Hi there, I was in a similar situation, except that my last completed courses were in 2006. The small print in the application process at the grad school I applied to said that if you've graduated more than 6 years ago, academic references aren't necessary.
Actually, in my situation it was a bit worse, because on paper I'd graduated in 2011 after taking a summer course to complete my degree where frankly I couldn't even remember the name of the lecturing prof and he certainly wouldn't remember me at all. In any case it turned out fine when it came to applying.
You should feel free to call up the offices for the program you're applying to clarify the requirement for academic recommendation for someone in your position.
You could get recommendations from people you've volunteered with or under and work supervisors. Also, go through your list of professionals that you are friends with or who have known you over the years - would any of them be able to speak to the qualities that make you a good grad candidate (creativity, flexibility, time-management etc)? Do you know anyone else who's in the field you're applying to? Or have you collaborated on projects with anyone who could speak favourably about you?