The propane tanks that are buried on our properties belong to each homeowner and thus we each are responsible for their maintenance.
The tanks should be tested regularly for leaks. Signs of tank leakage might be an odor or dead grass around the tank area. If discovered, contact your gas supplier immediately.
In addition, all of our tanks have an anode buried with them that prevents rusting of the tank. The anode contains magnesium powder which prevents the rusting. The useful life of the magnesium anode is between 6-10 years based upon the tank and the soil.
Our tanks are certainly in that time frame. You should contact your gas supplier to have them test your tank annually for the anode integrity. FAILURE OF THE ANODE WILL CAUSE THE TANK TO RUST AND PIT AND YOU WILL THEN NEED TO HAVE YOUR TANK REMOVED AND REPLACED AT A COST OF AROUND $4,000. The cost to replace the anode is around $250.
See the following information about “anodes”.
Magnesium anodes come in all shapes and sizes. The magnesium in a packaged anode weighs from 1 pound to 50 pounds. The most commonly used anode in the United States is a 17 pound anode. With 28 pounds of powdered backfill packed around the magnesium, a packaged 17 pound anode weighs about 45 pounds. It comes with 10 feet or 15 feet of #12, insulated solid copper wire. The backfill consists of 75% powdered gypsum, 20% powdered bentonite clay and 5% sodium sulfate. This mixture is a low cost, nonhazardous, electrically conductive earth backfill. A cotton bag holds the backfill around the inner metal bar. It decomposes over time in the ground. The anode is shipped in an outer disposable, plastic or paper bag to protect it from rain or snow. It is recommended that 5 gallons of water be poured on the anode after it is placed in the earth to wet the backfill. This lowers the resistance between the magnesium and the earth causing more electric current to flow. This provides more protective current than would be possible in dry soil.
Cathodic protection is a procedure used to protect an object from corrosion by making it a cathode. To make a tank a cathode, you have to attach an anode to it. Both have to be in an electrolyte such as earth or water. To protect a propane tank, you would attach an anode consisting of a 17 pound bar of magnesium metal packed inside a cloth bag containing 28 pounds of conductive earth backfill with a wire that is attached to the magnesium and to the tank. The magnesium metal is a source of electrons for the iron atoms and it is from where d.c. current originates. As long as enough electrons flow from the magnesium through the wire and the connections to the tank, the tank will not corrode. At the same time, a small amount of direct current flows from the magnesium metal, through the earth to the tank. The current is less than one amp.