Nice to hear you are interested !
In my day ( ages ago ) you could apply directly for admission into the Faculty of Engineering at the U of A. You selected a discipline such as civil, mechanical, electrical, petroleum or computing science. Environmental was a part of civil, and bio-medical was a hybrid that you specialized in after you completed one of the mainstream disciplines. Most of the courses in the first two years were common for all disciplines, and the third and fourth years were when you took courses geared towards your specialization.
This now has changed. First you apply for admission into the Faculty of Science. You complete the first two years and as all the courses are common. Be prepared for a gruelling study regimen. The first two years are an extreme challenge studying calculus, physics, chemistry, statics. There was also quite a bit of fun as engineering students really have a ' work hard, play hard ' disposition. However I would not be surprised if this has changed. Tuition and books back then were about two grand. Today I hear that it is about six large. That is a significant amount of money so maybe there is a whole lot less partying, drinking and all purpose cornholing the dog.
After completing the first two years, you apply for admission into the Faculty of Engineering. It is very competitive and admission hinges on your grades over the first two years. Of course you select a specialized discipline and your courses are specific to that area of specialization. Upon graduation you spend about two years working under a ( or several ) P.Eng(s) and then you write an exam. If you pass you get your stamp and you have the privilege of being a Professional Engineer.
Career wise most people are satisfied with doing the techie / design type work. It pays well, and with the software available most of the shit work is now done by computer. You really don't have to break a sweat. For the more ambitious, I strongly recommend that they also focus on the commercial part of the profession. Take businesss management courses part-time, volunteer to wrestle with some of the tedious commercial details, study areas such as contract law and the like. As with everything else these days, it isn't just about the money - it's only about the money. Building and construction contracts are now as commercially complex as they are technically challenging. This is not easy to do, but if you are even semi-competent in both the technical and commercial aspects of the profession then you can basically write your own ticket anywhere in the world. There is a saying: I can find a hundred and fifty guys who can conceptualize, design and draft the best bridge in the world, but I can't find one lousy cocksucker who can sell it to the client, keep all the stakeholders working together, deliver the project on time, stay within budget and make some fucken money doing it.
Hope this helps. Cheers !