A disused wastewater liftstation can be situated in a municipality. The pumps are at the maximum lifespan and the controls are dated and the access hatch is deteriorated. However, the concrete wet well remains structurally sound.
Do you think the station should be completely destroyed? Not necessarily. One of the most important questions to ask is whether the current infrastructure can accommodate the pumping system of the latest standards, without compromising reliability and capacity.
Image credit: romtecutilities.com
Retrofitting an existing pump station can be a fantastic method to preserve infrastructure, and also replace parts that are no longer functioning.
Begin with the structure nobody would like to replace.
The wet well is typically one of the most costly and difficult components to replace as it is located underground, linked to existing pipes, and crucial to the process of removing wastewater.
If the concrete structure is in good condition, retaining it could minimize excavation and construction work.
However, damage to the access hatch could affect the decision. Romtec Utilities identifies wet well hatch replacement as an usual retrofit requirement. Instead of gluing a hatch to cement that has deteriorated, replacing the entire top layer can be a more durable option. This could increase the accessibility to the structure and prolong its lifespan, without needing to replace the entire structure as well.
A More Powerful Pump Changes the Engineering
Consider a neighborhood that has experienced a significant increase since the opening of the lift station. It’s possible that current pumps are not adequate to handle the increase in water flow.
A pumping station upgrade could involve higher-horsepower pumps, but equipment selection cannot happen independently of the surrounding system.
The engineers should also take into consideration the requirements for hydraulics of the system, such as flow rate and dynamic head total. A larger pump prior to assessing the requirements could create more problems than it solves. Planning for future expansion during initial design will make it much easier to build later.
Make sure that the waste water is flowing throughout construction
A retrofit to a wastewater pump station poses a challenge which normal equipment replacement projects may not have to face: the pump station may need to remain operational during construction.
The water continues to flow even when contractors are working. Depending on the project an interim bypass pumping system may be necessary to ensure the service until existing equipment is removed, and new equipment is installed.
Romtec Utilities addressed this type of challenge in the Federal Law Enforcement Training Center in Brunswick, Georgia.
The project consisted of replacing two wastewater lift stations that were in use as well as maintaining the operation of the facility. The project was able to adapt to the existing footprints of stations as well operating requirements using specific engineering for the site and system for replacement that is packaged. The example illustrates why the sequence of construction should be considered prior to installation.
When the Alternative is the Best Alternative
Some stations are not suitable for rehabilitation. If the sewer lift station is in need of replacement because of a damaged well, structural problems or significant changes to hydraulic requirements, it might be better to replace than modify.
When making a choice, it is important to consider the structural health of the structure, its compatibility with equipment, its accessibility to construction, continuity of service and long-term needs. Romtec Utilities begins retrofit and replacement projects by determining which elements will remain and which ones require replacement.
From there, the firm designs site-specific engineering solutions, preliminary designs, and budgetary estimates. Prefabricated components are also able to help organize installation and reduce some needs for construction on site.
The work isn’t done until the pumps begin to run.
The modernized lift station should operate as a system. Before returning it to regular service, startup testing and commissioning helps ensure that the controls, pumps as well as the equipment that is associated with them, are in accordance to the established design.
Manuals as well as training for operators are equally essential. Before taking on the responsibility of a station, maintenance personnel must understand new procedures, equipment and documentation.
Retrofitting infrastructure can preserve its value, while also fixing the issues that caused modernization.
This means that municipalities and facility owners need to consider more than just immediate repairs. The most effective project is one that integrates new equipment with existing structures, maintains essential services throughout construction, and then prepares the pumping system for years of continual operation.