From uncontrolled outdoor discharges. Notice the staining that indicates contaminated sheetflow direction. Greasy sheen on pooled water. If you look closer at the edge of the pooled water, the degredation of the asphalt can be seen. The oils that normally bind the asphaltic concrete have been removed and or washed away from washwater runoff containing chemical cleaners and or degreasers. "Etching of concrete" is a major clue.