Sinkhole causes problems for city, businesses along South Sprigg

Friday, October 12, 2007
A crew of workers pumped grout into a sinkhole just off South Sprigg Street on Thursday. (Aaron Eisenhauer)

Broken gas lines. A collapsing road embankment. A quarry filling with water.

Those are the symptoms of an aggravating sinkhole problem along South Sprigg Street in Cape Girardeau that city officials will try to address by bringing federal agencies, elected officials and businesses together next week.

The trouble began at about 10 p.m. on July 7, when employees at the Cape Girardeau Waste Water Treatment Plant smelled a strong odor of gas. Collapsing ground ruptured a six-inch AmerenUE gas main, sending city firefighters and utility maintenance employees scurrying to contain the potentially dangerous leak.

Late last month, the embankment along South Sprigg Street just north of the Cape La Croix Creek bridge gave way. City workers shored it up with concrete and large rocks.

Around the same time, the quarry at Buzzi Unicem's cement plant was filling with seeping groundwater faster than the pumps could remove it, said Steve Leus, plant manager. The company hired a contractor to put a concrete plug in the streambed of Cape La Croix Creek, and crews are continuing to pump grout into the ground to prevent additional seepage.

The city has identified numerous depressions that have formed in fields and along the road, said Tim Gramling, Cape Girardeau public works director. One was six or seven feet in diameter and about six feet deep, he said. Another was bigger, about 16 feet wide by 17 feet deep, he said.

The bridge over Cape La Croix Creek is safe, he said, but city crews are monitoring it for any signs that it, too, is sinking.

"We have our survey crews going out to check that bridge over Cape La Croix Creek, monitoring it on a weekly basis and taking some elevation shots," he said.

To better understand the magnitude of the problem, city manager Doug Leslie called a meeting for Tuesday afternoon that will bring together representatives of Ameren, Buzzi Unicem, Burlington Northern, federal agencies and members of Congress. The city needs to understand the long-term outlook, he said, and what could be done to prevent further damage to property.

"What we need is expertise," Leslie said. "It is a highly complicated, very expensive process, and it is not something we have the resources to do or the knowledge to do."

Sinkholes occur when groundwater dissolves the limestone underneath the soil. At some point, when the rock is weakened, it gives way and the ground above collapses into the void. Buzzi, formerly Lone Star Industries, has been dealing with the effects of that process for decades, Leus said. At various times, the company has used sandbags, rock and cement to plug holes in the streambed and embankments along Cape La Croix Creek to slow or stop the infiltration of water into the company's quarry, he said.

"I don't know how many times since the 1980s we've had to deal with it," Leus said. "We used to throw sandbags into the holes. It is nothing really new."

The gas line that ruptured was a main feeder line for AmerenUE's gas service to Cape Girardeau, said Mike Wetherell, superintendent of gas services for the region. The break interrupted gas service briefly to only two customers -- the Shrine Club building and a mobile home across the street, he said.

To prevent further disruptions, Ameren shifting about 1,600 feet of the pipeline as well as a 34-kilovolt electric transmission line to the west. Both lines will now run between Sprigg Street and the Burlington Northern railroad line through the effected area, Wetherell said.

"We basically just figured it was the best option we could do," Wetherell said. "We have completely relocated out of the area."

Moving the electric line was not a problem, but finalizing the relocation of the gas line requires cooperation from Burlington Northern, Wetherell said, and negotiations are continuing to obtain the needed permission.

No one is sure why the ground is more active at this particular time. Sinkholes often open up after a period of extremely wet weather. With the ongoing rainfall shortage, the lack of moisture could also be to blame, said Kent Bratton, former city planning director and a trained geologist.

"It happened over at Farmington from time to time in dry conditions," Bratton said. "The moisture and the water in the soil dries out, and the water helps hold the soil together. When it is dry, it is not as cohesive."

The city must take the lead on solving, or at least mitigating. the sinkhole problem, said Mayor Jay Knudtson. The federal agencies and representatives are being included in the discussions because they have the expertise and resources to help. "I'm just trying to make sure our federal folks know how potentially severe a situation we have so they can stand ready should we need financial assistance," Knudtson said. "Even if you figure out the solution, on a $50 million budget, you can't underwrite those costs."

A major aim of any project to address the sinkholes, Knudtson said, is to keep Buzzi operating. Buzzi is a major employer and the largest single consumer of electricity in Cape Girardeau, he noted. The cement plant is owned by an Italian parent company, and Knudtson doesn't want the sinkholes to be an excuse for the company to shut down.

"If their parent company makes a decision to shut down or relocate, we have a major issue on our hands," Knudtson said.

rkeller@semissourian.com

335-6611 extension 126

pmcnichol@semissourian.com

335-6611 extension 127

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A white minivan drove past a sink hole next to South Sprigg Street that has been filled with gravel and stones. (Aaron Eisenhauer)

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