Can someone provide a reference to the theory of well construction? I am looking at the installation of methane monitoring wells and want to feel comfortable about where the screen should be placed.

you need a geologist to review the drilling logs and he can direct the driller to install the screen to only capture the aquifer(s) that you want to monitor.

http://www.usbr.gov/pmts/geology/geolman/chap09.pdf

also try the Ground Water Manual by Bureau of Reclamation

A good book is the Roscoe Moss Handbook of Ground Water Development:

http://books.google.com/books/about/Handbook_of_Ground_Water_Development.html?id=6VM0Xqxe0QUC

or Groundwater and Wells

http://www.amazon.com/Groundwater-Wells-Fletcher-G-Driscoll/dp/0961645601

or Water well technology

http://books.google.com/books/about/Water_well_technology.html?id=cPVRAAAAMAAJ

Consider, too, how you want to construct the well so that the sampling personnel do not have an excessively long purge time. If these are shallow probes, you can get away with just a small diameter (1") probe. If these are deeper, you may want to consider the installation of some smaller tubing inside the probe that terminates at the screen depth and is connected to a petcock at the top of the probe. In a deep probe situation, you have a lot of stagnant headspace and ideally that would need to get purged to ensure an accurate reading at the screened interval. Depending on the pump rate of the instrument, that could take a while.

If you are near the water table, you want to ensure that the screen is long enough to not get flooded out due to seasonal water table fluctuation. If that happens, you will be monitoring the headspace above the water and not the unsaturated zone you are trying to.

Thanks for the help.

methane rises, water falls when acted upon by gravity. As such, the strategy for well installations differ.

f-d

¡papá gordo ain’t no madre flaca!