Geomembranes are commonly used to seal both the bottom and slopes of ponds, basins or deposits, to avoid any contact between the contained liquid and the supporting ground. However, in some cases it is also necessary to avoid the contact between the liquid and the atmosphere by providing a cover on the liquid’s top surface. Floating covers are a flexible and economic way of doing so, avoiding expensive and structurally complex rigid covers.
To create the floating cover the geomembrane is fixed at the crest of the slope and installed with a specific geometry in combination with a system of floaters and ballast lines, in such a way that the cover can move up and down following the level of the contained liquid, whilst maintaining always a certain level of tension. Unlike polyolefins, reinforced PVC geomembranes are not affected by this permanent tension and remain stable throughout the project design life. The system is then completed with vents to drain accumulated gases, access traps to allow for inspections, pumps to evacuate the rain, etc. The cover can be installed whilst the reservoir is in operation.
Floating covers are mainly used in drinking water, irrigation and industrial applications, due to the following benefits:
- Reduction of losses due to evaporation
- Protection against contamination by dirt and other atmospheric agents
- Control of liquid composition, avoiding interaction with rain
- Prevention of gas and odour diffusion
- Control of water temperature and blocking of sunlight