Improvements in relation to drainage of containment tanks

Abstract

A drain assembly 31 shown clamping a marginal section 32 of liner 14 hole 33. A lower annular ring 34 is welded to a corresponding opening in box 10. This ring has concentric O-ring slots 35 and 36 carrying O-rings 37 and 38. Porting pathways, in the form of internal conduits formed within the spokes of the rings, are provided for testing. The chamber 61 below the liner 15 is connected to a test valve 66 via an internal conduit formed in spoke 46. That conduit includes a vertical leg 63 and a horizontal leg 64, collectively forming a porting pathway leading to the test valve. The upper chamber 62 is connected via a second internal conduit 67 in another spoke to a second test valve 68. The chambers may be pressurised to test the seals for leakage at set-up and for ongoing integrity checks.

What is claimed is: 
     
         1 . A method for managing the integrity of a seal in a containment tank or pond, the seal being around a hole in a flexible liner, the method comprising forming the seal with at least one pressure test chamber; and pressure testing the seal before filling the tank, and further wherein the test is performed on a drain inlet assembly positioned inside a containment tank or pond, the assembly comprising:
 an opening in the flexible pond liner providing a flow path through the assembly; and   a seal adapted to adopt a fluid-tight seal with the flexible pond liner, the seal including the at least one pressure test chamber adapted to be pressurised to simulate a corresponding hydraulic pressure prior to filling the pond, the inlet assembly being positioned at one end of a drain assembly having an outlet located outside the pond.   
     
     
         2 . The method according to  claim 1 , wherein the pressure test chamber is supplied with pressurised air up to a predetermined pressure, and the integrity of the seal is tested by observing a pressure drop on a gauge or by applying a liquid capable of revealing gas leakage by bubbling. 
     
     
         3 . The method according to  claim 1 , wherein the seal comprises two chambers and each chamber has a corresponding test valve adapted to enable pressurisation of its respective chamber. 
     
     
         4 . The method according to  claim 3 , wherein one chamber is positioned above the liner and the other chamber is positioned below the liner. 
     
     
         5 . A drain assembly comprising:
 a drain inlet assembly positioned inside a containment pond or tank and comprising an opening in a flexible pond liner providing a flow path through the assembly;   a seal adapted to adopt a fluid-tight seal with the flexible pond liner, the seal including at least one pressure test chamber configured to be pressurised prior to filling the pond to simulate hydraulic pressure,   wherein the drain inlet assembly is positioned at one end of a drain assembly having an outlet located outside the pond.   
     
     
         6 . The drain assembly according to  claim 5 , wherein the seal comprises a first pressure test chamber located above a portion of the liner and a second pressure test chamber located below the liner, the respective portions of the liner being sandwiched between clamping sections of the drain inlet assembly. 
     
     
         7 . The drain assembly according to  claim 6 , wherein the clamping sections comprise first and second companion clamps and include a manually operable clamping means adapted to clamp the liner between the clamping sections so as to surround the flow path through the assembly. 
     
     
         8 . The drain assembly according to  claim 5 , wherein the seal comprises companion clamping parts configured to clamp the liner, and a connecting means between the clamping parts, the connecting means comprising a connecting rod, and wherein relative movement in an axial direction along the rod under a clamping pressure urges the clamping parts toward each other to sandwich the liner therebetween. 
     
     
         9 . The drain assembly according to  claim 8 , wherein the clamping parts comprise respective annular flanges extending around the liner, and wherein each flange carries spaced apart O-rings such that the pressure test chambers are defined between the O-rings, the liner, and the clamping parts of the inlet assembly. 
     
     
         10 . The drain assembly according to  claim 5 , wherein the pressure test chamber is fluidly connected to a test valve via a porting pathway, the pathway including at least one internal conduit formed in a spoke of a clamping component of the assembly. 
     
     
         11 . The drain assembly according to  claim 10 , wherein the porting pathway comprises a first conduit leading from a lower chamber below the liner to a test valve positioned above the drain inlet assembly. 
     
     
         12 . The drain assembly according to  claim 10 , wherein a second porting pathway connects an upper chamber above the liner to a corresponding test valve positioned above the drain inlet assembly. 
     
     
         13 . The drain assembly according to  claim 5 , wherein the clamping parts and associated seals form a removable subassembly adapted for replacement, servicing, or inspection. 
     
     
         14 . The drain assembly according to  claim 5 , wherein the annular flanges are each formed with a plurality of spokes extending radially from a central hub. 
     
     
         15 . The drain assembly according to  claim 14 , wherein at least one of the spokes includes an internal conduit forming part of the porting pathway between the pressure test chamber and a test valve. 
     
     
         16 . The drain assembly according to  claim 5 , wherein the connecting rod includes a protective sleeve to shield the threads of the rod during use and operation. 
     
     
         17 . The drain assembly according to  claim 5 , wherein the upper clamping ring includes a manually operable winged nut for advancing the clamp along the rod to apply axial clamping force. 
     
     
         18 . The drain assembly according to  claim 5 , wherein the lower clamping ring is permanently affixed or welded to a drain housing. 
     
     
         19 . The drain assembly according to  claim 5 , wherein the annular flanges are profiled in a conical configuration converging toward the central flow axis when assembled. 
     
     
         20 . The drain assembly according to  claim 5 , wherein the drain inlet assembly includes a pair of spaced-apart test valves located above the pond floor, accessible for pressure testing during and after installation.