You may have seen little flags in the ground, or painted markings on the ground and wondered what they mean. They mark underground utilities. Here's a guide:
RED - Electric power lines, cables, conduit and lighting cables.
YELLOW. (Yellow )- Gas, oil, steam, petroleum or gaseous materials
ORANGE - Communications, alarm or signal lines, cables or conduits.
BLUE - Potable water.
PURPLE - Reclaimed water, irrigation and slurry lines.
GREEN - Sewer and drain lines.
PINK - Temporary survey markings.
WHITE - Proposed excavation.
Green markings on a storm drain also mean it has been treated for mosquitoes.
From the Virginia State Corporation Commission, Division of Utility and Railroad Safety, July 2007