Rotationally molded subterranean tank with riser

Abstract

A subterranean tank assembly is provided which broadly includes a vessel, a cover, and a riser which is configured to permit the riser to be adjusted in axial length at the job site. The riser is configured to permit coupling of the cover to the topmost connector portion thereof and to a portal of the vessel. The riser includes a plurality of substantially parallel, axially spaced circumferentially extending flanges which mate with the rim of the portal surrounding the opening, whereby the flanges may be fastened to the vessel in lengths intermediate to the initial length of the riser without the necessity of altering the tank or the cover.

1 . A cover integrally molded of synthetic resin and adapted for interfitting to a portal of a subterranean tank, said cover comprising: 
 an upper wall; and    a lower wall, wherein said upper wall and lower wall are interconnected along a circumferentially extending outer edge, at least a part of said lower wall being spaced from at least a part of said upper wall to define a cavity therebetween.    
   
   
       2 . A cover as set forth in  claim 1 , wherein the upper wall includes a plurality of circumferentially spaced depressions adjacent to the edge.  
   
   
       3 . A cover as set forth in  claim 2 , wherein the upper wall and lower wall are interconnected and unitary along at least a portion of said indentations.  
   
   
       4 . A cover as set forth in  claim 3 , wherein said lower wall includes a circumferentially extending frustoconically shaped mating surface radially inward of the outer edge.  
   
   
       5 . A cover as set forth in  claim 4 , wherein said mating surface includes a plurality of radially inwardly extending, circumferentially spaced lugs.  
   
   
       6 . A cover as set forth in  claim 5 , wherein said lower wall includes at least one depression extending toward said upper wall, said lower wall and said upper wall being interconnected and unitary along at least a portion of said at least one depression.  
   
   
       7 . A cover as set forth in  claim 6 , wherein said at least one depression includes a plurality of said depressions.  
   
   
       8 . A cover as set forth in  claim 7 , where said plurality of depressions are elongated and radially extending to present a plurality of radially extending peaks where said upper and lower walls are unitary.  
   
   
       9 . A vessel adapted for receiving and retaining liquid therein, said vessel including: 
 an elongated bottom wall;    first and second longitudinally spaced end walls integrally formed with said bottom wall; and    an elongated top wall integrally formed with and connected to said bottom wall and first and second end walls to define an enclosed chamber, said top wall being substantially parabolic viewed in vertical cross-section.    
   
   
       10 . A vessel as set forth in  claim 9 , wherein said chamber extends along a longitudinal axis and said top wall includes a plurality of corrugations and connecting walls alternating with said corrugations which are substantially parabolic when viewed in vertical cross section perpendicular to said longitudinal axis.  
   
   
       11 . A vessel as set forth in  claim 10 , wherein said top wall includes a plurality of portals sized for permitting the entrance of a human into said chamber, said portals extending substantially vertically from at least one of said corrugations.  
   
   
       12 . A vessel as set forth in  claim 11 , wherein said bottom wall is substantially horizontal and said corrugations and alternating connecting walls extend through said bottom wall to substantially circumscribe said vessel in a direction substantially perpendicular to said longitudinal axis.  
   
   
       13 . A vessel adapted for receiving and retaining liquid therein, said vessel including: 
 an elongated bottom wall;    first and second longitudinally spaced end walls integrally formed with said bottom wall; and    an elongated top wall integrally formed with and connected to said bottom wall and first and second end walls to define an enclosed chamber, said top wall including at least one portal sized to admit the entry of a human into said chamber, said portal including a rim having a substantially frustoconically shaped upwardly and radially inwardly extending receiving surface.    
   
   
       14 . A vessel as set forth in  claim 13 , wherein said receiving surface includes at least one recess therein.  
   
   
       15 . A vessel as set forth in  claim 14 , further including a cover sized and configured for mounting to said rim of said portal, said cover including a frustoconically shaped surface thereon complementally configured with said receiving surface for fitting said cover onto said portal.  
   
   
       16 . A vessel as set forth in  claim 15 , wherein said frustoconically shaped surface of said cover includes at least one lug sized and configured for receipt in said slot of said receiving surface of said rim, whereby said lug may lockingly engage said recess for holding said cover on said rim.