Foundations are on hold due to terrible weather so I’m moving on to the waste treatment plant so I can eventually get the caravan hooked up and live on site. Well, after treatment plant, soak away and drainage pipes are laid that is;
Now I may be over thinking this but I can’t seem to make sense of the final depths required; what depth should I be siting the treatment plant (it’s a Graf one2clean 7 by the way)?
Please correct me if I’m wrong.
Total fall of Pipe;
From the furthest sewage outlet from the house, following the line of the drains on the plan to the plant inlet is 48m. In my head the bottom of the furthest sewage outlet as it exits the foundations will be classed as Zero depth (200mm below finished ground) so am I correct in calculating the following?
The fall for 100mm sewage pipe should be between 1:80 & 1:40 over the 48m, so depth of inlet to the treatment plant will be between 0.6m & 1.2m below Zero. (0.8 & 1.4 below finished ground).
Depth of Treatment Plant;
If I opt for the shallowest fall at .08m below ground the top of the plant is only 460mm above inlet so it’ll be below ground. Applying a neck extension gives me another 330mm according to the diagram, so I have 790mm above inlet, 10mm below ground. Are the tolerances normally this tight or am I missing something?