Galloping Gertie failed as a bridge, but it made a tremendous reef.
On Nov. 7, 1940, a 42-mph wind whipped the $6 million Tacoma Narrows Bridge into a frenzy and dropped it to the bottom of the Narrows channel - a disaster now regarded as one of the most spectacular and famously embarrassing moments in engineering history.
The wind destroyed the world's third-longest suspension bridge. But, as it happened, it also created the world's largest artificial reef.
The ghostly half-mile of highway, 200 feet beneath the surface, could not have been better placed for marine habitat. Now, 63 years later, it harbors a cornucopia of sea creatures, from lush bouquets of anemones and starfish to giant lingcod and octopuses.
Gertie's historical legacy is ever present in the minds of the engineers building the new bridge across the Narrows. Most studied the debacle in their college engineering classes, and its lessons inform their design decisions on a daily basis.
But Gertie's rich environmental legacy affects the construction of the new bridge, too. Environmental regulations intended to protect the marine life that flourishes in the Narrows have added months to the construction schedule and millions to its cost.
A cobblestone sea floor
Before Gertie crashed down on it, the floor of the Narrows was a barren place.
Extreme tidal changes force enormous quantities of water through the narrow channel four times a day. The resulting currents, powerful enough to scatter rocks the size of softballs, scour away all fine material, leaving a surface as hard and inhospitable as cobblestone.
The currents flush great quantities of marine life through the channel, sending everything from plankton to orca whales shooting past like fourth-graders on a Wild Waves ride.
Until Gertie fell, there was no place for marine life to stop and catch its breath.
When the bridge broke apart, chunks of the 39-foot-wide roadbed rained into the Sound. Where they landed, they created quiet spaces and refuges from the current.
Given the chance, marine creatures quickly colonized the new territory, thriving on the fresh supply of nutritious algae, plankton and krill that arrives with every tide.
Anemones, barnacles, mollusks and mussels attached themselves to twisted girders. Record-sized octopuses, lingcod and rockfish took up residence in broken concrete. Crabs, wolf eels and sea stars settled in, rounding out a mature ecosystem.
Times have changed
In 1939, when contractors built Gertie - and 10 years later when they built its replacement - environmental regulations were all but nonexistent.
In those days, the waters of Puget Sound were erroneously thought to flush neatly out to the open ocean each day like an efficient, natural sewer. Dumping construction waste was standard practice.
That made bridge-building go a lot faster. From the beginning of construction of Gertie to its opening to traffic in July 1940 took just 19 months.
During that time, thousands of cubic yards of dredging spoils were released into the current, and construction debris was routinely dumped over the sides of barges.
Those practices continued during the salvage operation on what was left of Gertie and during construction of the existing bridge.
"The regulations were a lot less strict in the early days," said Dennis Engel, the state Department of Transportation's project engineer on the Narrows project and an amateur historian who cruises eBay for Narrows bridge memorabilia.
"I've heard a lot of stories, about people throwing boards off and that type of thing," Engel said. "The rules keep getting more strict as we go. You look back and, 60 years ago, asbestos wasn't considered a hazardous material. They didn't have all the knowledge that we do now."
This time around, Tacoma Narrows Constructors, the company formed to build the bridge, faces a new world of environmental regulations.
The National Environmental Policy Act, the Shorelines Management Act, the Clean Water Act and the Endangered Species Act have generated shelves full of documents packed with conditions and mitigation plans.
In addition to the restrictions and precautions in the environmental impact statement prepared on the project, 22 regulatory permits place restrictions on construction.
Within those 22 permits, 853 environmental conditions must be adhered to, said Claudia Cornish, a transportation department spokeswoman.
For example, TNC can do no work on the shore between March 15 and June 14 because of migrating juvenile salmon.
The milewide Narrows passage provides the only migration corridor for salmon - including endangered chinook - in the entire South Sound.
And then there's the Pacific sand lance, a tiny fish that eats zooplankton and spawns along the shore. Work in sand lance spawning beds is forbidden between October and March.
No waste concrete or construction debris is allowed in the water, and lumber treated with creosote, a preservative from the 1940s and '50s now recognized as toxic, is forbidden.
When clamshell dredge buckets are used in the Narrows, operators must make sure their buckets are emptied before sticking them
back into the water. Dredge spoils must be carefully collected and hauled to an approved dump site.
When it prepared the site for the eastern bridge anchor, on the grounds of the War Memorial Park, TNC was required to excavate thousands of cubic yards of soil tainted by pollution from the old Ruston copper smelter. Watched over by state regulators in moon suits, contractors trucked the soil to the Tideflats and then hauled it by rail to a disposal site in Eastern Washington.
Noise levels of machines operating at night are carefully monitored. Even lighting is controlled: Lights necessary for nighttime work must be oriented so they don't shine on the water or into marine habitat.
Mitigation projects elsewhere
Still, some effects of bridge construction are considered unavoidable, such as the loss of shoreline habitat, increased runoff from new pavement and siltation from road work. For these effects and others, TNC has agreed to perform mitigation projects elsewhere to make up for the damage.
After the mitigation agreements were in place, TNC changed two features of its construction plan that were expected to have negative environmental consequences.
The original plan was to anchor the caissons with house-sized blocks on the sea floor. The blocks would have required dredging and would have remained in place permanently.
Instead, TNC went for a less-invasive system, which consisted of driving 64 steel beams deep into the Narrows floor and rotating them to lock them into place. The anchors will stay in the seabed when the bridge is finished, but the anchor lines will be cut and removed.
Also, the original plan envisioned two floating concrete batch plants and two onshore plants to mix the hundreds of thousands of cubic yards of cement needed to build the caissons and bridge towers. That raised the possibility of spills.
Instead, TNC built a single mixing plant on shore, near the western end of the bridge.
Both changes were made for practical reasons, but they turned out to be greener choices, too.
TNC decided to do the mitigation projects required for the more-invasive techniques anyway.
"When you consider the time and effort it would take to change it, it's easier to just go ahead and do the mitigation," said Rick Singer, the transportation department's business manager.
One mitigation project is removing remnants of an old, creosote-soaked pier near Titlow Beach. TNC will also build about an acre of new deep-water habitat at Toliva Shoal, at the southern end of Fox Island.
And they'll take out an old rock bulkhead at Doc Weathers park, a Pierce County waterfront park just south of the bridge, and replace it with more natural material such as tree trunks.
In 2007, when the new bridge opens, it will rest on foundations as big as 20-story buildings, planted deep in the Narrows floor.
Its main cables, stretching for a mile across the water, will be held in place with enormous anchors on shore, each made of 23,000 cubic yards of concrete.
Along with the challenge of building that complex structure comes a challenge equally daunting - assuring that, when the bridge is finished, life continues to flourish on the old bridge below.
Rob Carson: 253-597-8693