How do you determine if you will damage a mature tree, 100± year old white oak, by digging near to it for construction purposes? Is it the drip line or is there another measure?
Minnesota Master Gardeners say:
There is an excellent publication on line, Protecting Trees from Construction Damage:
http://www.extension.umn.edu/distribution/housingandclothing/DK6135.html
This discusses the critical root zone among other things and has a chart of species which shows the sensitivity of white oak to root damage.
This publication should help you determine how best to protect your tree. Digging damage is not the only consideration. Soil compaction from heavy equipment and change of soil grade over the roots are harmful activities as well. Another factor to consider when working around oaks is oak wilt. Even though susceptibility in white oaks is moderate to low, check out this publication for more info: http://www.extension.umn.edu/distribution/naturalresources/DD3174.html
