; (3) include an assessment of spill responses in a variety of likely and worst-case spill scenarios in those waters; and (4) include the supplemental study conducted under subsection (c). (c) Supplemental study The Secretary of Transportation shall conduct, in collaboration with pipeline facility operators and any necessary agencies, a supplemental study to evaluate the condition and structural integrity of onshore, underwater pipeline facilities in the Straits of Mackinac, taking into consideration the age, construction materials, external and internal corrosion, weld integrity, pressure, underwater currents, possible external damage caused by anchor strikes or dragging by recreational or cargo vessels, and the presence of in-line shutoff valves. Such supplemental study shall utilize both internal inspection technology and pipeline route surveys, depth of cover surveys, pressure tests, external corrosion direct assessment, or other technology that the operator demonstrates can further the understanding of the condition of the pipeline facility. (d) Termination of operation Not later than 12 months after the date of enactment of this Act, the Administrator of the Pipeline and Hazardous Materials Safety Administration shall terminate the operations of an onshore, underwater pipeline facility located in the Straits of Mackinac if the Administrator determines that, based on the studies conducted under subsections (a) and (c), such facility poses a sufficient risk of hazard to life, property, or the environment to necessitate the termination.