"1495 Interior of one of the diversion tunnels, showing panel of concrete lining being poured in the invert section of the tunnel. Side wall tunnel form is shown in the background. August 24th, 1932.
1479 Section of finished diversion tunnel, in which three-foot concrete lining has been poured. Gravel has been dumped on tunnel floor as a protection from damage. Arch section is coated with bituminous compound for curing concrete. August 22nd, 1932.
1497 Apparatus used in trimming the tunnels have been converted for use in drilling holes in the concrete lining for pressure grouting. August 24th, 1932.