First of all, "su" doesn't ordinarily change your directory - "su -" does. Check "man su"..
But you may need the environment for other reasons. If so, put a shell script in common_dev_user's home directory:
#!/bin/bash
# this is "thescript"
cd /wherever-you-like
bash
Then invoke the su like this:
su - common_dev_user ./thescript
That causes them to run "thescript" in their home directory which cd's to where you want and starts another shell.
Have you thought about using "sudo" instead for whatever it is you need to do?
Using sudo