Using iTOUGH2-EOS7C, a simple 1-D model was developed to represent a site in Ontario, Canada which is being considered for nuclear waste disposal. The site exhibits substantially underpressured water and potential evidence for gas phase methane within a thick section of sedimentary rocks. To investigate possible mechanisms for the development of the underpressure in a multiphase system, hydromechanical coupling during a glacial cycle was simulated with and without gas phase methane present. Results indicate that, while the gas dampened the effects of the loading cycle, it did not preclude underpressure development. This USGS data release contains all of the input and output files for the simulations described in the associated journal article (https://doi.org/10.1029/2019GL083027x).