I believe Nick has the right idea. Go with a piece of PVC, steel or whatever is available and go with a pipe big enough to go over the OD of the existing pipe and then some, fill the 2-3 inches inbetween the walls with concrete. The people at Easyway Plastics, Inc also in Georgia (1-877-387-5472) also told me if you use PVC , to take a grinder and grind the pipe to a long gradual tapered point, this will aid in driving the pipe into the dirt as far as possible but it also roughs up the smooth material so the dirt,concrete,etc have a better chance of sticking to the pipe. This method is a temporary fix , once again but I have 2 ponds that have this and their still holding..... (knock on wood)
