The Ontario Building Code | Support for Underground Horizontal Piping
220.127.116.11. support for Underground Horizontal Piping
(2) Nominally horizontal piping installed underground that is not supported as described in Sentence (1) may be installed using hangers fixed to a foundation or structural slab provided that the hangers are capable of,
(a) keeping the pipe in alignment, and
(b) supporting the weight,
(i) of the pipe,
(ii) its contents, and
(iii) the fill over the pipe.