The municipality has an old wastewater lift station. The pumps are at the end of their service lifespan, the controls require modernization and the access hatch has degraded. The concrete wet well is structurally sound.

Should the entire station be destroyed and rebuilt? Not necessarily. The more useful question is whether the infrastructure in place is able to support a modern pumping system with no compromise in the reliability, accessibility to maintenance and capacity.

Image credit: romtecutilities.com

Retrofitting a pumping station that is well-designed can help save precious infrastructure and also replace components no longer meeting functional requirements.

Start with the Structures That Nobody Would Like To Replace

Wet wells can be the most costly and disruptive element to replace because they are buried and connected to existing pipes, and crucial to the process of removing wastewater.

If the concrete structure is in good condition, retaining it could make it easier to dig and build.

However, the deterioration of the access hatch may complicate the process. Romtec Utilities identifies wet well hatch replacement as a standard retrofit requirement. It is possible to be more durable to remove the top slab instead of attaching a new hatch to a deteriorated concrete. This technique can be utilized to increase accessibility and enhance the structure’s usability without the need to replace the whole wet well.

A More Powerful Pump Changes the Engineering

Imagine a place that has seen a significant increase in population from the time of the first lift station installation. The existing pumps might not be able with increased wastewater flows.

The upgrade of a pumping system may comprise higher horsepower equipment, but this isn’t possible without taking into consideration the system around it. More powerful pumps may need adjustments to elbows for discharge, piping valves, electrical controls and other elements.

Engineers should also evaluate the hydraulic requirements of the system. This includes the flow rate as well as the dynamic head total. Installing a larger pump prior to assessing the requirements may cause more issues than it resolves. The planning of future capacity at the initial design phase can allow for later expansion much more easily.

Ensure that the waste water is flowing throughout construction

A retrofit of a wastewater pumping station poses a challenge which normal construction projects for new equipment do not face: the station may require operation throughout the construction.

Contractors continue to work and wastewater is still expected to arrive. Depending on the scope of the project the temporary bypass pumps could be required to keep service during removal and installation of existing equipment.

Romtec Utilities tackled this type of problem at the Federal Law Enforcement Training Center in Brunswick, Georgia.

The project involved the replacement of two outdated wastewater lifting stations, whilst maintaining operation at this facility. The project was able to adapt to the existing footprints of stations as well operating requirements using local-specific engineering and modular replacement systems. The case study illustrates the need to be aware of construction sequencing before installation begins.

In the event that replacing becomes the best option

Not every station is suited 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.

When making a choice, it is crucial to look at the structural health of the structure, its compatibility to equipment, access to construction, continuity of service and long-term needs. Romtec Utilities starts retrofitting and replacing projects by identifying the components that are to be kept and those that need to be replaced.

From there, the company designs site-specific engineering solutions including preliminary designs, as well as budgetary estimates. Prefabricated components are also able to help facilitate installation and cut down on building requirements that are required on-site.

The project won’t be finished until the pumps kick in

Modern lift stations should operate as a system. Prior to returning it back to regular service, startup testing and commissioning will help ensure that the controls, pumps, and the associated equipment work according to the approved design.

Training for operators and operation and maintenance manuals are equally important. Maintenance personnel should be knowledgeable with the latest equipment as well as operational procedures, as well as the manuals before they assume responsibility for the station.

Retrofitting infrastructure is a great way to preserve its value, while also addressing limitations that led to modernization.

Municipalities and facilities owners need to be aware of the need for more than just immediate repairs. The strongest project is one that integrates new equipment with existing structures, provides essential services throughout construction, and prepares the pumping system to last for years of continued operation.