I have noticed with that print, that too high of bed temps can creep up, this makes the material softer and more prone to curling up then squishing out.
Judging by the base, it looks like it's a little too hot, or your layer height is a little too close to the bed.
The ripple you talk of could be over-extrusion, filament variation or Z axis rounding errors or slight binding. What stepper/lead screw do you use?
Also how many shells did you use?