OCCOQUAN RESERVOIR
Underwater Inspection / Marine Construction
Coastal Engineering has performed multiple services at the Occoquan Dam. The first, at Tower 2, was to isolate (blind-off) the tower to allow for work on the discharge sluice gate. Our ADCI divers first installed blind flange plates on four Tower 2 pipes 48”-66” with assistance from a jib crane, then inspected and documented the intake’s condition. The team then performed debris calculations at Tower 3’s intake crib and inspected/documented a submerged air diffuser soaker hose. The final work required our divers to
locate the boat buster barrel barrier anchor connection, which needed to be reattached to its bottom tether. Our divers provided detailed dimensions so the correct fastener could be fabricated.
Mobilization II consisted of removing the blind flanges, bringing Tower 2 back online, taking Tower 3 offline, and removing the debris identified in Mob I. This required diver removal of the flanges and reinstallation of the threaded plugs, decking panel, and bar rack. The client then activated Tower 2 and take Tower 3 offline. Natural and man-made debris was removed, with man-made debris removed from the reservoir and disposed of. Next, the underwater inspector documented (3) actuator gear spline linkages for corrosion and wear. The final step for our divers was to reconnect the boat buster barrel barrier anchor.
