It’s Sprinkler Blowout Time Again

From Paul Turner of The Slice blog : “It’s about that time of year — Sprinkler blowout season — when grandfathers and others who enjoy pulling the legs of children get to take a few liberties with the facts. “Look, Jason. Lawn geysers! That means the Earth’s crust is fracturing and soon this whole neighborhood will be awash in oozing magma.”

Question: How do you know when it’s time to blow out the sprinklers? And/or: What’s a reasonable price to pay someone to blow out the sprinklers?