Jim, NN7K wrote:
"Not only that, BUT IF you use copper pipe, you may expect electrolysis,
which will actually eat the pipe, in 4 or 5 years, in soil."

I don`t have my CRC Handbook here with its metal activity series but I
was a sailor in WW-2 who replaced many zinc electrodes installed as
sacrificial anodes to protect other metals on the ship. I`ve also built
electrolytic cells which used copper and zinc as electrodes and sea
water as the electrolyte. I guarantee it is the zinc which is eaten
while the copper remains intact. Copper is poisonous to most sea
organisms and thus is not likely fouled. Don`t worry about copper it
does not waste away in the earth. I`ve worked in broadcast stations with
radials buried in the 1930`s. They are still pristine. Zinc is the metal
used to coat steel pipe when it is galvanized.

Best regards, Richard Harrison, KB5WZI