Narrator: NEW ORLEANS --
BUILT ON THE BANKS OF THE MIGHTY MISSISSIPPI.
[ TROLLEY BELL RINGS ]
THIS CITY SITS IN THE CROSS HAIRS
OF ONE OF NATURE'S MOST DEADLY FORCES...
THE HURRICANE.
Alongi: THE VAST MAJORITY OF STORMS COME RIGHT AT NEW ORLEANS
AND HIT THE COAST OF LOUISIANA.
THERE HAVEN'T BEEN MANY YEARS THAT HAVE PASSED
THAT WE HAVEN'T HAD TO CONSIDER EVACUATION.
Narrator: HOW CAN NEW ORLEANS SURVIVE?
TO FIND OUT, WE WILL STRIP THE CITY
TO REVEAL ITS SECRET, INNER WORKINGS
AND EXPOSE THE INGENIOUS TECHNOLOGY
THAT ALLOWED ENGINEERS
TO BUILD THIS CITY ON THE BRINK OF DISASTER.
-- Captions by VITAC -- www.vitac.com
CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS
NEW ORLEANS, HOME TO 1.2 MILLION PEOPLE,
A JEWEL IN AMERICA'S SOUTH.
[ CROWD CHEERING ]
Narrator: THE FRENCH FOUNDED THE CITY IN THE 18th CENTURY,
AND, ALMOST 300 YEARS LATER, IT'S STILL THRIVING.
[ SIREN CHIRPS, HORN HONKS ]
BUT ITS POSITION ON THE LOUISIANA GULF COAST
EXPOSES THE CITY TO DEVASTATING HURRICANES
THAT ROLL IN FROM THE ATLANTIC.
IN 2005, THERE WERE 15 HURRICANES,
ALL WITH THE POTENTIAL TO STRIKE NEW ORLEANS...
...THE MOST EVER RECORDED.
SOME ARE MORE DANGEROUS THAN OTHERS.
HURRICANE KATRINA
IS NOW DESIGNATED A CATEGORY-5 HURRICANE.
WE CANNOT STRESS ENOUGH THE DANGER
THIS HURRICANE POSES TO GULF-COAST COMMUNITIES.
Narrator: ON AUGUST 29, 2005,
HURRICANE KATRINA SMASHED DIRECTLY INTO THE CITY.
100-MILE-PER-HOUR GUSTS
PUSHED SEAWATER OVER NEW ORLEANS' LEVEES.
THESE BARRIERS, DESIGNED TO PROTECT THE CITY FROM STORMS,
FAILED IN 50 PLACES.
FLOODWATER SUBMERGED 80% OF THE CITY.
1,300 PEOPLE DIED.
900,000 LOST THEIR HOMES.
THE REPAIR BILL -- $200 BILLION.
IT WAS HEARTBREAKING.
WHEN YOU GO TO YOUR CHILDHOOD HOME AND THERE'S NOBODY AROUND,
THERE'S NO CARS ON THE STREET, AND THERE'S MUD AND OIL
AND A WATER LINE THAT GOES ABOVE YOUR CEILING,
IT'S VERY HARD TO PUT INTO WORDS.
Narrator: TODAY, ENGINEERS RACE TO HURRICANE-PROOF THIS CITY
BY CONSTRUCTING WIND-RESISTANT BUILDINGS AND BRIDGES
AND INSTALLING HUGE FLOOD DEFENSES.
THE MISSION TO PROTECT NEW ORLEANS
STARTS RIGHT AT ITS HEART -- DOWNTOWN.
THE SUPERDOME, THE PRIDE OF THE PRO FOOTBALL TEAM
AND AN ICON FOR THE STATE.
THIS STRUCTURE IS VAST AND URGENTLY NEEDS PROTECTION.
THE ALUMINUM WALLS OF THE SUPERDOME
SOAR MORE THAN 270 FEET HIGH.
ACROSS THE TOP, THE WORLD'S BIGGEST FIXED DOME
SPANS ALMOST 10 ACRES.
THE STADIUM'S TIERS HAVE ROOM FOR 73,000 SEATS.
BUT THE SUPERDOME'S HUGE SIZE
MAKES IT A PRIME TARGET FOR HURRICANES.
TO UNDERSTAND
HOW TO HURRICANE-PROOF NEW ORLEANS' BUILDINGS,
ENGINEERS FIRST NEED TO INVESTIGATE
THE DESTRUCTIVE POWER OF THESE MONSTER STORMS.
HURRICANES BEGIN IN THE TROPICS OVER WARM WATER.
AIR PASSING OVER THE OCEAN'S SURFACE HEATS UP,
CAUSING IT TO RISE,
LEAVING A REGION OF LOW PRESSURE IN ITS WAKE.
ADDITIONAL AIR SUCKED INTO THIS ZONE SOON HEATS UP AND RISES,
CREATING A DEADLY CYCLONE.
WHEN IT HITS 74 MILES PER HOUR, IT'S OFFICIALLY A HURRICANE.
ENGINEERS CAN TEST THE RESILIENCE OF THEIR BUILDINGS
AT THIS MILLION-DOLLAR WIND TUNNEL
AT THE UNIVERSITY OF FLORIDA.
THEY PUT SCALE MODELS IN THE FIRING LINE
OF HURRICANE-FORCE WINDS USING THESE EIGHT MASSIVE FANS.
HERE, WE CAN CREATE A HURRICANE IN THE LABORATORY.
AND THAT ALLOWS US TO FIND THOSE WEAK LINKS IN THE SYSTEM
THAT ULTIMATELY CASCADE INTO A TOTAL, CATASTROPHIC FAILURE.
Narrator: AS THE FANS BLOW,
AIR RUSHES AROUND THE BUILDING'S SKIN,
FORMING MINI TORNADOES CALLED VORTICES,
REGIONS WHERE THE STORM GETS EVEN STRONGER.
ON BUILDING ROOFS, GUSTS CAN HIT 200 MILES PER HOUR.
THE TEAM TESTS HOW REAL TILES
HANDLE THESE EXTRAORDINARY WINDS.
Dr. Masters: AS THE VELOCITY INCREASES,
THE PRESSURE UNDERNEATH THE TILE
AND THE SUCTION ON TOP OF THE TILE
ACT TO PULL IT UPWARDS.
BUT AT SOME LEVEL, WE'LL REACH A THRESHOLD
WHERE THE TILE CAN NO LONGER TAKE IT, AND IT SEPARATES.
[ WIND RUSHING ]
Narrator: THE SUPER-STRONG WINDS RIP THE TILES TO SHREDS.
WHEN HURRICANE KATRINA APPROACHED NEW ORLEANS
AS A CATEGORY-3 STORM,
20,000 CITIZENS TOOK REFUGE IN THE SUPERDOME.
THE VAST STRUCTURE LOOKED INDESTRUCTIBLE, BUT IT WASN'T.
THE WIND FOUND WEAK SPOTS IN THE ROOF.
Man: THAT WATER'S TRYING TO GET IN THERE.
AND THAT'S WHAT IT'S LIKE LIVE INSIDE THE SUPERDOME.
YOU KNOW WHAT I'M SAYING?
TRYING TO TAKE COVER FROM THE RAIN INSIDE THE SUPERDOME.
[ INDISTINCT SHOUTING ]
Narrator: THE STRUCTURE SUPPORTING THE ROOF HELD,
BUT THE ROOF COVERING FAILED.
ARCHITECT TREY TRAHAN DESIGNED
A NEW, SUPER-STRONG SKIN FOR THE ROOF, MAKING IT MORE RESILIENT.
Trahan: THE REBIRTH OF THE DOME WAS EXTREMELY IMPORTANT
TO NOT ONLY THE CITY BUT THE STATE
TO FEEL THAT WE HAD THE CAPACITY, THE CONVICTION
TO BRING SUCH AN IMPORTANT PIECE OF OUR CULTURE BACK.
Narrator: TREY'S TEAM SUPPORT THE NEW ROOF
WITH A STEEL FRAME ALMOST 700 FEET WIDE.
THEY COAT THE ROOF WITH OVER HALF A MILLION LIQUID GALLONS
OF IMPENETRABLE, HAND-SPRAYED POLYURETHANE FOAM.
IT'S THE SAME MATERIAL NASA ENGINEERS USE
TO PROTECT THE SPACE SHUTTLE'S FUEL TANKS.
THEY THEN ADD FIVE FURTHER COATS.
TOGETHER, THE STEEL AND FOAM LAYERS CREATE AN OUTER SKIN
TOUGH ENOUGH TO WITHSTAND 1,000-MILE-PER-HOUR WINDS
AND A STADIUM SAFE
FROM THE WORST WEATHER NATURE THROWS AT IT.
Trahan: THE ENTIRE ROOF IS COVERED IN THIS FOAM.
AND IT EXPANDS TO APPROXIMATELY 32 TIMES ITS LIQUID VOLUME
AS IT'S ACTUALLY APPLIED.
Narrator: TO REPAIR THE ROOF BEFORE THE NEXT STORM HIT,
TREY'S TEAM HAD TO MOVE QUICKLY.
THE NEXT HURRICANE SEASON WAS NOT THAT FAR AWAY.
MANY PEOPLE SIMULTANEOUSLY
WERE WORKING ON REBUILDING THEIR HOMES AT NIGHT
WHILE THEY WERE WORKING ON REBUILDING THE DOME,
AND I THINK THAT SPEAKS TREMENDOUSLY
OF THE PEOPLE OF NEW ORLEANS.
[ AIR HORN BLOWS ]
Narrator: WITH THE ROOF IN PLACE,
ENGINEERS THEN OVERHAULED THE REST OF THE BUILDING.
THEY ADDED 3,000 MORE SEATS...
...AND REPAIRED A 14-FOOT-WIDE GUTTER
AROUND THE ROOF TO COPE WITH RUNOFF.
THEY SURROUNDED THE BUILDING WITH SPECIAL RAIN SCREENS
MADE FROM ALUMINUM AND INSULATING FOAM
TO STOP STRONG GUSTS FROM SHEARING THEM OFF.
THE RESULT -- AN ALL-NEW, HURRICANE-PROOF SUPERDOME.
ONE ICONIC BUILDING IS SAFE,
BUT THOUSANDS OF OTHERS ARE STILL AT RISK.
EVERY YEAR, HURRICANE WINDS THREATEN THE TOWERS
AT THE HEART OF THE CITY.
IT TAKES INGENIOUS ENGINEERING TO STOP THESE SKYSCRAPERS
FROM CRASHING TO THE GROUND.
Narrator: DOWNTOWN NEW ORLEANS.
[ TROLLEY BELL RINGS ]
A THRIVING BUSINESS HUB CRAMMED WITH SKYSCRAPERS.
TALL BUILDINGS LIKE THESE ARE AT RISK WHEN HURRICANES STRIKE.
ONE SHELL SQUARE TOWERS ABOVE THE REST OF THE CITY,
WHICH PUTS IT RIGHT IN THE CROSS HAIRS OF EVERY HURRICANE
THAT MAKES LANDFALL.
THE BUILDING SOARS ALMOST 700 FEET HIGH.
IT'S THE TALLEST IN LOUISIANA.
LIGHTWEIGHT LIMESTONE PANELS
CLAD ITS STEEL-AND-CONCRETE FRAME.
ITS 51 FLOORS HOUSE MORE THAN 6,500 WORKERS.
ONE SHELL SQUARE HAS SURVIVED OVER 20 HURRICANES
DESPITE BEING BUILT
ON SOME OF THE MOST UNSTABLE GROUND ON THE PLANET...
...MARSHLAND.
NEW ORLEANS IS BUILT ON LAYERS OF MUD
LAID DOWN BY THE MISSISSIPPI RIVER.
I'LL SWING AROUND.
SO, YOU JUST STAND STILL, AND I'LL PIVOT.
Narrator: DR. SAM BENTLEY'S TEAM STUDIES THE COMPOSITION
OF THE MARSHLANDS ON THE OUTSKIRTS OF THE CITY.
UNDERSTANDING THIS SWAMPY TERRAIN HELPS ENGINEERS
ANCHOR TALL BUILDINGS SO THEY CAN SURVIVE HURRICANES.
AS WE WALK ALONG,
THE GROUND ACTUALLY VIBRATES WITH EVERY STEP.
AND THAT'S BECAUSE THE FIBROUS PEAT THAT WE'RE WALKING ACROSS
IS ELASTIC SORT OF LIKE A SPRING.
AND OVER TIME, IT CAN ACTUALLY DECAY AND SHRINK.
AND IF I WERE TO JUMP HARD ENOUGH --
I HAVE JUMPED PRETTY HARD BEFORE ON MARSH,
AND I'VE ACTUALLY BROKEN THROUGH THE SURFACE
AND SUNK DOWN UP TO MY CHEST.
Narrator: NEW ORLEANS SITS ON TOP OF MUD EXACTLY LIKE THIS.
JEFF, COME HERE. PUT A HAND ON.
WE COULD USE SOME EXTRA WEIGHT.
IT'S SCIENCE IN ACTION.
IT'S A WONDERFUL, WONDERFUL UNDERTAKING.
Narrator: THEY DRIVE A CORING TUBE DEEP INTO THE MARSH.
IT TAKES BRUTE FORCE TO PULL IT BACK UP OUT OF THE GROUND.
Dr. Bentley: SO, AS WE'RE STANDING HERE,
EVERY TIME KEVIN PULLS A STROKE ON THE WINCH,
WE CAN ACTUALLY FEEL THE LAND DEFORMING UNDERNEATH US.
IT JUST GIVES AN IDEA OF HOW UNSTABLE
AND SORT OF GELATINOUS THE MATERIAL IS.
THIS 15-FOOT-LONG CORE OF MUD CONTAINS 2,000 YEARS OF HISTORY.
Dr. Bentley: EVERY TIME WE OPEN A CORE,
THERE'S SOMETHING NEW AND EXCITING IN IT.
I STILL HAVEN'T FOUND ANY SPANISH GOLD,
BUT WE'RE LOOKING FOR THAT.
LOOKING AT THE CORE RIGHT OFF THE BAT,
THIS TOP PORTION --
IT'S MAYBE 1.2, 1.3 METERS -- IS MOSTLY ORGANIC-RICH.
IT'S THE PEAT THAT'S CREATED BY SALT-MARSH VEGETATION.
AS WE MOVE A LITTLE BIT FARTHER DOWN,
WE COME INTO A ZONE THAT MAKES UP PROBABLY MOST OF THE CORE.
THIS IS LIKE POTTER'S CLAY.
IT'S VERY SOFT, GOT A HIGH WATER CONTENT.
IT'S STICKY.
IF I PUT A LITTLE BIT IN MY MOUTH,
IF YOU RUB YOUR TONGUE AGAINST THE ROOF OF YOUR MOUTH,
THERE'S NO GRIT.
PURE CLAY HAS NO GRITTY FEEL.
Narrator: BUILDING A SKYSCRAPER ON SOFT GROUND LIKE THIS
ISN'T EASY.
BUT ONE SHELL SQUARE'S ENGINEERS DEVISED AN INGENIOUS SOLUTION.
THEY USE OVER 500 CONCRETE PILES
TO ANCHOR THE BUILDING INTO THE GROUND.
THE PILES STRETCH 210 FEET DOWN.
EACH ONE SUPPORTS UP TO 280 TONS.
THE FOUNDATIONS EXTEND OUT FROM THE BUILDING
AND ACT LIKE A GIANT RAFT,
SO THE BUILDING FLOATS RATHER THAN SINKS ON THE SOFT GROUND.
INJECTED AIR BUBBLES MAKE THE CONCRETE EXTRA LIGHT.
TOGETHER, THESE MEASURES HELP THE BUILDING WITHSTAND
150-MILE-PER-HOUR HURRICANE GUSTS.
[ METAL CREAKS ]
ONE SHELL SQUARE'S ASSISTANT CHIEF ENGINEER,
DARRELL ALONGI...
[ SIGHS ]
Narrator: ...INSPECTS THE DARK RECESSES OF ITS BASEMENT
AFTER EVERY STORM.
[ ALONGI GROANS ]
YOU KNOW, JUST ABOUT THE SIZE OF YOUR HAND.
IT'S NOT LIKE THE AMAZON AROUND HERE.
[ CHUCKLES ]
Narrator: HE'S ON THE LOOKOUT
FOR ANY CRACKS IN THE CONCRETE CASINGS
THAT SURROUND THE TOWER'S PILLARS.
Alongi: THE CONCRETE SEALS THE STEEL STRUCTURE OF THE BUILDING,
SO IF YOU LOSE THAT CONCRETE, YOU ALSO LET MOISTURE IN
AND WATER PENETRATE INTO THE STEEL
AND START DEGRADING THE STEEL.
Narrator: ONE SHELL SQUARE'S REVOLUTIONARY FOUNDATION
HAS HELD THE SKYSCRAPER STEADY FOR DECADES.
IT'S BECOME A TEMPLATE FOR NEW ORLEANS' RISING SKYLINE.
Alongi: RIGHT NOW, WE'RE ON THE ROOFTOP OF ONE SHELL SQUARE.
TO ME, IT'S AN ENGINEERING FEAT.
YOU'RE BUILDING SOMETHING THAT'S ON SOFT SOIL
THAT WEIGHS AS MUCH AS THIS BUILDING DOES,
AND THE FACT THAT WE'RE IN GOOD SHAPE, I THINK, IS A --
[ SIGHS ] IT'S REMARKABLE.
Narrator: ENGINEERS USE LIGHTWEIGHT,
CONCRETE-AND-STEEL SKELETONS
TO BUILD ALL THE SKYSCRAPERS IN NEW ORLEANS.
EXTRA-DEEP FOUNDATION PILES FIRMLY ANCHOR THE BUILDING
INTO THE SWAMPY GROUND
SO THEY REMAIN UPRIGHT WHEN A HURRICANE STRIKES.
THE CITY'S LARGEST BUILDINGS AND BRIDGES WON'T FAIL,
BUT HALF OF NEW ORLEANS STILL SITS BELOW SEA LEVEL.
ENGINEERS MUST BUILD HURRICANE-PROOF FLOOD DEFENSES
TO ENSURE THE CITY'S FUTURE.
Narrator: THE FRENCH QUARTER,
NEW ORLEANS' MOST HISTORIC DISTRICT.
[ MARCHING BAND PLAYS ]
EACH YEAR, OVER A MILLION PEOPLE COME HERE
TO CELEBRATE BOURBON STREET'S WORLD-FAMOUS MARDI GRAS.
[ CROWD CHEERING ]
Narrator: THESE ORNATE BUILDINGS HAVE STOOD HERE
FOR OVER 250 YEARS.
THEY EVEN SURVIVED HURRICANE KATRINA
WHEN 80% OF THE CITY FLOODED.
TO UNDERSTAND WHY,
WE NEED TO EXPLORE THE GROUND BENEATH THESE ANTIQUE BUILDINGS.
NEW ORLEANS' FOUNDERS WERE SMART.
THEY BUILT LA NOUVELLE-ORLéANS, THE ORIGINAL CITY,
ON A 5,000-YEAR-OLD LEVEE, A THICK EMBANKMENT
MADE FROM MUD LAID DOWN BY THE MISSISSIPPI RIVER.
THE LEVEE SITS SIX FEET ABOVE THE REST OF THE CITY,
HIGH ENOUGH TO BE PROTECTED FROM FLOODS.
THE REST OF THE CITY GREW OUT FROM THIS AREA.
IT SITS ON LOW-LYING LAND THAT'S MORE VULNERABLE TO FLOODING.
[ EXCAVATOR BEEPS ]
AS THE CITY GROWS, ENGINEERS ARE EXTENDING AND RAISING THE LEVEES
TO PROTECT THE NEW DISTRICTS.
THE ORIGINAL LEVEES THAT WERE BUILT TO PROTECT NEW ORLEANS --
IN SO MANY CASES, THEY'RE STILL THERE.
THEY'RE THE FOUNDATION.
WHAT WE'VE DONE OVER THE YEARS IS CAP THEM,
COMING UP HIGHER AND HIGHER AND BROADENING THE BASE OUT.
SO, THE ORIGINAL LEVEES ARE THERE,
BUT WE'VE LAYERED HIGHER AND HIGHER AND BROADER AND BROADER.
Narrator: BUT WHEN HURRICANE KATRINA HIT, THE LEVEES FAILED.
FLOODWATER UP TO 28 FEET DEEP SURGED OVER THE LEVEES.
IT SUBMERGED MOST OF THE CITY.
EVERY YEAR, THE FLOOD THREAT TO NEW ORLEANS GETS WORSE.
THAT'S BECAUSE OF SOMETHING THE FRENCH QUARTER FOUNDERS
COULD NEVER HAVE PREDICTED.
THE ENTIRE CITY IS SINKING.
THE MISSISSIPPI HAS FLOWED HERE FOR 12,000 YEARS.
IT DEPOSITS TONS OF SILT EVERY DECADE.
TODAY, THE LAYER OF SILT EXTENDS UP TO 150 FEET BENEATH THE CITY.
THERE'S MORE THAN A TRILLION TONS OF IT.
THE BUILDUP OF SILT IS SO HEAVY
THAT IT'S CAUSING THE EARTH'S CRUST TO SINK
AND, WITH IT, THE CITY ABOVE.
THE FIRST STEP TOWARDS SAVING NEW ORLEANS
IS TO DETERMINE EXACTLY HOW FAST IT IS SINKING.
LOOKS GOOD, MIKE.
TO DO THIS, COASTAL GEOLOGIST DR. MARK KULP
BORES UNIQUE OBSERVATION PIPES INTO THE MISSISSIPPI DELTA.
Dr. Kulp: WE'RE WORKING THROUGH OUR MAZE HERE.
ONE OF THE CHALLENGES DOWN HERE IS THAT THE LANDFORM,
THE MARSHES THEMSELVES ARE CHANGING SO RAPIDLY.
SO, WE'LL GET THERE EVENTUALLY, BUT WE'RE NAVIGATING RIGHT NOW.
THAT'S FOR CERTAIN.
Narrator: MARK DEPOSITS MAGNETS DOWN THE PIPES,
WHICH SIT DEEP IN THE SEDIMENT.
LET'S GO AHEAD AND DROP IT DOWN AND SEE WHAT WE FIND.
Narrator: AS THE LAND SINKS, SO DO THE MAGNETS.
[ BEEP ]
Dr. Kulp: AND THAT BEEP THAT WE JUST HEARD
MEANS THAT WE JUST HIT THE MAGNET AT 13.9 FEET.
AND WHAT THAT TELLS US IS THAT, IN THE SIX TO SEVEN YEARS
THAT THIS PARTICULAR LOCATION HAS BEEN INSTALLED,
WE'VE HAD FIVE TO SIX INCHES OF SUBSIDENCE.
THAT CERTAINLY IS A PRETTY SIGNIFICANT CHANGE.
Narrator: SIMILAR MAGNETS ACROSS THE MISSISSIPPI RIVER DELTA
SHOW THAT THE LAND IS SINKING BY AS MUCH AS AN INCH EVERY YEAR.
Dr. Kulp: THE SUBSIDENCE HAS LOWERED THE ELEVATION OF THE CITY
TO THE POINT THAT THE CITY
IS ACTUALLY BELOW SEA LEVEL IN MOST AREAS.
SO, IT JUST ACCENTUATES THE PROBLEM THAT EXISTS
WITH THE PASSAGE OF THE HURRICANE.
Narrator: 50% OF NEW ORLEANS NOW SITS BELOW SEA LEVEL.
IT'S MORE VULNERABLE THAN EVER TO HURRICANE-DRIVEN FLOODS.
[ TRUMPET PLAYS ]
27 MILES OFFSHORE, A MASSIVE, $20 BILLION PROJECT
IS NOW UNDER WAY TO BOLSTER THE CITY'S DEFENSES.
ENGINEERS USE THIS MIGHTY DREDGING MACHINE
TO SCOOP UP NUTRIENT-RICH SEDIMENT FROM THE SEAFLOOR.
THIS IS A REALLY BIG JOB.
WE'RE 25 MILES OFF THE COAST OF LOUISIANA IN 45 FEET OF WATER.
WE'RE GONNA TAKE THREE MILLION CUBIC YARDS OF THIS SEDIMENT
AND TRANSPORT IT TO PUT ON THE BEACHES OF SOUTH LOUISIANA.
WELL, WHEN A STORM SURGE COMES ALONG, IT TEARS UP THE MARSH,
RIPS IT UP, ROLLS IT UP, AND DESTROYS THE MARSH.
MORE SALTWATER COMES IN,
AND IT BECOMES HARDER AND HARDER TO GROW IT BACK.
WE NEED THE SEDIMENT TO HAVE THE SUBSTANCE OUT THERE
FOR THE MARSH TO ROOT IN.
SO, IT'S REALLY, REALLY IMPORTANT
BECAUSE THAT IS OUR PROTECTIVE BUFFER.
THAT IS OUR BARRIER BETWEEN US AND THE OPEN WATER.
WE BUILD LEVEES, AND WE BUILD FLOOD WALLS,
BUT WE HAVE TO KEEP THE WATER AT BAY
THROUGH THE NATURAL PROCESSES THAT NATURE PROVIDED.
Narrator: THE FIVE-STORY GIANT
IS ONE OF THE BIGGEST DREDGERS IN AMERICA.
A 2,000-HORSEPOWER ENGINE DRIVES A ROTATING CUTTER HEAD
TO BREAK UP THE MUD ON THE SEAFLOOR.
POWERFUL PUMPS MIX THE DEBRIS WITH WATER
AND SUCK IT UP TO THE SURFACE.
Man: THE SEDIMENT IS DREDGED UP
AT THE RATE OF 5,000 CUBIC YARDS PER HOUR,
AND IT'S PUT INTO BARGES THAT CAN HOLD 7,200 CUBIC YARDS.
Narrator: THESE BARGES THEN TAKE THE MIXTURE TO THE SHORE
AND SHOOT IT OVER LAND.
Man: AND HERE IT COMES FROM OUT IN THE OCEAN.
WE'VE BROUGHT IT HERE INLAND WHERE WE'RE GONNA USE IT
TO BUILD THE KIND OF BUFFER THAT WE NEED AGAINST THE STORM SURGE.
THIS IS GONNA PROTECT ALL OF SOUTH LOUISIANA.
Narrator: BULLDOZERS LEVEL THE SAND OUT
TO ESTABLISH THE NEW MARSHLAND,
MARSHLAND THAT COULD HELP SAVE NEW ORLEANS
FROM THE NEXT KATRINA-SCALE HURRICANE.
800 SQUARE MILES OF FORTIFIED COASTLINE AND BIGGER LEVEES
WILL HELP PROTECT LOW-LYING AREAS OF NEW ORLEANS...
...SAFEGUARDING THE CITY
WHEN THE NEXT BIG HURRICANE ROLLS THROUGH THE AREA.
BUT THE MARSHLANDS ALONE ARE NOT ENOUGH.
WHEN HURRICANES HIT,
THE CITIZENS OF NEW ORLEANS NEED AN ESCAPE ROUTE...
[ HORNS HONKING ]
...THE LONGEST CONTINUOUS BRIDGE OVER WATER IN THE WORLD.
Narrator: NEW ORLEANS, 7:00 A.M.
RUSH HOUR.
450,000 COMMUTERS.
HALF OF THEM NAVIGATE THE ICONIC BRIDGES THAT CONNECT THE CITY,
WHICH IS SURROUNDED BY WATER.
IN A HURRICANE,
THE BRIDGES PROVIDE VITAL ESCAPE ROUTES FOR THOUSANDS
EVEN THOUGH THE BRIDGES ARE IN DANGER, TOO.
THIS IS THE BIGGEST OF THEM ALL, THE NEW ORLEANS CAUSEWAY.
IT SPANS LAKE PONTCHARTRAIN NORTH OF THE CITY.
STRETCHING 24 MILES, IT'S THE LONGEST CONTINUOUS BRIDGE
OVER WATER IN THE WORLD
AND THE LARGEST PREFABRICATED BRIDGE BUILT AT THE TIME,
ASSEMBLED FROM 3,700 CONCRETE PANELS.
THE ROADWAY SITS ON TOP OF 9,000 HOLLOW BRIDGE SUPPORTS
DRIVEN 65 FEET INTO THE LAKE BED.
WHEN CONSTRUCTED,
THEY WERE THE DEEPEST PILES EVER SUNK UNDERWATER...
...DESIGNED TO WITHSTAND THE MONSTER STORMS
THAT SLAM INTO THE STRUCTURE.
DEAD TREE STUMPS CLUTTER THE LAKE
AND CAN STRIKE THE BRIDGE LIKE BATTERING RAMS.
DR. IOANNIS GEORGIOU FROM THE UNIVERSITY OF NEW ORLEANS
STUDIES HOW HURRICANES DELIVER THESE KILLER BLOWS.
Dr. Georgiou: SO, WE'RE HERE
ON THE SOUTHWEST SHORE OF LAKE PONTCHARTRAIN,
AND WE CAN ACTUALLY SEE THE PHYSICAL EROSION FROM STORMS
OF THE DECAY OF CYPRESS TREES.
Narrator: REPEATED STORMS EAT AWAY THE SHORELINE,
KILLING THE TREES.
EACH HURRICANE INFLICTS MORE DAMAGE ON THE BRIDGE.
Dr. Georgiou: THE IMPACT FROM ONE STORM MAY NOT BE SIGNIFICANT.
IN FACT, THERE MAY NOT BE ANY OBVIOUS EVIDENCE FROM THAT.
BUT AFTER SEVERAL STORMS, THE IMPACTS COULD BE CATASTROPHIC.
Narrator: LAKE PONTCHARTRAIN IS VAST --
40 MILES LONG AND 25 MILES WIDE
WITH NOTHING TO OBSTRUCT THE WIND OUT HERE.
IT SURGES ACROSS THE WATER, GENERATING POWERFUL WAVES.
BY THE TIME THE WAVES HIT THE CAUSEWAY,
THEY ARE LADEN WITH DEBRIS, EXTREMELY DESTRUCTIVE,
AND FULLY CAPABLE OF WRECKING THE BRIDGE.
THE CAUSEWAY SUFFERS DAMAGE WITH EVERY STORM THAT HITS THE CITY,
SO IT TAKES A WHOLE TEAM OF ENGINEERS
TO KEEP THE BRIDGE IN TOP CONDITION.
THEY'RE LED BY CHIEF CARY BOURGEOIS.
HUH? YEAH, MAN, WE NEED A DRIVER.
Narrator: CARY INSPECTS BENEATH THE ROAD DECK FOR DAMAGE.
YOU STOP HERE. WAIT, KEEP GOING.
THAT'D BE GOOD.
Bourgeois: WHAT WE LOOK FOR IS ANY PLACE WHERE IT'S DAMAGED.
WE ACTUALLY HAVE A SPOT RIGHT OVER HERE
THAT HAS A LITTLE BIT OF EXPOSED STEEL.
THE SALTWATER SPLASH WILL GET IN.
IT'LL CAUSE THE STEEL TO EXPAND, AND THE CONCRETE WILL POP OFF.
Narrator: TODAY, A MASSIVE, $15 MILLION PROJECT IS UNDER WAY
TO UPGRADE THE CAUSEWAY AND FORTIFY ITS 9,000 PILLARS
AGAINST THE WAVES.
CARY'S TEAM USE A BARGE
TO ACCESS THE UNDERWATER SECTIONS OF THE BRIDGE.
THEY WRAP A TRANSPARENT, PLASTIC JACKET
THAT FUNCTIONS AS A GIANT MOLD AROUND EACH OF THE PILLARS
AND PUMP GROUT INTO THE GAP.
IT CONTAINS GRAVEL TO SCOUR THE PILLAR'S SURFACE
AND HELP THE GROUT TO BOND BETTER TO THE BRIDGE
SO IT'S EXTRA DURABLE.
TRAPPED AIR BUBBLES CAN WEAKEN THE GROUT,
SO IT'S CRITICAL THAT THE MIX SPREADS EVENLY.
ONCE THE GROUT SETS, THE TEAM REMOVES THE MOLD,
LEAVING A STORMPROOF ARMOR
THAT SHOULD MAKE EACH PILLAR TOUGH ENOUGH
TO SURVIVE ANOTHER 50 YEARS OF HURRICANE WAVES.
Bourgeois: THE ENCAPSULATION IS THERE
TO PRESERVE THE BRIDGE FOR FUTURE GENERATIONS
SO THAT THE BRIDGE CAN BE HERE AS AN EVACUATION ROUTE
TO SAVE LIVES IN THAT WAY.
Narrator: WHILE THE CAUSEWAY SURVIVED KATRINA,
NOT ALL OF LAKE PONTCHARTRAIN'S BRIDGES WERE SO LUCKY.
THE OLD TWIN SPANS BRIDGE
CONNECTING NEW ORLEANS TO SLIDELL WAS DESTROYED.
POWERFUL WAVES SMASHED ITS LOW-SLUNG ROAD DECK TO PIECES.
THEY RIPPED 58 SEGMENTS OF ROAD FROM THEIR PILLARS
AND DUMPED THEM INTO THE WATER.
JOHN HORN WAS THE FIRST ENGINEER AT THIS SCENE OF DEVASTATION.
Horn: THE WAVES AND WIND AND WATER
WERE ALL PUSHING ON THIS STRUCTURE.
BUT WITH THE WATER ELEVATION,
THE BRIDGE WAS ABLE TO TRAP AIR UNDERNEATH IT,
WHICH MADE IT LIGHTER.
AND THEN, THE WAVES SLAMMING INTO THE SIDE OF IT
FROM THE WIND EVERY FEW SECONDS
ACTUALLY SHOVED THE SPANS OFF THIS SIDE OF THE BRIDGE.
Narrator: JOHN'S TEAM RECONNECTED NEW ORLEANS IN TWO STAGES.
FIRST, THEY REPAIRED THE COLLAPSED BRIDGE,
THEN THEY BUILT A HURRICANE-PROOF REPLACEMENT.
IT WAS A DAUNTING CHALLENGE.
Horn: IT WAS LIKE BEING DROPPED
IN THE MIDDLE OF THE WILDERNESS SOMEWHERE
AND BEING TOLD TO FIX A BRIDGE.
MOST OF THE PEOPLE WORKING ON THE PROJECT
DIDN'T HAVE A HOME TO GO BACK TO AT NIGHT.
THE FIRST BRIDGE WAS REOPENED 29 DAYS AFTER THE STORM.
THAT ALLOWED EMERGENCY RESPONSE AND ALLOWED CONSTRUCTION CREWS
TO GET BACK INTO NEW ORLEANS AND GET THE CITY BACK ALIVE.
Narrator: THE ROAD DECKS ON THE OLD TWIN SPANS BRIDGE
SAT FLUSH ON THEIR PILLARS.
THE NEW BRIDGE RESTS IN CONCRETE SHOES.
THESE PREVENT SIDEWAYS MOVEMENT
AND HELP THE BRIDGE WITHSTAND CATEGORY-5 STORMS.
THE BRIDGE IS BUILT
WITH REINFORCED-CONCRETE RESTRAINING WALLS
BETWEEN THE GIRDERS THAT YOU CAN SEE UP HERE
THAT PREVENT THE BRIDGE FROM BEING LIFTED UP
OR FROM BEING PUSHED TO THE SIDE.
Narrator: THE NEW BRIDGE IS ALSO 20 FEET HIGHER.
THIS MAKES IT LESS PRONE TO FLOODING.
ITS STRUCTURE IS STURDY ENOUGH TO SURVIVE FOR 100 YEARS
AND THE NEXT KATRINA.
TOGETHER, WITH THE RENOVATED CAUSEWAY,
THESE BRIDGES WILL ALWAYS BE OPEN
FOR THE CITY'S 450,000 COMMUTERS,
EVEN WHEN STORMS STRIKE.
NEW ORLEANS' BRIDGES MAY BE SAFE,
BUT ENGINEERS ARE ALSO BUILDING
THE ULTIMATE SOLUTION TO FLOODING --
THE BIGGEST DRAINAGE-PUMPING SYSTEM IN THE WORLD.
Narrator: NEW ORLEANS IS IN CONSTANT DANGER.
THE CITY LIES UP TO 10 FEET BELOW SEA LEVEL,
AND WATER SURROUNDS IT ON ALL SIDES.
WHEN A HURRICANE HITS,
FLOODWATERS FROM LAKE PONTCHARTRAIN,
THE MISSISSIPPI RIVER,
AND THE MARSHES THREATEN THE CITY'S LEVEES.
AND TORRENTIAL RAIN CAN FLOOD THE CITY FROM WITHIN.
TO PROTECT NEW ORLEANS AGAINST ANOTHER KATRINA, IN 2009,
ENGINEERS BEGAN BUILDING THIS --
THE WEST CLOSURE COMPLEX,
A BILLION-DOLLAR PUMPING STATION.
IT SITS HALF A MILE SOUTH
OF TWO CITY DRAINAGE CANALS ON THE GULF INTRACOASTAL WATERWAY.
THIS IS HOW IT WORKS.
RISING FLOODWATERS FILL THE CITY'S DRAINAGE CANALS.
11 GIANT PUMPS FIRE UP INSIDE.
THE PUMPS CHANNEL 9 MILLION GALLONS OF WATER A MINUTE
AWAY FROM THE CITY CENTER.
THE WATER FLOWS INTO THE GULF INTRACOASTAL WATERWAY BEHIND IT
AND, FROM THERE, OUT INTO THE SEA.
THE STATION CAN COPE WITH FLOODWATERS
MORE THAN 16 FEET DEEP...
...AN EVENT SO SEVERE
IT SHOULD ONLY STRIKE ONCE A CENTURY.
BUT WHEN A HURRICANE HITS,
RISING FLOODWATERS ARE ONLY PART OF THE PROBLEM.
STORM SURGES, THE WINDS THAT DRIVE INTO THE CITY,
ARE ANOTHER HUGE THREAT.
COASTAL GEOLOGIST DR. MARK KULP EXPERIENCED THE SURGE FIRSTHAND
WHEN IT SUBMERGED HIS HOME.
Dr. Kulp: I GOT FLOODED TO THE ROOF. I WAS DEVASTATED.
FOR YEARS, I HAD BEEN TALKING THAT, WITH A MAJOR HURRICANE,
THERE COULD BE FLOODING.
AND SO, WHEN IT DID ACTUALLY HAPPEN TO ME,
I REMEMBER DISTINCTLY KIND OF JUST SITTING BACK AND THINKING,
"WELL, IT HAPPENED."
Narrator: UNOBSTRUCTED AS THEY TRAVEL ACROSS THE GULF,
HURRICANES CAN BECOME EXTREMELY POWERFUL.
STRONG WINDS PUSH THE SEA TOWARDS THE CITY.
HERE, THE SHALLOW SEAFLOOR FORCES WATER
TO PILE UP ON TOP OF ITSELF.
THIS CREATES A STORM SURGE.
THIS WALL OF FAST-MOVING WATER CAN SOAR UP TO 28 FEET HIGH.
FOR A CITY THAT SITS 10 FEET BELOW SEA LEVEL,
THERE'S LITTLE TO STOP IT FROM WREAKING HAVOC.
Dr. Kulp: SO, THAT'S THE FIRST STEP.
Narrator: 40 MILES SOUTH OF NEW ORLEANS,
IN THE GULF OF MEXICO, MARK USES SONAR TECHNOLOGY
TO HELP PREDICT THE IMPACT OF INCOMING STORM SURGES.
HE USES SONAR PULSES TO MAP THE CONTOURS OF THE SEABED.
SO, I THINK EVERYTHING'S SET UP. WE'RE READY TO GO HERE.
IT'S TIME TO START DOING SOME SURVEYING.
WHAT YOU SEE HERE IS A SHALLOWING OF THE BASE SURFACE
GOING FROM RELATIVELY DEEPER WATER TO MORE SHALLOW WATER,
ABOUT 2 1/2 TO 2 METERS WATER DEPTH
TO APPROXIMATELY 1 METER OF WATER DEPTH.
UNDERSTANDING THE WATER DEPTHS OF THE BAYS
IS FUNDAMENTALLY CRITICAL TO DEVELOPING MODELS
THAT PREDICT WHAT STORM SURGES WILL BE LIKE AROUND THE CITY
WHEN A HURRICANE DOES HIT.
Narrator: THESE MODELS PROVED THEIR WORTH WHEN KATRINA HIT.
AUTHORITIES ORDERED A CITY-WIDE EVACUATION OF NEW ORLEANS.
THOUSANDS OF LIVES THAT MIGHT HAVE BEEN LOST WERE SAVED.
BUT STORM SURGES
POSE A GREATER THREAT TO NEW ORLEANS EVERY YEAR,
SO ENGINEERS ARE NOW BUILDING
AN IMPENETRABLE RING OF BARRIERS AROUND THE CITY.
IT'S THE ULTIMATE LINE OF DEFENSE.
Narrator: NEW ORLEANS IS FIGHTING FOR ITS LIFE.
THE ENEMY -- HURRICANES AND THE STORM SURGES THEY CAUSE.
THESE MEGA FLOODS FLOW
DIRECTLY FROM THE GULF OF MEXICO INTO LAKE BORGNE.
FROM HERE, THE SURGE CAN STRIKE AT THE HEART OF THE CITY.
TO HOLD THE GULF WATERS AT BAY,
ENGINEERS BUILD THIS MAJOR NEW DEFENSE,
THE LAKE BORGNE SURGE BARRIER.
WE'RE OUT ON THE FAR-EAST SIDE OF NEW ORLEANS.
OVER MY SHOULDER HERE IS THE CITY,
AND THEN OVER HERE IS THE MARSH WHICH OPENS UP INTO LAKE BORGNE
AND THEN THE GULF OF MEXICO.
Narrator: BUILDING THE BARRIER
TOOK JUST OVER 2 YEARS AND $1.1 BILLION.
Ragolia: THE STEEL THAT'S IN THE WALL --
THERE'S ENOUGH STEEL AND REBAR TO BUILD SEVEN EIFFEL TOWERS.
ALL THE CONCRETE WE USED -- IF YOU PUT IT ON A FOOTBALL FIELD,
YOU CAN GO UP 93 FEET.
Narrator: FOUNDATION PILES ANCHOR THE TWO-MILE BARRIER
DEEP INTO THE MUD.
CONCRETE COLUMNS REINFORCED WITH STEEL
BOLSTER ITS 5 1/2-FOOT-THICK WALLS.
HIGH WATER LEVELS TRIGGER A GATE CLOSURE.
FIRST, A 132-TON VERTICAL GATE DROPS DOWN.
NEXT, A BARGE GATE SWINGS ACROSS THE BARRIER.
IT FILLS WITH WATER, THEN SINKS.
FINALLY, AN ENORMOUS THIRD GATE CLOSES.
EACH LEAF WEIGHS OVER 600 TONS.
THEY CURVE AND ANGLE DOWNWARDS INTO THE FLOW OF THE WATER.
THIS WAY, AS A STORM SURGE HITS,
IT FORCES THE GATES TO FULLY SEAL.
TODAY, ENGINEERS WILL PUT THE BARRIER TO THE ULTIMATE TEST.
TROPICAL STORM KAREN IS HEADED FOR THE COAST.
METEOROLOGISTS PREDICT
IT WILL HIT LAND IN DOWNTOWN NEW ORLEANS.
THE LAKE BORGNE SURGE BARRIER KICKS INTO ACTION.
Ragolia: WE'RE IN THE CONTROL ROOM FOR THE SECTOR GATE.
THIS IS WHERE WE CLOSE THE GATE.
THE NOISE IN THE BACKGROUND IS THE HYDRAULIC PUMP
THAT'S ACTUALLY PUSHING THE PISTON TO CLOSE THE GATE.
THIS GATE WILL PREVENT
ALL THE STORM SURGE FROM MOVING INTO THE CITY,
LOWER NINTH WARD, EAST NEW ORLEANS, ALL OF IT.
Narrator: THIS IS ONLY THE SECOND TIME
IN THE BARRIER'S OPERATIONAL HISTORY THAT IT'S CLOSED.
1,350 TONS OF STEEL SLAM SHUT
TO KEEP THE STORM SURGE OUT OF THE CITY.
THE SURGE BARRIER PROVIDES A CRUCIAL PART
OF NEW ORLEANS' MULTI-BILLION-DOLLAR DEFENSES.
AND THE CITY ENGINEERS AREN'T FINISHED YET.
THREE MORE GIANT FLOODWATER-PUMPING STATIONS
ARE UNDER CONSTRUCTION.
THEY SIT AT THE MOUTH OF THREE CANALS TO STOP FLOODWATER
FROM SURGING INTO THE CITY.
WHEN FULLY OPERATIONAL,
THE PUMPING STATIONS WILL BE ABLE TO SUCK
ALMOST 11 MILLION GALLONS OF WATER A MINUTE
AWAY FROM THE CITY.
IN ALL, THERE WILL BE OVER 70 STATIONS ACROSS NEW ORLEANS,
A MONUMENTAL ENGINEERING FEAT THAT'LL KEEP THE CITY DRY,
PROTECTING NEW ORLEANS' BUILDINGS AND CITIZENS
FROM NATURE'S DEADLIEST HURRICANES.
NEXT TIME THE BIG ONE HITS, NEW ORLEANS WILL BE READY.
I'M AMAZED THAT THE CITY CAME BACK AS QUICK AS IT DID.
IT'S ONLY BEEN EIGHT YEARS, AND IT LOOKS FANTASTIC.
WE STILL BELIEVE. WE TRUST THAT WE CAN REBUILD.
WE CAN GET BACK TO WHAT WE WERE BEFORE, AND WE ARE DOING IT.
NEW ORLEANS IS COMING BACK REALLY, REALLY STRONG.
Narrator: INGENIOUS INNOVATIONS THAT PUMP WATER...
SECURE BRIDGES...
WINDPROOF INFRASTRUCTURE...
AND ANCHOR SKYSCRAPERS...
WILL HELP NEW ORLEANS SURVIVE
WHEN THE NEXT KILLER HURRICANE STRIKES.