Let's do this thing!

The shallow bowl shape of a traditional pond results in either a small deep zone in a moderate sized pond, or a moderate sized deep zone in a large pond.  To achieve a swimmable deep zone in a relatively small pond it helps to form the deep zone with vertical walls.  Two ways to do this are to (1) dig a deep zone, construct walls in it, excavate the surrounding regeneration zone and then lay a liner over the whole shebang, or (2) dig the entire pond, lay the liner in it and then construct a wood wall on top of the liner to separate the deep zone from the regeneration zone.  Each has its advantages and drawbacks.  For instance, option 1 is faster, but requires more liner and excavator work.  Option 2 would require less liner and excavator work for the same size pond,  but constructing custom walls on-site could be time consuming.

As you can see from the photos, we chose option 1.  I sourced galvanized steel in-ground pool walls from the local pool store.  At $3300 for a 16' x 28' structure with hardware, they were not cheap.  However, option 2 would have cost the same in materials suitable for long term submerged durability (white oak framing and Ipe decking to go over the framing), not to mention the labor involved.

With a nice, level excavated site, the walls were a snap to put together.  The walls are 42" tall in 4' or 8' lengths.  The corner sections are pre-formed in a 2' radius.  The panels are bolted together through pre-drilled holes and provided hardware -- a piece of cake!  Our excavator Brian and I had the wall together in less than three hours.

The next day we assembled and attached the provided steel bracing, one brace per panel seam.  Each brace is an isosceles triangle that extends out from the base of the wall to help withstand backpressure from the deep zone water and preserve the structural integrity of the pool.  The long leg of the braces use a rod and nut to help plumb the wall panels.

Once the wall is together, braced and plumb, it's time to pour a concrete collar around the outside to hold it in place permanently.  Concrete was poured from the bottom lip of the wall out to the ends of the braces (about 2') to a depth of 6" at a cost of $577.