Next I decided to turn my attention to removing the old tar board and seam sealer from the tunnel. I found using a fat chisel with wooden mallet to be an effective method and it would usually chip off in big chunks. Any residual tar could be taken off by gently scraping with the chisel held at a shallow angle:
What a satisfying mess:
So, not the most productive of weekends, but it sure felt good make a little headway after so long!