Locate marks, be they paint, stakes or flags, should be in sufficient quantity and close enough together to clearly identify the horizontal alignment of the buried facilities.
While locating equipment is becoming increasingly more sophisticated and accurate, parallel facilities, overhead facilities and nearby reinforced concrete structures all affect their accuracy. Locating is thus part art and part science, and locate marks are approximate only.
Locators should identify and mark the locations of abandoned facilities whenever possible. They should also identify the number of facilities the ground disturber can expect to find whenever that information can be determined.
Locators will not give depth, but should warn the ground disturber if they suspect a particular facility is deeper or shallower than might normally be expected.