I am working on a small ADA infill ramp and curb project. There are two about 700' street sections and a handful of isolated intersections with new ramps and crosswalks. Since i didn't set the control i started by occupying known control points from the cad file. There is a ton of different control points in the cad file because the area has been surveyed a lot over the years and the surveyor that did the topo set new project control as well as tied existing monuments and control points throughout the project as they went.
I started on the North end of the project occupying and backsighting the official project control points. I found quickly that some of the points were off horizontally and vertically about .07' consistently. I had to do a guess and check method to find which were the actual "right ones" with checks against manhole rim elevations on the plans. Was wasting a lot of my time and cutting into my profit.
Finally got ahold of the surveyor of record that set the control. They offered to paint the "good control points" for me and sent me a CSV of them. When i moved on to the first isolated intersection my setup over two of the points had an error of .07' vertical and .07' horizontal. Instead of wasting a bunch of time testing out setups on different points i just staked the ramp from the setup. My thought was at the end of the day i didn't get paid by the city to do the topography/control and i shouldn't be responsible for the crappy control. The points i staked for this ramp are correct relative to themselves and the point i used. Not like we are laying a sewer main at 0.2% here. I set a lot of control on my own and know i can expect them to be tight and this error isn't from my own equipment.
My question is if there was a bust somewhere and a ramp doesn't work do i really have any liability for it? I know it would be best to run levels through the whole thing, but that's not in my scope of work.
