A prefabricated composite concrete element for use in a corrosive sewer environment. The concrete element has a hollow reinforced cast concrete portion with at least one end having connection details, a premolded corrosion resistant inner plastic liner. The plastic liner lines an interior of the hollow concrete element and the connection details to provide abutting liner faces in an assembled joint to limit exposure through said joint of said concrete portion to corrosive materials arising in said sewer environment. At least two prefabricated composite concrete elements may be assembled end to end at a joint to form a concrete sewer system. Also disclosed are a method of prefabricating such a composite concrete element.

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 prefabricated composite concrete element for use in a corrosive sewer environment. The concrete element has a hollow reinforced cast concrete portion with at least one end having connection details, a premolded corrosion resistant inner plastic liner. The plastic liner lines an interior of the hollow concrete element and the connection details to provide abutting liner faces in an assembled joint to limit exposure through said joint of said concrete portion to corrosive materials arising in said sewer environment. At least two prefabricated composite concrete elements may be assembled end to end at a joint to form a concrete sewer system. Also disclosed are a method of prefabricating such a composite concrete element.

A prefabricated part comprises a concrete body that has the form of a pipe section with two pipe ends and a pipe inner side. The pipe inner side is lined at least in some areas by a lining made of plastic material connected to the concrete body, and at least one of the pipe ends is covered at least in some areas by a molded part made of plastic material connected to the concrete body. At least the pipe end, which is covered at least in some areas, has a connecting joint in order to connect the pipe end to a pipe end of a further prefabricated part. The lining consists of a thermoplastic material and the molded part consists of a thermosetting plastic. The lining and the molded part are connected to each other in a sealed manner.

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.

The invention relates to a frame system (1) for a manhole covering (100) having at least one first frame element (10) and one second frame element (20), which each include at least one first connecting surface (10a; 20a) and/or at least one second connecting surface (10b; 20b). The first and second frame element (10; 20) are connectable to one another in a friction-locked and/or formfitting manner along the opposing first or second connecting surfaces (10a; 10b; 20a; 20b), wherein in the connected state of the first and second frame element (10; 20) at least one joining region (12) is formed between the opposing first connecting surfaces (10a; 20a) or between the opposing second connecting surfaces (10b; 20b). The joining region (12) can be filled using a joining element (60) in such a way that the joined connection of the frame elements (10; 20) is detachable and reproducible wherein the joining element (90) comprises a hot melt adhesive. Furthermore, the invention relates to a manhole covering (100) having a manhole cover and such a frame system.

A prefabricated part comprises a concrete body that has the form of a pipe section with two pipe ends and a pipe inner side. The pipe inner side is lined at least in some areas by a lining made of plastic material connected to the concrete body, and at least one of the pipe ends is covered at least in some areas by a molded part made of plastic material connected to the concrete body. At least the pipe end, which is covered at least in some areas, has a connecting joint in order to connect the pipe end to a pipe end of a further prefabricated part. The lining consists of a thermoplastic material and the molded part consists of a thermosetting plastic. The lining and the molded part are connected to each other in a sealed manner.

The invention provides for a secondary overflow pipe and connector (10) connectable to a sewer system, the secondary overflow pipe increasing overall capacity of the sewer system during peak flows, the connector (10) connectable to a manhole (16) and shaped to define a funnel to reduce turbulence and facilitate a smooth flow pattern and maximum flow capacity.

A plastic article useful as a riser for a septic tank or as a water tank article is comprised of a multiplicity of plastic rings which are attached vertically to each other at joints. Ring pairs which alternately have inward and outward sloping conical walls nest within each other for shipment or storage. A lid is shaped for use with the topmost ring to cover the opening irrespective of which conical shape the ring has.

A kit, and an assembly formed with components of the kit, comprises a fitting for the top of a septic tank or water tank, one or more frusto-conical rings shaped to interconnect with an identical ring to form an undulating wall riser that extends upwardly from the tank top fitting, and a lid. The lid is shaped for multi-purpose use: closing off the opening of either the large end or the small end of a ring/riserwhichever is uppermost, or closing off the fitting when there is no riser. Joints between the rings of the riser, and between a ring/riser and the fitting of a tank, are held together by latching tabs and/or screws. A fitting may be integral with a tank top.