When a drive is failing with SMART, wiping is usually an "indefinite" process.
Instead of wiping, which is unnecessary on modern disks, zero it out:
dd if=/dev/zero of=/dev/whatever
then do the same with urandom (there is a faster alternative to urandom here: frandom
dd if=/dev/urandom of=/dev/whatever
Then destroy the disk physically. Wiping it (like 38 over-writes or something) is NOT necessary on modern disks. But if you insist, shred is probably faster than wipe (unless it's the same:P).