The sewer lift station of the municipality is old. The pumps are at the final stage of their life, the controls are outdated, as well as the access hatch is degraded. But the concrete wet well remains robust and solid.
Image credit: romtecutilities.com
Should the station be completely destroyed? Not necessarily. The most important question is whether the infrastructure in place can accommodate a new pumping system with no compromise in security, maintenance access or capacity in the future.
A carefully engineered retrofit of the pump station could preserve important infrastructure and replace components that do not meet current operational requirements.
Start with the Structures That Nobody Would Like To Replace
Wet wells are usually the most expensive and difficult component to replace as they are submerged and linked to existing pipes and are essential to the collection of wastewater.
The concrete structure can be retained to make it easier to dig and build.
But, any deterioration in the vicinity of the access hatch can complicate your decision. Romtec Utilities identifies wet well hatch replacement as a typical retrofit requirement. Instead of affixing a fresh hatch to a damaged concrete structure and replacing the entire top slab might offer a more long-lasting solution. This method can be used to improve access and the structural’s functionality without the need for rebuilding the whole wet well.
A better pump alters the design
Take a look at a neighborhood that has experienced significant growth since the installation of the lift station. Existing pumps may not be able with increased wastewater flows.
The modernization of a pumping system could include more horsepower, but this cannot be done without considering the entire system. Pumps with higher horsepower may require adjustments to the elbows for discharge and piping and electrical controls, valves, and other parts.
Engineers should also consider the hydraulic needs of the system. This includes flow and the total dynamic pressure. Installing a larger pump prior to assessing the requirements can cause more problems than it resolves. Making plans for future capacity in the initial design makes future expansion much easier.
Keep 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.
Even when contractors are in the process of working. Depending on the project, temporary bypass pumping may be required to maintain the service until existing equipment is removed and new equipment is installed.
Romtec Utilities embraced this challenge at the Federal Law Enforcement Training Center, Brunswick, Georgia.
The project required the replacement of two aging wastewater lifting stations, whilst maintaining the operation at the facility. Specific engineering for the site packages, replacement systems for packaged equipment, and bypass pumping strategies were used to allow for the station’s footprints as well as operational needs. The example illustrates why the sequence of construction should be considered prior to the installation process begins.
In the event that replacing becomes the best option
Each station is not able to be restored. A severely deteriorated wet well or a structural weakness or significant changes to hydraulic requirements could make an upgrade to a sewer lift station more appropriate than modifying the current installation.
The decision should account for structural condition, equipment compatibility, construction access along with service continuity and long-term operational requirements. Romtec Utilities starts retrofitting and replacing projects by identifying components that are to be kept and those that will need to be replaced.
The company then develops engineering solutions specifically for the site, preliminary designs and budget estimates. Prefabricated components are also beneficial to facilitate installation and reduce some on-site requirements.
The work isn’t done until the pumps begin to run.
The modern lift station must function as a complete system. Prior to returning the lift station back to service, tests of startup and commissioning tests will ensure that the pumps, control equipment and other components are performing according to approved design.
Training for operators and operation and maintenance manuals are equally crucial. Maintenance staff must understand the latest equipment, operating procedures and other documentation before they take over responsibility for the station.
A successful retrofit will preserve the infrastructure while also addressing the weaknesses that led to the need for modernization.
Municipalities and owners of facilities must look beyond immediate repair. The most successful plan is one that integrates new equipment into existing structures, keeps up with essential service throughout construction and also prepares the pumping system to last for years of continuous operation.