Lake Mead Intake No. 3 – Connector Tunnel

Completed in 2014 by Oscar Renda Contracting, the Lake Mead Intake No. 3 – Connector Tunnel project, located near the Hoover Dam, consisted of the construction of a deep-water intake, a pumping station, and a large-diameter water supply tunnel between the intake shaft and the pumping station. The project serves as a lake tap structure and conveys raw water to the Alfred Merritt Smith Water Treatment Facility. The intake shaft is 26 feet in diameter by 450 feet deep excavated by drill and blast methods and supported with rock bolts/mesh and a concrete liner. Two connector tunnels were constructed: 380 linear feet of a 20-foot by 20-foot horseshoe tunnel and 2,150 linear feet of a 14-foot by 16.5-foot horseshoe tunnel. Both tunnels were supported by rock bolts and shotcrete lined. A temporary bulkhead was installed in the IPS-3 connector tunnel. Pre-excavation grouting was constantly required throughout the tunnel to hold off 300 gpm of groundwater. Over 5 million pounds of cement was required to grout the entire project. The change order was directed by the Owner and included the following additional scopes of work: deepening an existing shaft; adding a stub tunnel; additional pre-excavation grouting; and additional marine/underwater work (modifying an existing underwater intake structure).