Locking system for grade level enclosures

An equipment enclosure assembly for buried placement near grade level, including a grade level box having a hollow enclosure, the grade level box having an opening in the bottom for receiving underground utility equipment, a lid for removably closing the top of the enclosure, and a locking assembly for locking the lid to the enclosure for securely locking underground utility equipment inside the enclosure, in which the enclosure has a locking surface on an inside wall of the enclosure, the locking assembly disposed in and located adjacent an edge of the lid for cooperating with the locking surface inside the enclosure, the locking assembly including an L-bolt rotatably disposed in the lid, the L-bolt rotatable between an unlocked position and a locked position, the locking assembly further including a slotted structure affixed to an underside of the lid, the slotted structure projecting downwardly away from the underside of the lid to a downwardly facing opening on the slotted structure which is spaced below the lid and positioned adjacent the locking surface, the L-bolt extending through a passage in the lid and the slotted structure on the underside of the lid, the L-bolt having (1) a locking projection located on the underside of the lid adjacent the locking surface and (2) a position adjusting device exposed to an upper surface of the lid, the locking assembly further including a separate locking piece inserted into the downwardly facing opening and into the passage in the slotted structure and positioned around the L-bolt to prevent removal of the L-bolt from the exterior of the lid once the L-bolt is positioned in the passage through the slotted structure, the L-bolt in its unlocked position allowing the lid to fit into a closed position on the enclosure, the L-bolt rotatable to its locked position by rotating the position adjusting device atop the L-bolt to thereby rotate the L-bolt and therefore the locking projection under the locking surface so that the locking projection can prevent removal of the lid from the enclosure, and in which the locking piece includes a flange that restricts rotation of the L-bolt when the L-bolt is moved between the locked and unlocked positions.