Has anyone had experience with permaculture projects on tile drained land? We found a very nice piece of land we'd like to buy - 28 acres, good southern slope, near our current land, hasn't been sprayed in at least 8 years (possibly longer). South slopes +no spray is not so common around here so it feels like a very good find. That said, we have never dealt with tile drainage before. And though I could see how they could perhaps be leveraged in a permaculture design (i.e. helping feed a managed pond system), we can see real potential downsides (indiscriminately moving water off the property). Before we submit an offer we are trying to find out:
1) where are the current drains? This helps us understand if they are pervasive or localized to one area. It also helps us with any water system design we would do post purchase
2) what "problem" were the drains installed to address (the current owner did not install the system)
For #1, we are working with the soil and water conservation district to see what they have on record. for #2, the district has also pointed us in the direction of the person they think owned the land prior to the current owners. He still lives nearby, so we may just go see him.
In case the additional context helps, we hope to use the land for pigs and poultry, a food forest and vegetable production. It's a lot of space so will clearly be a multi-year project.
I did find 2 threads on permies that talked about how to take tile drainage systems out of use (for example - one can put a temporary stop on the outlet pipe and then observe the changes to the land). However, we'd clearly have to actually own the land before we stop up the system!

Anyone have any wisdom and/or dealt with a similar situation? Any input could really help to inform our decision to buy/not buy.