Abstract: A lightweight manhole cover assembly includes a cover and a base, with the cover including an inner surface having a plurality of ribs extending therefrom. The base includes an inner surface having a plurality of receptacles extending therefrom. The receptacles of the base have a layout that corresponds to the ribs of the cover, such that the ribs are adapted to be inserted into the receptacles.

Abstract: A screw cap assembly for clamping a cover in an opening includes a threaded rod adapted to engage the cover and a clamp threadably connected to the threaded rod. A retainer is adapted to support the threaded rod and to limit the range of movement of the clamp along the threaded rod. Rotational movement of the threaded rod causes the clamp to rotate and travel toward the cover until it engages a first abutment of the retainer, which prevents further rotational movement of the clamp, such that only movement toward the cover in a direction parallel the threaded rod is permitted. Rotational movement of the threaded rod in an opposite direction causes the clamp to rotate and travel away from the cover until the clamp engages a second abutment of the retainer adapted to engage the clamp to prevent further movement of the clamp away from the cover.

Abstract: A lightweight manhole cover assembly includes a cover and a base, with the cover including an inner surface having a plurality of ribs extending therefrom. The base includes an inner surface having a plurality of receptacles extending therefrom. The receptacles of the base have a layout that corresponds to the ribs of the cover, such that the ribs are adapted to be inserted into the receptacles.