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: Barriers are placed over openings in the opposing sidewalls of leaching chambers used for receiving and dispersing water within soils. The barriers enable outward flow of water and hinder inward movement of soil. Exemplary barriers such as geotextile may be attached directly to the sidewall of the chamber. In another approach, panels comprised of barrier material contained with a frame, and the panels are placed on the chamber sidewall at the location of the openings.

Abstract: A molded plastic arch shape cross section stormwater chamber having a corrugated wall comprises separately molded half chambers which are connected by coupling features at a joint at the top of the chamber. Preferably, the half chambers are substantially identical and are made in the same mold. The half chambers may be compactly stored and transported. Near the point of use, the chambers may be assembled.

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: 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 plastic septic tank has a body made by rotational molding or blow molding and at least one access opening in the top. A ring flange is structurally attached to the top of the body so the bore of the flange fits the access opening. A plastic ring flange has a flexural modulus which is greater than 100,000 psi and at least twice the flexural modulus of the plastic material of the tank body. An exemplary flange is made of a plastic material which includes 5-30 weight percent glass fibers, a significant portion of which are aligned with the plane of the flange upper surface.

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: Arch shape cross-section leaching and stormwater chambers are connected together so that swiveled angling is obtained at the joint. Angling is accomplished by means of an integral or detachable dome end comprising a conical section. A like chamber with an ordinary end mates by overlapping the dome. Or a like chamber may have an opposing and overlapping end, which also comprises a dome. A coupling for connecting two ordinary end chambers is comprised of two spaced apart conical domes spaced apart by a connector. The connector between the domes is optionally straight or angled. The couplings enable chambers to be connected at diverse angles to each other, as well as to be connected parallel with offset, i.e., with zigzag path.

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 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 molded thermoplastic tank for use as a septic tank or storage tank when buried in soil has a combination of transverse peak and valley corrugations in combination with one or more lengthwise peak corrugations, to provide in effect a molded-in beam structure. The lengthwise corrugations may be at the top, between spaced apart access ports, along the bottom. In one embodiment, the top has an H-shape pattern beam structure. In another embodiment separately formed plastic beams and or a combination of vertical and horizontal struts are inside the tank.

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: A leaching chamber having opposing inwardly and upwardly running sidewalls extending toward a top portion is provided, wherein the leaching chamber includes a plurality of peak and valley corrugations formed by the sidewalls and extending over the top portion and a plurality of diagonally opposed ribs, the plurality of ribs extending diagonally across at least a portion of the top portion to form at least one X shaped pattern.

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.