Final answer:
Blue is sprayed on the dirt or street surface to indicate the presence of a pipe carrying sewer/storm drain.
Step-by-step explanation:
The color that is sprayed on the dirt or street surface to indicate that there is a pipe below carrying sewer/storm drain is blue. This color is commonly used in utility marking to identify underground infrastructure, including sewer and storm drain pipes. Other utility marking colors include red for electric power lines, yellow for gas lines, and orange for communication lines.
For example, in the United States, the American Public Works Association (APWA) has established a standardized color code for utility marking. According to this code, blue is used to mark water systems. It is important to note that utility marking colors may vary in different regions or countries, so it is always recommended to consult local regulations and guidelines for accurate information.