Advice for New Grad

I am a new grad with 5 years experience with my current employer and I just finish my BSc. With my position (Net Admin for 200 users) in the Washington, DC, I am making $15k/per annum less than my counterparts in the region. The excuse for this has always been that fact that I didn’t have a degree. Well now I do.

Can you good folks kindly give me some helpful advice on how to tactfully ask for just compensation without putting myself in a sticky situation?

thanks