In July 2010, North Coast Divers, conducted a visual inspection of the District’s outfall diffusers as part of routine maintenance activities. In conjunction with the inspection, a dye test was performed to detect any leaks in the outfall pipe. During the course of the inspection it was reported that diffuser #4 was missing (there are 10 diffusers with #1 being closest to shore and the most downstream diffuser designated as #10).
The District was “lucky” in that the missing diffuser was recovered. We don’t know what caused the damage, but we do know that the bolts gave way before there was substantial damage to the outfall and the diffuser was in good enough condition that it could be successfully reattached. Our one significant remaining problem was sand – the level of sand at diffuser #4 was ½ of the pipe; diffuser #6 the pipe was full and all flows were obstructed. With this obstruction it was questionable whether maximum flows during the coming winter could be accommodated.
The District contracted with North Coast Divers to dredge out all sand from the end of the pipe at diffuser #10 all the way to the wye, or where it bends away from shore. The work was completed in October 2010, below budget.