Question
I would like to plant some fruit trees in an area that our sewer lines run through.  I understand that some root systems invade sewer lines and cause sewer backups...  

Would fruit trees (apple or peach) cause this problem?  If so, how far away from the sewer line should I stay.

Also, I am planning to plant a new lawn.  My soil is tends to pack quite hard and seems to need some organic matter added to it.  I am considering tilling in some sawdust to provide the organic material, but have heard that the decaying sawdust uses up too much nitrogen in the soil...  
Can I take care of the nitrogen problem by applying commercial fertilizer?  Or do you have any other suggestions?

Thank you.

Thank you.

Answer
Hi Rex, I would stay at least 15' away from a line.  Your soil type, depth of the line, annual rainfall and tree type are all variables that determine whether tree roots find your lines. I'm comfortable with fruit trees at 15' away.
If the sawdust is rotten, then use it.  If not, then don't.
Decomposing sawdust does indeed rob the soil of nitrogen but by increasing your nitrogen, you'll speed up the decay but your grass will still not flourish.  Plus your pH will usually plummet because of the tannic acid in the sawdust which locks up many other nutrients your grass needs.  I'd prefer to use leaves, grass clippings or finely ground pine bark.  The most important part of soil preparation is loosening the soil.  What you add is not nearly as important.  Jim