Abstract: Risers for use in a riser assembly to provide access to below-grade chambers or vaults are provided. Risers may include an angled wall connecting a first end and a second end spaced apart along a central lengthwise axis. In an embodiment, the riser may include a plurality of latches spaced around the first end and the second end with radially extending lips and canted terminal end surfaces. A plurality of receivers may be spaced between the first plurality of latches on the first end and the second end. Alternatively, plurality of latches may include a first and second latch body extending to a terminal end that comprises a first circumferentially extending lip and a first canted terminal end surface. Risers may be configured to connect to other risers to form a riser assembly.

Abstract: A rectanguloid shape six-walled thermoplastic box for receiving and dispersing stormwater, when part of an array of like boxes that is buried in media, has interior bracing in the form of an irregular polyhedron structure comprised of up to six hollow pyramids. The truncated apexes of the pyramids meet near the center of the box. The base of each hollow pyramid is contact with, attached to, or integral with a wall at the location of an opening within which is a grate. A box may be injection molded as a single piece molding with living hinges. Alternatively, the pyramidal polyhedron structure may be formed as a separate element and placed within the walls of a box.

Abstract: A safety grating has an arch shape cross section and is useful within a riser having a frusto-conical shape wall which riser is attached to a septic tank or another structure. The grating comprises a hub and radially extending arms, one or more of which is rotatable relative to the hub length at a hinge joint, to decrease the size of the grating and enable installation of the grating by passing the grating a smaller end opening of a riser.

Abstract: 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.

Abstract: A plastic leaching chamber is provided and includes a chamber substrate constructed from a PET material and having opposing side base flanges which lie in a horizontal plane and extend lengthwise along the chamber substrate. The chamber substrate includes opposing sidewalls extending upwardly from each of the opposing side base flanges to a top of the chamber substrate and includes a lengthwise center plane which is perpendicular to the horizontal plane. The opposing sidewalls define a plurality of leaching openings having at least one tab slot opening located proximate thereto, and a plurality of louver articles constructed from at least one of a PE and a PP material. Each of the louver articles include a tab which is configured to engage a tab slot opening to securely associate the plurality of louver articles with the chamber substrate to cover the at least one leach opening.

Abstract: A set of three tubular drainage units, each comprised of expanded recycled polystyrene aggregate which is gray in color, is wrapped in film which optionally compresses the drainage units radially and which impedes transmission of infra-red radiation to the aggregate when the drainage units are exposed to sunlight during shipping or storage.

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 melted by internal heating of metal portions of the elements. Before heating of the elements, the flanges are gripped by a clamp which applies a resilient force which, during welding, causes the flanges to move toward each other and thereby a good weld joint is formed.

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 tank suited for use as a septic tank or for otherwise holding or treating water has a top hatchway large enough to enable an adult person to enter the tank. The hatchway is closed by a lid which has a port with a removable cover, where the port that is large enough to enable through-passage of a suction line for cleaning the tank, but small enough to prevent a child from entering the tank. Preferably the port area is less than 6 percent of the effective area of the lid and the centerline of the port lies at a location which is between 20 to 80 percent of the radius of the lid.

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 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.

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: 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.