Sinkhole problem may level off

The threat of sinkholes is expected to level off as the river level declines, according to Ken Eftink, Cape Girardeau's director of development services.

The prediction comes as the sinkhole task force of the U.S. Army Corps of Engineers, the city of Cape Girardeau and the Missouri Department of Natural Resources finishes its draft report on the causes of the recent wave of 20 sinkholes.

The group met last week and is expected to meet again in the next two weeks to finalize its findings. The final report is scheduled to be released May 31, but Eftink said the date may have to be pushed back because the final draft meeting may not have taken place by then.

The task force's initial idea, according to Eftink, is that last year's drought is thought to have lowered the water table and created weaknesses in the ground near Cape LaCroix Creek. When the Mississippi River flooded this year, water is believed to have been channeled into weakened underground chambers and agitated the surrounding soil. As the river ebbs and the water in flooded soil returns to a normal level, the threat of sinkholes is expected to decline.

The river has been above flood stage, 32 feet, since March 18. The five most recent sinkholes appeared after March 19.

The river has been falling and was at 34.53 feet as of 5 p.m. Wednesday, according to the National Weather Service. It is projected to fall below 34 feet by 1 p.m. today and is expected to be around 30 feet by Monday.

Eftink said he believed that the 20 sinkholes had been filled and that no new ones had developed as of Wednesday.

Representatives of Buzzi Unicem USA, one of the businesses affected by the sinkholes, could not be reached for comment to confirm whether the sinkholes on its property had been sealed.

Techniques involving cement, rock, water, pumped air and gravel have all been used, some with more success than others. When rock was used to fill Sinkhole 14, the rock was swallowed within 30 seconds.

"It just disappeared," Eftink said.

A more successful technique involved pumped air and gravel. Pumping air pushes the gravel into joints to seal off the sinkhole versus just filling the sinkhole with rock. Sinkhole 14 required 15 dump trucks of gravel before it was filled.

Sinkholes have been appearing in Cape Girardeau at an increased frequency since July and have appeared on city property and land owned by Buzzi Unicem USA, SEMO Stone Co., Burlington Northern Santa Fe Railroad, Southeast Missouri Regional Port Authority and AmerenUE. A ruptured AmerenUE gas line and an electric line have been moved because of the sinkholes. The railroad company has also had to repair several tracks.

tthomas@semissourian.com

335-6611, extension 197

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