Suction Side Underground Leak... verified by photos!

[arri]

I've battled a suction side leak since I purchased this new home which has a pool as seen in my signature and my introduction thread. With a mechanics stethoscope I was able to narrow down the potential location of air intrusion downstream of skimmers to two possible locations. One at the NW corner of my pool which is a fair distance from the pump and one very near a skimmer which is closer to the pump.

After second guessing myself based on reading here and discussing with others I still lacked the confidence to cut open the concrete decking in either location. So I purchased a cheap waterproof endoscope on Amazon with a 50' cable attached figuring I didn't have much to lose.

After focussing on the louder potential leak location nearer the pump for some time I was able to get a view of a T where I believe the further skimmer (the West one) joins the closer one (the North one) from which I was scoping the suction line.

This is what that T looks like with the camera laying on the bottom of the pipe because very little water is flowing (which helps get a better picture):


Whereas, with enough flow to suspend the camera in the water column provides a picture where one can see ample air flow as well:


There was no other evidence of air in the line between the North skimmer I fished the camera into and this T where I first encountered air. However, I was unable to rule out the source of air being upstream (the left entrance to the T coming from the other skimmer). So, I headed to the other skimmer with camera in hand to see if I could rule out that side.

The camera navigated the first elbow in the bottom of the West skimmer with ease, as well as two subsequent fittings within a couple feet of the skimmer which may have been 45's although I'm unsure. I allowed the camera to continue to be sucked I believe parallel to the West end of the pool, possibly straight through a T where the drain may have connected at one time even though it's no longer in service until I arrived at an Elbow with enough camera cable out to suggest it was the NW corner of the pool where I had previously identified the faint sound of air in the line through the deck.

This is where I found very clear intrusion of air into the suction line:


Out of curiosity, I decreased the flow to stabilize the camera and the air eventually stopped coming out of that joint although it's a little harder to see when the camera is laying on the floor of the pipe:


Then I turned the suction back up and reaffirmed immediately that this is where the air is leaking into the pipe.


I realize that underground suction leaks are relatively rare. However, this seems awfully clear to me that the glue joint at that elbow has either failed, the joint is pulled apart or the pipe has shrunk inside the elbow. It's not clear to me what kind of pipe (other than it being white) the camera is sitting in. It's also not clear whether that's a PVC elbow or something else as it's awfully dark compared to other fittings I navigated with the camera. Perhaps the influx of dirt when the suction side is turned on and sucks in dirty water before getting to air has darkened it?

Anybody have a good reason for me not to cut the concrete open where I've measured this out? How big a window should I cut?

arri

 

[Isaac-1]

I have replaced 3 elbow fittings that were under concrete on my pool over the last 5-7 years due to leaks, one of which was under the skimmer. The one under the skimmer required the largest hole about 2x2.5 ft (PB used DWV drain fitting not Schedule 40 pressure fittings), the smallest hole behind an eyeball fitting was about 2x2 and the one at the corner of the pool could probably also have been done with a 2x2, that section of decking was only a 3x3 slab so I removed the whole thing and repoured it to try to hide the patch. Unfortunately I made the mistake of letting contractor was doing some wall repairs handle the actual pour and they screwed up the surface texture so it does not match like it should, they also used cheap sack crete that had too much sand in it and it is flaking off. I should know if you want something done right you have to do it yourself, jackhammering it out and replacing it is still on the to do list 3 years later, most of the rest of the work they did turned out to be about the same quality also.

 

[arri]

I took the plunge yesterday and cut open the concrete deck in the location I measured out from the camera cable and using the stethoscope. We didn't do to bad, only about 4" off of the mark. In any case, come to find the pipe was actually grey not white because I think the camera's auto gain control was having trouble with close proximity to the pipe walls. Also come to find that the issue was not actually an elbow but a coupler that was about 8" shy of an elbow. The coupler, which from the photos above you may garner, was not well seated with pipe making a weak glue joint poorly bedded in the coupler. I also speculate that the contractor may have glued up the grey pipe on a hot day (easily in excess of 100 F around here) and immediately covered the ditch before pressure testing which could lead to substantial retraction of the longer runs of pipe when they cool.

Whatever the reason, it was easy to pull the coupler apart by hand enough to prime and heavily glue the joint. Then immediately held the joint together and buttressed the pipe so that it wasn't under any physical strain to pull apart again. BTW, 2' square was the perfect concrete cut size.


For the curious, the other two pipes are an 1 1/2" return and a 1" "Water Feature" return.