Abstract: A corrugated pipe manufacturing cell is configured to produce multiple corrugated pipes in parallel. The manufacturing cell may comprise an extrusion system that is capable of providing multiple independently regulated flows of plastic piping material to multiple die heads. The multiple die heads may feed a set of mold blocks having dual cavities for forming he multiple corrugated pipes. The pipe manufacturing cell may be converted between a first mode for producing large diameter single corrugated pipes, and a second mode for producing smaller diameter, plural corrugated pipes.

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: 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 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 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.

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 molded plastic tank, optionally a septic tank, for containing liquid, comprises two injection molded plastic half tanks that have concave exterior walls and integral flanges, and that nest within each other for shipment or storage. Lengthwise ends of the half tanks have grips, for manual or machine lifting of the half tank from the top of a concave-down stack of half tanks, and for then assembling whole tanks. A sling is used to machine lift one or several half tanks by attachment to the grips or to lifting lugs at the top of the half tank. A corrugated septic tank having spaced apart access port regions has a grid of ribs in the exterior top valley corrugations and running across the access port region, to provide strength during testing and use.

Abstract: An injection molded plastic tank for containing liquids, such as a septic tank, is comprised of mated half tanks which are clamped together at mating flanges. A clamp having a C-shape interior concavity has grooves which engage aligned pairs of nubs on the flange surfaces which are spaced apart from the joint surfaces of each flange. A clamp has one or more flared portions at the clamp leading edge end, leading to the grooves or to the inner concavity, to make easier installation of the clamp. When a clamp reaches its home position, the clamp is locked in place against further motion in one or both directions by interacting features on the tank and clamp.

Abstract: A method for treating wastewater in a leaching field comprises forming and burying in soil a continuous curve arch shape cross section injection molded thermoplastic leaching chamber. The chamber has inwardly curving sidewalls perforated with closely spaced horizontal slots and peak corrugations which are closely spaced apart on about 8 inch center-to-center distance or less. The chamber configuration in combination with certain plastic material properties and thickness provide strength sufficient to meet regulatory requirements when the soil above the buried chamber is subjected to load.

Abstract: A septic tank or storage tank has a corrugated thermoplastic wall which has a composite layered structure. A tank wall comprises an inner layer of solid plastic for containing liquid; an outer layer made of solid plastic, for resisting external mechanical forces, and a middle layer of closed cell foam plastic for both resisting liquid flow which penetrates the inner or outer layer and for heat retention which encourages biological processes. In an embodiment, the middle layer has less than about 55 percent of the density of the inner and outer layers, and the inner layer is substantially thinner than the outer layer. The three layers are integrally attached at the time of formation of the tank by rotational molding. The tank has good resistance to mechanical forces and provides insulation.

Abstract: A plastic leaching chamber has an arch shape cross section, corrugations, and one or more hollow pillars extending downwardly within the interior of the chamber, to support the top of the chamber when the chamber is under load during use. Chambers nest within one another to form a stack of chambers for transport or storage. Chambers have peak corrugations which are substantially wider than the intervening valley corrugations. Chambers having different widths and profiles have common size connectors.

Abstract: A plastic leaching chamber has an arch shape cross section, corrugations, and one or more hollow pillars extending downwardly within the interior of the chamber, to support the top of the chamber when the chamber is under load during use. Chambers nest within one another to form a stack of chambers for transport or storage. Chambers have peak corrugations which are substantially wider than the intervening valley corrugations. Chambers having different widths and profiles have common size connectors.

Abstract: In a family of plastic leaching chambers, each having an arch shape cross section and corrugations, there are chambers of different top heights and possibly different widths. Each chamber has a common size of end connector, so chambers within the family, of any size, can be interconnected. Preferably, the height of an end connector is no more than the top height of the smallest chamber in the family. Preferred chambers have one or more hollow pillars extending downwardly within the interior of the chamber; and preferred chambers have peak corrugations which are substantially wider than the intervening valley corrugations.

Abstract: A method for treating wastewater in a leaching field comprises forming and burying in soil a continuous curve arch shape cross section injection molded thermoplastic leaching chamber. The chamber has inwardly curving sidewalls perforated with closely spaced horizontal slots and peak corrugations which are closely spaced apart on about 8 inch center-to-center distance or less. The chamber configuration in combination with certain plastic material properties and thickness provide strength sufficient to meet regulatory requirements when the soil above the buried chamber is subjected to load.

Abstract: A continuous curve arch shape cross section corrugated injection molded thermoplastic chamber is provided and includes a body having a multiplicity of peak and valley corrugations running along the curve of the arch shape, wherein the multiplicity includes opposing sidewalls, each having a foot, opposing chamber ends connected to the body, the ends shaped to form joints with the ends of like chambers, a multiplicity of sprues, within spaced apart valleys, at elevations intermediate the foot and apex of the chamber, wherein each sprue has a first runner running upwardly alone the valley in direction of the apex, and a second runner running downwardly along the valley toward the foot, a base runner connected to the bottom of the second runner, running lengthwise along the foot of the chamber; and at least one third runner connected to the base runner and running upwardly along a peak adjacent the valley.