Do you have anything to base your skepticism on? The length of the whole canal is 200km and it took 10 years to build. I don't claim that it's exactly linear,

Do you have anything to base your skepticism on? The length of the whole canal is 200km and it took 10 years to build. I don't claim that it's exactly linear, but it sounds reasonable to assume a few weeks for just a 1km segment. The soil is soft and the canal isn't deep.