Description should include the following specifications:

Trench must have a 6-inch gravel base.
First course must be perfectly level, length and width.
Each corresponding course must lap back by the unit standards.
The back of the wall should be fortified with a minimum 12 inches of gravel.
A plastic/vinyl membrane should be installed in accordance with manufacturer specifications.
Wall should be capped with solid units provided, using exterior construction adhesive.

Process/Skill Questions:

What are the advantages of mortarless concrete masonry retaining walls over mortared retaining walls?
What is the purpose of a retaining wall?

NCCER Masonry Standards

Level Two, Module Five (28205-14): Advanced Laying Techniques

This module contains detailed information that directs the mason in accomplishing the actual construction of walls, arches, and other useful structures. The text explains construction techniques, safety requirements, and interaction with structure components.