Defining the boundaries of the concrete slab can be done easily with wooden stakes driven into the ground and a string line laced at a right angles.The pipes should then be covered with a small amount of crushed stone. Dig several small trenches for the insertion of perforated pipes that will be used for radon evacuation purposes (see "Radon gas evacuation" below).Vibratory plate compactors work best and are available at most construction rental outlets. Gradually fill and compact the rest of the trench as well as the undisturbed ground in the centre before spreading crushed gravel over it.Cover the trench with a layer of permeable backfill material.The barrier will prevent sediments from entering the drain while the gravel provides sufficient drainage.
Soil tests will often be ordered to determine how to proceed.
Building a thickened edge slab on grade with normal soil conditions.This page is about how to build a thickened edge concrete slab on grade FPSF footing on soil with a high water table to prevent frost heave, by first installing drainage below the slab. There are many different soil conditions and corresponding slab designs. Slab on Grade foundation, detail design the basics