Yea that does sound terrible lol. I guess my math was off on the bags per yard. We are paying 150/yard here though. My pool is 20 x 40 with full-width stairs. I assumed 7 yards for the bond and 1 yard for the stairs? I am struggling with the calculation on the stairs. Do people fill the whole stair part with concrete or backfill it with stone than concrete? I just want to make sure I do not have bouncy stairs.
Also, for backfill, does 45 tons sound right for 4' walls on a 20 x 40 pool? I plan to use a washed # 8 (3/8-1").
Thanks again!
My pool has full width steps with a tanning ledge which was 8'x18' in the bottom. Is yours just 3 steps? If so the steps are normally 1' 2" in width...so your bottom of the steps would be roughly 20' x 3' 6".
Steps (provided that you fill the bottom inside the steps 8" deep, I put closer to 6" inside my steps)
20 x (3+(6/12)) x (8/12) = 46.7 cu. ft.
46.7/27 = 1.73 cu. yd.
Bond Beam (8" deep all the way around)
(20 + 20 + 40 + 40) x 2 x (8/12) = 160 cu. ft.
160/27 = 5.93 cu. yd.
So it look like you will need roughly 7.5 - 8 yards of concrete. That is if your space from the back of the walls to the dirt is a full 2'...if it's less/more in some places you would need to take that into account. I would suggest pouring the beam 1st and make sure you get a full 8" depth all the way around. Then pour inside the steps and if you are a little short, it will not matter as long as you get 6" or so in there.
The gravel backfill is figured the same way. The steps are a little tricky, but I would break them down into 3 columns to calculate. I also poured concrete for the top surface of the tanning ledge and steps rather than pool krete. I was told since the water was shallow the force of jumping on it could cause the pool krete to dimple where concrete will not. I covered the entire steps/concrete in a layer of foam before installing the liner. So I had concrete in the bottom, then gravel up to about 2" from the top of each step, then put 2" of concrete over that the day I poured the 1st part of my deck.
Wall Back Fill (should have a height of 34 inches since the bottom 8" of the 42" tall wall is concrete)
(20 + 20 + 40 + 40) x 2 x (34/12) = 680 cu. ft.
680/27 = 25.2 cu. yd.
Steps Back Fill (assuming they are 1' 2" wide and roughly 10" tall, remember to take out the 8" of concrete)
Bottom Step 20 x 1 x (1/12) = 1.6 cu. ft.
Middle Step 20 x 1 x 1 = 20 cu. ft.
Top Step 20 x 1 x (22/12) = 36.6 cu. ft.
So...
59/27 = 2.2 cu. yd.
So roughly 27.5 cu. yd. of back fill gravel
No warranty expressed or implied, but I bet those numbers are really close.
