I am looking at a house with a 6.5 basement height. What is a ballpark figure for digging out a 15'x40' basement. There is bulkhead access to the outside. Philadelphia urban area.
The digging is not as expensive as the foundation shoring, and is very region specific.
A lot depends on how often it is done in the area.
Its done quite a bit, I just don't know anybody personally who has done it in the past few years. Actually one client I worked with who had two adjoined houses did it in 2008 but doesn't know how much that cost specifically because it was part of a gut rehab. They also dug out one basement and filled the other in essentially, based upon existing conditions in each basement even though they were adjacent.