Subterranean drain device with improved filtration

Abstract

A water-impervious, non-biodegradable, unitary drainage device with multi-directional rollup capability. The invention features a monolithic “sandwich” construction consisting of planar top and base sheets which are set apart by an array of supports. The supports are disposed between and integrally joined to the sheets. Selective and off-set through-cuts, in the top and bottom sheets, impart to the invention the multi-dimensional rollup capability. Rods, optionally hollow, are used as connectors to join two or more of the devices, so that their internal drain channels are in an efficient, confluent alignment. A filtering adjunct is provided that assures exclusion of particulate in soil emplacements, yet obviates the need for aggregate. The fabric used for filtration is prevented from occluding, by impaction, most drainage apertures; it being fixed to a permanent stand-off network of supportive projections from the top or bottom sheets.

What is claimed is:  
     
         1 . A filtering adjunct to a sandwich-type, subterranean drainage device comprising: 
 a network of stand-off elements that are fixedly disposed on, and project from, a planar surface of the device; and,    a fluid-permeable filter fabric overlain and adhered to tops of the elements, effecting a filter cover over, and set apart from, said surface.    
     
     
         2 . The adjunct of  claim 1 , wherein said elements are supportive projections selected from the class of formations consisting of tubules, detents, posts, ribs, elongate fins and sinuous/arced nodules, which are formable by extruding, molding and lay-down techniques.  
     
     
         3 . The adjunct of  claim 2 , wherein sufficient elements are disposed proximate a preponderance of apertures in the surface to effect a fixed fabric tent structure.  
     
     
         4 . The adjunct of  claim 3 , wherein the fabric is adhered to the surface at selected non-aperture portions to facilitate cutting of the device.  
     
     
         5 . A particulate filtration system for use with a sandwich-type, surface-aperture and interiorly channeled subterranean drainage device comprising a geo-textile filter fabric overlying and joined to tops of a plurality of discrete, fixed projections that emanate from at least one planar surface of the device, and including placement of the projections effectively about any aperture in said surface to effect a stand-off tenting of the fabric over said aperture.  
     
     
         6 . The system of  claim 5  further comprising projections of at least one morphology selected from the class of formations consisting of tubules, detents, posts, ribs, elongate fins and sinuous/arced nodules, which are formable by extruding, molding and lay-down techniques.  
     
     
         7 . The system of  claim 6  wherein the fabric is adhered to the surface at selected non-aperture portions to facilitate cutting of the device.  
     
     
         8 . In a sandwich-type, channeled drainage device that features at least one planar, multi-aperture surface, over which a geo-textile filter fabric is superposed, an improvement characterized by a multiplicity of stand-off elements disposed on and extending in a substantially orthogonal projection from said surface into fixed contacts with said geo-textile filter fabric, thereby effecting a fabric tenting that is discretely held and spaced away from at least a preponderance of apertures in said multi-aperture surface.  
     
     
         9 . The improvement of  claim 8  wherein the fabric is adhered to the surface at selected non-aperture portions to facilitate cutting of the device.  
     
     
         10 . The improvement of  claim 8  wherein said elements are projections of varying shapes and sizes so as to present a rigid, fabric-securing support structure proximate said at least a preponderance of apertures.  
     
     
         11 . The improvement of  claim 10  wherein said varying shapes of said elements are selected from the class of forms consisting of tubules, strings, arcs, ribs and flats.  
     
     
         12 . The improvement of  claim 10  wherein said varying shapes of said elements are molded into the device.  
     
     
         13 . The improvement of  claim 10  wherein said varying shapes of said elements are extruded with and as an integral part of the device.  
     
     
         14 . The improvement of  claim 10  wherein said varying shapes of said elements are adhesive in character and are applied to the device after its construction.