A municipality is home to an aging wastewater lift station. Pumps are about to expire their useful lives, controls need to be modernized and the access hatch has to be replaced. Although the concrete wetwell is structurally sound, it’s time to be modernized.
Image credit: romtecutilities.com
Should the station be completely destroyed? Not necessarily. The better question to ask is whether the existing infrastructure will be able to support a pumping system that meets modern standards without compromising reliability or capacity.
A carefully engineered pump station retrofit can preserve important infrastructure and replace components which no longer meet the operational standards.
Begin with the structure nobody would like to replace.
The wet well can be one of the most costly and disruptive parts to replace, as it’s submerged, connected to existing piping, and vital to wastewater collection.
If the concrete structure remains in good condition, retaining it could make it easier to dig and build.
However, damage to the access hatch could complicate the decision. Romtec Utilities says that wet well hatches are usually replaced as part of retrofits. Instead of attaching a hatch to cement that is degrading replacing the whole top layer could be a more durable option. This approach can be employed to increase access and improve the structure’s usability without the need for rebuilding the whole wet well.
The design of pumps that are more powerful is different
Imagine that the area of residence has exploded in size since the initial lift station installation. The current pumps may not be able with the growing flow of wastewater.
The improvement of a pumping system may be accompanied by higher horsepower equipment, however it is not possible to do this without considering the whole system. For more powerful pumps, you may need to make changes to the discharge elbows, or pipes. There is also the possibility of having to replace electrical controls or valves.
The engineers should also take into consideration the requirements for hydraulics of the system, such as the flow rate as well as the dynamic head total. The installation of a bigger pump without considering the circumstances could create more problems than it resolves. Planning for future capacity during the initial design process can allow for later expansion much more easily.
Keep the Wastewater Moving During Construction
A wastewater pump station retrofit introduces a challenge that ordinary equipment replacement projects may not face: the station may need to remain operational throughout construction.
Wastewater continues arriving even when contractors are at work. According to the scope of the project temporary bypass pumps might be needed to maintain service during removal and installation of the existing equipment.
Romtec Utilities accepted this challenge in the Federal Law Enforcement Training Center, Brunswick, Georgia.
The work involved replacing two of the old wastewater lift stations as well as maintaining the operation at the facility. The site-specific engineering packaging systems, packaged systems and bypass pumping techniques allowed for the existing station footprints and operational needs. This illustrates why the sequence of construction must be considered carefully prior to installation.
If replacing is the only alternative
Some stations are not suitable to be renovated. If the sewer lift station is in need of a replacement due to a badly deteriorated well, structural constraints, or significant changes in hydraulic requirements, it might be better to replace than alter.
Before making a decision it is important to consider the structural condition of the structure, its compatibility to equipment, the accessibility to construction, continuity of service and long-term requirements. Romtec Utilities starts retrofitting and replacing projects by identifying components to be kept as well as those that require to be replaced.
From there, the company creates engineering solutions for specific sites, preliminary designs, and budgetary estimates. Prefabricated parts can also help with installation and can reduce needs for construction on site.
The Project isn’t Fully Complete Until the Pumps are Beginning
Modern lift stations have to be operated as an integrated system. Before returning a lift-station to normal service, restart testing, commissioning, as well as equipment verification are necessary to make sure that all pumps, control systems, and equipment work in accordance with the specifications.
Training and manuals for operators are equally important. Before they can assume responsibility for a station, maintenance personnel must know about the latest equipment, procedures, and also the documents.
An effective retrofit will preserve infrastructure that still has value while addressing the issues which led to the need for modernization.
For facility owners and municipalities this means looking beyond immediate repairs. The best projects are those that integrate the latest equipment in existing structures, and continue to provide essential services during construction. Also, they prepare the pumping system to keep in operation for a number of years.