Project Overview
The $61.5 M Lockbourne Intermodal Subtrunk Extension Project required extending existing sewer service to the Village of Lockbourne, Northern Pickaway Joint Economic Development District and Rickenbacker International Airport.
Hydro-geological and geophysical studies were performed to select the best technology for tunnel construction that would reduce impacts to nearby residents.
The original design required the microtunneling installation of 10,218-lf. in fourteen reaches. Using a value engineered approach, the subcontractor was able to eliminate several launch and receiving shafts by extending the lengths of the tunnels. In the end, eight runs ranging from 530-1,880-lf. were installed.
Challenges
• Wide mixture of ground conditions and high groundwater
• One microtunnel reach under Big Walnut Creek
• The first and last microtunnels were to be completed with no surface access, thus requiring the use of an airlock chamber
• Restricted hauling hours and designated hauling routes
• Construction depths of 30 feet below ground at the launch site to end at 65-foot depths below ground as a result of ground elevation increasing
Solution
The subcontractor utilized the following Akkerman equipment system to approach the project:
• SL82P Periphery Drive Microtunnel Boring Machine with Face-Access
• AZ100 TGS tunneling navigation system
• Automatic Bentonite Injection System (ABIS) for exact bentonite injection where it was needed
Outcome
• Eight alignments successfully completed with precision accuracy
• Value-Engineered approach reduced the number of launch and reception shafts for cost savings to the owner
