City officials weigh options for persistent sinkholes

Sinkholes have been a problem that has plagued the city's south side for at least seven years.

They have forced the closure of a portion of South Sprigg Street, ruptured a gas line and caused flooding in the Buzzi Unicem quarry. But city officials are hopeful a solution to their sinkhole problem soon could be found.

Tim Gramling, the city's public works director, said the city has been working with the Missouri Department of Transportation and a number of federal agencies on the issue. Recently, he said the city was told it qualifies for federal emergency recovery funding to help find a more permanent solution.

Last year, Federal Emergency Management Agency and Missouri State Emergency Management Agency officials came through Cape Girardeau County after a federal emergency declaration was approved in July because of the severe flooding in the area. In Cape Girardeau, the Mississippi River rose nearly to the "major" flood mark of 42 feet and was slow to subside.

While most cities dealt with more typical flooding issues, Cape Girardeau suffered from aggravated sinkholes. Gramling said the fluctuating river levels make the sinkholes more active.

Since that time, he said not much has been done with them. In the past, there have been efforts to fill the sinkholes with gravel and concrete, but the fixes were short-term, as the sinkholes eventually swallowed up the materials.

"There's been no major change since last year," Gramling said. "The [sinkholes] are moderately active and continue to grow over time."

That status could change soon, however. As the city approaches flood season, Gramling said a moderate rain could push the river up to flood stage, which is 32 feet. This could accelerate the growth of the sinkholes, similar to what occurred last year.

So far this year, he said the river has remained around 22 feet.

Since discovering the city qualified for federal funding, Gramling said officials have tried to focus on the positive. Members of the public have speculated South Sprigg Street may be permanently closed -- because of sinkholes on the road and near the South Sprigg bridge -- but Gramling said the city is not considering a permanent closure or rerouting the road at this time.

"We're still optimistic that we'll find something to get the street back open, so that's kind of our mindset right now," Gramling said.

The first step in finding a solution is hiring a consultant to review the sinkholes and conduct a technical investigation to suggest a more permanent fix. The city and the consultant also would work with Buzzi Unicem officials.

Last year, Gramling said part of the reason it was so difficult to find a viable solution was because of the unique characteristics of Cape Girardeau's sinkholes. That still could be an issue, but Gramling is confident a consultant can successfully identify a solution.

"The consultant will draw on whatever experience they have," he said. "The fact that we have the river on one side and a quarry on the other side about 350 feet deep -- because of those features [the sinkholes] are fairly unique. But all sinkholes have some of the same basic characteristics ..."

Most of those characteristics are water-related; water from rain or groundwater sources can displace or erode the soil, or dissolve minerals in the rock, leaving it unstable and likely to collapse.

He said it's difficult to determine how many sinkholes exist in Cape Girardeau, since many are technically part of the same system and others may not have been discovered. Gramling estimates the number is probably a little more than 40.

The sinkhole that formed underneath the South Sprigg bridge, like the others, continues to grow, but he said the bridge is still "pretty steady." A water line also runs through the area -- dubbed the South Sprigg Sinkhole area by city officials -- but Gramling said it remains stable as well.

The city has not yet selected a consultant, but he said that should begin soon. Once one has been chosen, Gramling said the technical investigation should only take a few weeks.

srinehart@semissourian.com

388-3641

Pertinent address:

2524 S. Sprigg St, Cape Girardeau, Mo.