a completely new one. In contrast to other replacement projects, the station will require continued operation throughout construction.
Wastewater continues arriving even when contractors are in the process of working. According to the study, a temporary bypass pumping system could be required to sustain service while the existing equipment is taken down or new equipment is installed.
Romtec Utilities fought this kind of challenge in the Federal Law Enforcement Training Center at Brunswick, Georgia.
The project involved replacing two older wastewater lift stations, while still maintaining the operation at the facility. Site-specific engineering and packaged replacement systems and bypass pumping strategies were used to make room for the station’s footprints and operational needs. The scenario illustrates the importance of focusing on construction sequencing prior to installation.
In the event that replacing becomes the best option
Not all stations are suited to be renovated. 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 important that the decision made takes into consideration structural requirements as well as equipment compatibility and accessibility to construction as well being long-term operational needs. Romtec Utilities starts retrofitting and replacing projects by identifying components that will be retained and those that need to be replaced.
From there, the business designs site-specific engineering solutions initial designs, as well as budgetary estimates. Prefabricated parts can also help with installation and can reduce on-site construction requirements.
The project isn’t finished when the pumps start
Modernized lift stations should operate as an integrated system. Prior to returning the lift station to service, tests of startup and commissioning are a way to make sure that the pumps, controls and other equipment perform as per the an approved design.
Training for operators and operation and maintenance manuals are equally crucial. Before they can assume responsibility for the station, personnel responsible for maintenance must know about new equipment, procedures and documents.
A successful retrofit helps preserve structures that are still useful while addressing the issues that forced modernization.
For municipalities and facility owners this means looking beyond immediate repairs. Most successful projects blend new equipment with existing structures. They will maintain the essential services during construction and prepare the pumping systems for a lifetime of operation.