CS221479B1 - Foil ground tank - Google Patents

Abstract

The purpose of the invention was to find a design for an underground tank that would comply with safety regulations, especially in terms of possible groundwater pollution. This goal is achieved by having the walls and bottom of the tank consist of three layers, namely a lower safety foil, a damping layer and an upper storage foil. The damping layer has a thickness of up to 10 cm and is made of loose, possibly flexible material, such as sand, fly ash, etc. The tank is suitable for storing liquid fertilizers.

Description

The invention relates to the construction of the walls and the bottom of the foil earth tank.

The advantages of foil earth tanks for the storage of large volumes, such as liquid fertilizers and phosphoric acid, are obvious and well-known, since they are much cheaper in investment compared to above ground steel tanks. Construction of foil ground tanks (construction) is very simple. A rectangular pit with a maximum width of 12 to 15 m is excavated in the wall, which is the maximum dimension of a suitable roof structure. The length is not limited. The depth of the pit is about 3 m, with the side walls sloped at an angle of 30 to 60 °. The walls and bottom of the pit thus formed are covered with a layer of sand, the slags for the signaling device of any leakage of liquid are laid and laid on the layer of sand (welded foil of PVC, neoprene or other plastics). Warehouses are called "Pitt storage".

Liquids stored in this way are usually hazardous to groundwater, so if the film is damaged, the contents of the tank need to be pumped immediately. Since there is always a time lag between the liquid leak signaling and the pumping, the leaked liquid can penetrate the subsoil and contaminate groundwater. It is precisely for these safety reasons that foil earth tanks were designed and built, in which the walls and the bottom of the excavated pit were concreted and only this concrete pit was lined with foil. Even this solution does not seem optimal, as it is investment-intensive, concrete requires protective coatings, construction time is increased by concreting and the concrete may become cracked by deformation or shifting, which will damage the load-bearing foil.

The foil earth tank according to the invention appears to be substantially more advantageous in that its walls and bottom consist of three layers, namely a lower security film, a damping layer and an upper storage film. The damping layer has a thickness of up to 10 cm and consists of a loose or flexible material such as sand, fly ash, rubble rubbish, etc.

The construction of the foil earth tank according to the invention eliminates the leakage of stored liquid to a minimum, especially as compared to single-layer foil earth tanks. The cushioning layer prevents damage to the lower security film when the upper storage film is punctured. The liquid leaks only into the damping layer and is retained by the lower safety foil. Signaling sensors located in the damping layer signal leakage and the tank is pumped without contamination of the ground. Compared to tanks having a concrete backing layer, the solution according to the invention is cheaper, simpler and faster.

The lower security film need not be identical in design to the upper storage film, it may differ from it in strength, thickness, surface finish, type of material, etc. While the upper storage film has a smooth surface allowing flushing of dirt or deposits, a rough surface that allows the application of a loose damping layer on the inclined walls of the tank.

The cushioning layer between the two films is formed by a free-flowing or granular material that does not disrupt the films and is not subject to rot or mildew. The thickness of the damping layer depends on the puncture safety requirement and is about 2 to 3 cm. The most common material of the damping layer is float-free float sand with a maximum particle size of 1.5 cm. Also suitable is power plant fly ash, rubbish from rubber waste, expanded polystyrene, etc. Sensors are inserted into the damping layer to signal leakage of stored liquid.

The top storage foil is usually made of PVC foil 1 to 2 mm thick.

The upper and lower foil walls and the bottom are created by welding, gluing or heat heating of individual strips. The connections are visually inspected. The service life of such a tank, which is usually roofed, is assumed to be at least 10 years. The foil ground tanks according to the invention are particularly suitable for storing liquid fertilizers and other aggressive liquids.

Exemplary embodiment

In the ground, a pit of 11 x 25 m was excavated 2.5 m deep with side walls sloping at an angle of 30 °. The surface was rolled by a light cylinder and the unevenness was leveled by a layer of fine sand. Strips of polypropylene fabric were laid on the treated surfaces, which serve as a backing layer for the lower security film and prevent any possible damage of the film by sharp stones under load. A lower safety foil was placed on the polypropylene webs. The film was formed by heat sealing a PVC film containing a nylon fabric. * Three pairs of liquid leak indicators were installed at the bottom of the tank so lined and then a 2 to 5 cm thick cushioning layer was applied to the PVC film. It was net float sand. An upper storage foil welded from sheets of pure soft PVC with a thickness of 2 mm was then laid on this sand layer. Through the threaded rods, the foil was attached to the upper edges and the bottom was still covered with a discarded rubber band, thereby loading the bottom and allowing access to the bottom of the tank without the risk of damage to the foil with a shoe. The 270 m ³ storage facility thus created was roofed to prevent contamination of the tank contents by leaves and straw. Construction time was 1 month.

Claims (2)

WE'RE GOING ' Foil earth tank characterized in that its walls and bottom consist of three layers, namely a lower security film, a damping layer and an upper storage film. 2. A foil ground tank according to claim 1, characterized in that the cushioning layer has a thickness of up to 10 cm and consists of a loose or flexible material such as sand, fly ash, rubble, etc.