palm tree - any suggestion?

[JoeW]

For my last pond I poured a footer with rebar and inexpensive irrigation pipe for return lines in the footer, then I dug out the sand inside the "ring." The pond is on an ancient sand dune so I was concerned about sand caving in while digging. I found that the roots of nearby trees held the sand in place while I dug. I was very careful to cut roots and not pull on them to prevent the sand collasping. The pond walls are nearly vertical down to 4ft on one end and about 5 1/2 feet on the other end. I draped two foot wide strips of carpet over the edge and held it in place with heavy stones on top of the footer. Once the water was in the pond I stopped worrying about the sand collasping.

Later I learned that some type of retaining material should be used if the vertical walls are deeper than about two feet. I guess I was lucky to get by with what I did. If I were to do it again I would use building block like you mentioned or gunite it.

Before I built my present pond I took out the liner from an earlier pond. I was pleasantly surprised to find under the liner a "cobwebbing" of small roots under the liner from nearby oak trees. None of the roots were larger than 1/4 inch in diameter (none came through the liner) and I imagined had the effect of supporting the liner.

I like the footer I poured as it provided a solid base for a double row of solid half-blocks 4x16x8. I ran the liner under the first row and up and over the second row then anchored that with a roughly 17x17 capstone. This hides the liner from view. The water level was planned to come up midway on the side of the outter row of solid block. I could have gotten fancy and added decorative tile to the outter block but never got around to doing that.