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 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: 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 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.

Abstract: A continuous curve arch shape cross section leaching chamber made of molded thermoplastic has closely spaced corrugations and sidewalls, portions of which are perforated with horizontal slots. Either or both of the slot height and the local wall thickness of the sidewall portion which defines the slots may vary with slot elevation from the base. The chambers are free of interior and exterior strengthening ribs. They provide high interior storage volume and high leaching area in combination with low mass or weight of plastic material. An exemplary 34 inch wide chamber has more than 1.5 cubic feet of water storage volume per foot, less than 4 pounds weight of thermoplastic material per foot, and at least 30 square inches of slot-provided leaching area per foot.

Abstract: A continuous curve arch shape cross section leaching chamber made of molded thermoplastic has closely spaced corrugations and sidewalls, portions of which are perforated with horizontal slots. Either or both of the slot height and the local wall thickness which defines the slots may vary with slot elevation from the base, so that a perforated sidewall configuration is achieved which resists entry of surrounding soil.

Abstract: A continuous curve arch shape cross section leaching chamber made of molded thermoplastic has closely spaced corrugations and sidewalls, portions of which are perforated with horizontal slots. Either or both of the slot height and the local wall thickness which defines the slots may vary with slot elevation from the base, so that a perforated sidewall configuration is achieved which resists entry of surrounding soil. In one embodiment, the slotted sidewall has slots with all the same slot openings and the wall thickness decreases with elevation.

Abstract: A leaching chamber, particularly a chamber which lacks ribs and is therefore flexible along its length, has a length in the range 4 to 5 ft, a length to width aspect ratio of between 1.2 and 1.6 and a weight of less than 3 pounds per foot, preferably about 12 pounds for a 4 ft chamber. Since the chamber length is less and the mass is more favorably concentrated, handling of chambers, and installing chambers in trenches is improved. The ability of a string of interconnected chambers to curve is increased.

Abstract: In one embodiment, pallet substructure can comprise: a reinforcement structure disposed in a plane, a foot member, and a gusset. The gusset can be disposed in mechanical communication with the reinforcement structure and the foot member, wherein the gusset is configured to restrict movement in vertical directions when the substructure is oriented for use.

Abstract: Two identical arch shape cross section chambers are joined together so that a dome shape part of one end of the chamber is overlapped by the opposing plain end of the second chamber. Thus, one chamber may pivot in the horizontal plane, for adjustment during installation. A latch at the top of the joint between the chamber pair inhibits vertical motion and separation of the overlapping chamber, while permitting horizontal plane pivoting. A latch comprises a tang which cantilevers outwardly from the top of the dome end, to engage a catch which is a flared portion of lip on the overlapping plain end.

Abstract: A continuous curve arch shape cross section leaching chamber made of molded thermoplastic has closely spaced corrugations and sidewalls which are perforated with slots which slope downwardly, running from interior to exterior of the chamber. The slot height and or wall thickness vary with slot clevation from the base, to achieve a desired minimum Soil Threshold Angle in the slots, where said Angle parameter relates to resistance to entry of surrounding soil. Slotted wall thickness is less than about two times the thickness of the basic chamber wall thickness elsewhere. The chamber has properties and performance approximating prior art chambers, but has substantially less normalized weight and total weight.