; and (ii) capable of reducing noise, airport emissions, or water quality impacts in measurably significant amounts. (k) Authorization for the transfer of funds from Department of Defense (1) In general The Administrator of the Federal Aviation Administration may accept funds from the Secretary of Defense to increase the authorized funding for this section by the amount of such transfer only to carry out projects designed for environmental mitigation at a site previously, but not currently, managed by the Department of Defense. (2) Additional grantees If additional funds are made available by the Secretary of Defense under paragraph (1), the Administrator may increase the number of grantees under subsection (a). 159. Aircraft noise exposure (a) Review The Administrator of the Federal Aviation Administration shall conduct a review of the relationship between aircraft noise exposure and its effects on communities around airports. (b) Report (1) In general Not later than 2 years after the date of enactment of this Act, the Administrator shall submit to Congress a report containing the results of the review. (2) Preliminary recommendations The report shall contain such preliminary recommendations as the Administrator determines appropriate for revising the land use compatibility guidelines in part 150 of title 14, Code of Federal Regulations, based on the results of the review and in coordination with other agencies. 160. Community involvement in FAA NextGen projects located in metroplexes (a) Community involvement policy Not later than 180 days after the date of enactment of this Act, the Administrator of the Federal Aviation Administration shall complete a review of the Federal Aviation Administration’s community involvement practices for Next Generation Air Transportation System (NextGen) projects located in metroplexes identified by the Administration. The review shall include, at a minimum, a determination of how and when to engage airports and communities in performance-based navigation proposals. (b) Report