We are going to be pouring a driveway slab over about 10′ of empty 4″ clay drain tile, about 7″ underground. We’ll be compacting gravel over the ground surface before we pour. I’d like to pump it full of grout, but I don’t want to go to the trouble/expense of renting/setup/teardown/cleaning of a grout pump. Anybody got anything they have used to do something like this? Garden hose? PVC pipe?