What do you guys do about the small red and yellow flags marking underground natural gas lines and other wires. Do you mow around them or pick them up and throw them away. How long do they have to be there? This is in a new developed areas. What about the wooden stakes for elevation markers? Can I take them down or should I leave them up? I do not want to piss anybody off. I want to do the right thing, but not cost me money in time and effort by weed whacking around these annoying things.