Construction delays are never good news for a community’s residents. The problems only intensify if those delays are related to wastewater lift stations, as a community in South Carolina discovered. The city of Conway received a $6 million grant from the Economic Development Administration in February 2021 for wastewater infrastructure upgrades. Supply chain issues delayed the start of the project, which included increasing the size of the lift station – for two years. Wastewater flooding along a major thoroughfare, Highway 501, left raw sewage floating through some neighborhoods close to the highway.
“One of the worst parts of not only experiencing flooding like that is having raw sewage floating through your yards and homes that you love so dearly,” city spokesperson June Wood told local WMBF News.
Lift station failures are common. In the past two years, communities ranging from Pennsylvania and New York to Louisiana and Texas are among those who have faced problems with failed lift stations. Construction delays—whether they are related to supply chain issues, weather, or unforeseen difficulties—place further stress on already compromised systems.
The community of Northglenn, Colorado, recognized one of its lift stations, called Lift Station A, needed to be replaced. Delays could have led to sewage backups within the community. “The biggest driver on this project was to replace the existing lift station,’’ says David Campbell, the construction manager on the project for Filanc Construction. “It was old and pretty much at the end of its anticipated service life.”
Northglenn replaced its lift station and in a separate project, replaced the city’s biggest sewer line. The combined cost of the projects reached $26 million, including $10 million for the new lift station.
ESTABLISHING WET WELLS
One of the biggest challenges for the Northglenn project was a 54-foot vertical excavation for the wet well on a very tight geographical footprint.
Lift stations require deep excavation to establish wet wells, which are a holding zone for the wastewater collection system. The lift station pump continuously lifts the sewage through a pressurized sewer force main. The force main elevates the wastewater to a higher elevation and pushes it along to the treatment plant.
“Shoring up the excavation and the excavation itself was difficult on this project,’’ Campbell says. “Then we had to complete extensive ground de-watering. Otherwise, it was a straightforward project.”
Filanc has extensive experience in constructing and expanding wastewater facilities. Since its founding in 1952, the company has completed more than 300 projects in California and the Southwest.
PROJECT SCOPE
Construction of the 4.5 million gallon per day (MGD) station included four submersible pumps located in a dual chamber, cast-in-place concrete wet well. A prefabricated electrical and controls building houses switch gears, VFDs and controls. An emergency backup generator—a must-have for any lift station—can provide full electrical loads. Valve and metering vaults, 8- to 24-inch ductile iron pipes, buried site piping and fittings and surge/transient mitigation equipment were also included in Filanc’s scope of work.
“Lift Station A was replaced with a newer, more efficient and easier to maintain model,” Northglenn adds in a message to residents.
ESSENTIAL EQUIPMENT
One essential piece of lift station construction requires access doors to maintain equipment. The Northglenn project includes 14 doors made by BILCO, the manufacturer of specialty access products. Filanc installed fourteen doors that provide safe access to pumps, process pipes and grinders for routine service and maintenance.
“They met the specifications for this project,’’ Campbell says. “BILCO doors are the industry standard are used frequently in projects of this scope.”
The doors, purchased with support from Dalco Industries, feature stainless steel construction and are constructed with a channel frame. They are commonly used in exterior applications where there is concern of water or other liquids entering the access opening. The doors include engineered lift assistance for one-hand operation. They also have a twenty-five-year warranty, which is the approximate service life of most lift stations.
The doors are also made with corrosion-resistant materials, an important distinction in the corrosive nature of the wastewater environment. The pumps must be inspected a minimum of four times a year and are the lifeblood of the system.
Grinders have also become increasingly important for inspection and servicing. Flushable and sanitary wipes have become a major issue for wastewater treatment plants. Grinders reduce pump clogging, improve sludge processing and protect downstream equipment.
DENVER SUBURB
Northglenn sits about 9 miles north of Denver, includes approximately 38,000 residents and more than 500 acres of park systems, hiking trails and magnificent lakeside vistas. The city encompasses about 7.5 square miles and includes more than 37,000 residents. The first residential development in Northglenn was established in 1959 and the city is known for its recreation offerings. The amenities include parks, trails and Croke Reservoir, a top spot for nature lovers to fish, stroll around the lake and observe wildlife is one of the community’s most popular attractions.
Like many communities, however, Northglenn is facing issues with its aging infrastructure. Each year, the town sets funds aside to replace sections of water distribution lines throughout the community. Much of the city infrastructure was installed in the 1960s, and proactive measures will reduce the number of water line breaks, emergency repairs and interrupted water service.
The town is in the midst of a three-year, $6 million project to improvement its handling of solids. About 40 to 60 million gallons of water per year at the Northglenn Water Treatment Facility is transferred to the Wastewater Treatment Plant for processing and return to the watershed.
MUCH-NEEDED PROJECT
The second piece to the project was the installation of a 27-inch force main that runs 11 miles from Force Main A to the wastewater treatment plant. BT Construction completed the project in about ten months. While a temporary inconvenience to the community, the improvements were much needed. No one wants the upheaval that is associated with lift station and sewer line replacement. The alternative, however, is far worse.
“Big infrastructure replacements are messy and disruptive … and also important,’’ civil engineer Michael Roman says in a message to the community. “Frequent sewer line breaks due to aging sewer lines are a lot more disruptive, though, so we really need to get this replacement done.”
PROJECT AT A GLANCE
What: A new $10 million, 4.5 million gallon per day lift station in Northglenn, Colorado.
Why: The existing lift station that served the community of about 38,000 residents reached the end of its useful life.
The challenge: Workers excavated 54-feet on a tight geographical footprint to establish a wet well.
Equipment access: Fourteen corrosion-resistant, stainless steel floor doors from BILCO were included in the project. The doors provide safe access to pumps, process pipes and grinders for routine service and maintenance.
Did you know? A separate project that ran in conjunction with construction of the lift station was the installation of a sewer line to help convey wastewater to a water treatment plant.
FOR MORE INFORMATION
Thomas Renner writes on building, engineering and other trade industry topics for publications throughout the United States. The BILCO Company has served the building industry since 1926. During these years it has built a reputation among architects, engineers, specifiers, and the construction trades for dependability and for products that are unequaled in design and workmanship. For more information, visit www.bilco.com.
MODERN PUMPING TODAY, January 2024
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