Seattle Mayor Greg Nickels last week unveiled a new underwater camera system the city is now using to monitor deterioration along the Alaskan Way seawall. The city invested in the underwater video system when engineers discovered the seawall's ekki wood facing was deteriorating faster than previously anticipated.

"We've learned from New Orleans not to wait for catastrophe to strike. The seawall is our levee and is under constant attack by marine borers and worms," said Mayor Nickels. "The deteriorating seawall must be replaced, along with the Alaskan Way viaduct, before Mother Nature does it for us."

Over the years, saltwater corroded the steel portion of the nearly 70-year-old seawall, and marine life such as gribbles and large shipworms (bankia setacea) have attacked the timber facing. The wood facing is what holds the soil under Alaskan Way and the viaduct in place.

In 1985, the steel sheets anchoring the seawall were faced with Ekki wood, a dense hardwood that is normally impervious to marine borers such as gribbles.

Because of the accelerated deterioration, the Seattle Department of Transportation (SDOT) has started inspecting the seawall more frequently. SDOT used to conduct full underwater inspections using marine engineer divers once every five years. The inspections cost about $15,000 each. SDOT now conducts underwater inspections at least every six months using the underwater camera. The system cost $2,500 and is operated by SDOT engineers from a boat.

KW