What Kind of Dam Liners We Should Use for a Pond

May 18, 2022

We are often asked what kind of liner we should use for a pond. The answer is not simple. There are many variables:

• What is being stored? What is the PH of the liquid being stored? This will determine the type of polymer that is to be used if indeed a polymer is suitable at all. Liner manufacturers produce chemical resistance charts – these should be consulted.

• Once the chemical compatibility is determined then we can decide what thickness of the liner is to be used. The thickness will be determined by the condition of the subgrade (How many rocks and what size and shape) and what life is required from the liner. The thicker the liner the more resistance there is to subgrade conditions and the longer the life in the sun. Resistance to rocks in the subgrade can be increased by the use of geotextile under the liner. It has been shown that a geotextile will act compositely with an HDPE liner to give better performance. HDPE is provided with antioxidants and UV stabilisers in its composition. The antioxidants are provided to give protection against oxidation during the manufacturing process and long term. The UV stabiliser is usually carbon black.

• What colour liner. White liners expand less in the sun than black liners and produce smaller ripples when heated up. If the pond is an evapouration pond and is to be empty some or most of the time then the use of a white liner should be considered.

• The batter slope and length will also have an effect on the type of liner. Where the batter length is long then the use of a rough-textured liner should be considered to give added frictional restraint to the sub-grade.

Liner type and thickness and configuration is a science on its own and has been the subject of extensive research. When making the call on a liner type consult someone with a background in the subject.