Section 51.110 - Attainment and maintenance of national standards(a) Each plan providing for the attainment of a primary or secondary standard must specify the projected attainment date.(g) During developing of the plan, EPA encourages States to identify alternative control strategies, as well as the costs and benefits of each such alternative for attainment or maintenance of the national standard.51 FR 40661 Nov. 7, 1986, as amended at 61 FR 16060, Apr. 11, 1996; 61 FR 30163, June 14, 1996