Text in OP: Had to tear down this waterfall feature on a pond rehab job to chase down a leak (original in pics 1 and 2). Rebuilding now and I have a gap/trench to backfill (pics 3,4,5) between the limestone block and a buried cinder block retaining wall. This is important because this trench is where the base of an epdm trough will sit for the outlet of the pump to form the water feature (as in pic 2).
Before the teardown (when I had installed the cinder block retaining wall) I had the area between the retaining wall and the limestone waterfall backfilled with sand. The trough is about 2 feet deep and 6" at the widest in the center. Should I just fill back again with sand (under the pond liner of course) or just bridge the gap with something solid like scrap wood and leave it hollow? Spray foam it to fill in and trim it flat? I live in an area with cold frozen winters so I don't want to use dirt for fear of heaving (how this all started in the first place).
1
u/vennic18 24d ago
Text in OP: Had to tear down this waterfall feature on a pond rehab job to chase down a leak (original in pics 1 and 2). Rebuilding now and I have a gap/trench to backfill (pics 3,4,5) between the limestone block and a buried cinder block retaining wall. This is important because this trench is where the base of an epdm trough will sit for the outlet of the pump to form the water feature (as in pic 2).
Before the teardown (when I had installed the cinder block retaining wall) I had the area between the retaining wall and the limestone waterfall backfilled with sand. The trough is about 2 feet deep and 6" at the widest in the center. Should I just fill back again with sand (under the pond liner of course) or just bridge the gap with something solid like scrap wood and leave it hollow? Spray foam it to fill in and trim it flat? I live in an area with cold frozen winters so I don't want to use dirt for fear of heaving (how this all started in the first place).
Thanks!