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 region at the top of the chamber, which coupling feature optionally includes at least one locking rod running lengthwise in proximity to the joint region. Preferably, the half chambers are made in the same mold and modified so they are mirror images of each other. The half chambers may be compactly stored and transported in nested condition. Near the point of use, the chambers may be assembled.

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 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 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 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: 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 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 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 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.

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: An end plate for closing off the end of an arch shape cross section corrugated storm water chamber, which receives water for dispersal beneath the surface of the earth, has a dished portion which projects outwardly from the end of a chamber to which it is attached, preferably by means of a flange which engages the corrugations of the chamber. Ribs inside the end plate add strength.