ᐅ Sewer Pipe Installed at Non-Frost-Protected Depth – Is It a Significant Risk?
Created on: 2 Mar 2018 19:55
H
HokusaiHello everyone,
We have a small challenge related to our wastewater connection :-)
We need to cover about 75m (82 yards) from the house to the sewer.
There are two bends near the house wall (each almost 90°).
The sewer is located 1.51m (5 feet) deep in the street. I calculated this based on the information from the water supplier’s plans as follows:
Height of the sewer or sewer pipe above sea level: Do 35.98 - Sh 34.22 = 1.76m (5.8 feet)
Minus 25cm (VT250 sewer pipe) = 1.51m (5 feet)
The average ground surface in the planned building area is at 35.54m (116.5 feet) above sea level, which is 44cm (17 inches) lower than the street level. That results in a total height difference of about 1.07m (3.5 feet) over 75m (82 yards).
With a 1% slope, if my calculations are correct, the wastewater pipe would need to be installed at a depth of 32cm (13 inches) exiting the house, which would be above the frost line. :-(
We want to avoid installing a lifting station if possible (due to purchase cost, maintenance, operating noise, running costs, etc.).
Our site manager pointed out that wastewater is usually warmer anyway (coldest wastewater from toilets is about 10°C (50°F)), that warm wastewater constantly flows in (from shower, dishwasher, washing machine), and that due to the slope, the pipe should not contain standing water that could freeze. Therefore, freezing is very unlikely or even ruled out, even in frost conditions.
Additionally, we are considering heating the first nearly 50m (55 yards) of the pipe during ground frost with an electric trace heating system. There are systems with thermostats that only heat at sufficiently low temperatures, making them relatively energy-efficient.
Our questions:
1) Are my calculations (based on the numbers above) correct?
2) Can anyone evaluate the assessment regarding the "frost-resistant wastewater pipe" (relatively warm water, no standing water but flowing) – ideally from personal experience?
3) Does anyone have experience with wastewater pipes installed significantly deeper than the commonly recommended 80cm (31 inches), and can share practical insights?
4) Has anyone used electric trace heating in soil for wastewater pipes?
Otherwise, any other tips are very welcome :-)
Thanks in advance!
We have a small challenge related to our wastewater connection :-)
We need to cover about 75m (82 yards) from the house to the sewer.
There are two bends near the house wall (each almost 90°).
The sewer is located 1.51m (5 feet) deep in the street. I calculated this based on the information from the water supplier’s plans as follows:
Height of the sewer or sewer pipe above sea level: Do 35.98 - Sh 34.22 = 1.76m (5.8 feet)
Minus 25cm (VT250 sewer pipe) = 1.51m (5 feet)
The average ground surface in the planned building area is at 35.54m (116.5 feet) above sea level, which is 44cm (17 inches) lower than the street level. That results in a total height difference of about 1.07m (3.5 feet) over 75m (82 yards).
With a 1% slope, if my calculations are correct, the wastewater pipe would need to be installed at a depth of 32cm (13 inches) exiting the house, which would be above the frost line. :-(
We want to avoid installing a lifting station if possible (due to purchase cost, maintenance, operating noise, running costs, etc.).
Our site manager pointed out that wastewater is usually warmer anyway (coldest wastewater from toilets is about 10°C (50°F)), that warm wastewater constantly flows in (from shower, dishwasher, washing machine), and that due to the slope, the pipe should not contain standing water that could freeze. Therefore, freezing is very unlikely or even ruled out, even in frost conditions.
Additionally, we are considering heating the first nearly 50m (55 yards) of the pipe during ground frost with an electric trace heating system. There are systems with thermostats that only heat at sufficiently low temperatures, making them relatively energy-efficient.
Our questions:
1) Are my calculations (based on the numbers above) correct?
2) Can anyone evaluate the assessment regarding the "frost-resistant wastewater pipe" (relatively warm water, no standing water but flowing) – ideally from personal experience?
3) Does anyone have experience with wastewater pipes installed significantly deeper than the commonly recommended 80cm (31 inches), and can share practical insights?
4) Has anyone used electric trace heating in soil for wastewater pipes?
Otherwise, any other tips are very welcome :-)
Thanks in advance!
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