Metal septic tanks were invented in the 1940s. They were
used in North Carolina, but it is highly likely that the steel
tank you have is past the end of its life. You get about
20 years from a metal septic tank.
If you have discovered that you have a metal septic tank it is
probably because it is caving in or leaking.
If you have a metal septic tank it needs to be replaced, not
repaired.
If the tank has a hole or is leaking I doubt that the county
will let it be repaired. There is too much risk that the
other parts of the tank will cave in immediately or in short
order.
There are also legal risks for the person who repairs the tank
as well as for the county and the county employee who gives a
repair approval.
Here is what I was taught at North Carolina State University:
~If you find an old metal tank strongly
encourage the homeowners to have it replaced
~Put up wooden stakes with danger/caution tape
around the vicinity of the tank before you leave the site
~If the homeowner/s are elderly and do not have
any grandchildren or children that will be playing in the yard,
yes they can keep the tank. And when they pass away or
sell the home the tank needs to be replaced.
If I was going to purchase a home which had a metal septic tank,
I would negotiate a tank replacement into price or I would
require that the tank be replaced as a condition of purchase.