Using a shovel, mark the ground where the retaining wall will be built. Drive long wooden stakes into the ground at each end. If the distance is greater than 8’, drive additional stakes so that the gaps do not exceed 8’. Tie a string to a stake at the wall’s desired height and stretch across to opposite stake or stakes. Use a string level to ensure that all the heights remain level and constant.
Excavate the entire area to a depth of 8”. Spread approximately 4” of gravel evenly in the trench and rake the gravel smooth. Use a hand or power tamper to compact and level the area. Check for level and add or remove gravel as necessary until the appropriate height is reached.
Staring at one end, place the first course of concrete blocks top side up on the crushed rock with the front lip facing up and towards the front of the wall. Check the level and alignment of all blocks as you go along, adjusting them with a rubber mallet. Fill the concrete cores with crushed gravel.
Sweep away all debris from the top of the first course of block with a broom. Stack the second course of blocks on top of the first course making sure they remain level. Fill the concrete cores with crushed gravel. Backfill with gravel behind the wall to cover the drainage pipe. Top with soil. Continue with following courses and soil until desired height is reached.