By Steven H. Miller, CDT
The project consisted of 8.2 miles of floodwall, the deadline was termed “do or die,” and the construction time was diminished by a third. Still, Cajun Constructors of Baton Rouge, an AGC of America Mississippi Valley Branch member, finished LPV 148.02 in the Chalmette Loop Levee four days early and earned a 2012 Alliant Build America award in the category of Federal and Heavy New for this model of mobilization, organization and quality control.
One of the areas hardest hit by Hurricane Katrina was St. Bernard Parish, La. The 25-ft storm surge was higher than the roofs of many houses. It destroyed the levee system and most of the buildings those levees had been protecting. The US Army Corps of Engineers (USACE) designed improvements and extensions of the levee system. One of the very last links in the chain of protection was LPV 148.02, a new reinforced concrete T-wall supported by steel H-piles, built on top of the earthen levee from Verret to Caernarvon.
The earthen levee had been repaired, and raised three to four feet higher than its pre-Katrina elevation, but USACE computer modeling suggested that the wall needed to be significantly higher than before – 13-15 feet higher – and that could not be done effectively with earth.
The contract was awarded in late February 2010 as an early contractor involvement (ECI) project, with a construction schedule of about a year.
USACE designed a pile-supported concrete floodwall to sit atop the earthen levee. It had sheet-pile cutoffs driven down the center 42 feet deep and long H-piles driven at oblique angles. The project included one highway gate, five environmental and utility gates, and installation of new knife valves at St. Mary Pump Station.
Then, due to an engineering delay, USACE did not release the H-Pile schedule until October 2010. However, the June 1, 2011, deadline remained, compressing total construction to just eight months.
“The colonel [USACE New Orleans District Commander Col. Alvin Lee] had promised two different presidents that the people of Louisiana would be protected,” explains Cajun Constructors’ project manager Thomas Charrier, “so it was June 1 or die.” Failure was not an option.
“It was definitely a very ambitious and aggressive schedule,” recalls Chris Gilmore, USACE project manager for St. Bernard Parish, “but we had no doubts that we’d be able to meet the deadlines. We had a very committed team, both the government staff and the contractor. We were fortunate in being able to award this contract to a very well-qualified contractor.”
Massive resources were brought to bear. The project was divided into five management areas, and subdivided into 18 work areas each comprising 2,500 feet of wall. Up to 1,400 people worked on-site, 1,100 of them direct hires and 300 subcontractors. Each management area had a quality control (QC) manager and two or three QC personnel, a total of 23 QC personnel on-site.
They built 8.2 miles of limestone access road and crane leveling pad.
Then 1.8 million sq ft of sheet pile started to arrive. There were ultimately 18 pile drivers working on the site, six of seven of them working on a 24-hour basis.
The project required 18,000 H-piles, 2.2 million linear feet. Over 7,500 piles were in the 144-to-166-ft range, but the longest pile they could buy was 130 feet, so they had to be spliced. Fifteen splicing yards were set up, 11 at locations along the length of the project, two others with land access, and two with marine/land access, with some yards working around-the-clock, and 150 welders working them. There were 30 full-time welding inspectors, since 100 percent of splices had to be visually inspected, as well as 25 percent subjected to magnetic particle inspection and 25 percent to ultra-sound inspection.
Extended trucks and water barges delivered the H-piles. One complication involved a bridge that could only carry ¾ ton loads. Large loads couldn’t make the 100-yard trip and had to take a 16-mile detour instead.
Another complication was alligators. “Several gators were removed by animal control,” chuckles Cajun’s quality control manager Jesse “Tres” Wilkins. “The biggest was about 12 feet. He was laid up against the sheet piling one the morning.”
Soon the site resembled a forest of cranes, 136 of them at one point, ranging from 90 tons to 350 tons. As the H-piles were received on the jobsite, pile-driving crews immediately began driving them. Then came a stabilization slab crew with a 65-ton picker crane, then a base slab crew with an 80-ton lattice boom crane, and finally a wall crew with a 100-ton lattice boom crane.
On their best day, they placed almost 34,000 linear feet of pile.
By early April 2011 they had logged one million man-hours. They were placing on average 2,000 cubic yards of concrete per day. Twenty on-site technicians field-tested concrete properties. They had two batch plants set up exclusively for the project, going seven days a week, with 60 dedicated trucks rolling from 2 a.m. until 8 p.m. They used 129,000 cubic yards of concrete in all, reinforced by 9,000 tons of rebar.
Despite 24-hour work schedules at multiple locations performing dangerous activities, Cajun Constructors did not have a single OSHA-recordable safety incident. Hurley Henson, Cajun’s divisional safety manager of division 01 (flood walls), credits a far-reaching and rigorously enforced safety program.
“We always have a very intense safety orientation,” says Henson, “but we went further this time, because 90 percent or more of the workers had never worked for us before.”
Everyone went through Hazard Awareness Training comprising 52 topics, with new employees having safety mentors for the first 90 days. Once in the field, anyone involved in an incident or serious near-miss had to go back and re-do the entire training before they could return to work.
“We had a lot of pile driving,” explains Henson. “That directly relates to the safety hazard. You have to barricade your swing radius, and make sure non-essential persons are out of range. H-piles are driven with a diesel hammer. The pile can come out of the template. You don’t want non-essential employees in there because you want to minimize the hazard.”
Henson’s ”very aggressive safety team” were required to be in the field 80 percent of the time looking for hazards. “We had safety people assigned to each area, and a safety committee of at least two employees from each area. They would spend an hour a day walking the site with the safety person. We swapped out committee members every two weeks, so each employee learned the process.”
They poured the last part of the wall on May 27, 2011, four days before the impossible deadline.
Gilmore says, “That job was managed extremely well. I think they went above and beyond. It was an extraordinary accomplishment.”