Tunnelling is due to resume under a revised design on the 8.3km long, 3.9m diameter Arrowhead East section of California’s $1.2bn Inland Feeder project. Originally, the tunnel had an unbolted, ungasketed lining, but excessive groundwater depletion in the area lead to tunnelling being put on hold. The new design includes a gasketed and bolted lining system that will require a wider TBM cut.
