In recent times, many old underground coal mines are being converted into opencast workings. In the process, removal of waste rock over the old galleries and maintaining a stable slope is a very difficult task. In such cases, continuous slope monitoring may be required. Though there are many methods of slope monitoring, zigbee based wireless sensor network is cost effective and gives real time monitoring. Slope stability depends upon various parameters like bench height, slope angle, berm width, geometry of old workings, thickness of partition, geological discontinuities etc. Here, influence of thickness of partition for a 3m height and 4.2m wide gallery is assessed using WSN. The data is validated using conventional method of slope monitoring using LVDTs.