Any garden swing set should have soft material beneath it to cushion a kid’s fall if he slips off. Though it sounds odd, pea gravel makes a good base to provide safety for your little ones. The small stones disperse easily, providing a safe surface, and won’t rot like mulch or blow away like sand. If you want to base a swing set in pea gravel, you need to secure it so that the pea gravel doesn’t disperse over time.
1. Measure the area where you intend to put the swing set, from corner to corner. You want the area to be as level as possible (the pea gravel will help ensure this) and have at least 2 feet of extra space around the swing set to provide a comfortable base of safety.
2. Get enough lumber to frame the area you have measured. The lumber should be 2 inches by 8 inches, and long enough to match each side of the intended area of the swing set. You can join two lengths of lumber together with galvanized screws if you cannot find a length long enough to fit a side.
3. Assemble the lumber into a rectangle; like a sandbox frame; fitting the intended area for the swing set. Nail the corner pieces into position and use a framing square to ensure that they are joined at 90 degree angles. You can also attach metal brackets to the corners of your newly formed rectangles to make sure they fit evenly.
4. Dig a narrow trench in the earth, matching the parameters of your newly built frame. It should be about 4 inches deep; deep enough to secure the rectangle, but shallow enough to leave a good 4 inches or so sticking above the ground.
5. Lower the lumber rectangle into the trench and fill up the remaining space with earth. Pat the earth down firmly so that the lumber is reasonably secure and doesn’t wiggle.
6. Set the swing set down inside the rectangle and secure with any anchors or bolts. You should double-check the swing set to make sure it is level and that the base is secure.
7. Fill the rectangle with pea gravel, distributing it evenly so that the ground around the swing set is level, and the gravel can disperse easily if anyone falls on it. You should also make sure that the swing set has enough clearance for the kids to use it without scraping the ground.
If you don’t want to build a wooden barrier to keep the pea gravel in, you can lay down bricks or set up inexpensive plastic barriers. The only requirement is that the barrier should keep the pea gravel in place and prevent it from being dispersed.