Two brush fires in the same Lone Tree open space within three months have some nearby residents concerned about the fire risks posed by power lines and an Xcel Energy substation in the area.A fast-moving brush fire on March 21 near Ridgegate Parkway and South Peoria Street burned 20 acres before South Metro Fire crews extinguished the flames. Watch the full story in the video player below. Brush fires in Lone Tree open space prompt concerns abou…