Funny, was just in a different thread about a slide, so its fresh on my mind.
Is that the final placement of the slide? The stub out from the ground should be close to the back of the ladder if you want a clean look. The pipe coming out of the ground will be connected to a pipe that comes with the slide and sits in that recessed part of the back of the ladder. If I remember correctly, there is a coupler that goes on to the ground stub, to the slide plumbing, then to a valve, then to the top of the slide where water comes out.
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For mine, the stub out of the pavers was right the hose from the slide would connect to. Here is mine before the slide when into place.
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There is concrete under there for the slide to mount to, and am guessing in yours this is a mock up, as you would need a concrete base.
If the stub out is not close to where the slide will go, you will see the plumbing, and that's not probably what you want. The slide has a slot built in to kind of hide the plumbing so i would check on that.