Complex Flooding Issues in Alaska Town Leads to Unique Lift Station Design

Overview: August 2024 – Stormwater – Upgrade of the system to accommodate storms and mitigate flooding. If the flooding wasn’t addressed then the problem would continue potentially affecting homes, utilities, and infrastructure. With existing utilities, a stepped-down wet well was utilized to prevent any problems with those utilities.

Category: Blogs, Water/Wastewater, Case Studies March 20, 2025

Intended Audience: Water sector, public works sector, flooding issues. Beginning/Middle

Objective: An existing development that was built in the late 1970s and early 1980s in Eagle River, Alaska was having issues with flooding during storm events and in the spring when there were additional freeze-thaw events.

Description of System: An existing development that was built in the late 1970s and early 1980s in Eagle River, Alaska was having issues with flooding during storm events and in the spring when there were additional freeze-thaw events. In 2008, a flood caused damage to residents in the existing development. Later in 2011 drainage work included installing two 36” pipes leading to the state drainage system along the Glenn Highway. Even with the addition of the larger drainage system, flooding was still an issue.

A civil engineer reached out to Romtec Utilities for assistance with the design and supply of a stormwater lift station to help alleviate the flooding issues. Eagle River’s Public Works Street Maintenance Division was the driving force behind the use of lift station in place of any other potential options. Refer to Figure 1 below for a location overview.

Figure 1: Location overview of site

Description of Intervention: “Though this “fix” was working adequately the need to put the water subsurface was definitely a need as our department struggled in the spring with freeze thaw weather accompanied with surface drainage [creating] some potential flooding issues to some property owners.” Deput Director of Public Works Eagle River Street Maintenance, Tony Winsor said.

This led them to search for a company to design a lift station to solve these problems.

“The project was rather problematic with the footprint and depth of the hole (with running ground water) for the lift station, coupled with the volume and location of underground utilities, weaving in, out, over, and under was interesting for sure,” Winsor said. “All in all, a very challenging project but fun for the crew.”

There were several underground power and communications lines in the area where the lift station needed to be located. The crew doing the excavation work for the project had to be very careful and move the underground utility lines out of the way to facilitate the lift station installation.

Design pumping rate is 4.8cfs, draining from an area of about 30 acres. The lift station receives flows from gravity storm drains and pumps to an existing vault. Flows will then gravity feed to a treatment system. There is an existing stormwater bypass on-site sized for the 100-year storm event. Due to this being an existing development, existing utilities were a concern for the overall design. Groundwater is estimated at 6′-8′ below finish grade.

Summary of Results: The final design of the lift station includes a “stepped” down wet well ID going from 12′ ID at the bottom and then reduced to 8′ ID closer to the finish grade. This is due to a very tight site with lots of existing utilities.

The stormwater lift station features duplex 15hp submersible pumps, a primary controller, a backup controller, primary level sensing is with a pressure transducer, and backup level sensing with two float switches. See Figure 2 below. The SCADA system was a cellular autodialer.

Figure 2: Cross-section of the wet well

Conclusion: This lift station was able to solve flooding issues by dealing with surface drainage, freeze thaw, and weave through complicated underground existing utilities.

Written by:
Josh Gaunt, Content Writer, LinkedIn
Year of Publication: 2025