The people building the new elephant exhibit at the Oregon Zoo in Portland let the elephants help select the sand for the outdoor habitat.
They spent a year testing sand for cushioning and drainage and looked at several varieties from Cal Portland's aggregate plant in Vancouver.
The Columbian reports a fine masonry sand held too much water. A rougher sand drained well, but the elephants didn't like it. They like the same sand used on golf courses, known as USGA topdressing. It's not too course and drains well. Project engineer Wayne Starkey calls it the Goldilocks sand -- just right.
The elephant exhibit will use 15,000 cubic yards of sand at 4 feet deep.
Elephants started spending time last month in a part of the 6-acre exhibit.