What a mentor that mark is ! Mark taught me so well not to backfill irrigation lines with any rocks in the soil to prevent future damages to pipe . 15 years later I move to the granite state and cant find an ounce of soil without a rock in it . Hmm do I screen on site ? or import some of that sweet jersey dirt ? Just finished a 25 zone install in Hampton falls N.H. for the founder of Planet fitness. Thanks for the Education in 1987. Paul Controlled irrigation N.H.