High water table- french drain??

[fun4stuff]

Hi, im looking for suggestions on installing a pool with high ground water. Mostly just want to make sure things sre sone right.

We will be getting a fiberglass pool (14x33’). The inner string rectangle above is where pool will go and outer rectangle is the concrete deck.

Our water table is fairly high. The blue arrows show the flow of water. The top blue arrow is the lowest point- to left of the image (like 30 yards) is a creek that flows away from our property. We have gotten quite a bit of rain recently, but digging at the lowest point in back left of image we hit water after about 3 feet.

There is a french drain (right to left) where the top arrow is. When it rains really hard (like 1”+) we get a couple inches of standing water where that bridge is that lasts for a few hours and then the water drains away. The house gutters connect to buried poly pipe which run to that french drain.

There is a gentle slope as you go from front to back away from patio (like 1.5’). There is also a slope from right to left. It slopes back up a bit toward arborvitaes… so that top blue arrow (and picnic table) are at the low point of the yard.

Spoke once with our installer and plan to go over again in more detail. He said we would have well points and gravel around the pool. He may put pool up “a bit” (like 1-2’).

My questions are:
1) Any tips on helping water flow away from pool?
2) Should we install additional french drains along the left and right of pool that tie in with the back French drain (blue lines on second images) that connect with roof gutters? Could these go in the stone we are having around the pool?
3) should we maintain the low point and slope right-to-left behind pool and possibly install another French drain in rocks back there?
4) If pool is built up (particularly at the back), would we need a retaining wall??

 

[Bperry]

2) Should we install additional french drains along the left and right of pool that tie in with the back French drain (blue lines on second images) that connect with roof gutters? Could these go in the stone we are having around the pool?

Dont do that. The goal of the stone around the pool is to allow a water that is in the soil to flow more freely and allow a well pump to remove that water and put it somewhere else. Directing water from gutters to the stone around the pool is the opposite of what you want. Gutters should get their own separate drainage. Connecting the gutters to a french drain is also not a good idea. When the french drain gets saturated, the gutters/downspouts cant remove water as fast as they need to and can back up onto the roof. Ask me how I know.

French drains are ok to collect surface water and direct it away from an area, but if the area is already sloped the way you want, it sounds like you dont need that or you just need it where the water pool in that corner?

 

[fun4stuff]

Dont do that. The goal of the stone around the pool is to allow a water that is in the soil to flow more freely and allow a well pump to remove that water and put it somewhere else. Directing water from gutters to the stone around the pool is the opposite of what you want. Gutters should get their own separate drainage. Connecting the gutters to a french drain is also not a good idea. When the french drain gets saturated, the gutters/downspouts cant remove water as fast as they need to and can back up onto the roof. Ask me how I know.

French drains are ok to collect surface water and direct it away from an area, but if the area is already sloped the way you want, it sounds like you dont need that or you just need it where the water pool in that corner?

Hmm, good point about gutters being tied to a French drain. That makes sense. The gutters will need their own separate drainage poly tube.

Yeah, I’m hoping to go over with installer. I’m sure he plans to maintain proper slope. Maybe won’t need a french drain per say… i was just thinking it would be cheap and easy to add them along sides of pool now rather than later. But I’m no expert.

The water is probably pooling in that spot because they’re currently connected to the French drain- doesn’t help the situation anyway. I can definitely see why they should be separate!

 

[alvindo]

I built my pool half into a hill and and the low end had horrible ground water issues. We went a little bit overboard and I have a drain around the retaining wall in the hill. Then two French drains under the long sides of the pool which are connected to above drains in the decking. Then around the outside of the pool area we have another set of drains.

It was probably overkill considering the whole pool is surrounded by gravel especially only the side we built up. We only have a retaining wall on the hill side. On the side we built up we just graded it out. More water runs through the gravel build up than the drain pipe.

I don’t mind overbuilding it though, the cost of gravel and pipe was cheap compared to the overall project.

 

[Jimrahbe]

Fun,

I have a 'French Drain' on two side of my gunite pool, because we built the pool on top of an unknown small spring..

The pipe part of the French Drain is about 6' down into the ground, below about 5' of rock.. A French Drain by itself will not help unless the water it collects has a place to go. You either need to have an opening further down hill from the drain, so the collected water can just drain out, or you will need to pump the water out.

In my case, I have a sump pump that runs 24/7.. Here is a pic of the little guy that runs the pump..

Yard Art 5.jpg

• Jimrahbe
• Feb 2, 2023

Thanks,

Jim R.

 

[Bperry]

The water is probably pooling in that spot because they’re currently connected to the French drain- doesn’t help the situation anyway. I can definitely see why they should be separate!

The water pooling in that spot may be helped by a french drain as long as theres some downhill area to route the water to. If its ground water pushing up though then you may want to pump it out to somewhere it can flow away from the property.

 

[fun4stuff]

Yes, I already have a french drain along the back (horizontal blue arrow). It dumps into a creek to the left in the picture which flows away from our property. It's the perfect place to re-route water.

That low area was marshy cattails 5 years ago until we put the drain in.

I guess my main question was if it would help to have a french drain along the sides of the pool that connect to the drain already in place. Or is this overkill?

Also, since we plan to have pool 1-2' up at the back end of the property (the low end), do you think we need a retaining wall? It slopes 1-2' across the short width of the pool (front to back of property)?

 

[Saturn94]

Fun,

I have a 'French Drain' on two side of my gunite pool, because we built the pool on top of an unknown small spring..

The pipe part of the French Drain is about 6' down into the ground, below about 5' of rock.. A French Drain by itself will not help unless the water it collects has a place to go. You either need to have an opening further down hill from the drain, so the collected water can just drain out, or you will need to pump the water out.

In my case, I have a sump pump that runs 24/7.. Here is a pic of the little guy that runs the pump..

Yard Art 5.jpg

• Jimrahbe
• Feb 2, 2023

Thanks,

Jim R.

That thing gives me the creeps every time I see it!

 

[Bperry]

Yes, I already have a french drain along the back (horizontal blue arrow). It dumps into a creek to the left in the picture which flows away from our property. It's the perfect place to re-route water.

That low area was marshy cattails 5 years ago until we put the drain in.

I guess my main question was if it would help to have a french drain along the sides of the pool that connect to the drain already in place. Or is this overkill?

Also, since we plan to have pool 1-2' up at the back end of the property (the low end), do you think we need a retaining wall? It slopes 1-2' across the short width of the pool (front to back of property)?

Overkill is great, the question would be whether its a good idea or not. Having multiple drains all heading to one spot could overwhelm the drain capacity. The drisn might need additional flow capacity.

 

[kimkats]

If the side of the pool is "up" what will be put around it to keep it from bowing or such?

 

[fun4stuff]

If the side of the pool is "up" what will be put around it to keep it from bowing or such?

Well that was kind of my question. I have another meeting with the installer and plan to ask that. What is commonly done? Can you slope up to it? Do you need a retaining wall if it's placed up??? He just mentioned he could put it up 1-2 ft in the back at low end of yard.

 

[kimkats]

You can build the are up and put in a retaining wall to hold all of the dirt in and then put concrete on top of it for decking.

 

[alvindo]

If the side of the pool is "up" what will be put around it to keep it from bowing or such?

We built out low end up with gravel basically making a hill of gravel then grading it down to the original grade over about 15 feet.

 

[Bperry]

We built out low end up with gravel basically making a hill of gravel then grading it down to the original grade over about 15 feet.

 

[fun4stuff]

We built out low end up with gravel basically making a hill of gravel then grading it down to the original grade over about 15 feet.

this is what i imaginged he meant, need to clarify

 

[alvindo]

We didn’t do a retaining wall on the low end for a few reasons but you certainly could do it. We discussed it with our builder. Fortunately, or I guess unfortunately we live an area with a lot of hills and he let me look at other pools he built in similar situations. Just that fact alone gave me some comfort.