Section 450.11 - General definitions(a)New source. New source means any source, whose discharges are defined in 40 CFR 122.26(b)(14)(x) and (b)(15) , that commences construction activity after the effective date of this rule.(b)Infeasible. Infeasible means not technologically possible, or not economically practicable and achievable in light of best industry practices. 74 FR 63057 , Dec. 1, 2009, as amended at 79 FR 12667 , Mar. 6, 2014