what an interesting idea! So , these vertical "tubes" of sand kind of suck moisture from the surrounding soil and mud?
The holes we dug were to get through the layer of clay and into the dirt underneath, which will allow the water to drain down into these holes, pass through the sand and into whatever is underneath the layers of clay instead of dealing with the standing water.
I filled them back up with sand, really packed it in there, we thought about pea gravel and then just doing the sand ontop, but quite frankly, sand is cheaper and it's already proving to be very successful.
Using an auger to create each hole took approximately 5 minutes per hole. 4 of them were just to break through the clay and then 1 simple minute to go the rest of the way down and pull the auger back out.