McIntyre Sewer Extension
Project Overview
In response to the growing development needs in Lansing, KS, the city enlisted GBA’s expertise to design a new gravity sanitary sewer extending from the Nine Mile Creek Interceptor. GBA managed the comprehensive project, which included engineering design and coordination.
GBA’s services include:
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The Solution
As the primary design consultant, GBA spearheaded the project from inception to completion. As part of the Wastewater Master Plan for the City of Lansing, GBA modeled the interceptor sewer from this new development basin to the Nine Mile Interceptor, and evaluated alternative alignments, including pumping and gravity sewer. Through discussions with the City, the gravity sewer alignment was selected.
To serve future developments from this basin, multiple stream crossings would be required. Due to existing sewer elevations on the Nine Mile Interceptor, this would require an aerial sewer elevated above Nine Mile Creek. Although not a preferred alternative, through discussions with the City staff and KDHE, it was selected to enable future growth while not necessitating lowering the entire interceptor at this time. While the new sewer is sized to accommodate all future growth in the watershed, the aerial crossing was downsized to only serve intermediate developments. The City has plans to deepen the Nine Mile Creek Interceptor sewer in the future. This will allow the aerial sewer to be removed and replaced with a more traditional crossing buried beneath the stream bed. This solution accommodates upcoming developments in the City while reducing initial pipe costs. GBA was instrumental in coordinating with KDHE to provide explanation and gain approval for this aerial sewer crossing.
Complexities & Resolution
The most complex part of the project involved navigating alignment challenges to connect with the existing sewer interceptor, while also addressing multiple stream crossings, utility conflicts, sewer depth challenges and the concerns of property owners.
The team handled these challenges through thorough coordination with utilities, evaluating multiple alignment options—including unconventional ideas and those proposed by property owners. GBA’s stream team was able to design stream crossings that will protect the City’s assets long into the future and will maintain the natural environment. By maintaining open communication with the City, the team successfully implemented a solution that effectively tied into the existing sewer, avoided utility conflicts and minimized disturbances. Our stream team
Unique Aspects & Innovations
The project included an innovative aerial sewer crossing including long-span ductile iron pipe to minimize piers within the creek, a 275-foot horizontal bore beneath K-7 Highway and the relocation of a drainage area to optimize long-term protection of the sanitary sewer assets.
Community Impact
The completion of the McIntyre Sanitary Sewer Extension unlocks new development opportunities for Lansing and provides residents with access to municipal sewer connections as an alternative to existing septic systems.
Project Timeline
The conceptual layout of the sewer alignment was done in the City’s Master Plan which was completed by GBA and subsequent South Sewer Study. The design component began in the Fall of 2021. Construction for the project started in the fall of 2023, with expected completion in 2024.