Monday, June 3, 2024

French Drain stops working

 The French drain was put in back in 2003 and has been working fine since then.  It was extended and terminated into the blue rock pool in 2008, and then the front end was rebuilt when we built the retaining wall in the front yard.  We exposed parts of it when we moved the gas line, and when we dug out the stumps of the two elm trees.

But when we got the roof replaced in 2023 and new gutters installed, it seemed to stop working.  Heavy rains would cause the downspout in the front West corner to overflow and erode away the dirt around where the downspout went underground to enter the French drain.

The first step to fixing this is to expose the end of the French drain in the blue rock pool in the backyard, between the Bamboo Grove and Zone 7.

The pipes in the French drain should terminate at the rock wall, under the rock.  So first we remove the blue rocks.

That exposes a badly weathered landscape cloth.  Removing that we find a layer of limestone rock.

Removing that, we get down to the actual pipes. 

The center one, sticking out the most, is the main pipe that should go all the way back to the downspout.  The other two, one on the left and one on the right should be perferated drain lines that run parallel to the main pipe, just to drain more.  The main pipe is 39 inches from the fence, and down 16 inches from the top of the rock wall between Zone 7 and the blue rock pool.

We can test for a problem by putting a house in the downspout and turning on the water.  After a long enough time, the downspout is full of water, but nothing is coming out of the pipes in the blue rock pool.

If we put a hose up the pipe from the blue rock pool, we get about 30 feet up the pipe before hitting something that keeps us from going further up.  But we do manage to flush out a dark material we believe is decomposing leaves and the protective granules from the asphalt roofing.

In trying to understand the French drain, we notice old pictures of it showed a clean-out pipe which would now be under, or in, the Rive of Rocks, and digging just a little, we find that.

Pushing the hose down from this clean-out pipe into the French drain, we only get about 9 or 10 feet before it stops.

But the French drain is not just a straight pipe.  It was imagined originally as going along the fence, and only later brought over to attach to the downspout.  So it goes from the clean-out pipe back under the fence gate and then turns right to the fence.  There it turns left and follows the fence down until the fence turns left again and follows the fence to the blue rock pool.  So there are 3 turns.  I think those were 30 degree turns, but possibly 45 degrees, or a mix of the two.  Those turns may be what is stopping the hose.

We tried a Large Drain Bladder from Home Depot ($21.97).  That is a balloon type device that you hook to a garden hose and then stick into your clogged drain.  The water pressure causes the bladder to expand until it seals the drain and then water shoots out the end at high pressure washing away any clog and debris.  Putting it in at the clean-out should then push all the roof granules and decomposed leaves out the other end into the blue rock pool.

That didn't do anything either.  After running the water for about 10 minutes, there was some seepage from the pipes at the blue rock pool.

So we called a Radiant Plumbing to clean out the line.  They could come out two days later.  Matt showed up and after inspecting things offered three solutions: (1) a water blaster for $740, (2) a rotating cable for more, or (3) both the water blaster and the rotating cable for $1074.82.  We went for the least expensive -- the water blaster.

That was similar to what I had done, but with better equipment.  The water blaster put out much higher pressure out the front to break up any clogs, and also put water out the back to (a) move the head forward into the pipe all by itself, and (b) to push anything that was loosened up back out the pipe.  We tried it from the clean-out pipe

and from the blue rock pool back up the pipe.

And then back to the clean-out pipe again.  But we were getting nothing.  Well, almost nothing.  There were small artifacts of PVC pipe and some small pieces of shingle that had worked there way into the drain, but unless there were more, bigger, pieces that didn't really tell us anything.

 So we decided to try the cable snake to see if that would clear things out.

It seemed to get a bit further, but it was hitting something solid and could not get all the way thru the drain.

But we were able to get some flow.  Putting water in at the clean-out pipe would cause water to come out at the blue rock pool, but out of the wrong pipe!  It seemed to come out of the left pipe, not the center one.  Which made no real sense.

Since we had some flow (although we did not understand why), we had done as much as it seemed we could.  The cable hitting something hard was puzzling too.  So the suggestion was to bring a drain camera out and put it down the clean-out pipe.  The drain camera would give us a good view of what was in the French drain, and that would tell us what was needed next.