Jeff Layman wrote:

I doubt that there is an evergreen climber that hardy, from what you
have said.

But why not use that curse - leylandii - to make a hedge which you would
just have to trim back every year or so. You could buy it as a
well-grown plant (not sure how many you would need. How long is the
tank?), and within a few months you would have your screen.

Well, Jeff, that's certainly an idea, though a curse, indeed! Our
previous property came with said curse and I'm glad to have escaped it.

Leylandii would certainly do the job though, and with regular attention
it could be kept thin but dense.

Do you know how the roots might behave if the leylandii was kept as a
thin six-foot high hedge? I need to consider this because the exit pipe
from our septic tank empties into the ground about 15 feet away from the
gas tank. So we can't risk planting anything around the gas tank which
has roots that will go charging off into the soakaway and possibly
reaching the exit-pipe of the septic tank. Certainly planting even just
one leylandii and letting it rise unchecked would be out of the
question.

Would a number of leylandii forming a low L-shaped screen, about 8'
along one side and 6' along the other, bother sending roots out widely?

Eddy.