Welcome Plaza-Lift Station 4B Improvements

Gig Harbor, Washington
Sanitary Sewer
City of Gig Harbor
Parametrix Inc.
Stellar J. Construction
Technical Description:
  • Product: DuroMaxx® SRPE Storage System
  • Diameter: 84-in.
  • Length: 84 LF
  • Volume: 23.189 gal.
November 2016

Located in Pierce County, Washington, the City of Gig Harbor is a city dedicated to preserving its unique history and character, even as it undergoes unprecedented growth. Recently becoming a local mecca for tourism, Gig Harbor boasts an expansive history in the boat building and commercial fishing community dating as far back as 1800s when its name was placed on the Wilkes 1841 map. For more than 100 years, fishing and related industries have dominated the rhythm of life in Gig Harbor. The legacy of Gig Harbor’s past, with new modern amenities, restaurants, galleries and shops, can be experienced as you walk along the waterfront.

On September 6, 2016, the City began an extensive construction project to upgrade Lift Station 4 and build a new welcome plaza in Skansie Brothers Park. Lift Station 4 receives approximately one-third of the city’s sewer flow which is pumped to the nearby wastewater treatment plant. As part of the improvement to the Welcome Center/Lift Station, an expansion of the lift station was needed. 

The City selected Parametrix Inc.

to be the consulting engineer for the project. Given the complexity of the system, tight site constraints, and design requirements, Parametrix reached out to Contech Engineered Solutions for their assistance as Parametrix was familiar with solutions provided by Contech and confident one could easily be identified that would meet the design requirements for this project.

Ultimately, a DuroMaxx® steel reinforced polyethylene (SRPE) storage system was selected. The system was designed so that the normal flow would be handled by the half round 16-in. diameter low flow channel which is at the invert of the 84-in. DuroMaxx SRPE storage system. The system was designed to provide excess storage in the event the main and backup pumping systems failed, such as during severe wet weather events. Should the flow rate exceed the capacity of the low flow channel in those high flow occasions, the 84-in DuroMaxx system could then manage the additional flow that the 16-in. pipe was not capable of conveying. 

The low flow channel was certainly a unique aspect of this project. The half round pipe was premanufactured and installed into the 84-in. pipe at the plant to ensure an easy installation of the entire system upon arrival at the site. The DuroMaxx SRPE storage system was delivered in two pieces and welded together at the site by Stellar J Construction.

David Dinkuhn, P.E., Senior Consultant from Parametrix, commented, “I enjoyed working with Contech staff to develop the design for this project. The problem was a bit unique and required a custom approach. The DuroMaxx pipe provided us with the storage volume we needed and fit within the tight confines of the project site. I’d say the project is a solid success.”
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