The purpose of this report is to describe the field tracer test and pumping test performed in July, 1983, at the Hanna, Wyoming, and coal gasification research area and to evaluate the tracer test data to derive the effective porosity of the Hanna No. 1 coal seam. The effective porosity is required to determine if contaminants in the groundwater resulting from the coal burns are reasonably responsible for changes in the total dissolved solids (TDS) and sulfate concentrations observed at the monitoring wells CB0142 and CB0155, which are located over 1000 feet down gradient from the nearest coal burn area. Previous estimates of groundwater velocity (Radian Corp., 1981) are of the order of a few feet to tens of feet per year. Accordingly, with these low velocities one must assume that the increasing sulfate with time that has been observed in the monitoring wells is not related to the burn activities on the site. Fifty or more years would be required to transport the contaminant: from the nearest burn area (1000 feet away) using the previous assumed groundwater velocity.