Floating covers for reservoirs and lagoons are often compared to the simple solar or winter covers used on backyard pools. While they may share similar appearances, floating covers for commercial holding and processing ponds are far more durable and complex. Stretching a large sheet of the wrong material, over a pond of challenging, chemical-laden wastewater could result in expensive losses. Especially if the cover breaks down after only a few months or years of use. Make sure you understand the basics of these floating covers before attempting to add one to your holding pond, reservoir, or wastewater lagoon.
How Floating Covers Work
The covers don’t work alone but are part of a larger system that begins with a liner or a tank as the base. This serves as the containment method for the liquid and must attach firmly to the cover to create an enclosed space that is capable of controlling gases and vapors. While these covers definitely float on the surface of the water, they don’t do it on their own. A wide range of equipment is used to maintain tension and keep the cover at just the right level, depending on the design of the tank or pond. Most ponds call for the floating cover to rest as close to the surface of the water as possible to control gas build-up and evaporation, but some designs require an air gap for gas capture. Regardless of the liquid held in the tank or pond, it’s piped in between the liner and cover layers to create a completely contained body of water. Floating covers offer benefits like:
- Odor and harmful gas containment to protect homes and businesses located near the pond or lagoon
- Improved security and access control to keep birds, wildlife, and people from accessing the water and potentially falling in or consuming wastewater
- Meeting stricter emissions requirements for methane and CO2 producing wastewater ponds and lagoons
- Control over the exact evaporation rate of a particular pond, essential for both freshwater storage and controlled wastewater treatment processes
- Prevention of environmental contamination by controlling runoff and splashes that could spread chemical or bacteria rich wastewater
- Temperature regulation to aid in water treatment and storage processes.
The Various Types of Floating Covers and Their Alternatives
While all floating covers are used for similar purposes on ponds and lagoons, there are a few different types. The most reliable type is a solid, sheet covering made from an appropriate geomembrane material. Another option is a distributed layer of floating balls or plates that fit loosely together over the surface of the water. In addition to floating or suspended covers, rigid covers are also used for similar purposes. However, they’re not as flexible or durable as floating membranes. This is especially true in gas-producing industries like biodigesters and manure lagoons.
What are Geomembranes?
Geomembranes are a type of geosynthetic designed with a very high impermeability to keep water exactly where you want it. These solid barrier membranes are made from high performance polymers with varying characteristics, depending on the intended final use. Geomembranes work well as floating covers for lagoons and covers because of their durability, flexibility, stretch resistance, UV resistance, and chemical compatibility. Many other materials commonly used as floating or rigid covers, such as plastic and steel panels or concrete vaults, react too much to chemicals commonly found in wastewater. Geomembranes are also used as liners for ponds, reservoirs, and lagoons. Choosing the same material for both the liner and cover makes it easier to get a vapor-tight seal around the edges.
Impermeable vs Permeable Covers
Many alternatives to floating geomembranes lack the impermeability needed for total control over evaporation or rainwater entering the pond. Floating ballast balls and panels, in particular, only offer limited evaporation control and do nothing to stop water from flowing into the pond and increasing the volume more than what’s expected. Don’t confuse impermeable and permeable liners. Only a solid material like a geomembrane can stop both gases and liquids from going in or out of the storage pond. In an environment where every gallon matters, it’s not reliable enough to stick to an impermeable material alone for water control.
Not all ponds and lagoons require covers but failing to install them on sensitive water features could result in both environmental penalties and product losses. Don’t guess at the best floating cover material for your particular application. Get expert advice based on your specific needs by discussing the application with us at BTL Liners. You can find a full range of both cover and liner materials made from durable RPE that is ideal for both purposes.
