I have engaged a plumber to re-do the stormwater drainage system on my property which is mid-70s and had blocked/cracked clay pipe drains.
The works has included installing a new underground PVC drain. During the works the plumber suggested not bedding crushed rock at the bottom of the trench in order to provide more cover between the top of the pipe and the drain. The plumber commented that crushed rock is usually provided at the bottom to minimise movement, but my soil was dry and rock solid so not doing so shouldn’t be an issue. So this is effectively the scenario in the top left corner (Illustration 1 below), where the pipe has been laid on an undisturbed base of the trench and crushed rock provided around the pipe. My understanding is that this is only permissible on stable Class A soil clear of tree roots or rocks (per VBA).
My concern is that the bottom of the pipe could potentially still be vulnerable to tree roots. There are some large adjacent trees which cracked and blocked the previous clay drainage pipes.
Just wondering if anyone could comment whether this would be compliant to local codes (i.e. VBA) and if not, do I have any recourse with the plumber?
Should I be worried about a scenario where leaks at potentially poorly glued PVC pipe joints could invite roots?