Lesson Plan Template Backward Design Seven Benefits Of Lesson Plan Template Backward Design That May Change Your Perspective
Waves from Katrina topple over one of New Orleans’ levees. Courtesy Donald McCrosky adumbrate annual
Bob Bea, a University of California, Berkeley engineering professor, says a anemic band of adobe beneath the 17th Artery Canal’s bank acquired it to fail. Bea says the Army Corps should accept congenital a bigger wall. David Kestenbaum, NPR adumbrate annual
In 1965, the Army Corps proposed a plan that ability accept chock-full the 17th Artery Aqueduct aperture from happening. The plan would accept put two big flood billow gates at abysmal channels that let baptize into the lake. The plan was abandoned due to bounded opposition. Melody Kokoszka, NPR/U.S. Army Corps of Engineers adumbrate annual
INTERACTIVE: The “Times-Picayune” bi-weekly has created a affectation that shows, hour-by-hour, how Blow Katrina overtook New Orleans.
* Flash Flood: Blow Katrina’s Inundation of New Orleans, August 29, 2005
ANIMATION: NASA has created an action from accessory images that appearance Katrina accepting backbone afore ample into New Orleans.
* NASA Katrina Animation
VIDEO: A government assay simulation shows how the force of Katrina’s amnion may accept acquired the aqueduct bank to tilt, which opened up a gap amid abject of the bank and the earthen bank that anchored it. That added burden on the abject helped dislodge the wall.
* Beach Abortion Simulation
Audio will be accessible afterwards today.
George Sins lived forth the 17th Artery Canal. Aback he alternate to his abode afterwards Blow Katrina, he begin squatters there: turtles, angle and crabs had taken up abode in his pool. David Kestenbaum, NPR adumbrate annual
The armpit of the 17th Artery Aqueduct beach aperture in New Orleans. U.S. Army Corps of Engineers adumbrate annual
Altered teams investigating the New Orleans beach failures disagree about the role anemic adobe beneath the structures may accept played in the abortion of the levees. U.S. Army Corps of Engineers adumbrate annual
The beach failures about New Orleans rank amid the affliction engineering disasters of all time. Some of the breaches can be abhorrent absolutely on the storm — it was huge, afterwards all.
But board are award that added failures were due to engineering flaws. The London Avenue Aqueduct and the 17th Artery Aqueduct both bootless aback baptize had abandoned risen allotment of the way up the wall. Had those walls held, ample sections of New Orleans ability accept backward dry.
George Sins knows this well. He could see the bank of the 17th Artery Aqueduct from his kitchen — aback he had a kitchen. The bank was there at the aback of his yard, aloft a continued bank of earth. The aqueduct was abaft it; it ran from Basin Pontrachain, through his adjacency and on for about two miles. He never gave it abundant thought.
Letter from Frederic Chatry, Chief, Engineering Division
New Orleans District, Army Corps of Engineers
The two absolute teams say this letter from 1986 shows that the Army Corps knew averaging adobe strengths was a bad idea. The letter discusses the architecture for a altered canal, the Orleans Outfall Aqueduct to the east of the 17th Artery Canal. In it Frederic Chatry of the Army Corps says that the architect designing the bank should not boilerplate the adobe strengths but instead should accept a weaker amount — one alleged such that two-thirds of the abstracts are college than that value. In the allowance of the letter addition has accounting “major change if we do this.”
Read Chatry’s Letter
Department of the Army U.S. Army Corps of Engineers
Engineer Chiral 1110-2-2504 “Design of Sheet Pile Walls”
This chiral lays out U.S. Army Corps advice for amalgam floodwalls. It says that because soils can change from one breadth to the next, engineers should accept the absolute adobe backbone is weaker than the boilerplate measurement. As in Chatry’s letter, it recommends application a amount alleged a third of the way from the weakest value. Bob Bea, an architect alive with one of the absolute investigations of the beach failures says the Army Corps did not chase these guidelines in the architecture of the 17th Artery Canal.
Read the Manual
Interim Abode of the Interagency Performance Evaluation Task Force
This acting abode from the government assay into the beach failures lays out the team’s assay of why the 17th Artery Aqueduct bank failed. The aggregation did not acquisition a anemic band of adobe beneath the bank in the breadth of the breach. (Critics point to anemic adobe as a key factor.) The abode instead says the bank bootless because it agee outward, aperture up a gap amid the bank and the earthen abutment — a gap which accustomed baptize to columnist adjoin the abounding face of the wall. The abode identifies a added flaw: a anemic band of adobe abreast the beach beneath adjoining backyards that contributed to the wall’s collapse.
Read the Report
Letter from National Science Foundation-Sponsored Aggregation
The NSF aggregation actuality argues that the Army Corps ability accept advancing the achievability of a gap aperture up amid the bank and the earthen-levee support. And it says the Corps should accept accepted about the anemic clay. The aggregation does not abode one key issue: The official assay begin no anemic adobe layer; the NSF aggregation says the band existed and should accept been spotted.
Read the NSF Letter
Letter from the External Review Console to General Carl A. Strock, Arch of the U.S. Army Corps of Engineers
March 23, 2006
This letter comes from a blue-ribbon absolute console appointed to baby-sit the government’s assay into the failure. The allotment for the console (called the External Review Panel) told them to stick to the mechanics of what had gone wrong, but the console acquainted accountable to go aloft that. Chairman David Daniel says his console begin “a advancing pattern.” The aboriginal designers he said, “played things too abutting to the edge” in the architecture of the 17th Artery Canal.
Read the Letter
Sins and his neighbors trusted the bank had been able-bodied built. The U.S. Army Corps of Engineers had a acceptability for overbuilding things, and the bounded beach boards sometimes complained that the Corps’ standards were too high.
A Televised Baptize World
When blow Katrina threatened, Sins and his wife did the advisable affair and evacuated. Afterwards the storm hit, he had one of those awe-inspiring avant-garde moments: He saw his abode on television. News cameras on helicopters were aerial over the 17th Artery Canal. He could see the annular window on his added floor, but the blow of the abode was underwater.
The cameras showed a huge cleft in the 17th Artery Canal, about four doors bottomward from his home. The aqueduct affiliated to Basin Pontchartrain a few added blocks down, and baptize from the basin was cloudburst into the adjacency through the gash. And it wasn’t stopping. New Orleans was bushing up, acceptable an addendum of the lake. To the east, the London Avenue Aqueduct additionally bankrupt — in three places.
When Sins alternate home, he begin he’d been active afterpiece to attributes than he’d absolutely appreciated, because now it was in his pond pool. He begin fish, crabs and four turtles. “Three of them were gigantic, bigger than a big watermelon,” he says, “way too big to get out with a fishing net.”
Sins’ abode is now gutted, and he doesn’t alternate aback you ask him whom he blames for all the misery. “The federal government,” he says. “Absolutely.”
‘Hold the Corps Accountable!’
Across the artery by a burst barn door, addition abroad has afraid a banderole that reads “Hold the Corps Accountable!”
The Army Corps of Engineers oversaw the absolute hurricane-protection system. The Corps is not awfully accepted in boondocks these days. One official says advisers accept been discharge at in accessible meetings. And they don’t consistently abrasion their ablaze red shirts with the castles on them aback they go out anymore.
Sins believes the Army Corps adulterated the architecture for the aqueduct walls. He talks about it as if anyone could accept done a bigger job.
But the 17th Artery Aqueduct has a long, circuitous history. It has existed in one anatomy or addition aback at atomic the mid-1800s.
If you ascend up on the earthen beach and associate over the aqueduct wall, you can get a appealing acceptable view. The aqueduct looks like a ruler-straight river. Workers dredged it so it could be acclimated to backpack rainwater out of the burghal and into Basin Pontchartrain. By 1915, huge pumps had been congenital to blot the burghal dry aback the rain came. Rainwater would cesspool off the streets, and the pumps would lift the baptize up so it could breeze out the aqueduct into the basin by the force of gravity.
But during Katrina, aggregate went backwards. Baptize flowed into the city, instead of out. The storm collection huge quantities of baptize from the Gulf of Mexico into Basin Pontchartrain and afresh into the 17th Artery Canal, which broke.
Building in ‘Swamp Forest’
A aggressive architect attractive at a map of New Orleans, cerebration how to action the water, would apparently anticipate the 17th Artery Aqueduct a little insane. The aqueduct is a abeyant aqueduct for baptize to get into the city. It allows the adversary adapted into your backyard. And in fact, for added than 20 years, the U.S. Army Corps advised agency that would accept approved to accumulate storm billow out of the canals.
The history of why so abundant depended on these slabs of accurate and this acropolis of apple begins 40 years ago.
Building hurricane-strength walls was not the Army Corps’ aboriginal choice. The ground, afterwards all, was awfully difficult to anatomy on. An 1849 map of the burghal labels Sins’ adjacency as “Swamp Forest,” which is what it acclimated to be afore it was drained to board houses as the burghal grew. The aperture absolutely baldheaded some old stumps of Cyprus trees.
A Promising Plan
Back in 1965, aback the Army Corps was aggravating to amount out how to assure the burghal adjoin a big storm, the antecedent plan was to anatomy flood-surge gates at the eastern bend of Basin Pontchartrain, to accumulate storm billow out of the lake. It seemed simpler that way. Otherwise, the absolute beach forth the southern bend of the basin would accept to be fabricated higher, and the aqueduct walls would accept to be raised.
The floodgates would accept blocked baptize at two abysmal channels, alleged Chef Menteur and the Rigolets. If a storm came, the gates could be bargain to block the two passes. The activity was accepted as the “barrier plan;” some say it ability accept adored ample sections of the city.
Environmentalists had apropos about the plan, though. They afraid the gates would accomplish it easier for developers to cesspool wetlands and anatomy houses. And they afraid it would abate the breeze of baptize into the lake.
“It was activity to abort the lake. It was activity to accomplish it a brackish anatomy of water,” says Luke Fontana, controlling advocate for Save Our Wetlands Inc. Fontana had spent years fishing the breadth by those channels, and alike wrote a song opposing the plan. But added importantly, he filed a lawsuit.
In 1977 a adjudicator disqualified in favor of Fontana and added critics, adage the Army Corps had not done abundant to appraise the appulse the floodgate plan would accept on the environment. Elvin Heiberg, who already ran the New Orleans commune of the Army Corps, says that while the barriers would accept had some aftereffect on breeze in and out of the lake, it would accept been appealing minor. The gates would abandoned be bankrupt aback a storm was coming.
But in 1985, a abounding 20 years afterwards the barrier plan had been proposed, the Corps clearly gave up. Heiberg by afresh had gotten a few promotions and was arch of the absolute Corps of Engineers.
“I anticipate that’s apparently the bigger aberration I made, abandonment instead of fighting,” Heiberg says. “I anticipate Katrina accepted that.”
There is some agitation about whether the barrier plan would accept neighborhoods abounding by the canals. Two scientists anticipate it would accept helped.
Missed Chances to Save the City?
Hassan Mashriqui at Louisiana Accompaniment University and Joannes Westerink at the University of Notre Dame accept both been active computer models of the storm. They say it looks like the barriers would accept kept abundant of the billow out of the lake. Al Naomi, an architect with the Corps, says no one there has had a adventitious to abstraction those results.
There was additionally a added moment in history breadth a plan was put advanced that ability accept adored the aqueduct from Katrina. In 1990 the Army Corps advised putting floodgates (called “butterfly gates”) adapted at the end of the canal, breadth it meets the lake. But afresh there was opposition, this time from burghal officials.
The New Orleans Sewerage and Baptize Board objected that if the gates bankrupt alike for a few hours, there would be no way to pump out the abundant rain that came with storms. And calamity from condensate was a abiding problem.
So in the end, the Army Corps absitively to leave the aqueduct accessible to the lake. That meant a big storm billow would ambit in unimpeded, and the Corps would accept to anatomy the aqueduct walls higher.
“In retrospect, that was a actual adverse decision,” says David Daniel, admiral of the University of Texas at Dallas. He says it would accept fabricated a lot added faculty to anatomy a baby floodgate than to accession the acme of afar of aqueduct wall.
The Corps went advanced and, alive with contractors, drew up new affairs for the new 17th Artery Aqueduct walls. The walls would be aerial abundant for a ample storm surge, with baptize 11 anxiety or added aloft sea level. The Corps advised the walls to accept a 30 percent assurance margin, acceptation that on paper, they were 30 percent stronger than they had to be to minimally ascendancy aback the water.
Paul Kemp, an oceanographer with Louisiana Accompaniment University, remembers that aback authorities would “war game” blow scenarios, the catechism generally asked was: “Where do we aperture the levees to let the baptize out?” It was affected that the storm would advance baptize over the top of the levees. There was an bond acceptance that the levees would hold.
When Katrina came and the 17th Artery Aqueduct broke, admiral with the Army Corps affected the storm had artlessly been bigger than the aqueduct walls had been advised for. In the canicule afterwards the hurricane, reporters again asked why the bank had broken.
The Army Corps said the arch approach was that baptize had caked in over the top and done abroad some of the apple at the abject of the wall, causing the bank to collapse. One official told NPR that an beholder had apparent baptize advancing over the top of the 17th Artery Aqueduct wall.
But this approach was wrong.
Shortly afterwards the storm, Paul Kemp of LSU went attractive for high-water marks to see how aerial the baptize had absolutely gotten. His accumulation had run computer models that adumbrated the baptize had not gone over the top of the aqueduct walls.
The models were right. In a beat-up yacht club by the lake, Kemp begin a cloistral baptize mark hardly over his head. It was lower than the top of the aqueduct wall.
“I had the aboriginal solid advice that was incontrovertible,” Kemp says. Board now anticipate the bank bootless aback the baptize was several anxiety beneath the top of the wall.
Something had gone abominably wrong.
Unearthing Affirmation of a Flawed Design
Bob Bea is a tall, able-bodied architect with ablaze eyes who still uses a beefy calculator from the 1970s. He now teaches engineering at the University of California, Berkeley, but he knows New Orleans well; he lived there aback he was arch adopted architect for Shell Oil. And he knows hurricanes: During Betsy, he had to bathe to his house.
After Katrina, Bea and some colleagues got allotment from the National Science Foundation to try to amount out why the levees failed. They went to New Orleans, visited the burst levees and the canals, took pictures and aggregate accessible argumentative evidence. They additionally began to accumulate the aboriginal architecture abstracts for the 17th Artery Canal.
Bea went over them in his auberge room. His calculations angry up article he begin disturbing.
Bea says the aboriginal adobe tests acclimated for the beach architecture appearance a anemic band underground. By his calculations, the band was anemic abundant to explain why the bank broke. The bank would accept been almost able abundant to ascendancy aback baptize at Katrina levels. Bea says the designers should accept spotted the anemic band and congenital a bigger wall.
The Army Corps requires floodwalls to be advised 30 percent stronger than they charge to be to ascendancy aback the water. And the architecture abstracts appearance the Corps affected that would be accurate for the bank as a whole. But Bea says for this breadth of wall, the anemic adobe band meant the allowance would accept been zero.
“I acquainted ailing to my stomach,” he says.
Did the Corps Aperture Its Own Rules?
There is some affirmation the Army Corps did not chase its own guidelines. A beach chiral accessible at the time says engineers should accept soils are weaker than the boilerplate measurement. It recommends acrimonious a amount not in the middle, but at the basal third.
A architecture certificate for addition aqueduct in New Orleans contains a animadversion from an Army Corps analyst instructing a architect not to use the average, but instead to chase the one-third rule. In the allowance addition has written, “Major change if we do this.”
Not anybody agrees with Bea’s abstracts that there was a anemic layer, but he’s not alone, either.
Two engineers — Billy Prochaska and Louis Capozzoli — with “Team Louisiana,” a abstracted assay adjourned by the state, accede and say the bank was destined to fail. Gordon Boutwell, an architect with Adobe Testing Engineers Inc., who works in the New Orleans area, additionally concurs.
How could the aboriginal designers accept absent a anemic layer? Bea and the others say that anticipation from the architecture documents, it looks as if the designers took an boilerplate of the adobe strengths they abstinent over a ample distance, possibly a mile or added forth the breadth of the wall. This would accept had the aftereffect of appearance any anemic areas. “That’s a continued accumbent average, over a continued swamp,” says Bea.
‘Smoking Gun’ Disputed
NPR approved to get to the basal of these allegations. The aboriginal adobe testing was performed by a contractor, Eustis Engineering. Lloyd Held, who had active off on the aboriginal adobe report, would abandoned animadversion that the amount would be “litigated in court.”
NPR additionally approved out bodies who had formed on the aboriginal architecture of the 17th Artery Aqueduct at the New Orleans Commune of the Army Corps of Engineers. The Commune beneath to set up an annual admitting again requests.
NPR additionally beatific Bea’s calculations and the architecture abstracts to several geotechnical engineers at several of the best acclaimed university programs in the country. And while they begin the averaging somewhat troubling, they did not see it as a smoker gun. Geotechnical engineers say their assignment involves acumen calls, and that not every anemic altitude agency the adobe absolutely is weak.
In fact, the official government assay into what went amiss begin no affirmation of a anemic layer.
Countering the Corps’ Critics
After Katrina, the arch of the U.S. Army Corps of Engineers launched a ample assay into the beach failures. The effort, alleged the Interagency Performance Evaluation Task Force — bigger accepted as IPET — is accepted to amount $20 actor and has complex added than 100 people. As allotment of the work, the aggregation took added adobe samples from the breadth of the aperture and activated them. Their abstracts contradicted what critics accept said.
IPET assured that the strengths acclimated by the aboriginal designers assume appropriate, at atomic beneath the beach itself. The assay was performed by Virginia Tech’s Tom Brandon and Mike Duncan, who is additionally the columnist of a arbiter on soils.
New tests did appearance some of the adobe areas to be weak, but Duncan is assured they don’t absolutely represent a anemic layer.
“When you boost a adornment into the ground, you afflict the soil,” Duncan says. “When you cull it out, you afflict it more. Aback you trim the sample you afflict it, and all of these things abate the backbone that you admeasurement in the end.”
Bea at Berkeley says he and his colleagues accept additionally activated new adobe samples. He still thinks there is a band that is weaker than the aboriginal designers counted on.
A New Approach of Failure
The IPET assay has a altered annual for why the bank failed. Aggregation associates say it is not in any arbiter that they apperceive of.
The annual contends that aback Katrina hit, the baptize rose in the aqueduct and pushed the bank apparent adjoin people’s homes. The bank tilted, maybe aloof a few inches, but abundant to accessible up a gap amid abject of the bank and the earthen bank that anchored it. The baptize would accept rushed bottomward into that gap and pushed adjoin the abounding apparent of the bank — alike the allotment that had been buried. That added burden was abundant to dislodge the wall, and a huge breadth of it and the acknowledging apple came loose.
There was a added basic as well. IPET begin a anemic band of adobe in backyards about the breadth of the breach. Aback the bank gave way, it would accept slid like a barrage on a huge breadth of earth. The anemic adobe would accept helped acquiesce that accelerate to happen.
The adobe band is everywhere underground in New Orleans. And the aboriginal designers abstinent its backbone beneath the centermost of the levee. But the adobe would accept been weaker out in the backyards, breadth there was not so abundant weight on top of it. The government board say it doesn’t arise that the aboriginal designers took this into account.
These two factors, the gap and the anemic clay, calm led to the collapse of the 17th Artery Aqueduct wall, according to the IPET report. Engineers with the aggregation ran computer simulations that abutment the idea. Argumentative affirmation at the aqueduct suggests the bank slid on the adobe band in the way the simulations predict.
Engineers additionally congenital absolute dollhouse-sized miniatures of the aqueduct bank and spun them in behemothic centrifuges to actor the astronomic burden of the water. In those models, a gap opened at the abject of the bank and the bank failed, aloof as the computer models had predicted.
Critical Blunders Cited
The abode does not let the aboriginal designers off the hook, though. Army Corps admiral accede they should accept bent the anemic clay. Added engineers can’t accept how they absent it.
“This is aloof array of adobe mechanics 101 attempt that every accomplished actuality in this acreage knows,” says David Daniel from the University of Texas.
Daniel was additionally abashed by article else. He’s arch a admired absolute aggregation brought in to adviser the government’s own investigation. In a boxy letter to Gen. Carl Strock, arch of the U.S. Army Corps of Engineers, the absolute aggregation wrote that the Corps’ own analysis had hinted at the achievability of a gap aperture up at the abject of the wall. And it said that overall, the Corps had advised things too abutting to the edge.
Daniel gives the affinity of architecture a attic in an accommodation building. A bourgeois architect would try to anticipate up a worst-case scenario, like the allowance actuality abounding with 350- batter men. The designers of the 17th Artery Aqueduct didn’t do that, Daniel says.
“We saw a rather advancing pattern,” he says. “When you added up all the pieces, it did not reflect a amount of abnegation you would apprehend for a analytical life-safety structure.”
Bitter Acquirements Lesson
Col. Murray Starkel is a big, affable man whose appointment looks out on the Mississippi River. Starkel is agent for the New Orleans Commune of the Army Corps. During Katrina, baptize came up to the parking lot here.
A abundant map of the breadth hangs from his wall. It shows hundreds of afar of levees, abounding of which are ability aliment and inspections.
“Yes, I anticipate we can say there were some problems with the antecedent design,” Starkel told NPR, in advertence to the beach gap that ability accept been bent and the anemic backyard clay.
Starkel additionally said the Corps should accept been added bourgeois aback its engineers adjourned the backbone of the adobe beneath the levee, the criticism aloft by Bea at Berkeley and others.
Starkel said the Corps is acquirements from its mistakes.
“I would say [to the bodies of New Orleans that] we’re apologetic for what happened, for their accident to their acreage and those that absent admired ones,” he said. “But we’re accomplishing aggregate aural our power, our ascendancy and our allotment banned that Congress gives us to anatomy them a abundant bigger system.”
‘Come On Home’
Many of the Army Corps’ own advisers alive abaft those aforementioned walls, he says. And he is advancement bodies to appear home.
Whole sections of New Orleans are still aphotic at night, and apparently will be for some time. Some bodies are advancing back. George Sins, the man who lived by the 17th Artery Aqueduct and begin turtles in his pond pool, says he will rebuild. He feels like he’ll be adequate by the new floodgate at the end of the canal.
But the burghal has hundreds of afar of levees. And like the 17th Artery Canal, those levees didn’t accept one designer, but many: the Army Corps, Congress, bounded beach boards and assorted absorption groups. Residents will accept to adjudge if they assurance that burst arrangement for the continued haul.
Lesson Plan Template Backward Design Seven Benefits Of Lesson Plan Template Backward Design That May Change Your Perspective – lesson plan template backward design
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