A pit and an extension, each having flanges extending perpendicular to an axis of the pit and extension. The pit includes holes extending outwardly in the wall of the pit, preferably these holes are located at one end of the pit. Surfaces of the flanges are configured to mate together and clips secure the flanges together to inhibit movement apart of the pit and extension along the axis. In certain embodiments, the extension includes support ribs which may be both interior and exterior and the extension narrows from its flange towards an opposite end thereof.

A permanent on-site manhole casting system comprising a top, a main barrel, and a base. Each component consists of a ribbed plastic outer barrel and a ribbed plastic inner barrel with a plurality of plastic tie strips used to connect the said outer and inner barrels. A coupling mechanism consisting of a plastic outer coupling ring and a plastic inner coupling ring is welded to the coupling ends of the top, main barrel and base which connects the top, main barrel and base components. A concrete mixture is poured into the space between the coupled outer and inner barrels where the concrete is then allowed to set and cure and the filled form is then completely buried.

A liner for a manhole cover is made up of stackable sections. Each stackable section is formed of a plurality (e.g. 4) pieces. Each piece comprises a first arm and a second arm which are substantially perpendicular to one another, the first arm being longer than the second arm, and both arms comprising connection means to allow the pieces to be connected together. The respective dimensions of the first arm and the second arm are chosen such that, when the piece is incorporated into a stackable section comprising three other corresponding pieces that are connected to each other in a sequence of a second arm of one piece connected to the first arm of an adjacent piece to form a quadrilateral stackable section, a further corresponding piece can fit within the stackable section along an axis substantially parallel to the longitudinal axis of the first arm. Further corresponding pieces can thus be arranged within a complete stackable section to maximize the number of pieces that can be transported in a given space.

A permanent on-site manhole casting system consisting of three basic components (a top, a base and a main barrel) which comprise an outer barrel, an inner barrel, a plurality of tie strips used to connect said outer and inner barrels, a coupling mechanism which connects the three basic components, and a concrete mixture that is poured into the space between the outer and inner barrels and allowed to set and cure is provided. The on-site manhole-casting system is designed to create a single manhole unit which is chemically resistant and configurable to numerous manhole and utility system needs.

A plastic multipurpose component that is suitable as a building block and is filled with filling bodies is used to form a sheet-like assembly from a plurality of components. The multipurpose component has double-walled outer frame parts (2) with an outer frame wall, an inner frame wall and a tread surface connecting them, at least one coupling device (6, 8) for connecting two adjacent components being provided on each of the outer lateral surfaces thereof. Where appropriate inner walls (4) divide the interior of the outer frame (2) formed by outer frame parts into a pattern of cellular lead-throughs (6). Inner bottom support frames (11), and where appropriate, bottom transverse struts on the double-walled outer frame and inner frame serve for stabilizing and supporting at least one filling body introduced in the plastic multipurpose part.

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 liner for a manhole cover is made up of stackable sections. Each stackable section is formed of a plurality (e.g. 4) pieces. Each piece comprises a first arm and a second arm which are substantially perpendicular to one another, the first arm being longer than the second arm, and both arms comprising connection means to allow the pieces to be connected together. The respective dimensions of the first arm and the second arm are chosen such that, when the piece is incorporated into a stackable section comprising three other corresponding pieces that are connected to each other in a sequence of a second arm of one piece connected to the first arm of an adjacent piece to form a quadrilateral stackable section, a further corresponding piece can fit within the stackable section along an axis substantially parallel to the longitudinal axis of the first arm. Further corresponding pieces can thus be arranged within a complete stackable section to maximise the number of pieces that can be transported in a given space.

A portable pit-type hunting blind of thermoplastic exterior which can be carried and placed into a dug hole, providing a securable preserved cavity of variable depth, and rotatable seat proximate to the earth's surface.

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 method for manufacturing a precast concrete utility vault is disclosed, focusing on fabricating a single-piece, rectangular lower riser section using an upside-down monolithic pour of reinforced concrete. The method employs a formwork system configured to form a lower riser section with four walls, a slab section, and a sump channel, ensuring precise dimensions and high structural integrity. The upside-down pouring technique facilitates uniform concrete distribution and efficient curing, producing a robust vault component suitable for housing large electrical transformers. The method enhances manufacturing efficiency and product reliability through a streamlined, single-pour process.