This article describes the work performed by Steve Otway in partial fulfillment of the requirements for an M.Sc. degree in the Department of Agricultural, Food and Nutritional Science at the University of Alberta. His work has furthered some of the initiatives taken to extend the development and application of the Canadian Forest Fire Danger Rating System initiated in the late 90s. For example, Steve was able to identify from his fuel moisture sampling and sustained smouldering ignition testing a critical threshold for sub-surface fire persistence around a Duff Moisture Code (DMC) 27 and Drought Code (DC) 300. Elk Island National Park (EINP) has maintained a robust prescribed fire program, but ground fire may limit its use. The Fire Weather Index System is the nationally recognized means of assessing moisture. The Duff Moisture Code (DMC) and the Drought Code (DC) report moisture in the shallow and deep duff layers, but have not been evaluated for the aspen forest. This study developed and validated DMC and DC relationships and quantified duff ignition within aspen stands of EINP. The role of soil bulk density and inorganic content were also evaluated. Moisture relationships and ignition thresholds at various DMC and DC were established. The DMC, as modelled from summer moisture under leaf-on conditions, appears suitable as a conservative tool for assessing fire risk. This research may also form the basis for new moisture codes for the D-1 aspen fuel type, improving prediction of ground fire occurrence.