HELP! Blocked storm water pipe under liquid limestone

Hi all,

I'm half way through a backyard landscaping project and have realised that a storm water pipe is blocked or damaged, causing the downpipe to back up with any meaningful rainfall. The problem is, the pipe is now covered by liquid limestone making repair difficult.

Pic here: http://img204.imageshack.us/img204/6964/img0017small.jpg

I've had a roof plumber out but he was unable to unblock it (even after hacking a nice hole at the bottom of it). He suggested that I'll need to cut up the limestone to find the suspect pipe. Not happy with that idea, so I've come on here to hopefully come up with an alternative.

By the way, all stormwater pipes at my place connect to a common stormwater catchment (group of villas) and not soakwells. I've poked some hose down the downpipe but can't tell which way the pipe heads underground.

Ideas I'm currently tossing around:

- Tunnel underneath, find the storm water pipe, connect a new joint and run the pipe to a new soakwell. Sounds good in theory but I'm not sure how to tunnel without impacting on the structual integrity of the liquid limestone. It would also need to be a big enough tunnel for me to crawl into in order to make connect up new piping.

- Move the downpipe towards the window and allow the water to run across the limestone onto what will soon be grass. Or, as an extention of this idea, install a drain between limestone and grass which would capture the water and run it to a soakwell.

Any thoughts on these ideas or any other creative solutions would be greatly appreciated!!

Steve

Tricky one.
I can't see any alternative but to cut out those two slabs of LL and fix the drainage problem. Dont know about the idea of running to a central drainage system, I'm guessing that tree roots have found the drainpipe somewhere and have expanded into it which means it will always have a problem.
If you cut out those two slabs you could install a soakwell or ag pipe under the lawn and drain to that, that way they are accessable. When reassembling use a drain grate and have your downpipe stopping above it so in a flooding situation you wont have water in your eves.
Those two slabs would be easy to repour as they are basically formed up for you. LL is not difficult to do. PM me if needed.

Thanks for the feedback keen, I really appreciate it.

I've spoken to the limestone guys (they only poured it a month ago) and they recommended trying anything before cutting and repouring, as it would be difficult to match the existing colour and height. Perhaps they just weren't too keen to come back for a small job.

I was thinking that it could be possible to just cut the rectangle of limestone immediately north of the sprinkler, redirect the piping to a new soakwell in the grass area, then try to re-lay the same slab of limestone like a paver. Not sure how feasible this is given that the underside of the limestone probably wouldn't be smooth like a normal paver.

This project has just been problem after problem!!!

You could try that. Problems you might have though is once you saw cut that slab you have a gap between it and surrounding pavers, I would be more inclined to repour it. That looks like plain limestone & cement, I dont know why colour matching would be a problem, ask the concreters if anything else was added. As for level, the surrounding slabs provide the formwork, should be able to screed to them and it should be perfect.
You may want to bring this post to the attention of a couple of guys from the paving section on this site (CClarity, onc_artisan) I am just a DIYer.
cheers

You think I'd have much luck in cutting a square of limestone around the downpipe for a drain grate, then tunnelling some pipe under the limestone and connecting it up to a soakwell in the lawn area?

Worth a try. I would excavate a bit of a hole to work in in the lawn area, push a bit of drain pipe in on an uphill grade, use a hose to wash out the sand as you push in. May well work. When fiished try try backfill and compact as much s possible (ram the dirt in)
Good idea.

I wonder if the pipe was blocked during the LL pour considering how short a time it was after it that it has blocked.

You could try asking a plumber to put one of his drain cleaning machines down the pipe, could save having a patchwork in your paving

It's possible it was blocked during the pour, or perhaps when I had a bobcat in to remove all the grass a couple of weeks prior.

I've had a plumber round but he didn't have any luck, despite using all the high pressure gear.

probably not the best idea. But have you considered getting rid of this downpipe all together and/or perhaps putting in a downpipe in another location, even if it means adjusting the flow direction of the guttering. This may be a cheaper option still if it is possible.

The problem with that idea is that the downpipe in question also services the patio roof which has a separate gutter. Also the house gutters already struggle with roof catchment thanks to sagging eves. Agree that it would be a hell of a lot easier/cheaper though!!

Why not cut the pipe at concrete level. trim the down pipe shorter. Install a grate on top of the outlet at the concrete level. Might have to use a small grind but done carefully will look fine. Cost a few dollars and will mean you won't need to move the whole down pipe

Is it perpetually blocked, or does it eventually clear? If it clears, try pouring measured amounts of water into the hole in the downpipe, then you can work out roughly how far the blockage is... maybe it's not even under the LL.

Can you reach the other end of the stormwater system? Maybe you can put a hose up there??

Ed