'Trench' in the Bible

So Elijah used the stones to build an altar to the name of the LORD. But then he dug a trench around the altar large enough to hold two measures of seed.

"Do it a third time," he said. So they did it a third time. The water ran down around the altar and completely filled the trench.

Right then the LORD's fire fell and consumed the burnt offering, the wood, the stones, the dust, and even the water that was in the trench!