  The HAWC (High Altitude Water Cerenkov) gamma ray observatory observes muons
with nearly-horizontal trajectories corresponding to zenith angles greater than
$80^{0}$. HAWC is located at an altitude of 4100 meters a.s.l. (70 deg.
atmospheric depth of 2400 g/cm$^{2}$) on the extinct volcano, Sierra Negra in
Mexico. In this poster, we summarize the CORSIKA and GEANT4 as well as
toy-model based simulations performed to determine the effective area of HAWC
to muons from high zenith angle cosmic ray primaries. We are developing an
updated GEANT4 based detector response simulation that includes a model of the
volcanoes that are located near HAWC. These simulations are investigating the
capability to use muon multiplicity and rates to differentiate between the
primary particle composition (proton or iron) and measure the primary energy.
