I’m assuming the pianist is capable.
The answer is a highly qualified “Yes.”
Ordinary HS orchestra? Sure, they could plow their way through it with no significant injuries or loss of life. Would they play it well? Probably not.
All-State or Regional orchestra made up of the very best HS-age performers selected from among thousands of HS orchestra members? Sure, and they would probably play it well, assuming that they’re being led by a conductor who knows what he or she is doing.
Likewise, an orchestra at the Interlochen Arts Academy, while made up of high-school age kids, could pull it off, and they do have the benefit of a good conductor.
My HS orchestra could have done it, but we were way above average. 
And there’d be a lot of faking in the tail ends of the string sections. But of course the hardest part would be finding a soloist.
And are you referring to the entire concerto or just the 1st movement? 'Cause they should be able to handle the 1st (and of course the 2nd), but the 3rd is a killer.
Thanks for the answers. I was referring to the whole concerto. I figured since the piano part is so difficult, the orchestral part would be too.
In high school I played in a very good symphonic band (won the main national competition a couple of years) and we played several pro-grade pieces. I don’t know the piece you are refering to, but I will say this… when we did the really hard pieces in high school we would spend a lot of time working on them. Sometimes upwards of a month or even more. Over time with a lot of practice we would sound pretty good. We did have an excellent conductor and the time to work on things. That is the main thing that is very different from real pros that can sit down and play the hard pieces after a couple of read-throughs. With enough time and good coaching any HS group could play any piece… well most any piece.
Apparently Rachmaninoff left all the virtuoso work to the soloist, and the orchestral parts seem to be comparatively easy. I even take back my comment that the 3rd movement is “a killer.” If you really listen to the orchestra and tune out the piano, it’s not so bad.