Four and a half years ago we built a shed on our property. When we hooked up the rural water we had the installation come through a hydrant in the utility room. The reasoning behind this was in case we wanted to turn off the heat in the winter and drain the water in the pipes we would have a means of turning off the source of the water.
When we started the plants in the greenhouse, my brother noticed that water was coming up in the sand trap in the room and water was coming out under the slab in back. He thought that the pipe had frozen under the slab as we had left the water on all winter and it was not used even though we had heated the living area.
When we came home this month I rented a jackhammer and put my son to work to get to the bottom of the problem.
We ended up at the bottom of the pipe and pulled the hydrant. Note the hole right above the brass piece. The pipe had corrosion to the extent of putting a hole in it after only 4 and 1/2 years. There must have been some kind of reaction between the galvanized pipe and something in the soil.
In order to prevent this from happening again in four to five years we wrapped the pipe in duct tape a couple of times and and then put the hydrant in some pvc pipe, sealed up the bottom with plumbers putting and taped it. This should make this hydrant outlast me.
Really hate to be spoil sport but may not know all the details.
Your son was in a very compromized situation if no shoring was used. The hole was in previously disturbed soil. The soil was likely wet from the leak with high pore pressure. These are all ideal conditions for a cave in.
That was my concern when we first started. The shed is built up on fill which may sound very precarious, but it was not. The soil was taken from my property and very heavy clay. It was packed down with a roller that vibrated. It took them about eight hours of digging time to get down six and half feet. It was almost like diggin in rock. In the beggining I was considering using shoring material but after the first six inches of sand under the cement it was not needed.
When working on the farm and doing projects safety is always my first concern.
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<font color="blue"> There must have been some kind of reaction between the galvanized pipe and something ...</font color>
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I believe the reaction is between the galvanized pipe and the brass fitting. This site (from a Google search) has a good description of the dielectric union that is required for this type of connection. Hammer Zone - Plumbing System Components
You might ask how I know this. I am:
A) a chemist.
B) a plumber.
C) a regular guy with a leaking plumbing connection on his hot water heater.
The question that you have to ask is: if this is going to occur why don't the manufacturers use different pitch threads on the galvanized as compared to the copper/brass so these can not be threaded together?
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