The wastewater lift station of a municipality is old. The pumps are nearing the maximum lifespan and the controls are inefficient, as well as the access hatch has damaged. Although the concrete wetwell appears solid in its structure, it is in need of to be upgraded.
Should the station be destroyed? Not necessarily. The more important issue is whether the existing infrastructure is able to support a modern pumping system, without compromising the reliability, accessibility to maintenance or capacity in the future.
Image credit: romtecutilities.com
A thoughtfully designed pump station retrofit can preserve vital infrastructure while replacing components which no longer meet the operational requirements.
Start With the Structure Nobody Would Like to Replace
Wet wells are often the most expensive and difficult component to replace, as they are constructed underground and attached to existing pipes, and vital to wastewater collection.
Retaining a concrete structure which is still functional could help in reducing the excavation and construction.
However, the deterioration of the access hatch can make the decision. Romtec Utilities identifies wet well hatch replacement as a standard retrofit requirement. Instead of gluing a hatch to deteriorated cement, replacing the whole top layer may be a better option. This could increase the accessibility to the structure as well as prolong its usefulness, without having to rebuild the entire wet well.
The engineering of the pump with more power is different
Let’s say a residential area has exploded in size since the original lift station was installed. The current pumps may not be able to deal with increased wastewater flows.
The modernization of a pumping device could be accompanied by higher horsepower equipment, however this isn’t possible without considering the whole system. Higher horsepower pumps might require changes to discharge elbows, piping valves, electrical controls and other parts.
Engineers must also consider the requirements of the hydraulic system, including the flow and head total dynamic. Installing a larger pump without considering the circumstances may cause more issues than it resolves. Making plans for future capacity prior to designing the initial design makes expansion later much easier.
Make sure that the wastewater is kept moving during Construction
Retrofitting a wastewater pump station could be an entirely new challenge. As with other equipment replacement projects, the station will have to remain operational for the duration of construction.
Even if contractors are busy they continue to receive wastewater. According to the project an interim bypass pumping system could be required to sustain service while the existing equipment is taken down or new components are added.
Romtec Utilities accepted this challenge in the Federal Law Enforcement Training Center, Brunswick, Georgia.
The project required the replacement of two old wastewater lifting stations, and maintaining the operation at the facility. The project was able to adapt to existing station footprints as well as operational requirements by using site-specific engineering and modular replacement systems. This case illustrates why the sequence of construction must be considered carefully prior to installation.
When replacement is the better alternative
Some stations may not be suitable for rehabilitation. 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 selection should consider the condition of the structure, compatibility with equipment, construction access, service continuity, and long-term operating needs. Romtec Utilities begins retrofit and replacement projects by determining what components will be retained and which require replacement.
The company creates engineering solutions that are specific to the site initial designs, as well as budgetary estimates. Prefabricated components can be useful to facilitate installation and reduce certain requirements on site.
The project won’t be finished until the pumps begin to run.
Modern lift stations should be able to function as a system. Before returning a lift-station to normal service, startup testing, commissioning, and verification of the equipment are essential to make sure that all pumps, controls, and other equipment are operating according to design.
Training for operators and operation and maintenance manuals are equally crucial. Before taking over responsibility for a station, maintenance personnel must be aware of new procedures, equipment and documentation.
Retrofitting successfully preserves the infrastructure and addresses the limitations which required modernization.
This means that municipalities and owners of facilities need to take a look beyond the immediate fixes. The most successful projects integrate new equipment into existing structures. They maintain essential services during construction and also prepare the pumping systems to run for many years.