pier footing drawing

We have been approved to put an addition onto our house, in the back. We are building it onto piers, using pier footings instead of traditional cement foundation. It was approved. Of the 12 holes we made, 1 of them close to the house, we hit a rain cistern as we were digging the 42 inch (for frost line)-the city said we need a structural engineer to draw up a safe plan for our footing, for that specific hole, to make sure it is sound and safe. Even though, we have removed all cement under the ground--we have some left to remove, but once u remove all cement, and fill it and pack it, and put in the footing they already approved, it will be fine. Every engineer has agreed that will work, but they want to see that written and drawn first so they know it is structurally safe. It is a bit ridiculous, and my husband who does construction agrees., but we have to do what the city says. So pretty we need you to give us a drawing for it, saying how we should do it. We have 11 other holes that are perfectly sound and have no issues, it is just this 1 hole. I can even send you a video. You dont have to visit the property, if you dont want. It should be a pretty easy and simple job.