How can I make some “dirt putty” to add back a shelf?

[combatwombat]

I’m building a negative edge skimmer and the weir on my waterfall is too low as I initially dug out the area for a different purpose.

Rather than build it up over the liner with rocks and try to waterproof it with foam, I think it’s best to raise the height of the soil below the liner about 8”.

Here’s what I need to achieve:

Any ideas for how best to do this?

I have a 100lb bag of Portland cement sitting around looking for a use. Thought of just mixing it in a wheelbarrow with a bit of native soil to see if I can create a kind of dirt mortar that will hold itself up.

Another option would be to build it up with CMU blocks and just fill the cores with dirt. Not sure what to do about the sharp corners that would create against the underlayment, though.

 

[mrsclem]

What about using several smaller bags of cement- unopened! They will harden with time and no sharp edges.

 

[Lisak1]

Oh I like @mrsclem 's idea! Sounds brilliant!

We never had this issue as we have nothing but clay clay clay. I could build you a clay hut in my backyard if you needed it and it would last a century. Terrible for digging - I'd like to say "especially when wet" but dry is no picnic either - but great for creating things that aren't going anywhere!

 

[combatwombat]

What about using several smaller bags of cement- unopened! They will harden with time and no sharp edges.

so, like using a sand bag, but an unopened bag of cement instead?

 

[poconojoe]

so, like using a sand bag, but an unopened bag of cement instead?

I like that idea too!

 

[mrsclem]

so, like using a sand bag, but an unopened bag of cement instead?

Yes- I saw this somewhere and I think it was on this forum many years ago.

 

[combatwombat]

Yes- I saw this somewhere and I think it was on this forum many years ago.

Just did a little research on this. Some people do this for retaining walls. Important detail: the bags have to be paper-only! Lots of concrete sacks have a plastic liner now to prevent setting up before opening.

 

[mrsclem]

Yes, last couple bags I got had the plastic lining which does help if the bags are not kept in a dry area. I would think you could puncture the bags in several places to allow moisture to get in but even if you didn't, the bags would still make a solid berm.

 

[islandboy]

A crease in the bag may also create a sharp edge over time.

 

[mrsclem]

And a tree root may grow and puncture liner. It was merely a suggestion.