Missing sprinkler solenoids

I was contacted by John and asked if I could find some missing sprinkler solenoids in the ground. I wasnt sure exactly what he was looking for but I told him I would try. At some point previously homeowner had sod put down and most of the access covers were covered. There was one solenoid cover exposed that I was able to pick up a metalic signal with my detector. When I detected a similar reading I put a screwdriver into the dirt to confirm the plastic cover. I found all five missing solenoid in about 1 hour.