Part 6 – Water Supply

6.12    Anchor Or Thrust Blocks

Concrete anchor blocks shall be provided on mains exceeding 50 mm internal diameter at all points where an external thrust occurs.

The design of anchor blocks shall be based on the allowable bearing capacity of the site soil conditions, except that the maximum value used shall be 75 kPa. The inner face of the block shall not be of a lesser thickness than the diameter of the fittings, and shall be constructed so as not to impair access to the bolts on the fittings. Concrete shall have a minimum compressive strength of 17.5 MPa at 28 days.