More on the chestnut sidewalk

    The second problem with the storm drain area involves a sink hole behind the storm drain basin. We had no idea what the problem was but we knew we couldn't pour a sidewalk over a sink hole without finding what caused it and then we must repair it. The city had filled in the sink hole with some dirt in the past but there was already a hole developing again. Once we removed all the kudzu and the broken fence (that was built in the right of way) we could see this sink hole, the wall, the pipe and the spring fed stream feeding the pipe. The below shot shows the retaining wall, the spillway that will be rip-raped that will allow the flue to drain into the stream bed and also where the sink hole is located. As you can see the sink hole is right under where the sidewalk needs to be.
    The next shot shows a closeup of the problem. What has happened is the first section of pipe has pulled out of the next section of pipe that is attached to the roadside storm water drain basin and the pipe then continues under the road. Right now the only problem is with this first section of pipe, as the rest of the pipe under the road is all OK. But if this isn't repaired fairly soon, it will erode the dirt around the pipe under the road and the whole road will need to be dug up!  That would easily quadruple the cost of this repair.

    This is typical of the kind of problem that creates a sink hole and is why pipes like this need to be sealed up well. It's also a good example of why you don't want to pipe a stream unless you have to, like in this case where the stream goes under a road. There are a couple of ways of repairing this and right now we are letting the city storm water manager look into this issue and how best to fix this.

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