The municipality has an old wastewater lift station. The pumps are approaching the end of their service lifespan, the controls require modernization, as well as the access hatch has deteriorated. The concrete wet well is solid and sturdy.
Should the entire station be demolished and rebuilt? Not necessarily. It is important to inquire if the system already in place is capable of supporting a modern system of pumping without compromising capacity in the future, reliability, or maintenance accessibility.
Image credit: romtecutilities.com
Retrofitting a pump station can be a fantastic way to save infrastructure, and also replace parts which are no longer in use.
Start with the Structures Nobody wants to replace.
It’s expensive and difficult to change the wet well because it is buried beneath the earth, and is connected to piping and is essential to collect wastewater.
If the concrete structure is functional, it is possible to reduce excavation and construction work.
The loss of space around the access hatch might cause problems with this decision. Romtec Utilities identifies wet well hatch replacement as a typical retrofit requirement. Instead of gluing a hatch to deteriorated cement replacing the whole top layer can be a more durable option. This could increase the accessibility to the structure, and extend its lifespan, without needing to replace the entire structure as well.
A better pump alters the way engineers work.
Consider a neighborhood that has seen significant increase in population since the construction of its lift station. The current pumps might not be sufficient for increased flows of wastewater.
An upgrade to the pumping station could require higher horsepower pumps, but the choice of equipment cannot be made independently of the system in which it is located. To make the pumps more powerful it is possible make adjustments to the discharge elbows or piping. There is also the possibility of having to alter electrical controls and valves.
Engineers should also consider the hydraulic needs of the system. This includes flow and total dynamic pressure. If you add a larger pump and do not consider these aspects this could result in operational problems rather than resolve these. Planning for future expansion during initial design will make it much easier to add more capacity later on.
Check that the waste water is flowing during construction
Retrofitting a wastewater pump station poses a challenge which normal equipment replacement projects may not be able to overcome: the station may need to remain operational throughout construction.
When contractors aren’t busy the wastewater still flows in. According to the type of project the temporary bypass pumping might be necessary to keep the service until existing equipment is removed and new components are put in place.
Romtec Utilities accepted this difficult task in the Federal Law Enforcement Training Center, Brunswick, Georgia.
The project consisted of replacing two wastewater lift stations that were in use in the meantime, and maintaining the operation at the facility. Specific engineering for the site, packaged replacement systems, and bypass pumping strategies were used to adapt to the station’s footprints and operational requirements. This example shows why it is important to take into consideration the sequence of construction before installing.
If you think replacement is the better option
Each station is not able to 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.
The choice should take into account structural integrity, equipment compatibility access to construction along with service continuity and long-term operating requirements. Romtec Utilities begins retrofits and replacements by identifying parts that are to remain and those that need to be replaced.
From there, the company designs site-specific engineering solutions including preliminary designs, as well as budgetary estimates. Prefabricated components are also able to help to organize installation and decrease some on-site construction requirements.
The Project is not Complete When the Pumps Are In Place
The modern lift station must operate as a system. Before returning the lift station back to service, testing its startup and commissioning will help ensure that the pumps, control equipment and other components work in accordance with established specifications.
Both manuals and training for operators are equally important. Before taking over responsibility for a station, maintenance personnel should be familiar with new equipment, procedures and documentation.
Retrofitting infrastructure is a great way to preserve its value, while also addressing limitations that led to modernization.
This means that municipalities as well as facility owners must take a look beyond the immediate fixes. The most successful plan is one that integrates new equipment into existing structures, maintains essential service during construction, and also prepares the pumping system to last for years of continual operation.