New Pool Construction Concern

We are looking for ideas for building a pool wall less than 3' from an existing retaining wall that will not compromise the retaining wall "angle of repose" support.

We want to put in a 10'x35' shotcrete lap pool (4 shallow end - 7' deep end) in a 23'x53' courtyard area which is enclosed on three sides and open on the downslope 23' side.

The 10'x35' pool will be placed lengthwise - 3' away from the retaining wall and 10' from the house wall (min. code req.).

The 23' and 53' retaining walls are 1' thick reinforced concrete with cantilevered footings on the earth side of the wall and a footing which extends 1' on the pool side. The 23' wall is 11' tall, the 53' wall is 11' tall and slopes rapidly down to 4' continuing the length at 4'. The deep end of the pool will be next to the 4' high retaining wall section.

The soil unconfined compressive strength is probably about 4K psf (type A - silty clay/sandy clay) and the soil is undisturbed.

Does anyone have useful experience in this structural area? We don't need exact specs for anyone to worry about, just strategies.

I'm guessing you're an engineer, or have engineering training? (Terms like "angle of repose" and "unconfined compressive strength" don't show up here very often!)

I think the best you're going to do here, or on other forums, is find some seat of the pants strategies that have worked. I've had a lot of engineers and even JPL "rocket scientists" here -- but I don't recall a self-identified civil or structural engineer. I think that you'll get MUCH more useful input with pictures and sketches, than with an engineering description. But, from your description, I think you are right to be concerned.

Post them on Photobucket, Flickr or Picasa, and link them in. Or if your willing to wait, email them to me at poolforum@gmail.com.

Still, you may need to actually consult with an engineer. I know that high-end builders in hilly markets, like some areas of California, routinely talk to engineers about problems like yours. Atlanta? Not so much, but that doesn't mean it's a bad idea, just that you're going to be hard put to find an engineer who can combine textbook knowledge with adequate field experience.

In my own personal background, I've worked almost exclusively with engineer designed large commercial pools, and I could give you a 200 item list of dumb things done by registered PE's. My remaining local customer is a country club pool that has a 4" diagonal corner to corner off-level, due to a local engineer ignoring the soil study reporting a plastic layer of alluvial soil 20' down!

If you get the pics up, you may want to post on poolspaforum.com, which has far more pool industry member than I allow here, and ask for a practicing engineer knowledgeable about pool construction. I can assure you that there are NONE in my area (110 miles N of you) and that quite a few of the engineers in your area who've been involved in commercial pool design . . . shouldn't have been involved!

Thanks PoolDoc, I was an engineer years ago but in I.T. now. That experience definitely came in handy the last few years as we designed and built our home.

This pic alone should lay it out: http://i166.photobucket.com/albums/u...olplans005.jpg

At the shallow end of the pool the retaining wall will be about 9' tall.

We did have an initial consult with an engineer who has been doing commercial and residential pool design work around Atl for many years. He definitely seemed knowledgeable and recommended 1' thick wall with heavily supplemented rebar. That seems like a good design but was curious to hear if anyone had worked it out a different way successfully. I was even wondering about drilling into the wall footing and joining the pool wall concrete to it with rebar.

Thanks for the advice, I may try the other forum as well.

Uh, yeah.

I've done some strange things with pools over the years, and they've all worked. But I wouldn't touch that, without having a genuine civil or structural engineer look at that. And by "genuine", I mean one who still remembers how to run calculations, and not just look it up in a manual AND who has real field experience to temper his trust in numbers and tables.

Good luck!