Corps to blast river channel

Sharp rock points under the surface of the Mississippi River near Thebes, Ill., will be blasted to deepen the navigation channel, the U.S. Army Corps of Engineers announced Wednesday.

A prolonged drought that has disrupted flows from the Missouri, Mississippi and Illinois rivers is forcing the corps to take extraordinary steps to keep the barge channel at the legally mandated 9-foot depth, corps project manager Leonard Hopkins said. "All three basins are low, and they all happen to be hitting at the same time," Hopkins said.

The work will keep the river open to shipping if the river falls to 0.8 feet on the Cape Girardeau gauge, Hopkins said. At this time, he said, the river is only capable of supporting a 9-foot depth if the Cape Girardeau gauge falls to 3.8 feet. The gauge stood at 7.6 feet and falling Wednesday at Cape Girardeau.

The record low gauge reading in Cape Girardeau is 0.6 feet, set in January 1905. The lowest modern reading was 2.96 feet set Dec. 20, 1988.

The corps is going through the process of soliciting proposals from contractors and evaluating the environmental impact of blasting the rock, Hopkins said. That process should be complete by February, he said, with work beginning soon afterwards and lasting up to 45 days.

Contractors will blast rock at 11 sites from just north of Thebes, Ill., to near Commerce, Mo., with the aim of removing 4,140 cubic yards of rock. The corps will also blast at two additional sites near Grand Tower, Ill., to remove 560 cubic yards of rock.

The rocks have the potential to damage the bottoms of towboats pushing barges in the river. While barges can be raised by carrying lighter loads, corps spokeswoman Nicole Dalrymple said, towboats typically need at least nine feet of water to move safely through the river.

If low water closes the river, barge operators stand to lose $16 million a week, the corps said.

Along most stretches of the river, dredges can remove sand that settles in the navigation channel. But at Thebes and at Grand Tower, the river runs over limestone bedrock that cannot be dredged.

The project at Thebes and Grand Tower will be far smaller than a similar operation in 1988 and 1989 that removed 145,000 cubic yards of rock. A drought in those years caused many gauges along the river to reach record or near-record lows. Hundreds of tows with their barge loads were stranded near Greenville, Miss., on the lower Mississippi River that year. Those conditions are unlikely to be repeated because the Ohio River is running at about three-quarters of its flood capacity.

Low water already caused three towboats to bump the river bottom just south of St. Louis earlier this month.

"We must take all possible measures to prevent damage and protect against harm," St. Louis district commander Col. Lewis F. Setliff III said in a statement.

Low water levels have cause the U.S. Coast Guard to warn towboat operators that run deep to leave the upper Mississippi River, and towboat operators have been told to limit their tows to 36 northbound barges, with only 20 loaded.

Two endangered species live in the region of the river slated for blasting work -- the least tern, a shore bird, and the pallid sturgeon. The least tern is only in the region during spring and summer breeding seasons and the pallid sturgeon is expected to move away from any blasting, the corps said in a prepared statement. In addition, the work will be completed before the spring spawning season for the pallid sturgeon, minimizing the impact on the fish.

Most of the rock to be removed is from locations where work occurred in 1988 and 1989, Hopkins said. Improved scanning equipment revealed rock points missed during the previous work, Hopkins said.

"The technology then couldn't find everything," he said. "It will be a nip here, a tuck there to complete the project and get the channel cleaned up."

rkeller@semissourian.com

335-6611, extension 1