Ponds are useful in a variety of functions, serving in processes such as water treatment, thermal storage, farming and more. Regardless of their function, one of the most important considerations in pond design is containment. Containment is often handled through compacted clay liners (if available) or geosynthetic pond liners, which can made from a variety of materials such as reinforced polyethylene (RPE), ethylene propylene diene monomer (EPDM) and high-density polyethylene (HDPE).
In this article, AGRU will outline guidelines for installing an HDPE pond liner, as well as additional tips and considerations for large ponds.
Preparing a location for a large pond installation
Pond site conditions can vary significantly, requiring prep work to ensure the installation goes as smoothly as possible. Basic site preparations include performing due diligence when it comes to regional weather patterns to determine the history of flooding and groundwater pressure. Other basic information includes setting a pond depth that is well above the water table and checking soil conditions for potential gas generation or buildup. If significant gas generation is present, then a venting system should be included in the pond design.
Once the selected location passes through all the basic requirements, the next step is to perform groundwork to clear the area of debris that could damage the pond liner. Removal of sharp rocks and other objects like vegetation and stubble from the subgrade is important to create intimate contact between the pond liner and the subgrade.
If gas buildup is a concern in the pond liner area, then specifying a gas venting layer is critical. There are several means to vent the gases to the perimeter top of slope including AGRU geocomposite and Integrated Drainage System (IDS) products. The IDS product is installed with the drainage/venting studs facing down into a nonwoven geotextile that rests above the subgrade. This layer will eliminate critical issues from gas buildup underneath the liner.
Choosing the right pond liner material
After the selected site has been prepared, the next step is to choose the right material for the pond liner. HDPE pond liners carry many benefits. They are tough, flexible, and highly resistant to chemicals and corrosion—properties that make HDPE liners among the most durable and long-lasting liners on the market.
Another benefit of choosing HDPE is that the material can be fusion welded together, which can streamline installation time and help reduce potential for leaks. The ability to weld HDPE pond liners with a double wedge weld also allows installers to form seals in the field, simplifying transportation logistics and overall installation complexity. The double wedge weld is significant because it allows the installer to test the seam and ensure its integrity.
Tips for large pond installations
Large ponds come with several unique challenges. First, the large surface area will necessitate a protracted preparation phase, requiring careful planning to avoid weather delays. Second, to keep installation time within reason, the installation contractor should utilize a pond liner manufactured in large rolls and stationed to support the site’s logistics. Using larger rolls will reduce the number of welds needed and, therefore, drastically decrease installation time.
Sandbags are especially helpful with larger sheets of liner and can help keep the pieces in place prior to welding. After all the sheets are in their correct position welding can take place. The weld settings themselves should match the properties of the chosen geomembrane, taking into consideration the melt index, thickness and resin type. A higher melt index, for example, allows the seaming process to take place at lower temperatures and at higher speeds. Specifying a higher melt index can improve installation time and liner integrity.
Lastly, construction quality control is essential for all pond installations—especially large ponds. This step involves bringing in site test equipment, conducting nondestructive and destructive testing of the field seams, and inspections. Certain nondestructive tests, like spark testing, requires the use of a conductive geomembrane liner.
During the final inspection, the entire HDPE pond liner surface should be examined by the inspector to confirm that the liner does not have any defects, holes, blisters or contamination. If necessary, the surface should be cleaned to facilitate the inspection process. Any areas that do not pass the inspector’s criteria will be marked for additional testing. If the pond liner passes the inspection process, then the installation is considered complete upon site cleanup and the submission of required certifications.
Partnering with a large pond liner specialist
Looking for a new pond liner for your next large pond installation? Consider using HDPE, which offers a host of advantages as a pond liner. AGRU HDPE Smooth Liner not only exceeds GRI-GM13 test values, making it a highly reliable and effective material for lining ponds, but also receives frequent third-party testing for added quality control.
Smooth and Textured Liner is available in thicknesses between 30 and 100 mils (0.76 and 2.54 mm) and can be manufactured with a color or specialty layer for unique properties. A conductive layer, for instance, enables construction quality assurance testing for holes, punctures, tears, cuts, cracks, and similar breaches over the partial or entire area of an installed geomembrane using test method ASTM D7240.
This article originally appeared on the AGRU America blog, https://agruamerica.com/blog.