Metal detecting an unusual search target burried in Maine ice and snow

I got a call from some friends asking if it was possible locate a PVC drain cover with 3 metal retaining screws, buried under several inches of ice and snow? Snow melt from warmer tempatures and rain had caused flooding in their backyard, however a thick sheet of ice below the snow was obstructing the in ground drainage system from removing the water. The small screws registered to indicate the drain cover location and utilizing some ice melt and a pick the cover was accessed to allow drainage through about 10 to 12 inches of ice.