Dam repairs
Pre-storm preparations
On Saturday, August 27, while Katrina was a Category 3 storm harvesting force in the Gulf of Mexico, the Army Corps of Engineers' Mississippi Valley Division was preparing and positioning elements from as far away as Hawaii. Anticipating the possibility of a Category 5 storm placing water on New Orleans, preparations for drainage operations began.
On August 29, 2005, when Katrina made its second and third landfalls on the Louisiana-Mississippi coast, Corps of Engineers District Commander Col. Richard Wagenaar and a team worked from an emergency operations shelter in New Orleans. Other crews waited in the storm's path across the Gulf Coast.
The Corps of Engineers worked with the U.S. Coast Guard, Army National Guard and other state and federal authorities to bring in all available assets to expedite the process. "We are trying to contract for materials like rock, super sandbags, cranes, etc., and also for transportation modes like barges and helicopters, to close the gap and stop the flow of water from Lake Pontchartrain into the city," said Walter Baumy, engineering division chief and project manager.
Flood
The Corps of Engineers initially believed that water in the 17th Street Canal had overtopped the flood barrier, drained behind the wall, causing it to collapse. However, three local fire captains confirmed with video footage that the retaining wall had failed before the water reached the top. The retaining wall opened on the lower side (west end of New Orleans) inward from the Old Hammond Highway Bridge.
There were three major breaks in the Industrial Canal; one on the upper side near the intersection with MR-GO, and two on the lower side along the Lower Ninth Ward, between Florida Avenue and Claiborne Avenue. The London Avenue Canal opened in two locations, on the upper side just behind Robert E. Lee Boulevard, and on the lower side one block from the Mirabeau Avenue Bridge.
On the night of August 29, 2005, approximately 28 levee failures were reported throughout the city. About 66% to 75% of the city was now under water. Wind and other storm damage had already brought the city to a standstill. Many power lines were down and the remains of trees and buildings blocked the streets.
As Corps of Engineers workers began collaborating with the Federal Emergency Management Agency (FEMA) with cleanup and civil engineering tasks, several boats inspected flooded areas and blocked the city's waterways. The Corps of Engineers used crane barges to remove barges that had washed atop bridges and other structures.
Plans were made to begin work on the levees, including placing 3,000-pound sandbags in the 17 Street Canal. Army National Guard helicopters began assisting in this operation on August 31. Meanwhile, Lake Pontchartrain began slowly draining and was expected to return to normal levels in about 36 hours.
Recovery
The break in the 17th Street Canal Levee, a combination levee and retaining wall, was found to be about 300 feet (100 m) long. The Corps began operating under the initial hypothesis that the force of the water overshot the retaining wall and swept through the structure from behind and then moved the levee wall horizontally about 20 feet (6.1 m). This hypothesis was later refuted by eyewitnesses.
The Corps of Engineers released two contracts to close the breach in the 17th Street Canal. The 3,000-pound sandbagging operation in the 17th Street Canal was postponed earlier in the day when U.S. Army Chinook helicopters were diverted for rescue missions. The Corps of Engineers continued to coordinate with Army officials to have helicopters assist in sandbagging the ruptures. The 3,000-pound sandbags were approximately 3 feet (0.91 m) square (1 m).
Corps of Engineers officials worked with the Town of Orleans, Louisiana Department of Transportation officials and New Orleans-based Boh Bros. Construction Co., L.L.C. to drive piles into the lakeshore and stop the flow in the 17th Street Canal. This would stabilize the flow of water and allow work on the levee, while also helping to stabilize the rest of the levee system.
Along with local and state officials, the Corps of Engineers also contracted to build access roads to the breach sites and fill gaps. Crushed rock/stone/concrete was transported by truck for road construction and gap repair. One plan called for building an access road from Hammond Highway to the 17th Street breach, and then south to the end of the breach.
To help drain the city, the Corps of Engineers delivered two 5,000 cubic feet per second (140 m³/s) pumps to the Louisiana Super Dome.
Construction
With Lake Pontchartrain almost returning to normal levels, little water was flowing out of the city. This allowed a change of plans, and marine equipment was used to drive sheet piles into the mouth of the 17th Street canal to seal the entire lake channel.
Shortly after 1:00 p.m. m., the first piece of sheet piling was driven, to form a steel wall across the lake entrance to the 17th Street canal. A contractor began bringing in rocks to build a road to the gap, which was south and east of the Hammond Highway bridge over the canal, with dry dirt on the west side of the bridge.
Rock was being transported off-site to complete the access road and closure at the 17th Street gap. Once the rock required to build the roads arrived in New Orleans and the access road to the breach was completed, the Engineers Department estimated that closure of the gap could be completed in three or four days. Several private firms offered volunteer services and have provided assistance in designing the closure.
Similar work was planned to seal a 300-foot (91 m) gap in London Avenue, although in that case the materials would come from the demolition of Lakeshore Drive. Five 42-inch (1,100 mm) bombs were ordered to help drain the city.
The 17th Street Canal levee was estimated to have a gap 450 feet (150 m) long. It was still believed that the water overtopped the retaining wall, traveled through the structure, and then moved the structure 20 feet (6 m) horizontally.
Work continued on nearby waterways, including several locks that were closed. Using some of the blockades required raising bridges. The Industrial Canal Lock needed repair, and its safety master raised the St. Claude Avenue Bridge, but lowered it due to hostility from civilians wanting to cross on both sides.
The flow of water stopped
By September 1, 2005, the mouth of the 17th Street Canal had been sealed with sheet piling that prevented lake water from reaching the levee breach. Since no more water can pass through the gap, it was no longer necessary to seal the gap itself. The next step was to run the existing pumps and bring in additional pumps to drain the surrounding city and canal. The canal was later drained so permanent repairs could be made to the dam. To allow drainage, backhoes mounted on marsh buggies and dredgers mounted on barges cut breaches in some other levees. Marsh buggies are tracked vehicles whose wide tracks allow them to operate on soft, swampy terrain.
Helicopters were dropping large sandbags made of strong, synthetic materials into the gap. Heavy equipment on the ground placed rocks. Access to the ground was created by building a rock road from the Hammond Highway, which is located about 700 feet (200 m) from the lake wing of the gap. The 17th Street Canal is a drainage canal whose dimensions and its major bridge, integrated into the flood control system, would not allow the entry of barges and tugboats to transport rocks and placing cranes.
A pumping station began pumping around 5,000 cubic feet per second (140 m³/s) into the Industrial Canal. A bomb was working in New Orleans East. At this point, the water removal process was estimated at 36 and 80 days, according to Brig. Gen. Robert Crear.
By September 3, 2005, the first of five new pumps was delivered. St. Charles Township loaned four more pumps to the Corps of Engineers.
Closed break
On September 5, 2005, the 17th Street Canal breach was closed. Blackhawk and Chinook helicopters had dropped more than 200 sandbags, with approximately 125 sandbags breaking the surface of the water. After the emergency ended, plans called for the canal to be drained and the wall to be repaired.
There were three 42" staggered mobile pumps and two 42" and two 30" pumps in the sheet pile closure. The sewer and water boards, electrical utility and 249 Engineer Battalion (Main Power) completed the pump room inspection. As the operation began, a 40 ft wide (12 m) opening was made in the sheet pile to allow water to exit the channel.
Pumping and moving on
By September 6, 2005, pump stations began connecting at the 17th Street Canal. Pump Station 10 was actually pumping at this point. Pump Station 6 was shut down to clear some debris from the area. Pump Station 1, located a little higher in the system, was pumping to Pump Station 6, to drain the upper area, the high areas. On the east side, Pumping Station 19 had been operating for some time. Two of the three large pumping stations in New Orleans East were operating, in addition to temporary pumps. At least one pumping station operated in Plaquemines Township.
It was decided to use sheet pile closure to stop the flow of water in the London Avenue gap, similar to what was done in the 17th Street Canal. A rock wall had initially been built there. The London Avenue canal was drained so that the breach could be repaired.
Portable pumps were used to extract water from the city. The estimated flood area was reduced to 60%. By Tuesday afternoon, 3 of the 148 permanent pumps had been restored to operation. Important steps to return more pumps to operation include repairing breaches in the London Avenue and Industrial canals. It was estimated that repairing the breach in London Avenue would require two weeks. Steps to repair the industrial canal breach included the removal of two damaged barges and one that had sunk.
On the morning of September 7, 2005, approximately 60% of the city was still under water. Blackhawk helicopters continued to deliver 7,000-pound sandbags to London Avenue. Sandbag filling operations continued 24 hours a day. The Corps of Engineers hoped to close two breaches in the London Avenue Canal within 24 hours. Employees and contractors were temporarily using sandbags to close these holes.
Several small breaches caused by the storm had been found and were being closed. It was estimated that draining the city would take 24 to 80 days. Volunteers from as far away as Germany and Holland offered to help with pumps and generators.
Engineers found two breaches on the east side of the Inner Harbor Ship Channel and one on its west side. They closed the larger of the two gaps on the east side and filled the smaller of the two gaps with clay and stone. Work would begin on the west side as soon as possible.
23 of the 148 permanent pumps were restored to operation. Three pumps were operating in the 17th Street canal, discharging water at about 2,250 cubic feet per second (64 m³/s). Pump Station 19 on the Industrial Canal, just north of Florida Avenue, was pumping 1,300 cubic feet per second (37 m³/s). Pump Station 8, located in St. Bernard Township in the vicinity of St. Mary, was operating at full capacity at 837 cubic feet per second (24 m³/s).
At this time, approximately 100 US Army Corps of Engineers workers were in New Orleans. More than 500 contract workers participated in repairs.
By September 8, 2005, of the 174 pumps now in the New Orleans area, 37 were in operation, drawing water at a rate of 9,000 cubic feet per second (250 m³/s). Nine pumps in Plaquemines Township removed water at a rate of 1,400 cubic feet per second (40 m³/s). However, officials were wary of operating the pumps at full capacity because of the possibility of damaging the newly repaired levees and losing bodies.
Last critical gap closed
The fourth and final critical gap in the Orleans and East Orleans areas has been closed. A road had been built, at a rate of 500 feet (150 m) per day, from the 17th Street canal work area to reach the London Avenue canal gap. From the gap on the west side of London Avenue, the road was built in the second violation area on Mirabeau Street.
As with the 17th Street Canal, at the London Avenue Canal, flow from Lake Pontchartrain into the canal had been cut off. Corps of Engineers contractors drove 150 feet (50 m) of steel piles through the channel to seal it.
Texas Army National Guard Chinook and Blackhawk helicopter teams had placed an average of 600 7,000-pound sandbags each day in the breaches. Depending on the lift capacity of the helicopters, Corps of Engineers riggers averaged one to three connections every two minutes during the day. Sandbagging operations ran for 24 hours over ten days and, with the breaches closed, were suspended on 10 September.
Several crane barges were also used to place bags of sand and gravel, and other barges were used to transport equipment, pumps, generators and people to the sites.
By Sunday, September 11, 2005, the number of operational pumps had risen to 74 from 174, and High Capacity Pumping Station 6 was expected to be back online within days. Officials reduced the maximum amount of time needed to evacuate water from New Orleans to 40 days or the end of October 2005.
By September 12, 2005, water had surpassed the temporary closure of the breach in the London Avenue canal due to operations at Pump Station 3. This caused the canal to rise faster than the temporary pumps at the end of the canal could drain. Operations at Pumping Station 3 were immediately stopped and some sheet piles were removed to allow the canal water level to equalize.
September 13
For nearly a week, Plaquemines Township floodwaters were naturally receding through three breaches and one deliberate notch. The dewatering operation was seeing results approaching 14,000 cubic feet per second (400 m³/s) pumping from Orleans, East Orleans, and St. Bernard townships. In the area of the 17th Street Bridge, water marks on homes showed evidence of at least a six-foot drop in water levels. In Plaquemines Township, five of ten permanent pumps were pushing more than 4,100 cubic feet per second (116 m³/s). 27 of 104 permanent pumps and 43 temporary pumps were operating, pushing more than 13,000 cubic feet per second (368 m³/s) out of the New Orleans metropolitan area.
Corps of Engineers crews in San Bernardo Municipality closed Highway 48 to allow drainage to Pump Station 8. At Pump Stations 1, 4, 6 and 7, the Corps of Engineers installed floating barriers to protect the facilities from oil hazards. The Corps continued to monitor the area. Crews also installed a temporary roof on Pump Station 7, allowing the station crew to begin necessary maintenance. The mission in the Municipality of San Bernardo was expected to be completed the following week.
At East Orleans, four more portable pumps were added in support of Pump Station 15 to increase total capacity to 1,100 cubic feet per second (31 m³/s). For the first time, the Jahncke pumping station reached its maximum capacity of 1,200 cubic feet per second (34 m³/s). The Citrus and St. Charles pump stations were operating at half capacity because the Citrus station had to draw power from a generator at one of the other two stations. The total possible capacity for these two stations was 1,750 cubic feet per second (50 m³/s).
The Corps of Engineers cleared the rock dam on Lake Shore Drive, removing the sheet pile and lifting the wire sheet to allow Pump Station 3 to continue pumping at high speed. Corps personnel were monitoring both rupture sites in the London Avenue canal throughout the day.
Corps contractors were expected to complete the road to the second London Avenue breach the next day.
Half is done
By September 15, 2005, the city's flooding had reduced from 80% to 40%, although the flooded areas were not expected to be habitable for long. In Orleans Township, most of New Orleans' Ninth Ward and the southern part of Orleans Township were dry enough for normal reclamation operations to begin. Water remained in the northern part of the municipality and would be pumped using pump stations 12 and 4, and reinforced with a dozen temporary pumps. Pumping efforts in the lower Ninth Ward were removing water at a rate of 12 million US gallons (45,000 m³) per day. Some construction work continued in the canal breaches at 17th Street and London Avenue where helicopters were precisely placing 7,000-pound sandbags to reinforce existing repairs and crews were armoring sandbag closures with rock. Contractors kept cranes at the sites to regulate flow levels by adjusting sheet pile walls at the mouths of canals in Lake Pontchartrain. Construction of the access road to the second gap of the London Canal north of Mirabeau Bridge was completed on 14 September. San Bernardo Township was almost completely dry, with the only significant water accumulation remaining in the Chalmette tract. However, recovery in the Municipality of San Bernardo was limited by the spill of petroleum products from local oil facilities. In Plaquemines Township, repairs to levee breaches continued and were nearly ready for large-scale pumping of the affected areas. Most of the fixed pump stations in Plaquemines Township had survived the storm.
The focus of pump repair efforts shifted from Pump Station 1, which was now operating, to Pump Station 4 in Orleans Township. On September 15, 7.5 billion US gallons (28,000,000 m³) of water were pumped out of the city. The previous day's estimate of 11.8 billion gallons (45,000,000 m³) was not met because one of the main pumping stations was running out of water to pump and most of the pumps in the Municipality of St. Bernardo were out due to the successful completion of the mission. The overall effort was estimated to be completed by early October.
Based on a field survey, the Corps of Engineers identified nine gaps that needed to be repaired to provide a minimum level of protection to the affected municipalities. Of these, seven had been repaired to date, one was being used to allow drainage to leave San Bernardo Township and one was being treated in Plaquemines Township. Furthermore, the dikes had been deliberately cut in two places in the Municipality of San Bernardo to facilitate the mission. Of these, one had been closed and one was still in use.
• - Gap in the 17th Street canal in the Municipality of Orleans. Repaired.
• - Northern gap in the London Canal in the Township of Orleans. Repaired.
• - Southern gap in the London Canal in the Township of Orleans. Repaired.
• - Northern gap in the IHNC in the Municipality of Orleans. Repaired.
• - Southern gap in the IHNC in the Municipality of Orleans. Repaired.
September 18
The U.S. Army Corps of Engineers conducted a detailed assessment of approximately 350 miles (560 km) of hurricane levee and developed a comprehensive, prioritized plan to repair it and the pumping stations supporting New Orleans and surrounding areas. "The system in its current condition did not guarantee that the city would be protected against flooding caused by storms or hurricanes," said Col. Duane Gapinski, commander of the Task Force. Gapinski said residents could put their lives and property at risk by re-entering flooded areas until additional repairs are made to emergency levees. State and local leaders were informed as assessments were completed and repairs were made.
The recovery of New Orleans was seen as a three-phase process: first and most immediate, to evacuate the city and evaluate flood protection. Second, provide an interim level of protection to get the city through hurricane season and subsequent flooding and, in the long term, to return the system to pre-hurricane conditions. This will require a great deal of study, research, funding and construction.
The Corps of Engineers estimated that the New Orleans area was more than 80 percent dry. Corps officials estimated that the overall drainage effort, given normal seasonal rainfall, would be completed no later than early October 2005. Tropical Storm Rita was being closely monitored at the time. Additional traffic in the city over the past three days caused some delay in travel to the job site and in the transportation of emergency repair equipment.
Preparing for Hurricane Rita
By September 21, 2005, the Army Corps of Engineers had begun closing two damaged canals at midday in preparation for storm surges associated with Hurricane Rita. The 17th Avenue and London Avenue canals were closed with steel sheet piling overnight and remained closed until the threat of severe weather passed. The steel sheets would be sunk deep into the canal beds near Lake Pontchartrain, providing protection from potential lake surges rushing into the damaged canals.
More than 800 filled sandbags were available, and another 2,500 were ordered. Work continued throughout the day to make emergency repairs to damaged walls and dikes.
Flood from Hurricane Rita
By September 23, 2005, although high water caused by Hurricane Rita flowed over the temporary closure on the Industrial Harbor Navigation Canal, the structure remained intact. This relocated part of East New Orleans.
November and December
The Corps of Engineers continued work in November and December 2005 to fill gaps in the London Avenue and 17th Street canals, as water continued to seep through temporary street gap repairs.
Completion of temporary repairs
In January 2006, the Army Corps of Engineers announced that temporary repairs to the Industrial, London Avenue and 17th Street canals had been completed. A project for more permanent repairs began.
Future improvements
In January 2007, the Army Corps of Engineers, after visiting the extensive "Delta Works" dike system in the Netherlands, awarded a $150 million contract to a group of Dutch engineering companies for the evaluation, design and construction management of dikes and retaining walls. special closure structures for the protection of communities adjacent to the Inner Harbor Ship Canal, major pumping facilities, and planning studies for enhanced levels of flood protection for New Orleans and southern Louisiana. The Delta works are a series of constructions built between 1953 and 1997 in the south-west of the Netherlands to protect a large area of land around the Rhine-Meuse-Scheldet delta from the sea. The works consist of dams, gates, locks, dikes and storm surge barriers. Work began after the 1953 North Sea flood in which 2,170 people died.
Since Katrina, the US, through the Army Corps of Engineers, has made a $14.45 billion investment in the area around New Orleans. Some of the projects include:
• - The world's largest water pumping station (Gulf Intracoastal Waterway West Closure Complex) which can pump 1 million US gallons (3,800 m³) per minute and will cost $1 billion.
• - Hundreds of improvements to dams and pumping stations.
• - The IHNC Lake Borgne Surge Barrier, the longest surge barrier in the United States.
• - The Seabrook Floodgate, a floodgate connecting Lake Ponchartrain to the Industrial Canal.