Replacing sprints for workouts

I live in Wisconsin in a fairly hilly yard which I can not do sprints in. The combination of bad weather and bad terrain to do sprints on make it very hard to do them on a weekly basis. The only place where I can do the sprints are at a nearby gym, but with schoolwork and extracurriculars, I don’t always get there. Are there any effective exercises to properly replace short and long sprints? I’m able to do long jogs because I live on a circle, so I still get some running in. Thanks!

What about tempo runs or fartlek’s? Basically, go for a long jog but pick up the pace for 30 seconds and then slow it down for 60 seconds. Repeat. This mix of faster and slower jogging is killer. Most runners train this way. However, hills can also be challenging and fun - so don’t overlook them as a way to mix things up a little with your conditioning. I do them once a week now and love them! 100 yards sprint up hill and walk back to start and repeat 6-10 times.

Thank you very much, I’ve done runs like this with 10 seconds of sprinting between a minute of light jogging, but your advice sounds much more beneficial.