Supporting Earth’s Ecosystems, Underwater Protection
“By using a galvanized coating, the team would not be introducing disruptive or harmful elements into the ecosystem.”
The nation’s system of 2.2 million miles of underground pipes that deliver safe, reliable drinking water is underfunded and with a water main break every two minutes, an estimated 6 billion gallons of treated water every day is lost. Replacement of damaged tunnels requires long lead-times, service interruptions and large investments. When contracted to address portions of Detroit’s freshwater tunnels in 2018, Ballard Marine Construction collaborated with Kelly Pipe to develop an innovative solution. Rather than replacing the cracking and degraded portions of the tunnel, they worked together to create a method of relining the existing structure. This new process would extend the life of the water utility without interruptions to service for a lower price.
The new 2512-01 underwater pipe carrier was designed to assist a team of divers with the installation of stainless-steel liner plates during off peak hours. The forklift style device is broken down in to five sections that fit through 7’ diameter access shafts and are easily assembled by the divers underwater. Liner segments are also brought down the shaft and assembled on the carrier for transportation to the installation point hundreds of feet down the tunnel. After installation, they are grouted in place and become an integral part of the tunnel.
The carrier had to be operational when fully submerged, creating technical challenges related to electrical safety and protection from the water itself. With several steel components included in the design, project members realized hot-dip galvanizing would be the best option since others were limited due to the harsh environment, rugged work requirements and safety of the drinking water. A galvanized coating does not produce pinholes due to its tightly bonded intermetallic zinc layers. Zinc is also a naturally occurring element that already exists in the environment and would not be introducing disruptive or harmful elements into the ecosystem, so it remained the most logical of all options.