Suspend or bury waste pipe?

[RossMcO]

Posted this in a very old post yesterday, but maybe the age of the post acted against but being read.  

Searching through the forum for advice, I found this old thread which is pretty close to my query but...maybe worth clarifying, if only for peace of mind.

 

Our build is timber frame over steel foundations and is 300-500 above ground on the low side (where the drains will run) and maybe 1200-1400mm above ground on the high side.   Our design has a buried waste pipe running the length of the house (~25m) before connecting to the waste treatment plant another 10m or 15m away (yet to be precisely sited).

 

The groundworker has asked if we prefer the waste pipe to be buried, or if he could avoid the access complications of digging and filling the trench around the concrete footers for the steel founds.  If we suspend the waste pipe it will go below ground before exiting the footprint of the building.

 

Don't think there is a major impact either way, but is below ground better to avoid risk of frost, or above ground for access/maintenance or other reason?  Not a huge deal in the scheme of things, but would save me a couple of days and maybe £1k-£2k.

 

Ross.