I ran across this list from the Environmental Daily Advisor that summarized the EPA's top 12 SPCC violations as presented at the 2013 National Institute for Storage Tank Management’s (NISTM) 15th annual conference in Orlando.
The attached presentation from the EPA on "What to Expect during an SPCC inspection" under 40 CFR 112 and provides some insights into what to expect and some pretty amazing photos of SPCC compliance issues.