Application: 005
Geomembrane Floating Covers
General
A floating cover is simply a geomembrane barrier designed to float on
the surface of a contained liquid. Two basic types of cover exist;
Single Goemembrane covers and Modular Covers.
The Single Geomembrane Cover
This type of cover can take many different forms dependent on the
design objective of the cover and the practical circumstances of the
installation. A number of technical points need to be addressed prior
to commencement of the cover design:
Chemical compatibility of the contained liquid with the proposed
geomembrane cover
Wet or dry installation, (Liquid in or out of the containment during
cover installation)
Purpose of cover & required service life
Fluctuation of contained liquid level during service life
Inlet/Outlet constructions
Gas collection system
Surface water collection system
Service hatches & Monitoring points
Perimeter geomembrane connection detail
A single geomembrane floating cover uses a combination of attached
closed cell foam floats and sand tube ballasts. These elements are
used to create drainage sumps that collect and carry storm water to
either submersible pumps or gravity drains for water removal into a
drainage system. If liquid levels within the reservoir fall, the slack
in the liner is given up as the defined folds reduce and then deepen
when liquid levels rise again. The floating cover itself is typically
fabricated using polypropylene or polyethylene geomembrane within the
specific high flexibility folding areas. Figure 1 is a schematic of a
typical configuration. Floats and ballasts are also encapsulated in
geomembrane for maximum longevity. Active gas collection can be
achieved using a perforated perimeter extraction pipe beneath the
cover under negative pressure. |
Geomembrane capping
Panel Installation
Dry Installation, Ireland
Wet Installation, France |
Dry installation of Geomembrane Cover
In general a dry installation of this design begins with the
construction of a basal liner. The floating cover geomembrane is
constructed directly on top. A wet installation will require the cover
to be partially constructed adjacent to the containment area and then
very gradually pulled across with construction of additional panels
taking place as the pull progresses. Examples of these two types pf
construction are shown in Figures 2 & 3.
The Modular Geomembrane Cover
The modular cover system consists of individual casings, which are
laced together during installation to form a complete cover over the
liquid in the containment. Each individual casing is comprised of
closed cell insulation sealed between two sheets of durable
geomembrane.
The result is a unique and flexible floating cover system to fit any
application. A schematic example and a typical field installation are
shown in figures 4 & 5.
Operational Benefits of a Floating Cover
· Cost Efficiency
· Odour Control
· Gas Collection & Management
· Algae Control
· Acelerated Biological Treatment
· High Durability
· Evaporation & Water Ingress Control
· Reduction of Reservoir Chemical Dosing
· Liquid Insulation
· Eliminate Airbourne Contamination
Target Industries & Applications
· Agriculture (Slurry, Lagoons)
· Diary Farming
· Waste Water/Liquid Treatment
· Utilities (Portable & Waste Water Storage)
· Food Processing
· Brewing
· Chemical Treatment
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