I just cut off the saplings. I didn't pull them up by the roots. I obviously should not have let the saplings get that tall but time slips up on you.
I found a discussion online about a septic drainfield in the woods
here. One guy made the following interesting comments. I wonder if I should get some copper sulphate.
In NC, we do not disturb the trees or the land...that would destroy the ability of the land to treat the waste. We snake the drainlines between the trees. It takes more land, but it is a better system than the ones in a grassy field, because the trees can get to the water. the trees remove the nutrients, too...returning them to the land, rather than letting them escape into the aquifer where they do no good for the land and contaminate the groundwater...and eventually the well water. The tree roots also keep the soil drier, so the system lasts longer because it doeesn't form an anaerobic biomat in the drainlines.
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Also, For those uf us with septic systems in woods, I add a half a pound of Copper sulfate to the outgoing drain line once a year. I buy it in the farm and garden store or in the ag supply or gardening shop. It is used to kill some pests for roses or some such. I forget what exactly, but it is commonly available and it's cheap, too. It kills roots that have invaded the system, but the copper does not accumulate in the trees and does does not harm the trees other than killing some of the roots.
Obed