FEHM executables are available on for Linux, MacOSX and WINDOWS. 

Linux (64-bit)  fehm_v3.10lin compiled with gfortran 4.5 or newer 
MAC OSX Intel   fehm_v3.10mac compiled with gfortran 4.5 or newer
PC Windows (32-bit) fehm_v3.10win32 compiled on Intel 
PC Windows (64-bit) fehm_v3.10win64 compiled on Intel

Latest versions of FEHM are available by request at https://fehm.lanl.gov/

FEHM is started by typing the name of the executable file from a command
line interface – no graphical user interface is provided. 
Detailed instructions are found in the FEHM User Manual. 

Copyright 2013. Los Alamos National Security, LLC for FEHM LA-CC-2012-083.
This material was produced under U.S. Government contract DE-AC52-06NA25396
for Los Alamos National Laboratory (LANL), which is operated by Los Alamos
National Security, LLC for the U.S. Department of Energy. The U.S. Government
has rights to use, reproduce, and distribute this software. Neither the U.S.
Government nor Los Alamos National Security, LLC or persons acting on their
behalf, make any warranty, express or implied, or assumes any liability for
the accuracy, completeness, or usefulness of the software, any information
pertaining to the software, or represents that its use would not infringe
privately owned rights. 

The licensed software, FEHM, may be Export Controlled. It may not be
distributed or used by individuals or entities prohibited from having access
to the software package, pursuant to United States export control laws and
regulations. An export control review and determination must be completed
before LANS will provide access to the identified Software.

Distribution of FEHM source code is limited to FEHM team collaborators with a
LANS approved and signed Contributor Agreement. Contact Terry Miller
tamiller@lanl.gov or an FEHM team member as listed at fehm.lanl.gov