Abstract: The present invention 10 discloses a disk-like member 15 that would be placed on the cover-retaining flange 20 in the manhole tube 22 on which the cover 16 would ordinarily rest. The operator would then insert a turnkey 24 through a central recess 26 in the manhole security device 10 until it matched up with its corresponding mate on the underside of the plate and then rotate the turnkey, thereby extending two locking members 46 in opposing directions until their tips 33 are imbedded in the soft metal of the manhole ring 18. The extended, imbedded locking members 46 below the cover retaining flange 20 prevent the manhole security device from being removed until the proper mating turnkey 24 is inserted and the locking members 46 are retracted. The manhole cover 16 is placed over the locked manhole security device 10 until such time that authorized removal is desired.

Abstract: The present invention 10 discloses a disk-like member 15 that would be placed on the cover-retaining flange 20 in the manhole tube 22 on which the cover 16 would ordinarily rest. The operator would then insert a turnkey 24 through a central recess 26 in the manhole security device 10 until it matched up with its corresponding mate on the underside of the plate and then rotate the turnkey, thereby extending two locking members 46 in opposing directions until their tips 33 are imbedded in the soft metal of the manhole ring 18. The extended, imbedded locking members 46 below the cover retaining flange 20 prevent the manhole security device from being removed until the proper mating turnkey 24 is inserted and the locking members 46 are retracted. The manhole cover 16 is placed over the locked manhole security device 10 until such time that authorized removal is desired.