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The last 8 posts

Thursday, August 16th 2012, 10:20am

by fweiss09

To make things simple...regardless of the system, if I just dig around the perimeter of the slab and cut/reroute any line going under it, then none of the sprinkler heads beneath will ever have a water source and will never present a problem. Correct?

Again, you have been most helpful. I greatly appreciate it!

Wednesday, August 15th 2012, 11:56am

by GatorGuy

Undercutting: run the water long enough to see if water comes out from under the slab. If you do so the water carries soil away with it leaving a void.

Best to find ANY pipe? Hard to answer but yes. If you re-route the main and still remove all pipes then you might end up moving pipes that are now disconnected and harmless. However, until you know they are harmless they are dangerous.

Main lines are usually, not always, larger. Also, the zones feed off the main. If you find a line with a zone coming off of it you have the main.

Looping. I almost didn't bring that up. It's done so rarely that it's probably not an issue. But sure as I didn't.....
Look at the picture:

Uploaded with
Most places are done like the red line: one long pipe to a dead end.
If you have low pressure/flow you can do a loop, indicated by the orange line, so it feeds from both directions.
First, if your valves are all in one place beside the house you don't have a loop. So valve manifold = no loop.

How do you find it if you do?
Not always easy. If your valves are in the zones and f you know where your last system valve is you can see if it ends there.
If not...
That leads to the shovel.

I'd assume you don't have one to start. Patch what you find, keep an eye out over the next few days for unexplained water.

Wednesday, August 15th 2012, 11:18am

by fweiss09

Could you explain these statements a little more?


Without running the system long enough to cause undercutting you can't really tell without digging.
What is undercutting? I assume you are referring to the slab here?

Is it best to try to find ANY piping at all leading under the poured slab and reroute it? You are right, that is a lot of shovel work, but certainly necessary IMO to avoid another head leaking everytime the sprinkler comes on.

How would I know if the 3rd line exposed is THE main line? Is there a test? How do I know if another main line exists? Is there a method for searching (like finding the boxes before)?


Or your line may have been put in as a loop to help with pressure and flow.
What are implications of a loop? How can I know if a loop was put in? If a loop was put in, what does this mean in rerouting the 3 lines found thus far? Will it do nothing?

I can't say thank you enough for your help thus far!

Wednesday, August 15th 2012, 8:17am

by GatorGuy

Burying your valve boxes reeks of incompetence.
That is ridiculous.

Without seeing the site:
IF you assume you know where the main line is and it is THE ONLY MAIN LINE then cutting it and re-routing would take care of anything down stream. However, the irrigator may have run two main lines, one to each side of the house. It's been done many times to avoid obstructions or extremely long runs. Or your line may have been put in as a loop to help with pressure and flow.

Finding other heads under the slab would involve a lot of shovel work. Without running the system long enough to cause undercutting you can't really tell without digging. The bright spot is if you dig a trench completely around the patio to move your main line you'll probably cut any line feeding heads under the slab.

You obviously have wires going under there also and need to replace at least two valves.

Good luck.

Tuesday, August 14th 2012, 10:38pm

by fweiss09

I really appreciate the response. I've called for a concrete guy to come check it out on Friday. I'm debating getting a roofing guy to check for anything major there since anything done may or may not be good workmanship. And maybe its smart to get in an engineer now since all the water was collected in the southwest corner (obvious sloping going on).


There are 3 lines that were exposed earlier today. One each for zone 4 and 5, the other being the main line I assume. Is is safe to bypass all three of these around the slab? Both "boxes" for zone 4 and 5 were found under the slab using the "metal detector" apparatus thing. I wasn't certain that by just bypassing these if the leak would be completely resolved. Could there be other sprinkler heads under the slab elsewhere that are leaking but are unnoticeable? Would those lines have to be found, cut and rerouted as well? Or is all safe if the main lines into the "box" are bypassed?

Thanks again...I at least feel at ease that the sprinkler solution matched your response.

Tuesday, August 14th 2012, 2:51pm

by GatorGuy

First, turn off the system.
Only an engineer could tell but a minor leak under a slab probably didn't kill the structural integrity.

However, I've done a great deal of concrete work in commercial construction, from building slabs to streets.
If the concrete was completely cured before you turned the system on you may have a small void or two but the slab is unharmed. Once the slab is cured it's pretty much impervious to leaks. It would take a long time to cause damage.
Excluding freezes. You get a hard freeze before this is fixed and all bets are off.

Even if you have a small void a good slab can span farther than you think without problems. If you have support columns over the void you have a different issue. If you do have a support column over a void you still may not have to rip it out. A hole can be drilled in the slab and grout injected under it to fill any voids. This is all routine stuff.

You have more than one head uncapped if both zones cause leaks. At least two.
Reroute around the slab. Don't let them move just one line. You have two zones leaking, that means you have two heads uncapped. Two lines need to be moved.

Sadly your situation is common.

Tuesday, August 14th 2012, 1:21pm

by fweiss09

additional info

It is a 6 zone sprinkler system and the back yard is covered by zone 4 and 5. When either of these two zones are in operation, the water will come up through the poured slab.

Much thanks to anyone who can offer advice.

Tuesday, August 14th 2012, 1:18pm

by fweiss09

poured concrete and sprinkler is seeping up through the seems

I recently extended my patio and was told that the previously installed sprinkler system would be capped and no problems would arise. Well, today I woke up to standing water on the patio and realized that the sprinkler system, when on, is leaking up through the seems in the cement.

I called the guy who did the work and he said the guys must have only capped one of the two heads but the easy fix is to just bypass the line and go around the patio, reconnecting the line on the other side (hope that description makes sense). I guess they will cut the line on both sides of the patio and drag the line around to the front, connecting the lines to make a U shape around the patio.

My question to ANYONE who knows what's going on is...will this be okay?! I'm worried now as the extension of the patio has been roofed over, connecting it to the existing roof. If the slab cracks (there is a crack at the seem of the concrete already), then the roofing overhead will be compromised, correct? This could be a world of trouble if not handled correctly.

Further question...will what has been done effect the integrity of the structure? Do I need to have them rip up the work?