Custom equipment25 August 2021
Underground tunnelling projects can often present unforeseen challenges which require innovatively designed equipment to help resolve them
With over 25 years of custom equipment design experience at Robbins and Kiewit, Brian and Cynthia Kelley founded Kelley Engineered Equipment (KEE) in 2007 to meet the growing demand for custom tunnelling equipment. It is now a growing team of more than 30 professionals with a new Seattle office staffed by employees who were previously with a major TBM manufacturer in the US.
Unforeseen challenges present themselves throughout underground projects, and in response engineering services need to be tailored to provide project specific designs for all tunnelling and/or custom equipment requirements. The company says that project challenges drive its innovative designs, and they focus on conquering operational difficulties and safety issues with elegantly simplified designs for complex problems. KEE represents Terratec TBMs in the US and Canada along with Roxard Industries (TBM cutters and soft ground tools) in North and South America.
Outlined below are some of the company’s most recent projects.
Underwater Pipe Carrier
Kelly has partnered with Ballard Marine Construction to develop a novel method of relining large diameter water tunnels. In 2020 the Great Lakes Water Authority (GLWA) contracted Ballard Marine Construction to design, build and repair portions of the Pennsylvania, Springwells, and Northeast raw water tunnels that supply fresh water to the city of Detroit in Michigan. The contract’s purpose is to fix extensive cracking and degradation of the tunnels observed in earlier investigations without interrupting utility functions and services.
Historically, new infrastructure has been constructed to replace failing tunnels. This is of course very expensive, time consuming and can cause extensive service interruptions when the new tunnels are connected. Ballard and Kelley have worked together to create a new method to re-line existing tunnels in-situ, thereby extending the life of the water utility without stoppage of service.
The intent is to utilise a self-powered, mechanised pipe carrier operated by a team of divers to install a stainless-steel liner during off-peak hours without dewatering the tunnel. The Kelley designed pipe carrier is a forklift style design. This means the pipes will be carried on one side of the machine which maximises workspace and minimises machine complexity. This also allows for the carrier to be easily broken up into five sections that will fit through the 2.1m diameter access shaft and can be assembled by the divers under water without making any hydraulic or electrical connections.
Liner segments will be brought down the access shaft and assembled on the carrier. After assembling two rings, the carrier will transport the liners over 259m down the tunnel and install them. After the pipe sections have been installed, they will be grouted in place and become an integral part of the tunnel.
Before deployment to the actual tunnel, the completed car will be tested by divers in full gear at the underwater testing facility at Oregon State University (OSU).
The Silicon Valley Clean Water project takes local collection systems and pumps wastewater to treatment plants located near San Francisco Bay. Kelley designed a pipe placement system including a mobile pipe carrier mating to a rounder and positioner.
The Pipe Placement System is incredibly flexible with the ability to shift in any direction to precisely position a fragile, 6800kg vinyl clad, fiberglass reinforced pipe (FRP) pipe. The rounder and carrier have roughly 40 remotely controlled hydraulic functions including a hydrostatic drive system and hydraulic disk brakes. The functions are all controlled by a radio remote or from the protection of the repositionable operator’s cab. The carrier has a top speed of roughly 16kmh during its trips to and from the shaft to receive pipes. The rounder mostly stays in place and tops out at around 1.6kmh for transport. The carrier has a low-speed mode for precise movement while thrusting the newest pipe section to ensure a trouble-free installation. A large range of motion allows for significant pipe alignment to correct deviations.
Careful consideration was given to the design of the system’s interface with the pipe, ensuring no damage occurs during the installation process.
The fully integrated carrier/rounder system was designed specifically around the fragile nature of the FRP pipe and its natural tendency to sag under its own weight when unsupported. The cleverly designed system includes a self-propelled pipe carrier to deliver the pipe an average of 12km from the shaft and through the tunnel to the previously installed section of pipe. Once it has arrived, it mates with the waiting rounder device to accurately position the bell and spigot connection ends of the respective pipes. When the carrier is in position with the rounder and the joints are adjusted for concentricity, thrust is applied to insert it into the bell of the previously laid pipe.