Thanks to the flexibility of materials like multi-layered RPE, it’s fairly easy to fit a liner to any size and shape of ditch. If the ditch is uniform in size and depth across its entire length, BTL Liners can custom fabricate the material to fit with no need to cut or seal seams on site. More uneven ditches will need a little extra work during installation, but the process is still less time consuming and easier on the workers than pouring concrete or moving heavy pre-cast sections.
Uncovered vs Covered Installation
First, you’ll need to decide if you’re going to cover the flexible liner with another material or leave it exposed after installation. Most ditch lining projects involve adding at least a thin layer of gravel, sand, or dirt over the liner to act as a ballast. This ballast both holds down the liner to prevent floating and keeps the majority of UV rays from reaching the material. Exposed installation is also possible so you can visually check the ditches for signs of erosion like increases in silt accumulation. However, you’ll need to choose an RPE product designed specifically for exposed installation to ensure it can withstand daily UV bombardment.
Edge and Bank Attachment
Since flexible liners aren’t rigid like concrete and pre-cast plastic sections, they will need some secure attachment to the edges of the ditch to properly cover its vertical or nearly vertical sides. On channels and canals with more gradually sloped sides, it’s a simple process of running enough apron material over the banks to keep the material from lifting up or rolling. For smaller ditches without sloped sides, pins and liner anchors may be required. Only use soil pins and anchors designed for use with geomembrane products. Trying to experiment with other tools will result in leaky and torn liners that don’t perform as needed. Other options include folding the material over the edges of the ditches and securing the upper lip with layers of heavy rock. This is particularly popular if the rest of the ditch is reinforced with gravel or rock ballast for a continuous layer of cover over the liner.
Before the liner is spread into place in the ditches, the soil itself may need some extra preparation and stabilization. Loose soil that is eroded or prone to washing out can leave the liner unsupported after a serious rainstorm. While the flexible liner material can handle this loss of support better than concrete, it will eventually stress the material. Stabilizing the soil with compaction, the addition of fill to washed out spots, and the removal of large rocks and roots exposed by erosion, will go a long way in protecting the flexible liner from damage.
Adding ballast is the most reliable way to preventing a flexible liner from floating. Ditches are particular prone to floating because of their relatively small size and location where storm runoff can trickle between the liner and the ground. Unlike a pond that has a lot of existing water weight pressing down the liner, a ditch can quickly accumulate more water under the liner than above it. Exposed liners may need other forms of anchoring, such as sealed pins or smooth and heavy weights placed along the bottom at regular intervals. If the ditch stays constantly full or at least partially filled during the rainiest parts of the year, floating is unlikely to cause problems in any case.
Custom Fabrication to Minimize Seams
As mentioned above, accurate measurements of uniform sized ditches allow manufacturers to custom fabricate ready-to-use sheets of material cut to size. The seam sealing methods used in the factory are much more reliable than those available on the job site, resulting in stronger bonds and reduced risk of leaks. You’ll also find that installation goes much more quickly and smoothly with custom fabricated liners that don’t need cutting to fit. Only some liner materials, such as multi-layered RPE, are easily fabricated on demand in this way.
Once you’ve considered these challenges that tend to pop up during installation, you’re ready to put your flexible liners in place. If any issues occur during your ditch lining project, you can always email or call us for help here at BTL Liners.