not level, low and wet base area

[NWMNMom]

Well in reviewing our new pool area to be, we have determined that there is risk of poor drainage, etc., with the area we plan on putting our 18x33 pool. It is not level, slightly lumpy and wet most of the time. Digging down and scraping level to the lowest area risks even more problems with drainage and wetness. The farm/farmyard is basically long ago drained swamp - swamp is only 50 yards away. It HAS to be filled to get it up and level, maybe about 6" - 10". This is the ONLY available area for the pool.

So, that being said, what is the best material to use to build this up? I read somewhere about a certain type of crushed rock or something with a very high "friction value" so that when compacted, it does not move? What is that? Also, then do we put sand or gravel over that and then the masonary or fine sand for the pool floor and coving? I checked around and nobody anywhere in our area carries vermiculite and/or Portland blends (one website said they are the best things to use) - just finding the fine sifted sand was almost impossible up here and we have to pay dearly because it has to be delivered from so far away.

Note: We had an 18'x 48" round softside pool in there before, which we had sifted gravel hauled in to level it up about 6-8" for about 22' round area - carpet padding was placed on the gravel, then the plastic ground cover, then the pool. Never had problems with it shifting etc, but this was not a HUGE perm pool with hard side weight bearing walls either. I was told of risk of perm pool wall settling and buckling if gravel is used to level/build up. So....help!

[CarlD]

It's called QP for "Quarry Product" and it is unwashed crushed stone, so it's stone and dirt and a lot cheaper than most gravel. If you use gravel, you want crushed stone with lots of edges.

You'll need to build a platform using retaining wall blocks. The platform needs to be pretty wide. Rule of thumb says however high the platform is (say, 1 foot) the distance the pool wall needs to be from the edge is double that--in this case, 2 feet. Us the highest point of the platform. So if your platform is 2 feet high, it needs to be four feet wider than the pool on each side. If that's too big, hire an engineer who knows road building to tell you how you can size it down, safely. I did for my pool and it was worth every nickel of the $500 I paid him.

Then you'll want to put perforated drainage pipe at the base of the inside of the platform, below the wall, and daylight it beyond the platform. You don't REALLY need it with retaining wall blocks and QP, but it can help. Fill with the QP, and then rent a tamping machine and tamp it down--level of course. Leave about 4" for sand and use that for the base of the pool. The QP drains as well as crushed stone, is cheaper, and has a higher friction co-efficient. Check with someone building a development where they are building roads as well as houses. They may well have the QP for sale--probably very cheaply.

[NWMNMom]

I knew I had read that somewhere, probably on the old forum from you? Anyway, thank you. We don't think it needs to come up more than a foot or even that much. Just enough to level it out - digging down to level would cause seepage.

So retaining wall bricks or pavers 2' out from the edges for support/wall/edge if we go up 6-8" or up to 1' (after leveling/tamping) then our sand for the bottom/coving? Do we put landscaping fabric or plastic over that before the sand? Would we want more than 2" of the fine sand for the pool bottom if putting on top of this stuff?

We plan on using landscaping plastic/fabric around the edges, then pea rock around the outside. No shrubs or plants so we don't have to deal with roots going up, in or under. Some potted stuff if anything.

Thank you! So appreciated. The pool is scheduled for delivery Monday. We won't be able to start set up for a while as frost is still in the ground and not thawed, but its getting there. Probably last week of April, start of May. We are soooo excited. Big job, messy yard, but years of enjoyment to come!

[CarlD]

I'm not an engineer but it sounds like you are on the right track. Landscape cloth is probably a good idea too. If your pad is 2' past the pool, it should not be more than 1' high--that's right.

[NWMNMom]

I explained to all contractors/sand-gravel/construction suppliers what I needed the materials for and that the fill must be very solid packed so that the weight of the pool walls do not result in shifting on the base and buckling of the walls.

*In Minnesota (checking locally within 60 miles both MN and ND as we are on the border) we found what is called Class 5 Gravel, which is the smaller fractured rock, gravel, black dirt fill and a higher mix of clay which is used for situations where a solid pack is required - they said they often use it for parking lots and other solid pack situations. In North Dakota they have Class 13, which they explained is used for the same reason. They said that the product should be damp (not muddy) when tamped and would result in a very-very solid base. *Some of them I checked with also had what they said was recycled concrete or ground concrete, which would result in a base that was nearly as solid and packed as concrete when tamped. (wondering if that would be too abrasive as a base even with the Masons Sand bottom?) *Found a tamping machine to rent. We have to wait until road load restrictions are off before anything can be delivered - probably after May 15.

I want to run this by again so I have this straight, if you don't mind. We do not need to build up/level very high, just that we cannot dig down to level or will have seepage and no drainage. So we want to fill area to level at 6" up where the pool will sit and continue the fill out 18"-2' from pool edge finishing with the surrounding concrete edger/block for support and prevent erosion. We have found concrete edger block that is 6" high. Should that have any kind of slight slope of 1/2 - 1" from the edge of the pool out to the edger support for drainage or should the entire filled spot be completely flat like a pad? After we fill/compact, is there any benefit to putting landscaping fabric over the entire area before setting the pool up and putting Masons Sand down for bottom/cove? I purchased the VERY heavy duty 20 yr landscape fabric intended to go under patio block, etc. We will install the vapour block lining suggested by Matt on the wall before the sand and coving go in. Are we going about this in the right direction? Thanks so much for the assistance.

BTW - the pool was delivered Monday. OMG, so many heavy boxes!!! Looks like a BIG job even after getting the base ready for the pool. Time to bribe neighbors and relatives with beer and barbeque.....waiting to get started is just about killing me!!!!