Facing unpredictably tough ground conditions, tunneling crews have worked all out this year to get Belfast’s $195-million, 9.4-kilometer-long stormwater storage tunnel system operational before Christmas. With work largely done, Northern Ireland Water (NIW) aims to recruit soon a design firm to handle its second deep-tunnel sewer project, likely to be just as tough to implement. Slide Show Photo: Northern Ireland Water Belfast CSO system has 19 shafts up to 10 m in diameter. The shafts and tunnels will be able to hold 85,000 cu m of wastewater. Photo: Northern Ireland Water Five heavy-duty pumps can lift 16 cu m of
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.