Project design - ornamental ponds

The ideal slope for a plastic lined dam is a 3:1 gradient, however if design constraints require steeper gradients, installation can still be achieved, although additional safety requirements would need to be considered. Waterlogic can supply ladders welded to the liner surface, alternatively you can opt for one of the options below, and soil cover the top perimetre of the dam, allowing maximum safety and aesthetics. 

It is recommended that plastic lined dams be fenced, to prevent damage or injury to humans and animals.

A trench will be needed around the entire perimeter of the dam in which to anchor the liner. It should be approximately 450mm deep and 450mm wide at a minimum level of 500mm above the projected water line.

In preparation of the dam surface (sub grade) ready for the liner installation, some earth works must be completed.This should bring the sub grade to a level that is a dry, smooth, firm and unyielding foundation, without abrupt elevation changes, voids, cracks, or standing water, free from vegetation, sharp edged rocks, stones, sticks, construction debris and other foreign debris. It is recommended to have the sub grade flat drum rolled just prior to the liner installation.


Finishing touches

Whilst the liner does not need to be covered, there are a few options available if you do not wish to see the liner above the water line.

For example:

Total backfilling of the dam is not essential but does give the liner extra protection against UV. Alternatively you can  partially soil cover the top perimetre. If the excavated site has good top soil, sand, etc. This can be re-used as the liner overlay, and should be stockpiled nearby, making sure all injurious materials such as tree trunks, roots, rocks or sharp protrusions are removed.

If you wish to keep back fill in place then batters should be no steeper than 3:1