Leak prevention system and method for a retention pond

Abstract

Leak prevention system for a liquid retention pond ( 10 ), the system comprising an upper membrane ( 3 ) to be covered by the liquid ( 1 ), a lower membrane ( 4 ) disposed on the bottom of the pond and joined in a sealed manner to the upper membrane on a peripheral portion to thereby form a normally sealed envelope ( 20 ) delimited by the two membranes, said envelope being filled with draining material ( 2 ), a plurality of passageways ( 6 ) disposed substantially horizontally in the draining material, a pumping device ( 5 ) adapted to generate an air vacuum in the drains, to suck leakage liquid that may have passed through the upper membrane, such that pollution of the surrounding soil is avoided in the event of a liquid leak through the upper membrane.

What is claimed is: 
     
         1 . A leak prevention system for a liquid retention pond ( 10 ), in particular for polluting or contaminating liquids, the system comprising:
 a sealing arrangement comprising an upper membrane ( 3 ) to be covered by a liquid-containing product ( 1 ), a lower membrane ( 4 ) placed continuously on the entire surface of the foundation ( 90 ) of the pond and joined in a sealed manner to the upper membrane on a peripheral portion to thereby form a normally sealed envelope ( 20 ) delimited by the two membranes, said envelope being filled with a continuous layer of draining material ( 2 ),   at least one pumping device ( 5 ) adapted to generate at least partial air vacuum,   a plurality of passageways ( 6 ) disposed substantially horizontally in the draining material, in fluid communication with the pumping device, to suck leakage liquid that may have passed through the upper membrane, such that pollution of the surrounding soil is avoided in the event of a liquid leak through the upper membrane.   
     
     
         2 . The system according to  claim 1 , wherein the system is configured such that the pumping device ( 5 ) releases/re-injects the leakage liquid in the retention pond ( 1 ). 
     
     
         3 . The system according to  claim 1 , wherein the system comprises a pressure sensor ( 12 ), the system being configured to generate a cyclical activation of the pumping (Ton, Toff), preferably with a duty cycle dependent on the pressure evolution in the envelope ( 20 ). 
     
     
         4 . The system according to  claim 1 , further comprising a collector between the drains and the pumping device and a check valve ( 11 ) between the collector and the pumping device, designed to close itself once the vacuum generation is interrupted, which maintains a vacuum pressure in the drains, even when the pumping is not activated. 
     
     
         5 . The system according to  claim 1 , wherein the draining material ( 2 ) is a prefabricated draining complex layer, based of macroporous synthetic material. 
     
     
         6 . The system according to  claim 1 , wherein the draining material ( 2 ) is a granular material such as sand. 
     
     
         7 . The system according to  claim 6 , wherein the passageways are drains in the form of pierced or porous pipes. 
     
     
         8 . The system according to  claim 7 , wherein the drains are arranged parallel to each other, at a distance between 30 cm and 3 m, and are connected to a collector ( 60 ) in communication with the intake of the pumping device. 
     
     
         9 . The system according to  claim 1 , wherein the pumping device comprises a separation chamber ( 7 ), an air vacuum pump ( 8 ) and a liquid backflow pump ( 9 ), with a liquid level sensor ( 13 ) to control the activation of the liquid backflow pump. 
     
     
         10 . A method used in a leak prevention system for a liquid retention pond ( 10 ), in particular for polluting or contaminating liquids, said method comprising:
 a—arranging a first membrane ( 4 ) at the bottom of the pond, forming a lower membrane, to cover the whole bottom,   b—arranging a continuous layer of draining material ( 2 ) over it, with draining passageways,   c—arranging a second membrane ( 3 ) over it forming an upper membrane, coupling it in a sealed manner at the periphery of the first membrane to form a normally sealed envelope ( 20 ),   d—disposing a pumping device ( 5 ) and performing a pumping from the draining passageways.