The Hawaiian Islands, essentially the exposed seamounts in a vast chain of oceanic volcanoes, have a long and fiery history. The volcanoes laid down basaltic bedrock that can sometimes prove to be a challenging substrate for underground construction projects. Tunnels in Hawaii have historically been smaller, of the microtunneling variety.
“I think we have the same problems with aging infrastructure as other municipalities. However, because we are an island state, some of our utilities aren’t as big as on the mainland. There is more opportunity for microtunneling. Big tunnels in Hawaii are not that common. It’s all new to us,” said an official on the project.
The big project being spoken of is Honolulu’s Kaneohe-Kailua Wastewater Conveyance and Treatment plan, which involved a deep, 4.6-km (2.8-mile) tunnel straight through the hard and often abrasive bedrock.
Plans for the tunnel were not straightforward…