ARJOU RESERVOIR DAM AND SPILLWAY REPAIR PROJECT

The Araujo Reservoir 1 dam requires several improvements to bring the facility into compliance with Division of Safety of Dams (DSOD) requirements. The improvements generally includes the following: (i) measures to enhance the stability of the dam and (ii) construction or improvement of the spillway structures, and (iii) installation or modifications to the emergency outlet conduit facilities. The repair plans include the excavation and removal of the downstream portion of the existing dam embankment; establishment of a seepage barrier (cutoff trench) within the embankment to limit subsequent seepage; installation of internal drainage features to collect and convey seepage through and away from the dam; and reconstruction of the dam embankment with additional height to provide adequate freeboard. Borrow material for the added embankment volume is proposed to be developed from borrow sites adjacent to the dam. The existing spillway structure will be removed and replaced with a new concrete drop inlet type spillway structure with adequate capacity to pass the design stormflow. Below/downstream of the dam embankment, the spillway discharge conduit will be connected to the existing spillway pipe that conveys and discharges stormflows from the reservoir to the primary stream channel below the dam. The control section of the spillway will be constructed to the original spillway elevation (pre-DSOD-required emergency repairs) to restore the original storage capacity of the reservoir. The existing outlet will be removed and replaced with a new outlet conduit that will meet DSOD requirements.