By Luke Carothers
The City of New Orleans in Louisiana is among the most revered cities in the world for its rich history and vibrant, diverse culture. A strong component of this cultural tradition is a sense of enduring resiliency, which is demonstrated through continually rebuilding after large-scale weather events. With much of the city located below sea level, it is no wonder that the citizens of New Orleans are experienced in dealing with floods brought on by hurricanes.
One New Orleans neighborhood–known as Gentilly–has seen more flood damage than most. The first residential neighborhoods in the Gentilly area were constructed in the early 20th century when residents piled earth on top of swamp land to create terraced homes. With Lake Pontchartrain bordering it to the north and Bayou St. John to the west, Gentilly is uniquely susceptible to intense flooding events. During Hurricane Katrina in 2005, Gentilly was among the hardest hit areas of the city when the London Avenue Canal Floodwall was breached in two places.
As a result, subsequent improvements in disaster preparedness have been proposed and undertaken by the City of New Orleans to improve the safety of the people living in the neighborhood. In 2015, the U.S. Department of Housing and Urban Development introduced the National Disaster Resilience Competition. The City of New Orleans participated by submitting a proposal to create the City’s first Resilience District in the Gentilly neighborhood.
Known as the Blue and Green Corridors project, the City’s proposal focuses on overarching goals such as: reducing flood risk, reducing subsidence, improving the community’s quality of life, and encouraging economic growth and social revitalization. To achieve these goals, there will be a combination of projects and efforts within the community that focus on innovative solutions to water management.
The City’s proposal was accepted and they were awarded $141 million in funding in addition to funding previously allocated through the U.S. Federal Emergency Management Agency’s Hazard Mitigation Grant Program. The City chose Stantec to lead the project, and they have developed a number of solutions that improve the area based on a triple bottom line analysis–flood reductions, healthier lifestyles, and economic activity. By building a team that includes engineers, landscape architects, and planners, it is clear the project was approached from a more holistic perspective. More specifically, a triple bottom line analysis not only looks at the cost of completing a project, but also value added by factors such as air & water quality, public health outcomes, public education, and heat island effect.
According to Bernadette Callahan and Dan Grandal, much of the work surrounding this project represents a “paradigm shift toward what it truly means to live with climate change…providing an example of a path to success to communities aspiring to resilient and sustainable living.”
This paradigm shift also applies to changing from the traditional approach to water management to something called “Living with Water”. Traditionally, cities such as New Orleans rely on a water management system that collected stormwater runoff in pipes that led to pump stations. Despite having some of the largest pumping facilities in the world and making improvements such as high levees, the area still struggles to deal with over 60 inches of rainfall annually as well as rising water from climate change.
“Living with Water” aims to lessen the burden on the City’s stormwater system by introducing “infiltration-based green infrastructure practices and strategic storage solutions”, according to Callahan and Grandal. More specifically, this means constructing, planting, and growing vegetated systems that are capable of managing stormwater runoff. Consisting of elements such as stormwater bumpouts and rain gardens , this green infrastructure “mimics the natural environment and pre-development flow patterns by slowing stormwater runoff and giving it a chance to infiltrate back into the ground”. In an area such as New Orleans, re-introducing water into the ground is particularly important due to the high clay content. Keeping the clay-based soil consistently wet helps prevent soil subsidence.
The team at Stantec also had the community in mind when working on the Blue and Green Corridors project, employing a concept known as the “Complete Streets” approach. In essence, the “Complete Streets” approach is predicated on designing streets that prioritize safety, comfort, and access for everyone who uses a street: walkers, runners, bikers, and vehicles. Because the team at Stantec completed extensive community outreach in the planning stages for the project, they were able to design in such a way that puts the community first. This includes steps such as including high visibility crosswalks and accessible curb ramps, but it also includes strategically placed infrastructure, such as the stormwater bumpouts, to slow vehicle speeds and reduce the distance between crosswalks.
According to projection models, improvements made by the Blue and Green Corridors project even have the potential to reduce flooding, even in the areas surrounding the project, by up to six inches. This highlights the potential of the system, and it demonstrates a path forward to reducing flooding in the City of New Orleans by building new systems that work in tandem with the old.
In a community where flooding is at the forefront of concerns, the Blue and Green Corridors project is proof that we can use new, innovative techniques to supplement our previous understanding in order to improve the lives of those who live in the community.
Mary Kincaid, PE–Project Manager
Dan Grandal, PE, LEED AP, CFM–Principal-in-Charge
Bernadette Callahan, PE–Project Manager and Green Infrastructure Lead
Will Bane, PE–Project Technical Lead and Drainage Design Lead
Amy Seek, RLA, WEDG
Travis Ewen, ASLA, WEDG
Mike Rutkowski, PE, AICP
Luke Carothers is the Editor for Civil + Structural Engineer Media. If you want us to cover your project or want to feature your own article, he can be reached at firstname.lastname@example.org.