Backfill Sides of EPDM Liner Pond

[scotlake]

I have a 3000 gallon EPDM liner pond 3 ft deep (apx 30 inches deep around sides) and 30 yrs old.

1. The existing sides are almost vertical with a slight inward slope at bottom.
2. The soil is heavy clay. Literally shaved the sides during construction to exact slope and shape that I wanted.
3. One Bottom Drain.
4. Used a 3/8 inch synthetic carpet pad under bottom and sides. It is still in good shape where I can see at edges.

On one side I need to reduce the size of the pond apx 18 inches. What can I back fill with to reduce the pond size.
PLAN:
Drain pond down to 1/2 full (that leaves about 15 inches of pond water.
I would then pull on liner and slide some double thick large cardboard pieces between existing clay soil sides and the liner underlament.
QUESTION:
What material can I backfill the void with to be solid and not settle very much ?

 

[Mmathis]

Hello and welcome….(from the land of heavy clay soil and high water tables)!

When I had to do some cosmetic as well as structural work on my pond, I used sand and tamped it down as tight as I could get it. I actually had to tweak my sides a little, and ended up using cinder blocks to make up part of the “new” wall edges. My original design had been too steep, so I wanted to change that and add some shelves. Not sure if that info will help you, but you’ll get a lot more advice from others on here.

 

[j.w]

@scotlake
I would think any kind of soil would work as it is going to be packed in there tight once the pond is refilled w/water.

 

[scotlake]

View attachment 163188@scotlake
I would think any kind of soil would work as it is going to be packed in there tight once the pond is refilled w/water.

That's what I was thinking, but I always over think everthing
Thanks for response