Shoring Up

Talk about an impregnable fortress: Good luck trying to damage the Naval Air Weapons Station.

The place bristles with advanced missiles. Eye-in-the-sky Hawkeye E-2s zoom overhead. Sentries patrol the gates. The only real threat is the ordinarily placid Pacific on the base’s western boundary.

But what a foe it is proving to be.

The eternal sloshing of tides gobbles about 4 feet of shoreline annually. Violent El Nino-driven storms lashed the base with huge waves this past winter. And a gaping underwater canyon, spreading apart like a zipper and poised to tear into a portion of the base’s 6-mile shoreline, poses a significant threat to structures and roads, officials say.

“You can protect the base from people, but you can’t protect it from Mother Nature,” said Ron Dow, head of the base environmental division.

In a bid to shore up coastal defenses, the Navy won approval Thursday from the California Coastal Commission to rebuild the base’s battered sea walls, which were heavily damaged by the winter storms.

The commission unanimously approved the project at its meeting in Eureka after finding the project would not harm shipping, the shore or the environment.

Rebuilding the sea walls will cost about $2 million, according to the Navy. Construction will begin Oct. 1 and be completed by Feb. 15--in time to avoid the breeding season for imperiled birds, including snowy plovers, least terns and light-footed clapper rails.

The improvements should help protect the base against big storms.

But they will not halt the spread of the underwater canyon, called Mugu Trench.

The canyon is hundreds of feet deep and growing via natural geologic processes. The rim is a few hundred yards offshore and swallowing the sandy bottom as it expands, and it is beginning to affect the shore at the naval base, said Mark Delaplaine, a commission staff member.

Mugu Trench is one of two deep-water chasms in the area. The other is Hueneme Canyon, whose depth enables ships to easily enter Port Hueneme, Delaplaine explained.

But at Point Mugu, the canyon is a nuisance. In past years, its expansion has been blamed for demolishing a pier, wrecking an officers club and other buildings, and damaging a sea wall.

Eventually, it will gobble up a portion of beach by the base as it attempts to slice a new entrance to Mugu Lagoon, officials say.

“In something less than a decade, they may have to relocate facilities and give up some areas to the ocean,” Delaplaine said. “Eventually, we’re going to have some serious problems.”

Mindful of those concerns, the Navy no longer constructs buildings in the area affected by Mugu Trench and does limited maintenance on buildings there, Dow explained. He added that core portions of the base are unaffected.

“We know the canyon is moving inland. It kind of has a life of its own,” Dow said. “But most of the base is not in its path and it will not affect the industrial core.”

Likewise, the past winter’s storms did little serious damage to the base’s buildings, but pounded the sea walls.

When functioning normally, the structures act as ramparts to turn back the angry sea and blunt its erosive power.

But El Nino-driven storms tossed massive boulders aside and punched holes in the walls, like a giant hand crumbling a sand castle.

Damage to base structures was less dramatic: a ruptured sewer line here, a downed bridge there. Beach Road was battered and water undercut the weapons department office.

Seabees from the nearby Port Hueneme Navy base were called in to stem the damage, and thousands of sandbags were filled to protect buildings from surging surf and swelling creeks that feed Mugu Lagoon.

In all, about $18 million is needed to repair damage from the storms, Dow said. Navy officials emphasized that neither base security nor its ability to perform its mission was compromised by the storms.

About 6,700 people are employed by the base south of Ventura. The Navy conducts research, development and tests aircraft and missile systems at the Point Mugu station, which was built in 1946.

Two sea walls will be repaired and heightened. About 25,000 tons of rocks will be used. Each sea wall spans 2,300 feet, and one protects an explosives storage facility, a regularly used runway and a road, according to the coastal commission.