Mass. Gen. Laws ch. 21K, § 5
(a) Except as otherwise provided in this section:
(b) The department shall provide an owner, operator or other party whom it reasonably believes to be responsible with an itemized bill of all costs incurred for which the department is seeking reimbursement. Such bill shall be so provided within 60 days from the department ascertaining the identity of the owner, operator or other responsible party reasonably believed to be liable and such bill shall:
(e) There shall be no liability under subsection (a) for a person otherwise liable who can establish by a preponderance of the evidence that the release of hazardous material and the costs incurred as a result of an emergency mitigation response by the department resulting therefrom were caused by:
(f) A person who owns or rents and occupies a private residence that is an emergency response site at which the department has incurred emergency mitigation responses costs for the release or threat of release of oil or hazardous materials shall not be liable to the department for those costs if the owner or occupant establishes the following, on a form to be provided by the department:
(i) Notwithstanding any other provision of this chapter, no person who is otherwise liable for a hazardous material release for which the department has incurred costs from an emergency mitigation response pursuant to this chapter, shall avoid, reduce, or postpone such liability or such person's ability to pay for such liability or be allowed to avoid, reduce or postpone such liability or such person's ability to pay for such liability:
(j) An agency of the commonwealth or a public utility company that owns a right of way that is a site at which the department has incurred costs for an emergency mitigation response shall not be liable to the commonwealth for such costs if the agency or public utility can establish by a preponderance of the evidence that: