How are the blocks terminated at the upstream and downstream ends?
If the ACB system does not start and end at an existing structure, typically the blocks (and underlying fabric) are tucked into an anchor trench and backfilled and compacted with the appropriate material. In some cases, the “appropriate material” may be: concrete grout, stone, or grouted rip-rap instead or soil. Trench depth is typically 1.5 times the potential depth of scour. If the ACB system starts or ends at an existing structure, a reinforced steel grouted interface treatment is typically used to secure the blocks and insure that hydraulic undermining will not occur.
