Looks similar to Daniel's "cruise intervals".
A 7.5 mile "tempo run" may be a bit far to keep a steady hard pace for such young runners. Even for experienced runners 7.5 miles as a "tempo run" would be pretty far to run fast unless it's just a faster easy run.
15 x 400m w/1:00 rest is just enough rest to bring the heart rate back down a bit and clear some lactate out. Then, just as it "starts to get hairy"...ie: after 15 straight reps you accumulate a lot of fatigue/lactate, etc, you then take a 4 minute rest and start again.
The problems would be 1)make sure the athletes don't run so fast and 2)make sure the athletes take the rest very easy.
How is this different than a marathoner doing 8x1mile with 1-2min rest? The only difference is that the reps are shorter.
It's a very good high density workout and a very good patience building workout. If you have athletes that like to be "gun-ho" this will calm them down pretty quickly and teach patience...something lacking in many younger runners.
Alan