There are breath tracks and breadth fields which are related to science - they usually have to do with science and society or science and history.
But now a question for you - I'm just curious as to why you see breadth to be such a bad thing and why you don't want to do anything unrelated to science. I can understand that science is what you are interested in and the degree you wish to get, but why the lack of interest in other complementary fields? I don't mean to sound accusatory, I'm just wondering!
Many find a break from their core studies to be very refreshing. I was disappointed that I couldn't take breadth in my old gen course. Additionally, my perspective of a well rounded education is one in which you step outside your chosen field and learn about something new. But maybe it takes being flooded with a whole lot of science (or anything really) to see things in the same light, I suppose. Perhaps you will feel differently once enrolled and out of high school, where you tend to be forced to participate in an array of subjects. You may find that you miss daydreaming through double English when it's no longer available to you! I never thought I would miss Science as much as I did, but look where we are now.
One thing I notice about accusations from those not enrolled at Melbourne about the Melbourne model is that many think /all/ breadth options will be completely irrelevant to your degree. But this isn't the case - as long as you choose your subjects wisely then there's no reason that you should be wasting your effort and money on something that won't benefit your education. And just because you choose something unrelated to science doesn't mean that it's pointless to your degree. Many tend to assume your breadth subjects will be things like wine camp and African drumming from the outset, and some students do choose these things - but that's their decision. I wouldn't make those choices myself, and you don't have to - there are a plethora of subjects which gauge your interests about life, society and the world in general as well as things you might like as hobbies like music or literature.
So I guess where I am going with this long rant, should you still be reading, is that the Melbourne model is not inherently bad in my eyes. I look forward to gaining a specialised education in my chosen field of science, whatever that is. But I also look forward to knowing that I've extended by education beyond that narrow field of view to something that will help me later on - not only in my chosen career, but also in my everyday life. For instance, subjects I've taken in politics have helped me to understand our political system and how it functions - obviously this isn't immediately valuable to a career in the biological sciences but it is valuable with regard to my credibility as a member of our society.
The biggest critics of the Melbourne model tend to be those in favour of vocational degrees. And so let me just conclude by saying - if you're so against the Melbourne model, is it because you wish your degree to be more vocational than 'academically' based? Because that not really what Melbourne ever intended to offer in a Bachelor degree, and it's best that you recognise this from the outset. There's no use getting frustrated with their broad take on education if you would much prefer a more narrowly based course.
Sorry if I sound like a massive Melbourne ad campaign, I usually don't voice my opinions on the model here, haha. In short, your breadth can complement your degree...but only if you want it to. Don't take things like Choir and invest your time and money in worthwhile endeavours.