(b)
Exceptions
Subsection (a) of this section does not apply with respect to a release or threatened release of a hazardous substance from a facility described in subsection (a) of this section if either of the following circumstances exist:
(1)
The release or threatened release was primarily caused by activities of the owner or operator of the equipment described in subsection (a) of this section.
(2)
The owner or operator of such equipment would be covered by paragraph (1), (2), (3), or (4) of subsection (a) of section
9607 of this title with respect to such release or threatened release if he were not the owner or operator of such equipment.
In the case of any release or threatened release referred to in paragraph (1), the owner or operator of the equipment described in subsection (a) of this section shall be liable under this chapter only for costs or damages primarily caused by the activities of such owner or operator.