The wastewater lift station in a municipality is old. Pumps are nearing the end their useful lives, controls need modernization and the access hatch has to be replaced. Although the concrete wetwell appears solid in its structure, it is in need of to be modernized.
Should the entire station be destroyed and rebuilt? Not necessarily. It is important to ask if the infrastructure already in place is capable of supporting a modern system of pumping without compromising future capacity as well as reliability or access.
Image credit: romtecutilities.com
A thoughtfully designed retrofit of the pump station could preserve important infrastructure and replace components which no longer meet the operational standards.
Begin with the structure that nobody would like to replace.
It’s expensive and time-consuming to repair the wet well due to its location in the ground, connected to pipes and essential for the collection of wastewater.
The concrete structure can be retained to help in reducing excavation work and construction.
However, deterioration near the access hatch can complicate your choice. Romtec Utilities says that wet well hatches are usually replaced as part of retrofits. It is possible to be more durable to repair the top slab instead of constructing a new hatch on concrete that has deteriorated. This will allow for greater access to the structure and extend its usefulness, without having to completely rebuild the wet well.
A more powerful pump alters the Engineering
Consider a neighborhood that has seen a substantial expansion since the establishment of the lift station. The existing pumps may not be able to handle the demand for increased flows of wastewater.
A pumping station upgrade could involve higher-horsepower pumps, but equipment selection cannot happen independently of the surrounding system.
Engineers must also take into consideration the hydraulic requirements of the system. This is a consideration for flow as well as total dynamic pressure. In the event of installing a larger pump, not studying these factors can lead to operational issues rather than solving these. Making plans for future capacity at the time of designing the initial design makes expansion later significantly easier.
Make sure that the wastewater is kept moving during Construction
A retrofit to a wastewater pump station presents a problem that normal replacement of equipment projects do not face: the station may need to remain operational through the entire construction.
Contractors continue to work, and wastewater is still expected to arrive. According to the study an interim bypass pumping system might be required to sustain service while the existing equipment is taken down or new components installed.
Romtec Utilities was able to take on this difficult task in the Federal Law Enforcement Training Center, Brunswick, Georgia.
The project involved replacing two old wastewater lifting stations, and maintaining the operation at the facility. Specific engineering for the site, packaged replacement systems, and bypass pumping methods helped accommodate the existing station footprints and operational needs. The example illustrates the need to be aware of construction sequencing before the construction process starts.
When replacement is the better option, replace it.
Not all stations are suited to be renovated. Sewer lift stations might need to be replaced if they have a severely damaged wet well or inadequate structural capacity.
The decision must take into consideration structural health, equipment compatibility construction access, service continuity, as well as long-term requirements for operation. Romtec Utilities begins retrofits and replacements by identifying parts that will remain as well as those that need to be replaced.
The company then develops engineering solutions that are specific to the site, as well as preliminary designs as well as budget estimations. Prefabricated parts can also help with installation and can reduce building requirements that are required on-site.
The Project Doesn’t End When the Pumps Begin to Run
Modern lift stations should be operated as a system in one. Before returning a lift-station to normal service, start-up tests, commissioning and verification of the equipment are essential to ensure that all pumps, controls, and related equipment operate according to design.
Manuals for operation and maintenance along with training for operators, are essential. Maintenance workers must be aware of the latest equipment, operating procedure, and the documentation prior to taking over for the station.
A successful retrofit helps preserve infrastructure that still has value as well as addressing the weaknesses which led to the need for modernization.
For municipalities and facility owners it is important to look beyond the immediate repair. The best projects incorporate new equipment into existing structures to ensure that essential service is maintained during construction. Also, they prepare the pumping system to keep in operation for a number of years.
