Industry activities such as steel production or fossil power station have generated a huge amount of CO_2 dense gas. The CO_2 dense gas had been captured and transported through pipeline to store in tanks. Accidents of continuous release of dense gas form the pipeline or storage tank will make a harmful and strong impact on the atmospheric environment. The dispersion of such hazardous gas constitutes a severe human health threat for inhabitants adjacent to the industries and storage areas. In the present study, wind tunnel experiments were performed to determine the dispersion characteristics of CO_2 dense gas continuously spilling from two identical sources with side-by-side in a turbulent boundary layer. Effects of different gaps between two sources and various source discharge strengths on the heavy gas plumes dispersion were conducted in the experiments. Experimental results reveal that two dense plumes do not merge at the near field as the gap of two sources is greater than 30 times of discharged source diameter for the cases of different discharging strength with the densimetric Froude number 20, 22, and 26. The maximum value of vertical concentration profile at each of the downstream station increases with increasing the densimetric Froude number of discharge. The dispersion length scale of merged dense plume increases along with the downstream distance.