Finally, Ready to Begin, but Now What to Do?

[JPaul]

The patio project that I had hoped would take three days has expanded to more like three months, but it is finally finished. It did come out much better than I had expected, but took a lot more resources (time, money, mental and physical energy) than expected. So I am finally ready to do something about the pond that was supposed to accompany it.



My new issue is that the hole for the pond, which was completed as part of the site prep for the patio, wound up closer to the patio than I had anticipated and with the heavy rains we have had in the last month it appears that I could have problems with the stability of the pond wall nearest the patio. I had originally hoped that the pressure created by 1200 gallons of water would cause this to not be an issue, but now I am not so sure.



I have corrected an issue with the flow of water off the roof by rerouting the gutters and adding an underground pipe so that the only water that will run towards the pond will that which comes off the patio itself.

My plan is to construct a retaining wall in the current hole for the pond on the side nearest the patio. This would be done with formed concrete block very similar to the wall in the patio photo, but designed for retaining walls with a lip so it would be angled slighly. It would be dry stacked on a packed gravel base and be approximately 12' by 36" x 8". This would get me another foot and a half between the patio and the edge of the pond. I would then fill behind the wall, and excavate the opposite side to get back to my original 12'x6'x3 size. The formed block is somewhat rough, so I thought I would cover with some old carpet before putting in the liner.

Any thoughts before I create more headaches for myself?

 

[sissy]

It may to a point but if you get a heavy down pour you will end up with everything on the patio in the pond ,meaning sand and dirt .That should work and you could make it a sitting wall for viewing and feeding the fish or try and make it a waterfall .But I would go with seating wall .It would be nice for people to sit and stare down at the fish .I just put a double layer of landscape fabric because there was a lot of the heavy stuff left when they lined the ditch along side my drive way but anything will work

 

[Waterbug]

I share your concern and the need for a retaining wall. No one can predict the future, but a good idea to minimize risk.

I would use regular concrete block, vertical rebar and at least one course with horizontal rebar. Use bond beam block for course(s) with horizontal rebar. Dry stacked and then fill with concrete. It's a much stronger retaining wall. normal much cheaper, uses less space than the retaining wall blocks you mention. You can also add a footer, which ever block you use, to reduce future risk further. You do want to check the limit for the retaining wall block you mention as they can't retain as much weight so the max height can be surprisingly low. Each product is a little different.

I also like to use a bond beam block on the top course so I can tuck the liner into the void (just fill 1/2 with concrete) and then fill with soil. Leaves just 2" of liner exposed giving me lots of options like planting right up to the edge of the pond. I sometimes cut or knock the back lip down a bit so soil can cover that, but not needed.