The wastewater lift station in municipal facilities is outdated. The pumps have reached the final stage of their life, the controls are outdated and the access hatch is deteriorated. The concrete wet well is structurally sound.
Should the station be removed? Not necessarily. One of the most important questions to ask is whether or not the existing infrastructure will be able to support an efficient pumping system that is in line with current standards without compromising reliability or capacity.
Image credit: romtecutilities.com
Retrofitting pumps that are carefully designed can save valuable infrastructure, and can also help in replacing parts that are no longer in compliance with the operational standards.
Begin with the structure nobody would like to replace.
It is expensive and disruptive to replace the wet-well since it is submerged in the ground and connected to pipes, and is necessary for wastewater collection.
If the concrete structure is serviceable, retaining it may minimize excavation and construction work.
However, the deterioration of the access hatch can make the choice. Romtec Utilities has identified wet-well hatch replacement as a crucial retrofit. Instead of attaching the hatch to cement that is degrading, replacing the whole top layer might be a more durable option. This could increase the accessibility to the structure as well as prolong its use, without the need to rebuild the entire wet well.
A More Powerful Pump Modifies the Engineering
Consider a neighborhood that has experienced a significant increase in population since the construction of the lift station. It’s possible that the existing pumps are no longer able to handle increased water flow.
The improvement of a pumping system may be accompanied by higher horsepower equipment, however this can’t be accomplished without taking into consideration the system around it. To make the pumps more powerful you might need to make changes to the discharge elbows or the piping. There is also the possibility of having to replace electrical controls or valves.
The engineers must also assess the requirements for hydraulics of the system, which includes the flow rate as well as the dynamic head total. Installing a larger pump without studying these factors can lead to problems in operation instead of resolving these. Making plans for future capacity at the time of initial design makes future expansion much easier.
Ensure that the waste water is flowing throughout construction
A wastewater pump station retrofit presents a problem that normal construction projects for new equipment do not have to face: the pump station may need to remain operational through the entire construction.
Wastewater continues arriving even while contractors are working. In the case of a project an interim bypass pumping system may be necessary to keep the service until existing equipment is removed, and new components are put in place.
Romtec Utilities faced this kind of challenge at the Federal Law Enforcement Training Center at Brunswick, Georgia.
The project involved the replacement of two older wastewater lifting stations, and maintaining the operation at the facility. Site-specific engineering and packaged replacement systems and bypass pumping strategies were used to make room for the existing station footprints and operational requirements. This illustrates the reasons why the sequence of construction should be carefully considered before installation.
If replacing is the only option
Each station is not able 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.
In making a final decision, it is important to consider the structural condition of the building, its compatibility with equipment, access to construction, service continuity as well as long-term requirements. Romtec Utilities starts retrofitting and replacing projects by identifying the components that are to be kept and those that need to be replaced.
From there, the company designs site-specific engineering solutions, preliminary designs, and budgetary estimates. Prefabricated components are also useful in arranging installation and decreasing the number of on-site requirements.
The work isn’t done until the pumps begin to run.
Modern lift stations need to be operated as an integrated system. Before returning a lift facility to normal service, startup testing, commissioning, as well as equipment verification are necessary to ensure that the pumps, controls and equipment work in accordance with the specifications.
Both manuals and training for operators are equally important. Maintenance personnel should be familiar with new equipment and operating procedures as well as the necessary documentation prior to taking charge of the station.
Retrofitting infrastructure is a great way to preserve its value, while also eliminating the limitations that prompted modernization.
For facilities owners and municipal authorities this means looking beyond immediate repairs. The most successful projects integrate the latest equipment with the existing structures. They ensure essential services while construction is underway and prepare the pumping systems to run for many years.