This is a big issues. There are several things you can do to help yourself. First, learn to identify potential environmental issues: USTS, asbestos, underground lifts, surface staining, drum storage, etc. Second, find an environmental consultant that you can trust. They are out there just like good shops. Third, become very familiar with your city's zoning. Zoning can make or break a deal. It has for me. If you have any specific questions PM me your phone number and I will call you. I worked as an environmental consultant doing Phase 1 & 2, permits, and remediation for 10 plus years.