I bought this plan by Training Peaks and i found this schedule on the deschiption after week9 :
Wk#9&10; 1 set 6 x 15″ sprints
Wk#11&13: 1 set 5 x 30″ sprints
Wk#14&15; 1 set 4 x 60 ” sprints
Wk# 17&18 1 set 4 x 2min @ Z5 (hard as you can sustain for all 4
Easy 3 min walk down recovery between each sprint.