Upgrading Aging Wastewater Infrastructure

Colorado community’s proactive approach eliminates potential problems with major lift station and sewer line

Upgrading Aging Wastewater Infrastructure

The replacement of Lift Station A in Northglenn, Colorado, was part of a larger project that included replacing the city’s largest sewer line. The combined project cost $26 million and took almost 18 months to complete.

Photography by Jenn Bakker

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Wastewater lift stations aren’t designed to last forever, and there are plenty of examples of communities suffering the consequences of delayed improvements. 

For one Colorado community, failure was not an option. The city of Northglenn recognized a major lift station was in serious need of an overhaul. 

Along with the lift station, the city also replaced its biggest sewer line. All told, the combined cost of the projects reached $26 million and required nearly 18 months to complete. The lift station replacement cost $10 million.

“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.”

Complete overhaul

Northglenn sits about 25 miles north of Denver, includes approximately 38,000 residents and more than 500 acres of park systems, hiking trails and magnificent lakeside vistas. Locales such as Northglenn and all they offer are part of the reason the state’s population has surged 34% since 2000, according to data from USAFacts.

The construction of Lift Station A in Northglenn, a 4.5 million gpd 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, variable-frequency drives 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. 

While no project is routine, 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. 

“We did increase capacity to a degree, but for the most part it was about replacing the station,’’ Campbell says.

Digging deep

Lift stations require deep excavation to establish wet wells, which are a holding zone for the wastewater collections 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. 

One of the biggest challenges for the Northglenn project, however, was a 54-foot vertical excavation for the wet well on a very tight geographical footprint. 

“Shoring up the excavation and the excavation itself was difficult on this project,’’ Campbell says. “Then we had to complete extensive ground dewatering. Otherwise, it was a straightforward project.”

Accessing equipment

One essential piece of lift station construction requires access doors to maintain equipment. Filanc installed 14 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 feature stainless steel construction 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. The corrosion-resistant materials were an important consideration in the wastewater environment. 

The pumps, which serve as the heartbeat of the lift station, must be inspected a minimum of four times a year. Grinders have also become increasingly important and require regular inspection and service. Flushable and sanitary wipes have become a major issue for wastewater treatment plants. Grinders reduce pump clogging, improve sludge processing and protect downstream equipment.

Down the line

Northglenn selected another industry veteran for sewer pipe installation. 

BT Construction has supported construction projects and completed more than 1,500 of them in Colorado since 1980. BT worked with Northglenn officials to blunt impact within the community. 

“Big infrastructure replacements are messy and disruptive … and also important,’’ civil engineer Michael Roman said 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.”

The work was done in sections and took about 10 months to complete. Lift Station A collects nearly all sewage from Northglenn and pumps it through the line, called Force Main A, to a wastewater treatment plant. The 27-inch force main runs 11 miles from Lift Station A to the plant, where it is treated before being discharged into Big Dry Creek and Bull Canal for agricultural irrigation. About three blocks along Force Main A required a new sewer line.

Down and dirty

A lift station can fail by either a force main break, power outage or pump failure. They are also susceptible to clogs from fats, oils and greases generated by restaurants and businesses. 

When the system fails, wastewater collects in the lift station wet well and backs up into the collections system. The result is sewer backups into homes or overflow from the lift station into the surrounding environment. 

Most failures are due to age or lack of maintenance. The new lift station and force main are part of Northglenn’s goal to keep its infrastructure operating at peak performance, but the community is not stopping there. 

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. The town is in the midst of a 3-year, $6 million project to improve its handling of solids.

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 waterline breaks, emergency repairs and interrupted water service. 

While the costs for wastewater infrastructure improvements are pricey, the consequences of delays are severe. Northglenn took important steps to ensure its community has safe and reliable solutions for managing its wastewater and avoid a messy situation that has impacted many other municipalities.


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