Crux provided difficult-access core drilling during the exploration phase of the project in 2009, and will return next month to commence construction activities.
The existing Blue Lake Project is located approximately 5 miles east of Sitka, Alaska, and consists of a dam, a submerged intake structure, a power conduit, three powerhouses and a switchyard. Growing electricity demands in the region have exhausted current resources and necessitated an increase in annual energy output. The expansion will include the addition of a third generating turbine and raising the dam 82 feet (from 164 feet to 246 feet). Once completed, the system’s potential energy output will increase by 27% and relieve Sitka’s dependence on diesel generated power.
Crux’s scope of work includes a foundation grouting program, rock anchor installation and micropile installation. Consolidation grouting will be completed, followed by curtain grouting in the left and right dam abutments to reduce the permeability of rock formations. Rock anchors will then be installed in both abutments for increased stabilization. Near the base of the dam, micropile installation will be completed to support the plunge pool scour wall. Additionally, Crux has been contracted to install pressure relief wells and to drill exploratory core holes from within a new drainage tunnel.
Drilling and grouting sites are in difficult-to-reach locations and will be accessed using a crane suspended platform. Crux utilized a similar approach during the exploration phase of the project and is familiar with unique logistical challenges of the area.