Michel Boufadel, chair of the Department of Civil and Environmental Engineering at Temple, discussed shale gas development before a large crowd Friday at Lycoming College. Boufadel said he is concerned with the long-term environmental impacts of shale gas development and he specifically pointed to the possibility that vertical joints and natural fractures in the shale could cause frack water to migrate into groundwater or to the surface. "I'm not saying there is proof (frack) fluid will return to the surface, but I would like somebody to tell me it will not," he said.