; (B) within which are located a military installation or another facility relating to national security concerns; or (C) that have— (i) populations that are highly vulnerable to urban flooding; and (ii) an uneven capacity for flood mitigation and response efforts resulting from socioeconomic factors. (h) Amount (1) Considerations In determining the amount of a grant under the pilot program, the Administrator shall consider the population of the grant recipient, which may be considered in terms of the tier under subsection (f)(2) with respect to the recipient. (2) Federal share The amount of a grant under the pilot program may not exceed 75 percent of the total cost incurred in carrying out the activities described in subsection (c). (i) Duration The Administrator shall require each recipient of a grant under the pilot program to complete the activities described in subsection (c), which shall be, subject to subsection (h)(2), carried out using the grant amounts, not later than 18 months after the date on which the recipient initially receives the grant amounts under the pilot program. (j) Use of census data The Administrator shall make all determinations regarding population under the pilot program by using data from the most recently completed decennial census by the Bureau of the Census. (k) Grantee reports to FEMA Each recipient of a grant under the pilot program shall, not later than 30 months after the date on which the recipient initially receives the grant amounts, submit to the Administrator a report that describes— (1) the activities carried out with the grant amounts; (2) how the activities carried out with the grant amounts have met the objectives described in subsection (c); (3) any lessons learned in carrying out the activities described in paragraph (2)