Geomembranes are designed to support roadways and reinforce retaining walls, so they also work great for keeping ponds and catchment basins watertight and easy to maintain. If you’re searching for a geosynthetic product to line a large area, use these tips to make the right selection of geomembrane.
1. Choose a Reinforced Material
Reinforced polyethylene (RPE) liners do more than just resist chemical and UV degradation. The reinforced design also offers greater tear and wear resistance. Cracks and rips are less likely to occur, both during installation and over the lifespan of the liner.
2. Stick with Neutral RPE
RPE is the best material to choose for geomembranes designed to hold water. If leaks are a major concern because of risks of contamination or environmental damage, you’ll need to stick with a material that forms reliable seams and offers easy testing opportunities. RPE is easily installed in a double liner configuration to allow for the use of constant leak detection systems. With this kind of equipment, any moisture that escapes the first layer of liner will set off an alarm before it can get through the second layer. You can drain the pond or holding tank and remedy the problem before any fluids make it out of the containment area.
3. Plan for Exposed Installation
Even if your designs call for a thick layer of protective ballast or cover material, liners can end up accidentally exposed over time. Shifting dirt and sand leaves bank edges uncovered right down to the geomembrane on many projects. If you choose a liner that can handle exposed installation, this temporary increase in UV rays won’t damage the material. Using liners rated for exposed installation is a good backup plan to ensure a long-lasting pond, even when you have to go months without making visual inspections.
4. Prevent Root Penetration
All liners and geomembranes are at risk for damage from aggressive tree roots. Look for a liner that’s reinforced to keep roots from puncturing the material and creating unintended weep holes.
5. Consider Fish and Plant Safety
Ponds designed for holding drinking water, growing food crops, or raising edible fish will need an appropriate liner. Don’t just settle for a material that claims to offer food and fish safety. Ratings from the NSF help you locate a liner that won’t hurt your fish or risk the health of your customers. If you’re raising ornamental water plants or decorative fish like koi, you’ll still want a fish safe liner. Geomembranes that aren’t tested for fish safety often contain chemical additives to increase durability and flexibility that leach into the water and harm the fish.
6. Pair with an Underlayment or Grid
Depending on the grade of the installation and the conditions of the soil, you may need a geotextile or geogrid underlayment for your liner. Pairing two layers of material can help you prevent tears and holes from rocks and sharp soil particles. Geotextiles with felt-like or fabric-type textures create a cushion against rough surfaces, making the installation of the flexible RPE liner go quickly and smoothly. It’s easy to get out wrinkles when working over a finished surface of geotextile.
7. Order a Custom Manufactured Liner
Custom manufacturing allows for fewer to no seams to seal on the job site. Even with professional installers, sealing hundreds of feet of seams is the most difficult part of the installation. A custom fit liner that’s already sealed in the factory will minimize the chance of leaks and reduce labor costs.
8. Match the Right Ballast
Ballasts cover the pond liner and offer both light blocking protection to reduce UV degradation, and weight to hold down the material so it can’t float. Since the ballast you choose must do both of these jobs well at the same time, you’ll need to match the right material to your project. Gravel is the most common choice, but some projects require larger chunks of rock to deal with greater lifting forces from rising water. Sand and dirt can also work well as ballast and cover materials but may not offer enough weight in some situations. Work out the details with your engineer to find a ballast that fits both the general needs of the pond and the functions of the liner.
9. Avoid Wrinkles
Wrinkles in geomembranes do more than just waste material. As the weight of the ballast and water presses down on the folded material, it’s likely to crack and form a leak. Wrinkled material is also more likely to trap gases from the soil and rise up into unsightly bubbles that stress the liner. Since the best method to remove wrinkles is to cut and patch the material, it’s best avoided by using a liner with high conformity, flexibility, and lay flat ratings. Reinforced liners are less likely to wrinkle.
10. Install Penetrations Correctly
Make sure to use matching boots and sealants when installing filters, drains, and other penetrations through the liner. Large ponds, with high water quality needs, tend to feature a dozen or more penetrations in the same liner. Treat each one with care and check it for leaks periodically since these openings are weak points in the system.
Shopping for a geomembrane liner is trickier than you think. Let us guide you to the right product for any project by discussing your plans with us here at BTL Liners. We’ve worked on projects of all types and sizes and can use our experience to make the process go smoother for you.