Since I live on a county road, I called the county and they told me the size culvert I needed. They also told me for $250, they would put it in for me, materials AND labor.
Several months later, when our builder started on our house, the first thing they did was put in a construction driveway. They tore out the culvert that I just had put in and replaced it with a new one. Even though our contract said, "culvert provided by owner", the builder said the county requires a 30 foot culvert, and we only had a 20 foot culvert. I told them that was funny, considering the county was the one who installed the 20 foot culvert in the first place! /forums/images/graemlins/confused.gif I ended up winning that one, the first of many issues while building the house!