The municipality has an old wastewater lift station. Pumps are about to expire their usefulness, the controls need modernization and the access hatch should be replaced. The concrete wet well is sturdy and solid.
Image credit: romtecutilities.com
Do you think the station should be demolished and rebuilt? Not necessarily. The better question is whether the existing infrastructure can support a modern pumping system with no compromise in the reliability, accessibility to maintenance or capacity in the future.
A carefully engineered retrofit of a pump station can help preserve valuable infrastructure while replacing components which no longer meet the operating requirements.
Start With the Structure Nobody Would Like to Replace
It’s expensive and difficult to replace the wet well since it is submerged in the ground, connected to pipes and is vital to collect wastewater.
If the concrete structure is functional, it is possible to reduce excavation and construction work.
However, the deterioration of the access hatch may complicate the choice. Romtec Utilities identifies wet well hatch replacement as an usual retrofit requirement. Instead of affixing a hatch to cement that is deteriorating replacing the entire top layer may be a more reliable option. This could improve access to the structure and prolong its use, without the need to replace the entire structure as well.
The design of pumps that are more powerful is distinct
Take a look at a neighborhood that has experienced a significant growth since the installation of the lift station. It’s possible that the existing pumps are no longer sufficient to handle the increasing flows of wastewater.
The improvement of a pumping system could be accompanied by higher horsepower equipment, however this isn’t possible without considering the surrounding system. Pumps that have higher horsepower might require modifications to the discharge elbows and pipes as well as electric controls, valves and other components.
Engineers must also consider the requirements for hydraulics of the system, which includes the rate of flow and the dynamic head total. Installing a larger pump prior to assessing the requirements could create more problems than it resolves. Making plans for future capacity in the initial design makes later expansion significantly easier.
Make sure the wastewater is 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.
The water continues to flow even while contractors are working. According to the study an interim bypass pumping system is necessary to maintain service as the old equipment is removed, or new parts are installed.
Romtec Utilities was able to address this kind of problem at the Federal Law Enforcement Training Center in Brunswick, Georgia.
The project involved replacing two older wastewater lift stations in the process of maintaining operation at the facility. The site-specific engineering packages, bypass pumping techniques helped accommodate existing station footprints as well as operational requirements. The example illustrates the importance of focusing on construction sequencing before installation begins.
In the event that replacing becomes the best alternative
Not all stations are suitable for rehabilitation. Sewer lift stations might have to be replaced when they have a seriously damaged wet well or a lack of capacity for structural strength.
When making a choice, it is crucial to look at the structural health of the structure, its compatibility with equipment, accessibility to construction, continuity of service as well as long-term requirements. Romtec Utilities begins retrofits and replacements by identifying components to be left in place and the ones that require replacement.
The company can then design engineering solutions specific to the location, including preliminary designs as well as budget estimations. Prefabricated components are also useful to organize installation and reduce certain on-site demands.
The work isn’t over when the pumps begin to run.
Modern lift stations have to be operated as a system in one. Prior to returning it back to normal service, it is necessary to start testing and commissioning ensures that the controls, pumps, and associated equipment perform according to the established design.
Training for operators and operation and maintenance manuals are equally crucial. Before taking on the responsibility of an entire station, the personnel in charge of maintenance must be aware of new equipment, procedures and the documentation.
A successful retrofit preserves the infrastructure, while addressing the weaknesses that forced modernization.
Municipalities and facilities owners need to be aware of the need for more than just immediate repairs. The most successful projects incorporate the latest equipment with the existing structures. They will maintain the important services during construction and also prepare the pumping systems to run for many years.