I finally took the time to get out the trusty flashlight and make that image on the back of The Hatch puzzle glow again so that I could copy down the code. Here it is:

First section (the first grouping on each line is underlined):
C12/1+3 C14/8 C21/9 C6/1 C1/5 C7/37 C6/1 C2/5

C21/9 C14/8 C18/2 (I think it's a 2 - this one was hard to read) C20/1+1 C12/1+3 C12/6+5 C12/2

C2/8 C10/1+1 C8/2 C11/1+3


Second section (the first grouping on each line is underlined):
C10/4 C11/2 C8/2+5 C2/7 C21/4

C18/3 C7/2 C11/3 C10/8 C8/2


Third section (no underlines):
C14/1 C3/1 C10/4 C9/2 C7/4+3 C1/5 C5/1 C7/37 C7/1 C10/8

C12/6+5 C14/8 C2/7 C1/13 C16/6+9 C9/2 C12/2 C14/8 C21/9 C10/4 C8/8 C7/8

C2/5 C16/13 C10/1+1 C10/1+2 C10/4 C12/1

C14/1 C1/1 C9/2 C3/1 C5/2 C3/1+5 C15/1

C20/2 C6/1 C12/2 C14/1+3


I do notice a couple that repeat - C9/2 and C14/8 stick out to me.


This section of the blast door map features the Arrow station. Here are some of the notes found on the back:

possible offshore data dump

intranet
this border? (this is right on the edge of the puzzle, so it may be part of a longer note)

primary function
restocking & staging area for DIHG

hub of DIHG
road system or other major route of overland travel?

suspected shutdown 10-28-84

final destination in case of code 42?

possible terminal for subterranean EFP tunnel network


The image takes up the lower lefthand corner of the back of the puzzle, so this is the upper righthand piece of the blastdoor map.


I'm working on puzzle #3 - The Numbers right now, and I'll post pictures as soon as I'm done!