Pond Boss Forums POND CONSTRUCTION Soil questions Soil retention on 3:1 coex RPE liner

I'm wondering if it is practical to put down 12" of soil on top of the liner for the first 15 ft or so. At 3:1 slope, will the soil stay put? Seems unlikely but if there is a way I can accomplish that I would love to hear about it.

Thans for the help!

Pond liners themselves are generally pretty slick. In addition to underlayment, most of the liner companies also sell "overlayment".

I believe those overlayment products are fairly expensive, but they are designed for the purpose of protecting your liner from punctures during covering operations AND making a rougher surface to resist sliding down the slope by your cover soil.

For a deep pond with only partial soil coverage on the liner, I have seen at least one installer that attaches perforated, flexible pipe (4" or 6") to the bottom of the overlayment to create a "bumper" to resist soil cover sliding.

For a "poor boy" version of overlayment, you might consider some quality landscape fabric pinned at the top in the same trench as the liner. Without UV damage, that might last many years under the soil, and create a surface with significantly more friction for your side slopes.

Finally, bottom contouring might be even more effective. If the builder has a dozer with a tilt blade, he can cut a slope at the reverse angle to the slopes of your pond. However, he must still be working on flat ground to do that. For example, if you want soil cover only the upper 6' of the liner, he needs to shape the pond basin and excavate the middle of the pond to a depth of only 6'. He then goes adjacent to your side slopes and makes a tilt cut to build a "bumper" on the bottom of the pond. He can then excavate the portions of the pond that will be deeper than 6'.

Another option would be to have the dozer/excavator complete the entire pond basin, and then have a good skidsteer operator with a 6-way blade cut your bottom contour bumper. It will be slow going at the very start while his tracks are tilting him towards the center of the pond. However, once he reaches the point where his tracks are horizontal (to gravity), then he should be able to pretty quickly create a reverse slope.

(Just thinking out loud, but you might ask your builder and installers about getting you an optimum final product for your pond.)