Question
What are main functions of bedding below storm water drains?

Answer
Bedding that is normally made of granular resources or concrete serves four main functions as optional by O. C. Young and J. J. Trott-

(i) To improve a uniform hold under pipes in order to decrease bending moment longitudinally;
(ii) To boost load-supporting strength of pipes;
(iii) For pipes with spigot and socket joints, it allows pipes to be supported all along pipe lengths in its place of pipe sockets. If not, irregular stress might be induced and it might damage pipes;
(iv) To provide platform for achieving correct placement and level during and after structure.