Construction to widen an Interstate 65 bridge used by many Marshall County residents when driving to Nashville and elsewhere is to be complete this fall.
However, preparations for the work late last year revealed several endangered species of mussels in the Duck River. There were 56 mussels moved because additional support was needed for the wider bridge and such work threatened their aquatic habitat.
That's according to a project manager and a spokeswoman for the Tennessee Department of Transportation who provided information from a TDOT consultant and the Tennessee Wildlife Resources Agency.
By late September or early October, I-65 motorists may expect all lanes open with a wider shoulder for the bridge over the Duck River a couple of miles north of the Highway 50 interchange, TDOT Community Relations Officer B.J. Doughty said.
The four-lane, 300-foot bridge built in 1963 was one of several interstate highway bridges without shoulders wide enough to give some tractor trailer trucks the width that's seen as needed, Doughty said.
"This is one of the last bridges to have this work done," she said of the bridge widening to provide road shoulders. "This makes for a safer structure for motorists, especially tractor trailers carrying wide loads."
Bell & Associates, the Brentwood-based construction company led by Ray Bell, was awarded the $2.5 million contract in December last year.
TDOT Project Manager Billy Potts is overseeing the job and explained that support columns are needed for the wider bridge. While the new columns won't be in the Duck River, there will be work close enough to the water to raise concerns about an effect on aquatic life in the river.
Abiding by federal environmental regulations has become a priority for TDOT in recent years. Examples of how they affect road construction were revealed several years ago when the extension of State Route 840 was halted by a federal judge who realized construction started before permits had been obtained.
"TDOT must go through a large volume of regulatory coordination for projects such as this," according to statements by TDOT Biologist Dennis Crumby as provided by Doughty. "We primarily coordinate with the U.S. Fish and Wildlife Service regarding federally listed endangered species."
TDOT also works with the TWRA, TVA and the Tennessee Department of Environment and Conservation. Private consultants are hired, as well.
"Freshwater mussels were relocated due to construction of bridge piers...," the officials reported. "Luckily, the largest concentration of the endangered mussels (and non-endangered mussels) was upstream of the bridge construction and therefore out of the area of potential harm."
Divers from the TWRA examined the bottom of the river just north of the bridge in October, officials reported. River conditions in that area do not provide the preferred habitat for mussels, so only about a dozen mussels were found.
Better mussel habitat was found by consultants in April just south of the bridge before construction of a new bridge pier. Civil & Environmental Consultants of Franklin reported in May that "A total of 56 live mussels representing 12 species were relocated" in April. They were placed about a quarter mile downstream from the bridge.
"Although the additional [bridge] piers were not located in the stream, their proximity to the stream raised concerns of the possibility of rip-rap or other debris entering the stream during construction," according to ecologists Tim J. Nehus and Jeff T. Duke of the consulting firm that has offices in seven other major American cities.
Given terms of the construction contract, it would appear that both traffic lanes for the I-65 bridge over the Duck River will be open in about 10 weeks.
Traffic has been restricted to the inside lanes of the north-south interstate highway for months. Contractor employees say that will change before the project is finished. The inside lanes of the interstate will be closed for resurfacing after the shoulders are completed.