I have a very long line of rhododendron bushes which are hardy but are
starting to wilt.

I noticed the animals chewed right through the thin plastic in just a
couple of spots.

I can't for the life of me, find where the water comes from that feeds
this irrigation line (it has always been dry since I bought the place
from the bank, owner unknown to me).

To get a background on this thin piping, what is an accepted repair
procedure?

And, normally, how does it get it's water? I find no sprinkler electrical
box that feeds this line???