Sewer pipe at a non-frost-free depth - big risk?

  • Erstellt am 2018-03-02 19:55:53

Hokusai

2018-03-02 19:55:53
  • #1
Hello everyone,

we have a small challenge in connection with our wastewater connection :-)

We have about 75m to bridge from the house to the wastewater sewer.
From the house wall, two bends (each almost 90°)

The sewer lies 1.51m deep in the street. I calculated this based on the information in the water supplier's plans as follows:

Height of the sewer or sewer pipe above Normal Zero: Do 35.98 - Sh 34.22 = 1.76m
Minus 25cm (VT250 sewer) = 1.51m

The average ground surface in the area of the planned development is at 35.54m NHN, so related to the cover elevation (Dh) 44cm lower than the street. In total, about 1.07m height difference over 75m.

At 1% slope, if I calculated correctly, we would have to lay the wastewater pipe 32cm deep from the house and thus be in a non-frost-proof area. :-(

If possible, we want to avoid installing a lifting system (purchase costs, maintenance, operating noise, operating costs, ...)

Our site manager said that wastewater is warmer anyway (coldest wastewater from the toilet is about 10°C), constantly warm wastewater flows in (shower, dishwasher, washing machine), and due to the slope, the wastewater pipe does not contain standing water that can freeze. Therefore, freezing is very unlikely or excluded even in frost.

We have also considered electrically heating the first almost 50m during ground frost with a trace heater. There are systems with thermostats that only heat at correspondingly low temperatures and are thus relatively economical.

Our questions:

1) Are my calculations (based on the above numbers) correct?

2) Can anyone evaluate the assessment of the "frost-resistant wastewater pipe" (relatively warm water, water does not "stand" but flows) perhaps even from their own experience?

3) Has anyone had wastewater laid significantly deeper than the generally recommended 80cm and can share practical experiences regarding this?

3) Does anyone have experience with electric trace heating in the ground on wastewater pipes?

Otherwise, we are also grateful for any other tips :-)

Thanks in advance!
 

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