ᐅ Drainage / Surveying / Surveying Methods / Slope

Hello everyone,

Can anyone tell me how a layperson can best measure the slope of a drainage system? We have four drainage inspection chambers around the house. I would like to calculate the position (the slope) of the drainage through these. What options do I have? I once attended a survey where they used a device mainly consisting of long tubes filled with liquid. I suspect this system measured based on pressure differences (possibly some kind of water level). Does anyone know what that might have been? Maybe such a device can also be rented? Another option would be to use a leveling instrument. I’m a bit worried about making mistakes with the measurements this way. I need a reliable method. Any ideas?
Thank you very much in advance for your help.

Schorschll

Schorschll schrieb:

My guess is that this system measured based on the pressure difference (possibly also a kind of spirit level).

Exactly! It’s called a water level. They come in very basic versions, for which renting isn’t really worthwhile, up to precision instruments that are more complicated to operate than surveying levels.
How precise do you want it? If it’s not urgent, you could ask a surveying office if they are willing to assign a trainee a good practice task and what the costs would be. You could also assist as a survey helper.

Schorschll schrieb:

Measurement errors

... can also be handled with the water level. And you still need to go down to the manhole bottom. How deep are the manholes approximately?

Hello Escroda,

thank you for the quick reply. Are these basically the two options I have for the surveying (leveling instrument and water level)? I want it to be precise, accurate to one centimeter (0.4 inches). Is this precise enough according to your question?

A brief background: there is a legal dispute between me and the developer regarding the house’s drainage system as well as its waterproofing. We have already had two expert assessors on site who surveyed the drainage. One of them seems to have made a measurement error at best. The statements I have concerning the drainage are therefore: everything compliant VS incorrect drainage layout. We are now at the point where the court will appoint an independent expert. As you can imagine, there is a lot of money at stake and my safety depends on the entire drainage system functioning properly. I want to be absolutely sure that the next survey regarding the drainage is accurate.

You can’t imagine the trouble I’ve already had with experts...

Thank you very much for your support.

Best regards

Forgot to mention. I would estimate the shafts to be about 3–4 meters (10–13 feet) deep.

Schorschll schrieb:

Hello Escroda,

thank you for the quick reply. Are these essentially the two options I have for surveying (leveling instrument and water level)? I would like it to be precise, accurate to one centimeter (0.4 inches). Is that what you meant by precise?
Maybe a brief background: there is a legal dispute between me and the developer regarding the house’s drainage system as well as its waterproofing. We have already had two experts on site who measured the drainage. It appears that at least one of them may have made a measurement error. The statements I have regarding the drainage are therefore: everything compliant VS incorrect drainage layout. Now, the court is about to appoint an independent expert. As you can imagine, this involves a lot of money and my assurance that the entire drainage system actually works. So, I want to be CERTAIN that whatever is measured next concerning the drainage is accurate.
You can’t imagine the hassle I’ve already had with the experts...

Thank you very much for your support.

Best regards

If you have a leveling instrument at hand… then everything should be fine and very precise! …if by chance you also have an existing reference elevation (NN height), you can directly convert to the correct heights.

However, the independent expert appointed by the court will still carry out their assessment.

Good luck

You can be more confident if a professional you hire takes measurements alongside the inspector. As you mentioned, you are not an expert and will likely get three different results from three measurements, which can cause confusion.

It would be helpful to know more about the specific issue:
What slope currently exists, and what do you believe it should be?
What exactly is the damage scenario you are concerned about?