Is this a retention/detention pond that they were required to install. If so, you need to check with the local poobahs as to whether they will permit a liner. I would not advise letting it silt over without some type of substrate at least 6" deep.
You will need to drain the pond. When/if you install the liner, do not trim it because you will be putting the liner over wet soil. As the moisture percolates out and the soil underneath the liner dries, you will get considerable settling due to the weight of the water. Leave a suitable amount of liner around the entire perimeter just to CYA.
You will know if there will be a hydrostatic problem when you drain the pond.
"Everybody is ignorant, only on different subjects." - Will Rogers
Last edited by tadpole; 01-11-2012 at 11:39 PM.
Reason: added more stuff