Even once you’ve narrowed down your wider canal liner choices to a geomembrane, you still have multiple materials to choose from. The wrong material will break down before its time and won’t be able to handle all of the challenges of a canal installation. Knowing the differences between the various geomembrane options will help you choose the right one, depending on the style and unique challenges of each installation. Explore the materials available to you and find out why RPP and RPE liners from BTL Liners stand out from the rest.
Which Materials Are Available?
The primary materials for geomembranes today are PVC, HDPE, LDPE, and RPP/RPE. All of these formulations are based on flexible and durable polymers, but they can vary widely. Flexibility often varies even within the same type of geomembrane because of the addition or lack of plasticizers, which can also leach into the water to damage fish or plants. Choosing a geomembrane material that offers flexibility with nominal additives, high freeze and thaw damage resistance, and a range of thickness options to match the canal design specifications, will ensure years of reliable performance with minimal maintenance.
Ballast Requirements
Some geomembranes work best when covered with a layer of ballast material. Ballast helps anchor geomembranes, to keep them from floating in the water or breaking down from UV exposure. Geomembranes that are designed to work with anchoring points or adhesives may not need ballast material, but it depends on the material’s ability to withstand sunlight if it’s exposed. Even through deep or turbid waters, a lot of UV rays can penetrate and degenerate the geomembrane at the bottom of the canal. Concrete blocks, concrete poured liners, and bricks covering the geomembrane as an underlayment eliminates the need for separate ballast materials.
HDPE
For a durable and chemical resistant canal liner, high density polyethylene (HDPE) can be a good choice. However, it is very stiff and therefore harder to conform to the shape of stepped or unusually sloped canals. That stiffness also makes it more brittle when frozen, reducing its durability in cold climates. Chemical resistance is high in HDPE and many formulas are free from leaching chemicals that could hurt plants or fish. Installation is slower and more difficult due to the weight and stiffness and the material also has a higher chance of detachment than your other options for canal liner. To combat these drawbacks, BTL Liners fabricates an industry leading HDPE-based product paired with layers of more supple LDPE. Thus, combining the best of each material while reducing the drawbacks of both.
LDPE
Another inexpensive geomembrane canal liner material is low density polyethylene (LDPE). LDPE shares many of the benefits of HDPE, but it’s also heavy and can be easy to tear if installed over rough soil with rocks present. Deformation can also occur with LDPE if it’s stretched incorrectly during installation or folded/rolled improperly for shipping. It is more flexible than HDPE and conforms better to curves and bumps, offering a tighter fit that is less likely to float in a canal or pond installation. Both LDPE and HDPE have decent UV resistance without specific additives but are still often paired with ballast material to prevent lifting and floating.
PVC
Polyvinyl chloride (PVC) is one of the most flexible geomembranes available, offering a tight grip and good adherence even without adhesives, anchors, or ballast. Unfortunately, it trades UV resistance for this level of flexibility and therefore must be covered to last in an exposed irrigation canal installation. It may still work well for drainage canals since it’s highly chemical resistant. Seaming sealing is easy with heat or adhesives, but you’ll need at least 12” of ballast, soil, or other cover to protect it from wear and tear. It has a shorter lifespan and isn’t necessarily fish or plant safe due to plasticizing chemical content.
RPE
For the best combination of benefits and the fewest drawbacks in a geomembrane, turn to reinforced polyethylene (RPE) materials. These products are generally built around an inner layer of string net or synthetic fabric to give the material superior tear resistance and strength. There’s no need for a secondary layer of underlayment to prevent this material from tearing as it’s dragged and stretched out over rocky, rough, and uneven surfaces. Thanks to the reinforced design and high strength of the polyethylene material, these liners offer superior durability while being thinner than any other geomembrane. Due to its light weight, RPE liners easy to install with only manual labor for smaller canal designs. RPE can last 30 to 40 years when covered and can also be installed exposed, when necessary, for short-term protection.
EDPM
Ethylene propylene diene monomer rubber (EDPM) is a thick and soft material that is popular for lining irrigation ponds but less widely used for canals. It doesn’t have good chemical resistance, so fertilizer or oil runoff from equipment in the fields could shorten its lifespan significantly. It’s also a lot of work to seal properly and is only available in certain sizes. It is very flexible and plant-safe, but the high cost makes it a less economical choice for covering miles of canal than the other materials listed above.
Underlayment or Primary Liner?
Not all geomembranes work well as either an underlayment for concrete liners or as the primary liner. RPE works equally well as both, while PVC may tear if concrete is poured or laid in place over it. Both LDPE and HDPE work well as a concrete underlayment but take a little more work to use as the primary liner. Various polyethylene membranes are widely used as concrete underlayment for other purposes like vapor barrier underneath building foundations with good results. Finally, EDPM is required as an underlayment in some designs since its rubbery composition and thickness can better brace very loose soils that are prone to collapse. However, RPE’s durability offers a similar effect and therefore can replace EDPM in many applications.
RPE is the clear winner when it comes to geomembranes for canal lining. If you’re looking for a product that can handle practically any installation challenge, RPE is the best selection for most projects. Check out BTL Liner’s ArmorPro for a great example of a tough RPE geomembrane that works effectively as an underlayment or primary liner.
