Notes
2 easy; 12x400 (400) at VDOT 55, which is 1:21 = 5:24/mile pace; 1 easy. Hard but doable. I can go faster. I often pulled up before the end when I saw that I was under pace, and occasionally that put me over pace. That doesn't explain numbers 10 and 12, though.
Training Plan Entry
repetition
9 mi
2 easy; 12x400(400); 1 easy