1 x 1600m @ Threshold pace (20-30 sec. slower than you 5k pace/mile); 1 min. recovery
2 x 800m @ 5k pace; 200m jog recovery
4 x 400m @ 5k pace or faster; jog across the grass back to the start for your recovery.
Modify if need to due to heat and your training regime. 🙂