Resin-based structures for use in corrosive environments. The resin-based structures may include a mixture of resin and aggregate. The resin-based structures may be formed in a mold by placing aggregate and resin into the mold. The resin-based structures may have thin wall design with high compression and tension strength.

A plastic article useful as a riser assembly for a septic tank or as part of another structure is comprised of a multiplicity of identical shape conical wall plastic risers. The risers are attached to each other at joints by tabs which engage rim segments; each end of the riser has alternating tabs and rim segments. A riser assembly wall undulates in the lengthwise direction. The risers nest within each other for shipment or storage.

A chamber base for an access chamber used in a below ground pipe installation is disclosed. The chamber base comprises a base body that is molded of a polymeric material as a single integral body and comprises a bottom wall and a side wall extending up from the bottom wall. The base body may further comprise at least one port formed on the side wall thereof that are spaced from each other. A flow path insert may be formed on the base body that defines a flow path from one port on the side wall through the flow path insert to at least one other port on the side wall.

Resin-based structures for use in corrosive environments. The resin-based structures may include a mixture of resin and aggregate. The resin-based structures may be formed in a mold by placing aggregate and resin into the mold. The resin-based structures may have thin wall design with high compression and tension strength.

A manhole sealing device to prevent environmental water from entering a manhole through the joint between the manhole casing, manhole cover, and cover frame. The device comprises a disc shaped inflatable seal for insertion into the upper portion of the manhole and inflated to provide a sealing means to prevent infiltration of water from the environment to the interior of the manhole. The disc shaped seal may include a first rigid stabilization portion surrounded by a flexible inflatable seal wherein the stabilization portion supports and assists in maintaining a seal to prevent water or other fluids from entering the manhole through the cover or the corbel joint thereof. The manhole sealing device can be installed in an existing manhole without replacing any of the structural parts thereof.

A manhole sealing device to prevent environmental water from entering a manhole through the joint between the manhole casing, manhole cover, and cover frame. The device comprises a disc shaped inflatable seal for insertion into the upper portion of the manhole and inflated to provide a sealing means to prevent infiltration of water from the environment to the interior of the manhole. The disc shaped seal may include a first rigid stabilization portion surrounded by a flexible inflatable seal wherein the stabilization portion supports and assists in maintaining a seal to prevent water or other fluids from entering the manhole through the cover or the corbel joint thereof. The manhole sealing device can be installed in an existing manhole without replacing any of the structural parts thereof.