I agree with everyone else, 30 does sound like a lot.
I worked about 20 hours per week throughout undergraduate, and I felt like I didn't really have much time for anything else. I think I've gone into more detail on it in the past, but during my senior year in college, I was working 20 hours and spending about 20 more hours in my undergraduate research lab on top of taking 12 additional units. Every day I would leave my apartment at around 9AM and I would never get home before 9PM.
If you want to put 30, it'll really depend on your ability to make a logical schedule and stick to it. You'll need to be good at using your down time in between activities to study, eat, etc.
There are 168 hours per week, I would recommend you write down your weekly schedule and see how many hours you have left over. Make sure to overestimate the time you'll use, so that you aren't short. There are a lot of things like travel time that people tend not to take into account. You'll also want to get close to 56 hours of sleep per week, and probably at least 50. (Cutting your sleep too much will make you less productive during the day, so it really isn't worth it)
Make sure to factor in relaxation time, as you'll want to avoid burnout as much as possible. I always reserved Sunday for myself to relax or do housework, unless I had an upcoming exam.
Another thing to make sure is that you'll be able to decrease involvement if you need to, without any major problems. If it ends up being too much you don't want to burn bridges with the company you're working with, but you'll have to prioritize your GPA.
Good luck. If you want more information, I can offer anything about my own experiences.