The Multi-Vent Underliner System is a patented, innovative and cost effective system designed to protect pond and lagoon liners from damage caused by methane gas and water accumulation. It can also serve as a leak detection system for the liner. Providing gas venting, drainage and leak detection in one system is effective and cost-efficient. The documented strength, capacity and longevity of this system make it a logical choice for pond liner protection. (Multi-Vent Flier)
Nearly every pond builder has likely encountered a pond where the liner floated up off the bottom due to excess water or air buildup under the liner. Areas where the soil is high in organic matter tend to give off excess methane gas while other areas have a high water table, especially after large rain events. Both of these can cause the liner to float part way to the surface, all the way to the surface or in extreme cases the liner will float above the surface creating what are commonly called "whale backs" (see photo at right). Previously the only way to vent this water or air from under the liner was by cutting the liner and installing a vent.
EasyPro is pleased to introduce another industry first...the patented Multi-Vent Underliner System! This easy to install system is effective, low cost and best of all does not require cutting the liner. Multi-Vent is a series of perforated tubes that install under the liner. The tubes are wrapped in a non-woven geotextile to prevent plugging. By simply laying a strip of Multi-Vent on the ground before installing the liner you can prevent costly future problems. It takes a great deal of pressure for the water or air to lift the liner. With Multi-Vent, neither water nor air can build up pressure under the liner. Instead it will vent through tubes to the outside of the pond, eliminating any chance of the liner floating. Because of its low cost, Multi-Vent is cheap insurance under any liner job!
Multi-Vent lines are rolled out over the prepared surface and are covered by the pond liner. This method avoids the need for trenching and it locates the Multi-Vent right where methane and other gases are most likely to accumulate.
Most often each end of the Multi-Vent is simply extended out beyond the liner allowing the air or water to drain out. You can also use Multi-Vent to capture ground water in a sump or monitoring pit. Multi-Vent can be connected to 3" pvc pipe which would carry the water to the sump. A submersible pump with automatic on/off floats can be used to remove excess water.
Multi-Vent is easy to install. Typical installation uses one strip of Multi-Vent every 15'. For ponds 30' or less, one strip should be enough. In larger ponds multiple strips can be run under the liner, each venting beyond the liner perimeter or they can be hooked together in a manifold / grid system.