Last summer, while trekking around Ames Monument and Vedauwoo, my curiosity was aroused by these pipes sticking out of the ground.  They emerged periodically across the prairie and though I'm sure they've always been there, it was only this time that I really noticed - and wondered - what they were. 

At certain intervals the pipes were accompanied by a sign like this - even then, I really didn't believe there could be a water pipeline clear out there.  After all, where would it be going?

Imagine my surprise when I googled  "B.O.P.U." and  found not only was it, indeed, a water pipeline but also a major source of water to the city of Cheyenne, Wyoming, 40 miles to the east.

(http://www.cheyennecity.org/MediaCenter.aspx?CID=Water-Department-1#player)

Though this explanation doesn't explain these odd pipes, further research found that pipes, or vents, such as these could serve one of two purposes:

           a) ventilation system for water pipes
        b) inflow preventer for water pipes

More technical than I could have imagined! 

Here is a link that explains it better:     http://www.valmatic.com/pdfs/ProtectingDrinkingWaterPipelines.pdf

Or,the ultra-brief explanation:

An Inflow Preventer is a mechanical device mounted on the outlet of an air valve or vent pipe to allow normal flow of air in and out of the water system and prevent inflow of contaminated water into a water system as a result of flooding or malicious tampering  [Landon, Phillip, “An Introduction to Inflow Prevention,” Pumps & Systems, March, 2006].

So, take a look at the everyday things you drive by - perhaps there's a whole story behind them as well!