The photo below shows what a fellow found under his driveway after hearing strange noises from below. That reminded me of my own connection to such a situation.
I had a fellow call one evening asking about what it might cost to have an elevation certificate filled out for the house he had purchased a month earlier. Once I was able to determine the exact location of this house, I laughed to myself. What he didn't know would fill a book. So....... I said, "Your lovely home has a basement, right?" He confirmed that it did. Then, I explained that was the primary reason he had been told he needed flood insurance. I went on to explain that I had surveyed that house years earlier and had been inside, where I saw the elaborate dumbwaiter system that went back to when the servants had to stay in the basement except when clearing tables or doing cleaning. He kept harping that there was no way his house could be subject to flood damage.
Thus, I had to blow his mind. A previous owner had beautified the property by building a fancy garage to match the house and added tons of landscaping dirt and bushes, trees and flowers. BUT, first he put a top on the huge concrete drainage canal that carried flood waters from a significant portion of the city. This canal is over ten feet deep and probably 30 feet wide AND on City Property, not the property he had been deeded.
A previous owner was rich and got what he wanted despite being sued by the City.
The potential client said there was no such drainage canal. I told him to go to his driveway and walk to the east side of the street and look down. I further suggested he find the ladder that allowed workers (or anyone) to get to the bottom of the canal and keep walking west until he could see blue sky again (more than one-quarter mile). That point would be two blocks west of the active railroad tracks. He called me back the next day expressing astonishment. I believe he resold the house a short time later.
The 4 rules for engineers:
1. Where does the water go?
2. Where does the water go?
3. Where does the water go?
4. There are no other rules.