Abstract: A plastic tank is comprised of two parts, a base and a top, that are permanently joined to each other by welding at a circumferential joint formed by two mating flanges of the parts. Fusion weld elements are captured on the faying surfaces of the flanges of the assembled parts, and the elements are melted by internal heating of metal portions of the elements. Two spaced apart circumferential welds which define an annular space are formed. The pressure within the annular space is changed in a test procedure to verify the integrity of the welds.

Abstract: A method of making a plastic tank suitable for containing water comprises forming a tank base which is partially or fully lined with a plastic layer that is different in character or color from the plastic material of the substrate of the tank base. The tank is alternatively formed by injection molding substrate material around the core of a mold which is partially or fully covered by the liner material, and by injecting liner material into the mold to bond it to the tank base substrate in conjunction with retracting part or all of the core, to provide space in the mold for the liner material.

Abstract: A method of making a molded plastic arch shape cross section stormwater chamber having a corrugated wall comprises molding half chambers which are connected by hinges at a joint at the top of the chamber. The chambers may be compactly stored and transported in splayed out configuration. Later, upward force is applied to the hinge joint location of each chamber, so the half chambers are rotated by force of gravity, whereby a faying surface on each half chamber is urged toward the like surface of the other half chamber. The faying surfaces are then fused to each other, preferably as a result of prior heating or by melting of a fusion weld element that is captured in the space between the faying surfaces.

Abstract: A plastic tank is comprised of two parts, a base and a top, that are permanently joined to each other by welding at a circumferential joint formed by two mating flanges of the parts. The faying surfaces of the flanges of the top and base have portions in the shape of a hollow truncated cone. Fusion weld elements are captured on the faying surfaces of the flanges of the assembled parts, and the elements melted by internal heating of metal portions of the elements.

Abstract: A plastic leaching unit for receiving water when buried in trenches in soil comprises a plurality of pillars interconnected by struts. A canopy made of sheet material is attached to the tops of the pillars. The pillars are arranged as spaced apart integral assemblies to enable lateral and vertical bending of the leaching unit, for conforming to a not-straight trench. Preferably, the canopy comprises a second perforated sheet overlying a first sheet having larger perforations, the combination arranged for flow of water and gases while hindering soil particulates. Preferably, the canopy extends a greater amount from the first end of each unit than from the second end, to facilitate end-to-end mating of the units. Leaching units may be stacked one upon the other within a trench.

Abstract: A large tubular plastic tank is formed by fusion welding together half-shell parts at lengthwise flange joints to form a tubular body. Then, end caps are fusion welded onto the outermost ends of the tubular body and an assembly of two or more bodies. Electric or electromagnetic energy is used to melt in situ the fusion weld elements which are captured between the joining surfaces of the parts. A fusion weld element is secured beforehand to linear a joining surface of at least one of two mated tank parts. The weld element exits the joint between two lengthwise-mated parts at the location of mating tabs extending from the mated tank parts; the tabs are subsequently cut away. A circumferential flange joint is made by securing a fusion weld element to at least one joining surface of the mated tank parts, where the ends of the element run through holes in the faying surface of the flange.

Abstract: A corrugated thermoplastic leaching chamber has sidewall louvers that define sidewall slot openings. Each louver comprises an outward extending canopy, a cap integral with the outer end of the canopy, having a down slope greater than the slope of the canopy, and a preferably concave fence at the inner end of the canopy, for inhibiting ingress of soil. The chamber may be made by first thermoforming sheet material, preferably two-layer PET plastic sheet to the shape of the chamber, followed by mechanically cutting and deforming the sidewall, to create the opening and the fence.

Abstract: The cover of a plastic tank suitable for containing water is attached to the tank base by means of alternative joints, including elastically engageable features and lock features to prevent unwanted release. The base of a plastic water tank is comprised of a substrate and a liner and is formed by means which include injection molding into a mold where the core part of the mold is surrounded in part or full by the film which forms the liner.

Abstract: A large tubular plastic tank, for use in holding unpressurized water or wastewater, is formed by fusion welding together half-shell parts at lengthwise flange joints to form a tubular body. Then, end caps are fusion welded onto the outermost ends of the tubular body and an assembly of two or more bodies. Fusion weld elements are secured beforehand to the joining surfaces of the tank parts at a factory; the tank parts are then economically stored or shipped in nested condition to a fabrication site remote from the manufacturing site. Electric or electromagnetic energy is used to melt in situ the fusion weld elements which are captured between the joining surfaces of the parts.

Abstract: A corrugated thermoplastic leaching chamber has sidewall louvers that define sidewall slot openings. Each louver comprises an outward extending canopy, a cap integral with the outer end of the canopy, having a down slope greater than the slope of the canopy, and a preferably concave fence at the inner end of the canopy, for inhibiting ingress of soil. The chamber may be made by first thermoforming sheet material, preferably two-layer PET plastic sheet to the shape of the chamber, followed by mechanically cutting and deforming the sidewall, to create the opening and the fence.

Abstract: A substantially cylindrical drainage unit for use when buried in soil as part of a wastewater leach field comprises a first plastic bead aggregate mass, optionally with a central perforated pipe, surrounded by a segmented-quilt exterior surface. Quilts are held in place around part or all of a drainage unit by straps, a circumscribing netting sleeve, or by being themselves in the form of tubular sleeves. Preferred rectangular quilt segments contain a second pebble aggregate that is smaller than the first aggregate. Quilts are fabricated by mating two horizontally-moving layers of geotextile and disposing the second aggregate into channels or cavities that are defined by seams that join the layers to each other.

Abstract: A plastic leaching unit for receiving water when buried in trenches in soil comprises a plurality of pillars interconnected by struts. A canopy made of sheet material is attached to the tops of the pillars. Preferably, the canopy is perforated and is overlaid with geotextile. The pillars are arranged as spaced apart integral assemblies to enable lateral and vertical bending of the leaching unit, for conforming to a not-straight trench. Leaching units may be stacked one upon the other within a trench.

Abstract: A method of making a plastic tank suitable for containing water comprises forming a tank base which is partially or fully lined with a plastic layer that is different in character or color from the plastic material of the substrate of the tank base. The tank is alternatively formed by injection molding substrate material around the core of a mold which is partially or fully covered by the liner material, and by injecting liner material into the mold to bond it to the tank base substrate in conjunction with retracting part or all of the core, to provide space in the mold for the liner material.

Abstract: A large tubular plastic tank, for use in holding unpressurized water or wastewater, is formed by fusion welding together half-shell parts to form a tubular body. Then end caps are fusion welded onto the outermost ends of the tubular body. Fusion welding fusion weld elements are secured beforehand to one of the mated joining surfaces of the tank parts at a factory; the tank parts are then economically stored or shipped in nested condition to a fabrication site remote from the manufacturing site. Electric or electromagnetic energy is used to melt in situ the fusion weld elements, thereby to make welds between the parts of the tank.

Abstract: A method of making a molded plastic arch shape cross section stormwater chamber having a corrugated wall comprises molding half chambers which are connected by hinges at a joint at the top of the chamber. The chambers may be compactly stored and transported in splayed out configuration. Later, upward force is applied to the hinge joint location of each chamber, so the half chambers are rotated by force of gravity, whereby a faying surface on each half chamber is urged toward the like surface of the other half chamber. The faying surfaces are then fused to each other, preferably as a result of prior heating or by melting of a fusion weld element that is captured in the space between the faying surfaces.

Abstract: A substantially cylindrical drainage unit for use when buried in soil as part of a wastewater leach field comprises a first plastic bead aggregate mass, optionally with a central perforated pipe, surrounded by a segmented-quilt exterior surface. Quilts are held in place around part or all of a drainage unit by straps, a circumscribing netting sleeve, or by being themselves in the form of tubular sleeves. Preferred rectangular quilt segments contain a second pebble aggregate that is smaller than the first aggregate. Quilts are fabricated by mating two horizontally-moving layers of geotextile and disposing the second aggregate into channels or cavities that are defined by seams that join the layers to each other.

Abstract: A substantially cylindrical drainage unit for use when buried in soil as part of a wastewater leach field comprises a first plastic aggregate mass that is contained within netting, with an optional central perforated pipe. A segmented quilt comprises the exterior surface of the drainage unit which is in contact with soil. Pebble aggregate that is smaller in particle size than the first aggregate is contained with the cavities of the quilt segments. Quilts having different segment shapes and sizes are manufactured by specialized apparatus which creates rectilinear or serpentine seams.

Abstract: A substantially cylindrical drainage unit for use when buried in soil as part of a wastewater leach field comprises a first plastic bead aggregate mass, optionally with a central perforated pipe, surrounded by a segmented-quilt exterior surface. Quilts are captured around the drainage unit by straps, a circumscribing netting sleeve, or by being themselves in the form of tubular sleeves. Preferred rectangular quilt segments contain a second pebble aggregate that is smaller than the first aggregate. Quilts are fabricated by mating two layers of geotextile and inserting the second aggregate into channels or cavities that are defined by seams that join the layers to each other.

Abstract: A septic tank is provided and includes a tank top, a tank bottom and a tank side wall which define a tank interior. The septic tank further includes a top channel structure that defines a top channel on an interior surface of the tank top, wherein the top channel structure includes a top channel latch that defines a top brace pocket and a bottom channel structure that defines a bottom channel on an interior surface of the tank bottom, wherein the bottom channel structure includes a bottom channel latch that defines a bottom brace pocket. The septic tank includes a supporting brace having a first brace end and a second brace end, wherein the first brace end is configured to be located within the top brace pocket and the second brace end is configured to be located within the bottom brace pocket.

Abstract: A molded plastic arch shape cross section stormwater chamber having a corrugated wall comprises separately molded half chambers which are connected by hinges at a joint at the top of the chamber. The chambers may be compactly stored and transported in splayed out configuration, with the arch is flattened out and the base flanges are widely separated. Near the point of use, the chambers are hinged to their arch shape use configuration. Preferably, the half chambers are substantially identical and are made in the same mold. Methods of molding the chambers enable providing a larger or smaller corrugation at one end of a chamber made from substantially identical half chambers.