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 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: 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: Abrasion resistant glass containers are manufactured by a process in which, after forming but before annealing, the containers are treated with a material which forms a metal oxide surface coating and with a solution, suspension or emulsion of a temperature resistant polymeric material.