I believe there may be some ways to apply it in Civil Engineering.
Continuing Education

pursue a master's degree..you'll find lots of math stuff even if it's in engineering,,more often involving derivatives and integrals.

If you feel like studying a bit on your own I would recommend a book like Strogatz' Nonlinear Dynamics and Chaos. It is a very well written introduction (and a little more) to the field of dynamical systems applied to biology, physics and chemistry. It is not filled with rigorously stated theorems and definitions, rather Strogatz wants to provide the reader with an intuitive understanding of the methods and theory - Strogatz has a very inviting way of writing. Furthermore you should be able to read it with the background you have, assuming you've had some linear algebra.
Once you've completed that one, if you want something more mathematically dense the book by Guckenheimer and Holmes is nice.
But it all depends what your interests are. Personally I have just started reading up on some graph-theory which I hope to use in conjunction with my knowledge of applied dynamical systems when I construct models of interactions between different immune cells.
I am a Civil Engineering student, and I have just finished the "last math class of my life" - Ordinary Differential Equations. I'm starting to miss math. I was wondering if anyone would have recommendations as to how I can continue the journey of math once my formal education in it has concluded.