10,500 yards a week seems like major overkill for someone's first sprint race, especially when they aren't comfortable swimming more than a few hundred yards at a time.

I'd suggest swimming 1500-2000 yards, twice a week. Focus on form and do lots of training drills (side kicks, fists, bilateral breathing, sighting, catch-up, fingertip drag, etc.) and some speed intervals. You'll get faster, stronger and find yourself swimming further without needing to rest.