A municipality has an outdated wastewater lift station. The pumps are coming to the end of their service life, the controls need modernization and the access hatch has deteriorated. But the concrete wet well remains structurally sound.
Should the entire station be demolished and rebuilt? Not necessarily. The most important question is whether the infrastructure in place can accommodate a new pumping system, without compromising availability, reliability or future capacity.
Image credit: romtecutilities.com
A carefully engineered retrofit of the pump station could preserve the infrastructure’s value while replacing parts which no longer meet the operational requirements.
Start with the structure nobody would like to replace.
It is expensive and disruptive to change the wet well because it is buried in the ground, connected to piping and is essential for wastewater collection.
Retaining a concrete structure which is still functional could minimize the digging and construction.
The degrading of the area around the access hatch might make this difficult. Romtec Utilities identifies wet well hatch replacement as an usual retrofit requirement. Instead of gluing a hatch to deteriorated cement, replacing the whole top layer may be a better option. This can make it easier to access and extend the structure’s usefulness without having to rebuild the entire wet well.
An improved pump changes the way engineers work.
Think about a community that has experienced significant increase since the opening of a lift station. It could be that the pumping system is no longer able to handle increased flows of wastewater.
A pumping station upgrade could involve higher-horsepower pumps, but equipment selection cannot happen independently of the surrounding system.
Engineers should also look at the hydraulic requirements of the system. This includes flow and the total dynamic pressure. A larger pump without evaluating the situation could cause more problems than it solves. Planning future capacity in the designing the initial design makes expansion later significantly easier.
Make sure that the waste water is flowing throughout construction
A retrofit to a wastewater pump station creates a challenge that regular construction projects for new equipment do not have to face: the pump station may require operation through the entire construction.
The water continues to flow even while contractors are working. Depending on the project the temporary bypass pumping might be required to keep services while existing equipment is removed and new equipment is installed.
Romtec Utilities faced this kind of issue at the Federal Law Enforcement Training Center in Brunswick, Georgia.
The project involved the replacement of two of the old wastewater lift stations, while still maintaining the operation of the facility. Site-specific engineering packages, replacement systems for packaged equipment, and bypass pumping techniques helped make room for the station’s footprints as well as operational demands. The scenario illustrates why the sequence of construction should be considered before the construction process starts.
If you think replacement is the better alternative
Each station is not able to be renovated. A seriously damaged wet well structure that is not strong enough, or significant changes to hydraulic requirements might make a the replacement of a sewer lift station better than making changes to the existing structure.
It is crucial that the decision made takes into account structural factors, equipment compatibility and accessibility to construction, as well as long-term operational requirements. Romtec Utilities begins retrofits and replacements by identifying the components to be left in place and the ones that require replacement.
The company also develops engineering solutions specifically for the site, preliminary designs and budget estimates. Prefabricated parts can help to make installation easier and less time-consuming, as well as reduce on-site construction.
The Project Isn’t Complete until the Pumps are Set to Start
The modern lift station must function as a complete system. Before returning the lift station back to service, startup tests and commissioning are a way to make sure that the pumps and controls and other equipment perform as per the established specifications.
Training and manuals for operators are equally crucial. Prior to taking over the responsibility of the maintenance of a station, employees should be familiar with new procedures, equipment and documents.
Retrofitting successfully preserves the infrastructure, while addressing the issues that forced modernization.
Municipalities and property owners have to consider more than immediate repairs. The best projects incorporate new equipment into existing structures to continue to provide essential services during construction. They also make preparations for the pumping system for continued operation for many years.
