Marion may use concrete to solve sink hole issue

Charleston Cove drainage pipe causing sub- surface problems

news@theeveningtimes.com

Marion may try to fill in an old drainage pipe which is causing sink holes on Charleston Cove with a liquid concrete substance rather than dig it up.

Street Department Manager Gordon Floyd told the City Council the city may be able to poke a hole in the pipe and fill it with a material called flowable fill.

Flowable fill is a liquid-y concrete mix – or “liquid soil” – capable of filling in hard to reach places that hardens in a matter of hours. The substance is a combination of cement, water, fine aggregate, and ash or skag. It has been used by contractors to fill in abandoned tanks, basements, mines, tunnels, and sewers instead of using compacted soil backfill.

“It’s something we are checking on,” Floyd said.

“It would be much more cost efficient.”

The pipe is three feet wide by about 400 feet long and was originally installed to drain a swamp,but was no longer needed and left in place by developers when they started the next phase of houses.

When the subdivision was built, developers put a temporary culvert in leading to a drainage ditch. Develop- ers changed the drainage plan and instead did more ditching. It was originally designed so that water from the ditch would relieve itself into the pipe. The runoff used to head north, but now flows south and the pipe was no longer needed.

The City made some repairs to sinkholes and experimented by blocking both ends of the pipe to see where the water goes, but the sinkhole problem is still ongoing.

Floyd said the pipe most likely has crumbled due to the weight of the dirt and is leaking at the seams.

“I’ve crawled all through that pipe,” Floyd said.

“That pipe is definitely a dead pipe. We blocked if off about a year ago. It had absolutely no effect. So that pipe has no real function.”

The city had planned to dig and fill the pipe in, but the pipe is about seven to eight feet deep and will cost about $20,000 to fix the problem.

Marion will have to take down a section of fence at a residence which runs over the top of the pipe and dig up a flower garden at another

The Road Department also does not have a trackhoe big enough to reach down to the far ends of the pipe to take it out and will have to borrow or rent one.

Floyd said with flowable fill, they might be able to dig down to the pipe and punch a hole in it and use the concrete to fill it.

“There are three different entrances to the pipe,” Floyd said. “And if it is graded correctly – and it looks like it is – I don’t see why we couldn’t block up a section and block it off and fill it in,” Councilman Kelly O’Neal said that solution, if it is feasible, would cause less disruption to the homeowners.

“You would tear up less yards,” O’Neal said.

Floyd agreed.

“We’re going to tear up some yards if we dig,” Floyd said. “But it will be less damage and more cost effective.”

Mayor Frank Fogleman said he likes the idea and asked Floyd to report back once he has a cost from Razorback Concrete.

“I think it’s a good idea,” Fogleman said. “It sure beats having to pull up some fences.”