This overview is designed to describe the reasons why 21E Site Assessments are performed and what they are intended to accomplish.

Massachusetts General Law Chapter 21E, formally known as the Massachusetts Oil and Hazardous Material Release Prevention and Response Act, does not state that a hazardous waste site assessment must be performed when commercial property changes ownership. M.G.L c21E does state that if a release of hazardous materials is detected on a property, all past and present owners/operators could potentially be held liable for that release by the Commonwealth of Massachusetts. For this reason, buyers and sellers of commercial real estate choose to perform a "21E Site Assessment" to verify environmental conditions present in the soil and groundwater beneath a site at the time of purchase, thus limiting or negating their liability.

A person who is liable for a release of hazardous materials is liable for up to three times the cost of any response, assessment, or remediation actions undertaken by the Massachusetts Department of Environmental Protection as well as any damages incurred by the Commonwealth of Massachusetts resulting from that release. This liability is joint and several, meaning that each responsible party can be held liable for the full cost outlined above, rather than to have the total sum divided equally between responsible parties. Damages are imposed jointly and severally without regard to fault. The Commonwealth is entitled to place a first priority lien on the property to insure that they can collect any costs they have incurred. For this reason, it is typical for a bank involved in financing a commercial real estate transaction to request that the buyer or seller perform a 21E Site Assessment.