How to Replace a Retaining Wall Around a Man-Made Pond

Look along the retaining wall's surface timber for any nails or screws that hold it in place. If screws were used, back them out with a drill and Phillips driving bit. If nails were used, pull them out with a pry bar. Set the top timber aside, then repeat this step to remove the remaining timbers. The ground will have been packed firm enough over the years to support itself momentarily.

Clean up the trench you removed the old retaining wall timber from with a shovel. Dig the trench down 12 inches and make it slightly wider than the new timbers you will build with. Lay a level in the trench periodically to ensure the trench remains flat.

Tamp the trench's base down with a hand tamper. Pour 3/4-inch gravel into the trench. Spread it out with the shovel to create an even 6-inch layer. Tamp the gravel down with a hand tamper and use the level to check that it is flat.

Cut a 4-by-4-inch pressure-treated timber to the same length as the trench using a circular saw. Apply wood preservative to the cut end with a sponge brush. Drill 9/16-inch pilot holes through the timber with a drill and extension bit. Space the holes approximately 24 to 36 inches apart. Lay the timber in the trench and set a level on it to ensure it sits flat. Hammer a 4-foot-long rebar spike through each pilot hole with a sledgehammer.

Continue to cut timber and secure it to the ground with rebar spikes until you have filled the trench. Measure the length from timber to timber across the man-made pond in two places to ensure they are parallel.

Cut the first timber for the second level in half to stagger the joints and build a stronger retaining wall. Apply wood preservative to the cut end. Set this timber on top of the first timber in the trench. Secure the top timber to the bottom timber with a landscaping screw every 8 inches. Continue to add timbers on top of the first level, staggering joints, and secure them in place with landscaping screws.

Pour a 3-inch layer of 3/4-inch gravel behind the second level of timbers. Cover the dirt bank behind the retaining wall and the gravel with landscape fabric. Lay a 4-inch perforated pipe along the landscape fabric over the gravel to provide drainage. One end of the pipe must remain exposed to allow water to drain.

Cover the 4-inch perforated pipe with 3/4-inch gravel. Fold the landscape over the gravel. Build up the retaining wall with one more level, securing each timber to the one below it with landscape screws every 8 inches.

Dig a 6-inch-deep T-shaped trench behind the retaining wall. Build a T out of two timbers and secure them together with two landscape screws. Make a 9/16-inch pilot hole through the T's left and right end. Lay the T into the trench and level it. Make the T's bottom edge flush with the retaining wall's front. Secure the T in place with two landscape screws. Hammer a 4-foot piece of rebar through each pilot hole. Position more deadmen around the retaining wall every 4 to 6 feet.

Finish building up the retaining wall to the desired height. Backfill behind the retaining wall with soil.