The Cherokee darter is a tiny fish, less than 3 in. long, found nowhere in the world outside the Etowah River basin; it’s been listed as a threatened species since 1995.
So when the Georgia Department of Transportation let the contract for interchange reconstruction at I-575 and Ga. Highway 20 on the outskirts of Canton, Ga., to low bidder C.W. Matthews Contracting of Marietta in December 2006, DOT Area Engineer Lou Chastain said they were glad to have a contractor with experience dealing with environmental concerns.
“This project is extremely environmentally sensitive. Canton Creek meanders around the entire project and it’s extremely sensitive,” Chastain said. “We have a culvert extension in Canton Creek and a 400-foot bridge over a tributary of Canton Creek. We’re taking some rather unusual steps to protect the species and the habitat.”
The $42.1 million 2.1-mi. (3.38 km) project calls for the reconfiguration of a two-loop design into a full diamond interchange and includes a new bridge over Canton Creek and widening for additional lanes to accommodate increased traffic from development in the area, according to Matthews Vice President of Roadway Division 1 Jeff Shropshire.
“It’s an extremely high traffic area,” Shropshire said. “It has a lot of existing development and a lot of new development coming shortly. The existing configuration is two loop ramps with two straight ramps and we’re constructing a full diamond interchange and retaining the loop ramps, using them to add some capacity. The existing loop ramps are asphalt and we’re going to repave those with concrete pavement.”
Shropshire said his crews are about 30 percent finished with paving and, if plans to modify the existing design work out, the contractor will complete the project, which started in January 2007, well under budget.
“We’ve actually got the mass grading done on the southbound on-ramp, and Stage 1 construction on the existing ramps is about 50 percent done,” Shropshire said. “We’re about to put the concrete paving on Stage 1 and flop traffic and do the other side. Where the bridge is we haven’t done much earthwork since they’re still building the bridge, but they’re probably at about 30 percent complete. They’re still putting in the substructure.”
Shropshire said Matthews is using a variety of subcontractors on the project.
“It’s a fairly standard wall and bridge, and specialty items are usually subbed out,” he said. “We are, as a rule, an asphalt, structures and grading contractor, and if we get a job like this with concrete paving we’ll sub the concrete paving out.”
Blount Sanford Construction of Atlanta is the subcontractor for concrete side barriers, curtain trucking and drainage for temporary barrier walls. D&G Boring of Marietta is handling the jack and bore pipes under I-575, and Pittman Construction of Conyers will handle the concrete paving.
Other subcontractors are working on the bridge caissons. Including subcontractors, Shropshire said, approximately 30 workers are on-site daily. The job has progressed with only minor single-lane closures so far.
Shropshire said the project involves moving hundreds of thousands of cubic yards of dirt.
“It’s a waste job,” Shropshire said. “Just about everything we’ve done now, all the cuts we’ve made, we’ve been able to put in fills on the project’s limits, but we’re going to be wasting dirt in the near future, I think probably around 200,000 cubic yards of waste.”
Shropshire said that Matthews gets most of its equipment from Yancey Bros. Co. On this project earthmoving is done by Caterpillar D6s and D8s.
“Our entire company is made up of Caterpillars,” he said. “On this job we’re running mass grading and loading with a Cat 345 track hoe and hauling with Cat 740 off-road dump trucks, 40-ton off-road trucks. It’s a really typical job with just one 345 track hoe loading three off-road trucks hauling and D6s and D8s placing.”
The atypical parts of the job, according to Area Engineer Chastain, are the ponds Matthews will leave behind at the site.
“As a part of this project we’ve incorporated five separate ponds, three of which will remain after the project is done and become permanent settlement ponds,” Chastain said. “The project has some unique designs. Even after we’re done, most of the storm water involved in the project will end up in one of those ponds, and they’ll serve during construction as temporary settlement basins. After the major drainage system is installed the storm drains from the project will actually empty into those ponds, which will then serve as retention/detention structures as well as filter out some of the less than desirable material before it can enter the creek.”
Shropshire said the environmental concerns make the contractor go the extra mile during construction.
“The warm water streams on this job that have got endangered species involve taking extra steps as far as specific types of permanent sediment basins being built,” he said. “We’re having to mulch every day at the end of the day — whatever we’ve got disturbed has got to be covered up with mulch to protect from erosion, and we’ve got special monitoring specs that require us to monitor the streams in a different way than is typical.
“Typically the monitoring is looking for turbidity, but this monitors the oxygen content in the water and the pH levels. It’s more in-depth than just looking for dirt — it’s also monitoring the quality of the water to make sure the project’s not affecting it.”
Completion is expected in September 2008, but it could come sooner.
“We have designed a fairly large retained earth wall that we’ll hopefully be able to eliminate and possibly save some money, and speed construction as well,” Chastain said.
Shropshire said he’s hopeful as well.
“The R.E. [retained earth] wall that was designed on this job, for an R.E. wall it was huge, 80 feet tall, and we did some investigation before we started work on the wall and found that the material the wall was going to be sitting on was unsuitable,” Shropshire said. “That was expected to some extent — it was already designed to be undercut maybe 4 feet and replaced with rock. We found out it was more like 15 or 20 feet, so what the DOT did was redesign it so that instead of having an 80-foot wall it’ll have a bigger slope.”
The change, if it comes out as a revision, is expected to save approximately $1.5 million.
Shropshire said the project is expected to continue on schedule, and Matthews has suffered no setbacks due to equipment failure so far.
“We have had no breakdowns. Everything so far has been fine. The direction our company has taken is to update equipment at a fairly early age. We keep up with hours and at certain hours, when it’s time for major components to start failing we get new ones before the time comes, so we’ve got a fairly modern fleet and we don’t have that many breakdowns. We do our own service unless it’s a warranty issue and we have to call Caterpillar.” CEG