The grant of conditional use in such case shall be based upon the existing conditions at the time; however, the Common Council, upon recommendation of the Plan Commission, may require improvements in general building appearance, in storage of trash and other materials, in the provision of more satisfactory off-street parking, in the use of planting fencing screens where necessary, and in operational matters relating to the control of noise, dust, odor, smoke, and excessive glare or illumination of lighting, provided that such measures are within the reasonable economic capacities of such a use. Any expansion or change in use shall require changing of the conditional use grant.