Although it is standard that geomembranes for water retention are formed or extruded from a single sheet of seamless material, reinforcement grid or tape adds an extra dimension of “lay flat” ability and durability to the material. A reinforced liner will be more reliable because the reinforcement adds toughness, and boosts fold and tear resistance. Over time, any folds that exist in a liner can be subject to cracking brought about by the weight of the contained wastewater and sludge. The reinforcement layer greatly reduces these risks. RPE material also simplifies installation because it is easier to fit to the contours of the lagoon, providing long-term protection against seepage.
Concerns Over Chemical Resistance
Waste ponds liners for manufacturing and industrial use should be unaffected by possible chemicals that might be components of the waste liquid. Chemical resistance is equally vital for the ponds or lagoons at wastewater treatment facilities. Reactive and corrosive chemicals are sometimes used to treat the sewage, to break down harmful bacteria and nitrates and improve water quality. The sewage itself can also be a corrosive mixture, thus, shortening the effective lifespan of low-quality geomembranes.
Here are the relative merits of existing geomembrane options:
- Reinforced Polyethylene: Often considered the ideal material for sewage lagoon liners, RPE performance is optimized because it combines multiple forms of polyethylene. Adding a reinforcement layer lessens the risk of damage during installation, and it is instrumental in preventing roots from breaching the material over time. RPE is highly resistant to common chemicals, and it has been demonstrated to store high concentrations of chlorine and other chemicals used for sewage treatment. It is this all-around suitability that makes it an excellent material for in-ground storage ponds, in addition to its record as a great option for smaller above-ground tanks.
- High Density Polyethylene: Also known as HDPE, high density polyethylene is tough, but it’s also more brittle, making it less desirable for most sewage lagoons. In addition, it lacks the specific resistance to many compounds found in sewage or used by water treatment programs. Cold outdoor temperatures can also be problematic, leading to cracks in HDPE pond liners. Leaks can be difficult to repair. Although it’s more reliable than sheet rubber or PVC, it is not a leading choice for sewage lagoons.
- Low Density Polyethylene: Offering some benefits over the high-density option, low density polyethylene (LDPE) is more flexible and less prone to freeze damage, helping it to better conform to pond curves and configuration. Unfortunately, it can be prone to rising and “floating” when used in sewage lagoons, particularly if any methane gas is generated by the waste. LDPE also has less than stellar chemical resistance, with susceptibility to damage from some of the chemical typically used for sewage treatment.
- Polyvinyl Chloride (PVC) should not be considered an option for a sewage lagoon, not even a small, or “backyard” treatment pond. It rates low on the chemical resistance scale and is far less durable that other polyethylene products; it is also extremely vulnerable to sun exposure, which could result in early failure of the material to meet your containment needs.
Concerns About UV Exposure
Damage from constant exposure to the sun’s ultraviolet rays is a risk with all flexible geomembrane liners. Liners that are initially covered with gravel, soil or sand may become exposed over time. Water movement or wave action is apt to erode the bank cover and wind can also expose the liner. Even if only a small portion of the total liner becomes exposed, leaks can occur in any liner that is only minimally resistant to UV damage. RPE is also the best option for UV protection. In fact, some BTL RPE liners are rated for multiple decades of use based on their resistance to sun damage. By selecting RPE as your liner, you shouldn’t have to worry about damage from accidental exposure, even though you will want to minimize exposure time by replacing the cover material as necessary.
Matching Covers for Sewage Lagoons
In addition to containing the liquid in the lagoon, many wastewater treatment plants attempt to control odors and noxious fumes from escaping into the atmosphere. Floating covers or suspended shields near the water line help to control the gases that are released during the breakdown of waste products in the water.
Other reasons for installing covers over sewage lagoons include aesthetic considerations and a need to prevent rainwater from overfilling a pond and allowing untreated liquids to escape the containment pond. If you consider a cover, regardless of the reason, its chemical and UV resistance should be equal to that of the lining material.
ArmorCover by BTL will coordinate perfectly with your liner, and will be a fitting complement to sewage lagoon, helping to control fumes and aiding in the ongoing processing of wastewater.
BTL – A Recognized Leader in the RPE Industry
BTL, with hundreds of thousands of satisfied customers throughout the world, can claim over 10,000 installed liner projects and fabricates millions of square feet of lining material every year. The company began operations in the 1980s. BTL Liners introduced the first reinforced heavyweight RPE liner. With a history of innovation and unparalleled service, BTL takes great pride in its record, strives to offer high value with every quote, and offers a wide variety of sizes and thicknesses to meet all your needs. With custom fabrication capability, BTL Liners should be your “go-to choice” for pond linings.
BTL Liners is committed to providing the best, highest quality, geomembrane containment certainty on the market today. Product quality, coupled with our reputation and expertise, sets BTL apart from the rest.
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