location of main drain pipe

[sks24]

Thank you for allowing me to join your forum. I need help determining the location of the main drain pipe which goes from my main drain at the bottom of the pool to the pump/filter. The reason for my asking is that I am all but certain that I have a leak in that pipe, and I would like to try and repair it on my own. (If I cap the main drain, the pool doesn't leak.)

I have both photographs and drawings/diagrams of my pool, and would of course be pleased to post them upon being enabled to do so.

Here's a link to a (shared Google doc) diagram of my pool:
https://docs.google.com/drawings/d/1JGv4BggsRpf0o_qjLejvJw098pe5JjPXG7qzv2mtKRU/edit?usp=sharing

It seems like the main drain pipe would run out from under the pool to either the east or the west. If it needs to run under the skimmer, then it would run to the west. I hope that's not the case, because there's a concrete pool deck which would run over the pipe if it runs around the pool tub on the west side of the pool. If it runs out to the east, the access to the pipe will be much easier, as the deck would not cover much of the the drain pipe, and I could easily dig under it safely.

Thanks in advance,
Scott

[PoolDoc]

It would make sense that builders would follow a consistent pattern in the way the locate pipes . . . but in my experience that's not true. I've seen pipes run just about every way they could have been.

About the only thing you can rule out, is any path that would have required the builder to cut through rock.

You *might* get some indication of how it runs, if you dig down and follow the line for 6 feet or so away from the equipment pad.

One caution: the MD pipe COULD run under the entire pool, to reach the drain. OR it could run around the walls (from either side) and then drop under the pool. For several reasons, there's a fair chance that the section under the walls is the location of the leak . . . and fixing a leak their is a major task. Usually, it's easier to run a new line.

One suggestion: verify that your pool's hydrostatic pressure relief fitting and valve ( IF it has one ) is not the source of the leak.

[sks24]

Thank you for your reply PoolDoc. I don't think I have any kind of pressure relief fitting. Here's my equipment pad (https://docs.google.com/document/d/1JYYZ9ETkK7lR-oTpgM2NnojU6EE5qzm82hHWU3OR1LI/edit?usp=sharing), and here's the top of my sand filter (https://docs.google.com/document/d/1-7rncvVVWYjWE-UgDyoLHBeKTyhwXGejWfU0rAQhYVI/edit?usp=sharing). When I try to turn off the skimmer with the pump running, and open the valve so that water can come from the main drain, the pump loses its prime because it sucks in air, presumably from the hole that's in the MD pipe (which, again, must be at the same level as my returns less @ 4 inches). I can bring a little water in from the MD, but only if about 75% of the intake is from the skimmer.

My main drain intake at the bottom of the pool does run off to the east, which is the side of the pool that the equipment pad is on. Here's a pic of the east side of the pool (https://docs.google.com/document/d/125QzwN_3w_LKoqIMbue-bT80616rX8SGshlPVYtxIrQ/edit?usp=sharing).

What comes to mind is to start digging just south of those black chairs that you see (that's the east side of the pool (I'm looking from the north)). If I'm lucky, the pipe runs under the concrete deck where the deck is relatively narrow, and the leak would be easily and safely accessible and repairable.

Running a new MD line would involve digging under the pool all the way to the bottom drain hole underneath the pool, no? This would no doubt require a permit, and cost thousands? I've seen solutions which involve running a new liner inside the pipes. Are there companies which sell kits to do this, or is there a DIY pipe liner solution? I saw one company, but apparently they're out of business.

The soil around this pool is very sandy, and so the digging would be easy to do by hand.

Again, thanks for your help with this matter.

[PoolDoc]

The hydrostatic valve, if there is one, is in the bottom of your main drain:
http://www.a1poolparts.com/-strse-835/Hayward-Hydrostatic-Relief-Valve/Detail.bok

[sks24]

I think there may be one in the MD next to the intake. I think I recall seeing two elements: the drain intake, and something else, which could be the hydro valve. Tomorrow I will dive down there and take a look at it. I think that there could be an "O" ring failure such that it would allow water through until the water was shallow, after which there wouldn't be enough pressure to breach the O ring. So that could account for the very specific level to which the water descends. But the inability to draw water exclusively from the MD? It seems like that air would have to come from a hole in the MD pipe.

Thanks.

[PoolDoc]

When hydrostatic valves fail, often it's because they've opened, and allowed ground water to flow into the pool -- what they are supposed to do -- but also allowed a bit of grit or organic matter to enter, and wedge the valve open a bit.

[sks24]

I didn't look at that drain today to verify whether there's a hydrostatic valve there. But I'm pretty sure there is, not least because when I drained the pool completely last month water would seep back into the pool via the MD, and very quickly. The water table is quite high here. I did try to remove the MD grate when the pool was empty, but there was no obvious way to do so.

Bottom line at this point is that it appears that the first order of business is to control for this valve. Since I don't have scuba gear, it looks like I need to drain the pool again, remove the BD grate, and just go ahead and replace the valve using the valve tool they sell at that site you linked to above. I guess I'll buy a new grate, too, since I might have to destroy the one which is on there now to get it off.

But my inability to get the pump to keep its prime if I try to pull more than about 25% of the water from the bottom drain concerns me. It seems like the only circumstance which could account for this would be a hole in that MD pipe.

A somewhat related question. I noticed a new problem yesterday on my equipment pad. When I run the pump with the selector which is on top of the sand filter set to either "Filter" or "Recirculate" some water leaks out of my exhaust drain. It seems like the handle is pretty hard to turn on that selector. What might be causing this? This just started yesterday. Here's a pic of the flow with the selector set to "Filter" : https://drive.google.com/file/d/0B4qPfb4MvEswWmRqMkd1cHFFRlU/edit?usp=sharing

[PoolDoc]

Bottom line at this point is that it appears that the first order of business is to control for this valve. Since I don't have scuba gear, it looks like I need to drain the pool again, remove the BD grate, and just go ahead and replace the valve using the valve tool they sell at that site you linked to above.

Do NOT drain the pool when the water is high; even concrete pools WILL float out of the ground. If you must drain, you MUST lower the water level around the pool.

[sks24]

Thank you for your reply PoolDoc,
Whoever had this house before us - we purchased it in 1997 - drained the pool when the water table was high, and the pool did lift out of the ground about an inch on the west side of the deep end. I've drained it perhaps three times over the past 15 years when it was dry, and it's been stable. About 18 inches of water will seep into the pool when the water table is low. Anyway, I will be careful to wait until we haven't had rain for awhile. There's a creek about 100yds south of the pool which all but runs dry occasionally, and that's when I empty the pool.

So is waiting until the rain subsides, draining the pool, and replacing the valve a reasonable way to proceed at this point? I realize that you would want to be very careful about specifically recommending any particular course of action. Please don't concern yourself over the consequences of anything I might or might do at your suggestion. I'm not going to fault you in any way if things go wrong. I'm sure I've agreed somewhere not to sue anybody over anything that might happen here, and of course that would be my preference, as I want for people to feel free to offer their best advice.

Thanks so much for your help,
Scott

[PoolDoc]

Actually, I don't have enough money to make me a target for any attorney with an IG above the double digits! ;)

My caution is more ignorance based: the sort of situation you're in tends to include surprises, even for very experienced service guys.

I would recommend checking the hydrostatic valve, simply because it's (a) a likely cause, and (b) one that can be repaired. Some of the other possibilities involve MAJOR expenses and demolition. In those cases, pool owners often end up abandoning their main drains.

On a positive note, the mere fact that you've repeatedly had water enter the pool via the hydrostatic valve greatly increases the chance that that valve IS the problem.

[sks24]

Ah-ha very good. :^) We've never used the main drain. What we've done is go out to the pool about 6 pm when the wind has died down, cut on the pump, remove the leaves with the screen thing on the end of a pole, and then have the pump shut down around 11pm using a timer. So we run the pump for about 5 hours a day after getting the leaves off the surface of the water so that the skimmer won't get clogged up. That has kept the water clear, and we don't have to worry about the pool pump getting starved of water and burning it up. So the easy thing to do here would be to somehow cap the MD and continue what we've been doing. What I have it capped with now is PFD foam wrapped in plastic wrap with three ten pound weight plates on it. But it doesn't provide a good seal, so the pool is still leaking a lot. Or maybe it is sealing the MD and there's a leak somewhere else. But I carefully went around the pool with ink and a syringe and tested every port and interface, and couldn't see that the ink was being sucked in anywhere.

Anyway, I will just keep it capped until we get another dry spell. Then I'll drain the pool and replace the valve. Then I'll go from there.

Thanks,
S

[PoolDoc]

You're welcome.

[sks24]

So what's the best way, or what are some options, with respect to capping the main bottom drain? My goal in this instance is to control for any leaks which might be associated with it. The main drain hasn't functioned properly for over ten years, and I assume this is the case because there's a hole in the return pipe which allows too much air to bleed in while the pump is trying to suck water through it. The current main bottom drain does does have a pressure relief valve in it, and I may replace it by way of determining whether that's the source of the leak. What I would like to do is cap the bottom drain, but have an easy way to uncap it if needs be: say, if I decide to try to repair the return pipe, or replace the pressure relief valve.

Right now I'm a few hours away from having the pool drained. I'm going to remove the bottom grate, and also the pressure relief valve if possible, so that I can get serial/parts number.

Thanks in advance,
Scott

[sks24]

After a hiatus, I've decided to dive back into this pool project. My pool has a leak, and it's probably associated with a faulty pressure relief valve, or perhaps a pipe separation at the bottom drain due to the pool having floated out of the ground @ one inch at one side of the deep end. It's been like that since before we owned the house, and the pool didn't have a leak until about two years ago. So I don't think the leak is a function of the pool floating up out of the ground a bit.

I decided to try to remove all the groundwater from around the outside of the pool. That way I can work on the main drain, pressure relief valve, and repaint the pool surface. My water table is @4-5 feet below the surface of the ground, and that's where the water level in my pool is. I've been able to drill down about 12 feet using the method described here: http://drillyourownwell.com/index.htm I can't go deeper than 12 feet because gravel accumulates at the bottom of the well hole, and my (metal) bit can't get through the gravel. But maybe 12 feet is enough, as the pool is 8 feet deep.

I haven't hooked up the well pump yet. What I'm hoping is that I can pump out water, and as I do so the pool will drain as well, through where I presume the leak is. In other words, as I lower the water table in the immediate vicinity of the pool, water in the pool will drain. Presently the water level in my pool mirrors the water table outside of the pool, so this seems like a reasonable supposition.

My questions:
1) Let's suppose my DIY well and well pump won't drain all the groundwater around the pool. How does one go about achieving this? Do I hire someone to come out and dig a big ditch and put a pump in it? Does one drill through the bottom of the pool and pull the groundwater out through the hole?

2) Let's suppose that I get "close" in terms of draining the water around the pool with my well and electric well pump, which is rated to pull water from as deep as 25 feet. So the water level inside the pool gets down to, say, three feet deep. I think I could then then go ahead and pump the rest of the water out of the pool and cap the bottom drain so I can paint the pool. I think it would be fine to do that, as I have drained the pool completely before without removing any groundwater at all, and the pool hasn't floated up out of the ground of the ground any more than the @inch is has already on one side of the deep end. (It's been like that since before we owned the house.)

So, my question is, how do I cap the drain so that water can't get in or out, and I can repaint the pool surface?

I would also remove the old pressure relief valve, replace it with a new one, and refill the pool to see if it holds water. If the pool still leaks, then I would want to cap the main drain somehow. I guess I could cap the drain hole, and leave the new pressure relief valve in so if people empty the pool of water it would fill back up with groundwater.

But, again, there's zero paint on the sides of the pool. So I want to do that, too.

Thoughts, advice?

Thanks,
Scott