; (5) a per mile cost calculation for each linear mile of the southern border given the type of physical barrier, levee, technology, tool, or other device chosen to achieve and maintain situational awareness and operational control for each linear mile; and (6) a cost justification for each time a more expensive physical barrier, levee, technology, tool, or other device is chosen over a less expensive option, as established by the per mile cost estimates required in paragraph (2). 213. Control or eradication of carrizo cane and salt cedar Not later than January 20, 2019, the Secretary, after coordinating with the heads of relevant Federal, State, and local agencies, shall begin controlling or eradicating, as appropriate, the carrizo cane plant and any salt cedar along the Rio Grande River. 214. Air and Marine Operations flight hours (a) Increased Flight Hours The Secretary shall ensure that not fewer than 95,000 annual flight hours are executed by Air and Marine Operations of U.S. Customs and Border Protection, with adequate accountability and oversight, including strong privacy protections. (b) Unmanned Aerial System The Secretary shall ensure that Air and Marine Operations operate unmanned aerial systems for not less than 24 hours per day for not fewer than five days per week. (c) Study and report (1) Study Not later than 60 days after the date of the enactment of this Act, the Secretary shall commence a comprehensive study to— (A) identify deficiencies and opportunities for improvement in the capability of Air and Marine Operations to fulfill air and marine support requirements for the U.S. Border Patrol and other components of the Department of Homeland Security, including support in critical source and transit zones; (B) assess whether such requirements could better be fulfilled through the realignment of Air and Marine Operations as a directorate of the U.S. Border Patrol