Creating a shallow pit underneath the hole gives the radon a place to collect before getting sucked up the pipe. You’ll need to remove several gallons of whatever base material is under your slab. The tighter the soil, the more material you’ll have to remove so the radon fan can do its job. For loose gravel, you need to remove only about 5 gallons. For tighter soils like sand, dirt or clay, plan to remove 15 gallons or more. A shop vacuum helps suck up the loose stuff. For tighter soil, you’ll probably need to do a combination of hand digging and vacuuming.ncG1vNJzZmivp6x7p63MoqOyoJGjsbq5wKdlnKedZLmqv9Nom6KxXaeupbvNZqmenKWYwaq7zWaqsqukmrpw