Canal Construction - Solar Altitude vs. Cover Height

Hi!

I have obtained the connection heights and the finished street plan for my property. The driveway is to be prepared so that I can drive onto the property by car.

I think I can use the sewer manholes as a rough reference for the final height determination. Now I come across two terms: Solhöhe and Deckelhöhe.

Can someone explain to me where the Solhöhe and Deckelhöhe of a sewer are located? Solhöhe equals the lowest point?

Thanks in advance, Torsan

You want to measure your house using the manhole covers? Dangerous! Especially in new development areas, they often shift / are raised. Normally, there are calibrated points where you can take measurements, otherwise hire a surveyor – that’s their job.

Of course, I don't want to survey my house. The house is already standing. I just have the heights of several manhole covers and want to roughly plan my driveway. Regards, torsan

I see
It was similar for us. We had no slope, so we could measure from the surveyed house. The manhole cover was actually 5 cm too low - it was then raised with spacer rings.

You want to survey your house using the manhole covers? Dangerous! Especially in new development areas they often shift or rise.
Normally, there are calibrated points where you can measure, otherwise hire a surveyor – that’s their job.

What is dangerous about that, ?

Nothing is rising and nothing is sinking, unless the street is completely resurfaced or something similar.

What matters for the water to flow out is the gradient between the house connection and the soffit elevation, and the water does not care whether it flows down from 100m to 99m or from 2m to 1m height – the gradient is the same, so the relative height difference between soffit elevation and house is decisive. The absolute NHN elevation of the manhole cover or its soffit is completely irrelevant, but of course it is indicated and also checked.

The calibrated point you mean is probably a bench mark. Elevations are usually not transferred from these benchmarks unless the gradient is very tight or differences in the sewer cadastre occur that cannot be easily resolved.

Usually, a manhole cover and its soffit can be determined by GPS – then you are accurate to about 5cm, if that matches the data in the sewer cadastre, that is sufficient as a check – exceptions prove the rule. Yes, also for the height determination of a completely newly planned house!

:

Cover elevation = height of the cover

To determine the soffit elevation, you have to open the cover and measure the distance from the top edge to the lowest soffit. If the difference between the two values in the sewer cadastre matches, that is a strong indication that the sewer is as recorded in the sewer cadastre and has not been changed. If you also control this at a second manhole and the relative heights between the two shafts all match, you are pretty safe.

In the end, the absolute height does not matter to you, you can align your gradient relative to the street and/or soffit elevation and define the soffit elevation or manhole cover height as "zero." According to the distance and the planned gradient, the driveway then simply has to be higher.

Best regards
Dirk Grafe

To record the invert elevation, you have to open the cover and measure the distance from the top edge to the lowest invert. If the difference between the two values in the channel registry matches, this is a strong indication that the channel is positioned as documented in the channel registry and has not been changed. If you also check this at a second manhole and the relative heights between both manholes all fit, you can be quite sure.

Ultimately, the absolute height does not matter to you; you can set your slope relative to the street and/or invert elevation, defining the invert elevation or manhole cover height as "zero." According to the distance and planned slope, the driveway then simply has to be higher.

Best regards
Dirk Grafe

Great! Thank you very much!

I did exactly that and found out that I have to make my driveway "steeper."

Best regards, torsan