A church near me was about to celebrate its 300th anniversary so they wanted to retrieve a time capsule that was buried in the 1970s. Since it was buried, they had put a new sidewalk in, pictures of that day 40 years ago were developed in reverse so everything looked backwards and add in that there was only 3 people there that were there to see it put in the ground. I thought it was going to be easy- not! Change was every where, pennies, dimes, nickel's, it looked like a movie, trenches/holes all over. they were taking turns digging in shifts, and deep, 4-5 feet deep. It was a 6" 8" piece of lead pipe, lead caps soldered on each end with a valve they used to put some inert gas into it with. The guys that put this together were phone company workers and Norwegian builders. They said burying it under the "Frost Line" in retrospect may have been going a bit overboard, I agreed with that statement. My machine wasn't any help, a half hour of looking and I was done. Just that week I had gotten my first ever pinpointer, a brand new garrett. on my hands and knees at the bottom of one trench I got a small single beep and gently uncovered a heavy piece of metal a few inches deep, I let them dig it out because I absolutely thought it was a utility, but it was their 60 pound 6' long lead pipe pressurized time capsule. I acted like it was a slam dunk, never a doubt in my mind thing, but I sweat that out.