Void-maintaining synthetic drainable base courses in landfills and other large structures, and methods for controlling the flow and evacuation of fluids from landifills

A method of forming drainable landfill or other large structure, comprising the steps of

• I. providing a base layer formed at least partially of one or more of native soil components and non-native soil components,
• II. providing a synthetic drainable base course element disposed above said base layer, said drainage element comprising
• A) a void-maintaining geocomposite, said geocomposite including
• i) a geocomposite core element having a plurality of ribs constructed and arranged to form a plurality of interconnected voids, said core element having an upper surface and a lower surface, a no-load thickness and a thickness under load, wherein said thicknesses are measured substantially perpendicular to said surfaces, and
• ii) at least one fluid-transmissible layer attached adjacent said upper surface,
• wherein said layers and said core element are constructed and arranged so that, under a load of at least 500 lbs/foot2 for a period of at least 100 hours, said geocomposite maintains voids of sufficient dimension that fluid from said landfill or other large structure can move freely through portions of said drainage element at a transmissivity of at least 19 gallons/minute/foot at a slope gradient of 33% and at least 33 gallons/minute at a slope gradient of 10%, and
• III. providing above said synthetic drainable base course, fill suitable to be drained, said fill comprising one or more layers, sections or quantities of refuse materials, or materials to be processed at least partially within said landfill,
• wherein at least a portion of said synthetic drainable base course is sloped downwardly in a gradient from a first portion to a second portion of said landfill or other large structure.

A synthetic drainable base course composite element suitable for providing drainage when positioned within a landfill or other large structure, said base course element comprising

• a void-maintaining geocomposite, said geocomposite including
• a) a geocomposite core element having a plurality of ribs constructed and arranged to form a plurality of interconnected voids, said core element having an upper surface and a lower surface, a no-load thickness and a thickness under load, wherein said thicknesses are measured substantially perpendicular to said surfaces, and
• b) at least one fluid-transmissible layer attached adjacent said upper surface,
• wherein said layers and said core element are constructed and arranged so that, under a load of at least 1,000 lbs/foot2 for a period of at least 100 hours, said geocomposite maintains voids of sufficient dimension that fluid from said landfill or other large structure can move freely through portions of said drainage element at a transmissivity of at least 19 gallons/minute/foot at a slope gradient of 33% and at least 33 gallons/minute at a slope gradient of 10%, and
• wherein said geocomposite is constructed and arranged so that said transmissivity is maintained within said landfill or other large structure when, fill comprising one or more layers, sections or quantities of waste or refuse materials, or waste or materials to be processed at least partially within said landfill, is disposed above said geocomposite,
• wherein at least a portion of said synthetic drainable base course is sloped downwardly in a gradient from a first portion to a second portion of said landfill or other large structure.