Road Construction Threatens Water Quality

I am a little disturbed to see deep asphalt roadbeds being laid for Bee Caves Road and in other nearby road projects such as West Bank and the ninth-grade school entryway off of Camp Craft Road. All of these roads are in areas that receive a lot of water that feeds quickly into our drinking water. How was it that these roads came to be constructed in this way rather than with a concrete bed? This just doesn't seem to be the best idea.