Omohundro WTP Mass Excavation, Tunneling, and Intakes

Garney Marine is supporting the expansion of the Omohundro Water Treatment Plant, one of America’s oldest water pumping stations, by increasing capacity from 50 MGD to 90 MGD through a new raw water intake system on the Cumberland River. As a subcontractor to Ward & Burke Tunneling Inc., Garney Marine is responsible for all major marine construction activities supporting tunneling operations and installation of the intake system. These activities include riverbed excavation, blasting coordination, MTBM retrieval, underwater pipe and header installation, and tremie concrete encasement. 

As one of only two primary drinking water treatment facilities serving Nashville and nearby communities, along with the K.R. Harrington plant, this project is essential to Metro Water’s long-term plans to meet the needs of a growing population. 

Solutions

Riverbed Excavation & Blasting Coordination: Garney Marine started the project by excavating a 140-foot-by-45-foot-by-25-foot-deep pit in the Cumberland River to install intake pipe headers and screens. The blasting phase required coordination with over 40 organizations, including Metro Water, the U.S. Army Corps of Engineers, the U.S. Coast Guard, the Tennessee Wildlife Resources Agency, CSX, boat rental companies, engineering firms, and environmental consultants.  

MTBM Retrieval & Dive Operations: Garney Marine will support the wet retrieval of two microtunnel boring machines as they enter the underwater excavation. The dive team will conduct alignment checks, install 54-inch blind flanges, assist with MTBM retrieval, and support all subaqueous tie-ins. Divers will also complete bolting and connection work on intake headers and pipe systems in near-zero-visibility conditions. Garney Marine uses sonar, diver cameras, underwater video, and Topcon GPS-equipped equipment to track bucket locations, define excavation limits, and guide precise placement of piping and headers. 

Multi-Contractor Work Zone: Four primary contractors worked simultaneously in a compact project site, requiring ongoing coordination of work paths, access points, equipment staging, and safety zones. 

Project Status

As of Spring 2026, the project has reached its halfway point and is on track to be completed by the end of 2026. Upcoming tasks include setting intake headers, connecting tunnel piping, and completing underwater tremie concrete placement.