In 2001 when the U.S. Navy Destroyer Mason slid down the incline at the Bath Iron Works’ (BIW) into the Kennebec River, the company closed a chapter in its 117-year history. The inclined ship building technique used by BIW was the same one used to launch ships since Roman times. A new, $241 million Land Level Transfer Facility brought BIW solidly into modern times, and made the company competitive for the federal contracts that drive the U.S. shipbuilding industry.
As a condition of the permits granted for the project, the Maine State Department of Environmental Protection, required BIW to treat stormwater runoff before it reached the Kennebec River. No small task, considering the final wharf structure would be a 14-acre slab of concrete lined with crane ways and ship rails.
According to Tim Reid, project engineer and associate vice president of Moffatt & Nichol Engineers, stormwater treatment at the site required what amounted to a sophisticated plumbing job. “The deck was completely flat, and we needed to figure out how to get the water off of it” said Reid. “But the deck holds such extreme loads that we couldn’t do anything to weaken the structure”
Using a series of sumps, Moffatt & Nichol was able to develop a system to move water along the
slab through a trench network into a series of 14 Vortechs Systems that treat the stormwater. “
Vortechs Systems were pre-approved for use in this application. We could pick an item off the shelf
that we had numbers for, and start with those,” said Reid, “which eased the permitting and kept the process moving along. It turned out that the design of the units was flexible enough that we could specify inlet and discharge locations without causing any problems with manufacturing and delivery schedules”
The Vortechs Systems were easily configured to move and treat the water effectively. They were built into the slab deck of the wharf suspended over the river, and were constructed with “wings” protruding from each end to hang from beneath the platform.
This innovative approach to stormwater treatment will help minimize additional impact of the new facility on the health of the Kennebec River.