How to Make a Stepped Ditch Retaining Wall

Layout, Excavation and Forms

• 1

  Drive a 36-inch long wood stake at the base and top of the slope at the area of the retaining wall with a steel mallet. Attach a nylon string line tightly between the stakes.

• 2

  Refer to the dimensions on the plot plan or site plan for the property to establish the precise location of the retaining wall in relation to a property line. Reset the stakes and nylon line at the outer line of the wall in accordance with the dimensions on the plan.

• 3

  Note the number of concrete blocks in the first course at each of the steeped sections of footing as given on the retaining wall plan. The number is predicated on the slope of the hillside when installing typical 16-inch long blocks.

• 4

  Start at the bottom of the slope and excavate the first stepped ditch to the required depth given on the plan, and the length as established by the number of blocks in the first course of wall construction. Excavate the ditch by hand with pick and shovels or with a trenching machine. Excavate each of the remaining sections of the stepped ditches.

• 5

  Drive a wood stake at the outer end of each excavated stepped ditch. Set up a builder’s level or transit at the base of the slope. Ask a laborer to hold a surveyor’s pole alongside the first stake at the lowest ditch.

• 6

  Sight through the lens of the level or transit and direct the laborer to mark the stake at the height of the first footing form with a lumber crayon. Repeat this procedure and mark the height of the forms at each of the remaining stakes.

• 7

  Install wood forms at the head, or lower end of a stepped ditch, and both sides of each stepped section with 2-inch thick lumber. The top edge of the head form is set at the mark on the corresponding stake. The tops of each side are level with the head. Brace the head and sides of the forms with vertical and diagonal wood stakes at 12-inch intervals.

• 8

  Refer to the details on the retaining wall plan and install the required steel reinforcement bars in each ditch. Cut the bars to length with a re-bar cutter. Install vertical reinforcement bars at the spacing given on the plan. Bend the lower section of each bar 90 degrees with a re-bar bender, and tie the lower sections to the footing re-bar with steel tie-wire and pliers.

• 9

  Multiply the combined length of each stepped footing by the depth of the footings from the top of the forms to the bottom of the ditches. Divide the result by 27 to establish the cubic yards of concrete for the footings. Contact a concrete pumping service and request a coordinated delivery of footing concrete.

• 10

  Pump the concrete into the ditches and forms. Allow the concrete to cure overnight before stripping the forms and stakes.

Wall Construction

• 11

  Stage the concrete blocks needed for each stepped section on the slope. Set up a mortar mixing machine or mixing tub and shovel at the base of the slope. Mix consistent batches of the mortar as laborers haul the mix to block masons in 5-gallon buckets.

• 12

  Place a uniform layer of mortar atop the concrete footings at each stepped section. Slide the cells of each block over the corresponding vertical reinforcing bars as you place the first course of blocks from the base to the top of the slope.

• 13

  Continue to mix batches of mortar and haul buckets of the mix to the block masons. Stagger each course of block as you construct each of the stepped sections to the designated height given on the plans. Allow the mortar to cure overnight.

• 14

  Multiply the combined length of each stepped footing by the height of the retaining wall. Divide the result by 27 to establish the cubic yards needed to grout, or fill, the cells of the blocks.

• 15

  Contact a concrete pumping service and request a coordinated delivery of the grout mix. Pump the mix into each cell of the blocks. Designate a laborer to smooth the grout at the top of the stepped sections of wall with a wood float. Allow the grout to cure for 14 days before backfilling soil against the outer face of the retaining wall.