Thank you.
Firstly, for a first orchestration it shows some remarkable insights. You haven't invited comment but as I looked through the score I might as well make some.
I presume none of the instruments have been transposed conventionally except the double bassoon and double basses.
There might be some problems with the scoring (which you can cheat with using rendered samples but not in real life). It depends what you want to happen with the score............The bassoon high A# in bar 55 is ok, but ff in bar 57 will be pretty weak. The high A# in Trombone(s) is doable but quite a strain. There may be other ways you can arrange these few bars to make it easier for a player as the low E on the Trombones here and there is reinforced by the Tuba. (However, again it works well enough with sample playing.) Bar 34=Horns. You mark Horn 1 to play alone. Did you intend 2 and 4 to play in unison, or just Horn 2?
I notice you marked various string parts detaché - nice touch... but do you intend other (string) phrases to be played legato? If so they should be slurred. Still leave in the detaché though to remind them. A last point is marking woodwind parts div. When there are two or more players and both are playing there's no need. Convention has it that when both are playing the notes in unison to put à2 above the part or state which one you want to play: 1 or 2. However, you don't have to follow convention as long as it's clear. When the divisi ends put "tutti" (or "all" as you did with the bassoons in bar 52 unless you want just one player on the part, then say which one.
The harp part. Harpists are used to looking at weird chords to save changing pedals. The second chord in bar 21 would be better as A# E# A# so the harpist doesn't have to change pedals and back again (twice). In bar 53 if you made the E-flat D# it would save a rapid pedal change from E in the previous bar down to Eb. And in bar 54, the F# could be G-flat to save the pedal changing from bar 52.
I've only made these comments because you've come up with a very nice-looking score, full of detail. And of course, it you're happy with things as they are, fine - you're the arbiter!
When you can render the piece on a computer it'll sound a lot better. At the mo the opening high E 1st violins harmonic is lost altogether. With the bass turned right down at my end, the low E pedal note on the double basses can't be heard.
All the best.
[Edit] Oh, a final point, if you're going to use the treble clef for the bass clarinet, transposing the part up an octave would make it far easier to read and would follow the playing convention. (However, that's something I don't do. I write it in the bass clef! Like I say you don't have to follow convention but if you don't, make sure the player knows what's expected.)