After digging a small hole for what I thought would be an easy fix, I discovered I was mistaken. 20 feet later I found the end of the cracked pipe nestled in a pile of tree roots. I got the repair made and tested the system for a few days before covering the hole. I suspect that the pipe froze during the winter when the temperature dipped into the minus twenties. I have been told that the frost level can go deeper on tightly compacted areas such as driveways and roads. The pipe is 24 inches deep and had a spider web type crack from one end to the other.