Lift Stations: What They Are and How They Work

While city planners choose the most efficient spot to establish a community’s wastewater treatment plant, it’s not always possible to place it at the most advantageous location, which is usually the community’s lowest point of elevation.

Hills and other natural ground surface changes make it challenging to provide a network of gravity flow sanitary sewers that all drain to the wastewater treatment plant.

This is where lift stations are essential. Lift stations are generally an expensive part of a community’s infrastructure, and city planners minimize their number, but they can be necessary to have. Let’s explore more about what a lift station is, how it works, and what you need to know when it’s time to replace it.

What Is a Lift Station?

Also known as a pump station, a lift station is a set of pumps that is part of a municipality’s wastewater collection system infrastructure. The lift station mechanically pumps wastewater uphill where ground surface topography prevents gravity flow sanitary sewers from being an option.

Lift stations are primarily located underground near the bottom of a hill, at the lowest point of a gravity flow sewer. As the name suggests, they lift wastewater to a higher elevation before it continues flowing downward in gravity-flow sewers toward the treatment facility. Oftentimes, municipalities may need multiple pump stations to move wastewater.

How Does a Lift Station Work?

Lift stations use centrifugal pumps to function. These pumps use electrical power to run intermittently. They can pump hundreds of gallons per minute, depending on the area’s needs and population density.

As a safety feature, modern lift stations use a backup generator that can operate automatically. This allows the station to keep pumping during a power outage, preventing potential wastewater spillage.

What Do Lift Stations Do in the Wastewater Collection Process?

Pump stations are essential, especially if the plant is at a higher elevation than the city’s sewer lines or if there are hills between the wastewater generators and the treatment facility. Without them, development would be limited—or in some cases, impossible.

In short, the wastewater lift station is essential for allowing a city to provide sanitary conditions to its residents.

Where Are Lift Stations Needed?

Suppose houses line the shore of a lake, which is lower than the surrounding area, but the wastewater treatment plant is a mile away and 10 feet higher in elevation. In this scenario and many others like it, the wastewater collection system would need a lift station at its lowest point.

Once the lift station pressurizes the wastewater, the wastewater travels through a force main to its discharge point. This is typically a gravity-flow sewer. Afterward, it continues to move ever closer to the wastewater treatment plant. It’s common for wastewater to be pumped through multiple pump stations, especially in areas with rolling hills.

Types of Lift Stations

There are two primary common types of lift stations: submersible, and wetwell/drywell. While other types of lift stations exist, such as air lift stations, these are less practical in the majority of situations.

Submersible

Submersible lift stations generally consist of two parts; a wetwell that contains the pumps and a valve chamber that contains pipes, valves, and other components. The pumps are located below the water level in the wetwell and can be removed from the surface to facilitate maintenance. Submersible lift stations are favored by most communities for their longevity, low maintenance, and ease of operation.

Wetwell/Dry Well

A wetwell/drywell lift station also consists of two parts; a wetwell whose function is to store a volume of wastewater, and a drywell containing the pumps, piping, and valves. The drywell portion of the station is intended for temporary human occupation when maintaining the station. This style of station is generally reserved for larger lift stations due to the high cost associated with human occupancy of below-ground confined structures.

Types of Pumps

Several different types of pumps exist that can be used in the various types of Lift stations. The three most common are grinder pumps, non-clog pumps, and chopper pumps.

Grinder pumps are small pumps used in low-flow lift stations. As their name suggests, they grind the wastewater before pumping it on its way.

Non-clog pumps are used in lift stations with larger flows. These pump the wastewater without a cutting action.

Chopper pumps, as the name suggests, chop the wastewater to reduce particle sizes of rags and other fibrous material while also providing large flow characteristics.

Ancillary Equipment

Each lift station has ancillary equipment to service the particular need of that lift station. As stated above, emergency generators are often a critical component to provide power when utility power is out due to storms or similar. Other equipment can be a bypass pumping station to accommodate conditions such as a broken forcemain or complete electrical failure due to things such as lightning strikes.

One critical component is the lift station’s control panel which can be thought of as the brain of the lift station. It takes in information and decides things like when to turn a pump on and how long to run it.

Another function of the control panel is to notify the operator when something goes wrong, such as a pump failure. This system often ties into the municipality’s SCADA (Supervisory Control and Data Acquisition System) and notifies a series of people via cell phones that the pump station needs immediate attention.

Lift Station Installation

At F&V, we are experts at designing and installing wastewater lift stations for both municipal and industrial users. Whether you’ve had a lift station installation project on your Capital Improvement Plan for several years, or you have an emergency pipe failure that needs to be addressed immediately, we can help you complete the project to fit your needs.

Here is the process of installing a lift station for your sewer lines at a glance.

How Are Lift Stations Installed?

Lift station installation first requires the expertise of a licensed professional engineer to design the lift station to the appropriate size. Thereafter, the lift station project must obtain the appropriate permits for the work required and will include a state-issued permit. It must also potentially obtain permits for wetland and floodplain disturbance. The number and type of permits needed would be determined during the design phase based on the lift station’s situation.

Construction of the lift station would generally include the following.

1. Digging a Hole: Because lift stations are mostly underground structures, a hole would be dug to the appropriate depth to install the wetwell and/or the drywell and valve chamber. Once the underground structures are constructed, the hole is backfilled. The hole often disturbs existing surface features that could include roads or other utility lines. The impacted infrastructure would be replaced as appropriate.
2. Install the Pumping Components: Once the engineer installs the structures themselves, they will install the lift station’s pumps, piping, and valves. This is also below ground, but is within the wetwell, drywell, or valve chamber structures and is mechanical.
3. Implement the Control Panel and Ancillary Equipment: Thereafter, the control panel can be installed with is usually the only lift station component located above ground. Other above-ground equipment can include the emergency generator, which would also be installed at this step. Once complete, grass is planted and it’s done!

How Much Does It Cost to Install a Lift Station?

Multiple factors can affect the cost of installing a new lift station, the primary of which is the flow the lift station needs to pump. The larger the flow, the more it will cost. A municipality can expect the average pump station to cost between $300,000 and $1 million depending on its location and other factors.

However, the cost can exceed well over this value if flow is high or other complicating factors exist. Our engineers here at F&V are skilled in estimating the costs of pump stations and can assist a community during their annual budgeting.

Other factors that may not be readily obvious can also impact the cost of the project, such as:

• Terrain: Installation of a lift station requires the use of heavy construction equipment, which needs significant room to be used. Sometimes the logistics of getting the equipment to the site can be difficult and expensive. Conversely, a lift station located in an accessible spot will cost less.
• Groundwater:  Sometimes groundwater is present in the hole, which requires dewatering. The cost of dewatering the hole can be expensive, but correct location selection can drastically affect the cost.
• Property rights: Most pump stations must be located on land that the municipality controls. This is sometimes accomplished via property ownership but more often takes the form of a permanent easement which allows the municipality to occupy, maintain, and replace a lift station located on land someone else owns.

Project Funding and Financing

While finding the funds to install a lift station can be challenging for some municipalities, F&V is happy to work with those who may be experiencing financing issues but need a new lift station urgently.

Work with F&V on Your Community’s Lift Station Installation

Want us to be part of your next RFP, or just have questions ahead of your lift station installation project? We can help. Contact Fleis & VandenBrink today and learn why we’re the best choice for your proposed project.