The sewer lift station of an urban municipality is old. Pumps are advancing towards the end of their usefulness, the controls require modernization, and the access hatch has to be replaced. However, the concrete wet well remains solid and sturdy.
Should the station be gone? Not necessarily. It is more important to determine if the infrastructure in place can support an advanced system of pumping without compromising capacity in the future and reliability or maintenance accessibility.
Image credit: romtecutilities.com
Retrofitting an pumping station that has been well-designed can help save precious infrastructure and also replace components that no longer meet operating requirements.
Start with the structure nobody would like to replace.
It’s costly and inconvenient to change the wet well due to its location in the ground and connected to pipes and essential for the collection of wastewater.
Intentionally retaining the concrete structure could reduce excavation work and construction.
But, any deterioration that occurs around the access hatch may complicate the decision. Romtec Utilities says that wet well hatches are typically replaced in retrofits. Instead of attaching the hatch to deteriorated cement replacing the entire top layer might be a better option. This option can ease access and enhance the utility of the structure without the need to replace the entire wet well.
A More Powerful Pump Modifies the Engineering
Imagine that the area of residence has grown significantly since the lift station’s initial installation. The existing pumps might not be able to cope with the increased flow of wastewater.
A pumping station upgrade could involve higher-horsepower pumps, but equipment selection cannot happen independently of the surrounding system.
Engineers should also consider the hydraulic requirements of the system. This includes flow and the total dynamic pressure. Installing a larger pump before evaluating the conditions could cause more problems than it resolves. Planning future capacity at the time of initial design makes future expansion much easier.
Check that the waste water is flowing during construction
Retrofitting an existing pump station may present a new challenge. Contrary to other equipment replacement projects, the station will have to remain operational during construction.
Even when contractors are at work. According to the study, a temporary bypass pumping system is required to ensure service is maintained as the old equipment is removed, or new components installed.
Romtec Utilities tackled this type of challenge at the Federal Law Enforcement Training Center at Brunswick, Georgia.
The work involved replacing two old wastewater lift stations in the meantime, and maintaining the operation at the facility. Specific engineering for the site and packaged replacement systems and bypass pumping strategies helped adapt to the station’s footprints and operational demands. This example shows why it is crucial to consider the construction sequence before installing.
If you think replacement is the better alternative, then replacement is the best
Not all stations are suitable to be renovated. If the sewer lift station is in need of replacement because of a severely degraded well, structural limitations or significant changes to the hydraulic requirements, it could be better to replace than modify.
The selection should consider structural condition, equipment compatibility access to construction, service continuity, and long-term operational requirements. Romtec Utilities begins retrofits and replacements by identifying elements that will remain as well as those which need replacement.
From there, the company designs site-specific engineering solutions as well as preliminary designs and budgetary estimates. Prefabricated components help make installation easier and less time-consuming, as well as reduce the time spent on construction.
The Project Doesn’t End When the Pumps Start
Modern lift stations need to be operated as an integrated system. Before returning a lift-station to normal operation, initial tests, commissioning as well as verification of equipment are required to ensure that the pumps, controls and other equipment are operating in accordance with their design.
Manuals for maintenance and operation and training of operators, are essential. Prior to taking over the responsibility of the maintenance of a station, employees must know about new procedures, equipment and also the documents.
A successful retrofit preserves the infrastructure, while addressing the weaknesses that required modernization.
For facility owners and municipalities this means looking beyond immediate repairs. The best initiatives are those that incorporate the latest equipment in existing structures, and ensure that essential service is maintained during construction. They also make preparations for the pumping system so that it can continue in operation for a number of years.