This may vary in your state, but s/p2 recommends keeping all environmental documentation a minimum of: a) 6 to 12 months b) 1 year c) 3 years d) 10 years

C)3 years

Explanation:

Documentation

Both OSHA and the EPA require shops to provide and keep specific documentation. Missing or improper documentation is a major cause of OSHA and EPA violations. Make it a policy to document all compliance-related actions—and keep your files up-to-date. Make sure files are accurately labeled and easy to find. During an EPA or OSHA inspection, the inspector will ask to see your files. Even if you handle and dispose of waste properly, you will still be subject to fines and penalties if you are unable to provide supporting documentation.

Always keep one copy of documentation on-site and a backup copy off-site.

Keep all compliance documentation for a minimum of three years—or longer, if required in your area. Laws can vary by state as to the length of time you must keep the paperwork. If a violation ever occurs, or the organization is sold, the business will benefit from a complete hazardous waste file.

For more details, visit CFR Title 40: Protection of Environment.