Need a alternate place to do sprints? Go to a baseball warning track and run foul pole to foul pole. The surface is usually fairly maintained and flat for sprinting. I found one today at Cabrillo Community College that worked out great. Warm up with a easy jog a and a few exercises that require you to use your hip flexors.
Go to your local yard and scope out a warning track for yourself and a workout partner or two. Seperate yourselves by 5 seconds and chase each other to the foul pole. The sound of your feet hitting the light gravel gives you the feeling in your head that you may be faster than you think you are.