I am beginning the process of finishing our walkout basement. One of the first challenges I have come across in laying out the walls is a number of plumbing and gas lines right at the top of the concrete exterior walls feeding the main and second story. The lines will prevent me from attaching the top plates for my stud walls to the joists above.

Is there a workaround outside of having the pipes re-plumbed?

All of the research I have done indicates that you do not want to attach the 2x4 stud walls to the concrete exterior walls for any reason.

Frame your wall with the top plate shy of the above piping so you have a completed framed wall. Attach 2x material, say 16" long, to the foundation about every other stud. Plumb the wall, then measure from the plumbed wall to the 2x secrured to the foundation. Cut another 2x piece the distance from the attched wood on the foundation to the stud. Take in account the 1 1/2" piece on the foundation and the width of the studs your using and add that to the measurement. You'll secure the framed wall to the foundation wall w/ this piece of wood. If you have a poured concrete foundation, Red Heads work well if block, Tapcons also work well.

Frame your wall with the top plate shy of the above piping so you have a completed framed wall. Attach 2x material, say 16" long, to the foundation about every other stud. Plumb the wall, then measure from the plumbed wall to the 2x secrured to the foundation. Cut another 2x piece the distance from the attched wood on the foundation to the stud. Take in account the 1 1/2" piece on the foundation and the width of the studs your using and add that to the measurement. You'll secure the framed wall to the foundation wall w/ this piece of wood. If you have a poured concrete foundation, Red Heads work well if block, Tapcons also work well.

Thanks for the quick reply!

If I understand your post, the stud wall will be out (depending on where the wall plumbs to) appoximately 5 1/2" from the concrete foundation wall > 1 1/2" stud attached to foundation + 3 1/2" stud wall + 1/2" drywall. This creates another problem in that the rough-in shower/tub and stool drain lines for the bathroom will be thrown off by that extra 1 1/2".

Is there any way I can maintain the proper spacing in the bathroom to avoid expensive plumbing re-work or special offset toilet?

I like to keep at least an 2" space from the foundation to the back side of the studded wall for air circulation. The 2x material your securing to the foundation are scrap pieces. They don't have to be full length studs. Your using these as an anchors so the wall is attached to these w/ a piece of 2x nailed to the side of the stud then to the 1 1/2 side of the foundation mounted piece.
If you have to keep the studs tight against the foundation because of the plumbing you'll be OK. If all else fails just surface mount firring strips to the foundation in the bath area where the roughed-in plumbing may be a factor. Place plastic over the foundation then mount the fir strips. Ridgid insluation between, then durorock over the studs in the shower/tub area & moisture resistant drywall over the other fir strips area. If I knew how to draw on the computer it would be easier to understand.

Using 5/4 pressure treated lumber in place of the 2X would work and save you the 1/2 inch. Won't hurt to have pressure treated against the masonry.