This means someone has marked the location of your underground utilities. Each color means something different.
White: Pre-marking of the outer limits of the proposed excavation or marking the center line and width of proposed lineal installations of buried facilities.
Pink: Temporary survey markings.
Red: Electric power lines, cables, or conduit, and lighting cables.
Yellow: Gas, oil, steam, petroleum, or other hazardous liquid gaseous materials.
Orange: Communications, cable TV, alarm or signal lines, cables or conduits.
Blue: Water, irrigation, and slurry lines.
Purple: Slurry and reclaimed water.
Green: Sewers, drainage facilities or other drain lines.