2 Questions: Are roots from oaks invasive and can you put a dollar worth on a thirty year ripened oak tree? I live in an established townhome area where on earth there are...

I live in an established townhome area where on earth there are oak trees (mostly tall white oak) in close proximity the swimming pool behind my home. There are sidewalks near the pool that inevitability to be replaced/repaired and the townhome management wants to remove several oak trees citing "safety" concerns and stating the treeroots are posing a problem. There is no damage to the pool or the cement decking around the pool. The trees are midway between my place and the pool, probably 15 feet to the trees and another 15 ft to the pool. There is no damage to my quad area and the trees have not cause any damage to the drains or water pipes as far as I know. These are elevated, strong trees and great cover for my patio which faces west.

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Answers:    Sounds approaching you need to call within a "consulting arborist", probably one with asca or isa certification.
http://www.asca-consultants.org/
http://www.isa-arbor.com/home.aspx

Yes, trees clearly have value -- on form, established trees in good locations are worth moderately a bit in home resale value. On the other appendage, poorly cared for or sited trees can be a detriment.

This is likely one I'd m¨ºl¨¦e tooth and nail if those trees are healthy -- my suspicion is your regulation is nervous of any tree over 10 ft tall.
http://www.na.fs.fed.us/pubs/silvics_man...
http://hort.ufl.edu/trees/QUEALBA.pdf
http://www.ipm.iastate.edu/ipm/hortnews/...

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