[handieman]

I never heard of irrigation donuts and donut hole cutters, till I came to TV. That being said I have had a lot of experience with both recently.
If you think for one minute you will remember where all your sprinkler heads are in your yard, then your a better man than I. Enter the item called a donut. Its made of green colored concrete and sized to fit around your sprinkler head to stop the growth of grass encroaching over the head and preventing it from "popping" up. It also helps you find the head once the grass becomes actively growing. I can't begin to tell you the situations I have seen with dead grass because of hidden, buried, broken and non functional sprinkler heads. There is a neet little donut hole cutter at home depot that will last for the average homeowner, that allows you to cut the surrounding grass and re-setting the donut. It's not strong enough for my use so I have an invention to "beef" it up if you break yours.
My advice to all home owners is spend the small amount for donuts and re-set them yearly and don't hesitate to run your irrigation system on manual and check to see that the coverage and function of all your heads are proper. So often I have seen sprinkler heads buried and locked down by grass growth and end up watering an area the size of a dinner plate. Water is precious in our country, so do your part to use it wisely.
Handie