Gotcha the manhole in the picture of the sewer inspection : https://www.openstreetmap.org/node/13783949495

https://historical.osm.be/#17/50.81274/4.32012/Vandermaelen18461854FL

also confirm the natural flow (for reference, it's offset and the railway doesn't exist at this moment , but the natural flow excactly correspond with 

- Aerial 2015 
- Digitaal Hoogtemodel Vlaanderen II (Vue aérienne, précision 0,25 m)
- picture of the document, in // of the changeset description 181657607

https://www.openstreetmap.org/changeset/182055476
