Hi Shane,
If you want to use a longer exposure then "something has to give" to compensate. In this case - since you shot at F8 - you could have stopped down more; ie 1 minute @ F11, 2 minutes at F16, 4 minutes at F22 etc. Also - if you want longer and you don't have an ND filter handy - then just keep shooting whatever you're shooting and combine them when you get back home; 8x 30 second shots will look the same at 1x 4 minute shot.
In terms of the image - as I see it anyway - you're getting there, but the biggest issue with that shot is that it's so wide there's no detail; this is a common mistake people make with wide angle lenses. A couple of "food for thoughts" ...
If you're going to use a wide-angle lens then push in aggressively to something in the foreground, like this ...
Often though, more pleasing shots can be accomplished more easily by using a long focal length and "zooming in" to just a portion of the scene in front of you, eg ...
![Early Wake up Call!](http://www.pbase.com/cjsouthern/image/136933715/original.jpg)