Single-walled polyester storage tank for the retention of water of density 1. 

Our pits are buried in stabilized, nonhydromorphic, non-floodable and ground water-free soil. 

Each pit is equipped with a polyethylene screw cap. 

Ventilation is provided at the manhole. 

As these tanks may be empty for long periods of time, they are not intended to be subjected to underground hydraulic surges. 

If the topography of the land allows it, carry out a drainage at the bottom of the excavation with gravity drainage to an eécutoire. (Type ditch, creek...) 

As a preventive measure, if drainage is not possible, it is advisable to lay the vat in a semi buried area by making a soil merlon all around the vat up to the level of the lid. This merlon will be made of glacis to protect the tank and must therefore be perfectly stabilized. It is recalled that the merlon will have to counterbalance the thrust of the tank with several tons of effluents. In the case of a semi-underground installation, a lifting station upstream of the tank must be provided. 

A padlockable closure system is to be provided by the installation company above the polyethylene cover to protect the structure against accidental risk in the tank.