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. In one embodiment, the slotted sidewall has slots with all the same slot openings and the wall thickness decreases with elevation.

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: The presently disclosed thermoplastic pallet advantageously incorporates fire resistance by virtue of one or more of the following aspects: a sprinkler friendly deck or frame; variable fire retardant or coating distributions; fire collapsible cross beams; foam filled or foam coated parts; and pallet design, including proportioning amounts of plastic and metal utilized in construction. Exemplary combinations of features enables the pallet to meet all the dimensional, mechanical behavior and burn test requirements. The use of metal components including a corrugated aluminum deck having specially position through holes for sprinkler water, and the engineered placement of hollows in the structural plastic parts enables a reduction in the amount of plastic, and the amount of fire retardant in what plastic there is and in the pallet as a whole.

Abstract: To make a thin-wall bottom groove in an injection molded plastic article, such as the type of V-shape grooves which define tear-out portions of an article, the space between the groove-defining land of the mold and the opposing part of the mold is changeable. During injection and filling of the mold, the space is large, to enable filling of the mold. As the mold fills, the space is made small, so the desired finished dimension in the part is obtained.

Abstract: An arch shape cross section thermoplastic leaching chamber, having sidewall slot perforations which flare inwardly, is made using a mold comprised of a mold cavity part and an inwardly retractable mold core part. The core part has opposing side slides with projections that define the perforations; they are separated by a center block. The center block moves downwardly and the slides move inwardly, under action of slide rods built into the mold core, to enable a molded chamber to be removed from the mold.

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 elevation 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.

Abstract: A molded plastic seal assembly, for use with a leaching or stormwater system component, comprises at least two embossed, preferentially eccentric, circles. Pulling on a tab tears out the interior portion of the seal, to create a hole which accommodates a first pipe diameter. A remaining crescent portion surrounding the hole has a multiplicity of perforations or other means for thinning. Thus, second larger diameter pipe pushed into said hole, deforms the crescent inwardly, so the hole diameter is increased, sufficient to fit and form a seal with the second pipe outside diameter. A seal assembly article made of polypropylene has a very thin wall at the bottom of the tear-out groove. Part of the injection mold is moved during molding, to enable filling of the mold in vicinity of the thin wall.

Abstract: A molded thermoplastic domed end cap, for attachment to the end of an arch shape cross section leaching chamber or stormwater chamber, has a multiplicity of buttresses, to provide facet surfaces where pipe connections may be made. The essentially planar surface portions have tear out or cut out regions, for pipe openings. The buttresses face in different directions, relative to the longitudinal axis of the end cap, to conveniently accommodate pipes running in different angular directions. Pipes, which pass through openings in the surfaces of the buttresses, are supported by molded in step-saddles of the buttresses. Molded in stops limit inward motion of pipes.

Abstract: A leaching chamber has sidewall perforations which flare inwardly, so that the smallest perforation dimension is on the exterior surface of the sidewall. The basic axes of the perforations run downwardly toward the chamber base, as the axes run from the inside to outside of the chamber. Mold cores having inwardly retracting slides, and which move in complex ways, are used to form the chamber. Thus, perforations are present down near the base flange of the sidewall, even though the base flange has an upwardly extending fin.