Exterior Sump Pump

Started by Adam Roby, June 22, 2022, 10:01:20 PM

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Adam Roby

We are having an in-ground fiberglass pool installed, and to prevent the pool from lifting, they are recommending installing a sump pump. 1/2 the guys recommend leaving the pump in the hole that goes down maybe 5' under ground, while the other half recommend just throwing it in when needed. I had the electrician install a box in the hole that I may fasten to the cover. I want to run a drain from the pit to the road. My thought was to i stall the pump in the hole in the spring, and remove it in late fall when winterizing.

My question would be, can you leave this permanently installed?
I would fear freezing, but also if you don't install it early enough, or remove it too soon, you run the risk of scrapping the pool.  They dug on Friday, by Monday there were just a few traces or water here and there. Well stayed dry all week., with the exception of a heavy rain yesterday and now I can see an inch or two of water.  There is a lt of clay here if that matters. Anyone deal with something similar? Options, recommendations?  At this point, cost is no longer a factor, I am already pushing back my retirement 7 years as a result. :)

JRR

Our experience is quite different.  We inherited a, cast in place concrete, pool that had not been serviced in decades.  It looked like a swamp.  It took a summer to clean and repair. We have pretty good ground drainage, so I have never been concerned about the pool lifting even when emptied for cleaning and painting.  This is in the South, and ground freezing is never an issue.

In your situation, I would ask "why should the pool lift"?  When will you fill the pool?  Once the pool is filled, I would doubt the pool would lift unless the surrounding soil is soaked and the surface of the pool water is below soil level.  If a sump hole is to be used for this protection,  a working pump may be needed to keep the pool from lifting.  I would just watch and see, but that's me and I take foolish risks sometimes.  (My wife says "often"!)

Do you have some neighbors with pools, whom you might ask?


NathanS

Just a thought - ground water levels are highest from late fall through spring. If hydrostatic pressure is an issue, and a full pool can actually be pushed out of the ground, that's when you'd want it running. Also, just from a practical standpoint, putting in and removing a sump pump as part of your maintenance routine is almost certainly something you will forget to do eventually. I know I would.

Also guessing the pool is sitting on and surrounded by non-expansive fill like sand or some type of gravel.

Adam Roby

Quote from: NathanS on June 25, 2022, 07:41:34 AMJust a thought - ground water levels are highest from late fall through spring. If hydrostatic pressure is an issue, and a full pool can actually be pushed out of the ground, that's when you'd want it running. Also, just from a practical standpoint, putting in and removing a sump pump as part of your maintenance routine is almost certainly something you will forget to do eventually. I know I would.

Also guessing the pool is sitting on and surrounded by non-expansive fill like sand or some type of gravel.

Quote from: JRR on June 23, 2022, 11:06:05 AM...In your situation, I would ask "why should the pool lift"?  When will you fill the pool? 

I had the same questions when we ordered the pool.  I believe the old cast in place cement pools are heavy enough to withstand the pressure from underneath.  This is a fiberglass pool, and even at a fairly large size of 32' x 14', 4 guys can move it around and adjust it prior to filling.  In fact, two guys lift a corner to allow some fill to fall under, then they jump on the edge to pack it back down to get it perfectly level.  I think with all the crazy weather we've been having these past few years, the pool companies had to come up with a way to prevent damage and liability.  In a very heavy rainstorm, the ground water can rise very quickly (we are mostly clay here).  As soon as there are a few days of nice weather, the ground dries out and becomes rock hard.

We immediately filled the pool, so it is at its max now.  I think we are in the safe zone.  We are on the island of Montreal in Canada, so freezing is my main concern with leaving the pump in the hole permanently.  Normally we have to empty all pool lines and fill the underground pipes with antifreeze for the winter.  If I were to leave the pump in over the winter, if we had a warm day with a lot of snow melt, the pump would activate and evacuate what is in the hole (if not frozen), but wouldn't the pump prevent water in the pipe from draining back into the hole and thus cause that section of pipe to freeze and burst?

This is the black 10" pipe where they want me to install the pump.  I had the electrician install a box at that location, which I will eventually screw to the underside of the skimmer lid that will be placed there once the paving stones are in place and they cut down the black pipe.


This is a view of the inside of the hole, that water level was at about 1/2 way up the pool level after 2 days of extreme rainfall.



Once cut level, the underground pipe will run from the street, next to the house and to the hole.  I will ask them put it about the same height as the electrical, so I can insert the pump with a flexible pipe, and have room to connect it to the underground pipe.



If I can, having a pump or solution that can stay year round would be ideal... I am just not sure about the possibility of freezing and how well it would work on those iffy days in the winter.

JRR

Why not drill a small "weep" hole in the pipe just above the pump?


Adam Roby

Quote from: JRR on June 26, 2022, 12:28:16 PMWhy not drill a small "weep" hole in the pipe just above the pump?
Just as a drain you mean?  I suppose I could... good idea. Figure that would case a loss of pressure?  I just bought a pump, only automatic one I could find that would fit the hole.  It's a 1/2 HP and says it has a head of 25', so my 5' hole should pose no problem.   The kit I bought comes with some 24' of hose, so I could do a first pass with a hole and worse case just replace it should it cause a problem. 

JRR

Yes, as a drain.  

But may not be necessary, it depends on the design of the pump.  If it is a submerged, self priming style ... with no inlet or outlet check valve, it will drain back on it's own.