An Overview Of Our Solution
More than 123 million people in the United States live in coastal areas (NOAA, 2010). As sea levels rise, weather patterns shift and extreme weather events intensify, more and more of these areas are in danger of catastrophic flooding. From Katrina's devastation of New Orleans in 2005 to Hurricane Sandy's flooding of New York in 2012, coastal areas previously thought safe from inundation are already at risk. The Buoyant Foundation Project aims to provide inexpensive retrofits to existing houses that will allow property and possessions to survive both repetitive seasonal and occasional extreme flooding. Unlike erecting extensive levee systems or rebuilding structures to a higher elevation, amphibious construction works in synchrony with a floodprone region’s natural cycles of flooding, while remaining relatively inexpensive and able to cope with ever-increasing flood levels. Most importantly, it is a bottom-up solution that individual homeowners can apply themselves, rather than a top-down solution dependent on infrastructure megaprojects and government relief agencies.
- Population Impacted: 300 at first; eventually it could be millions
- Continent: North America
Address
1105 Susan Street
Breaux Bridge, LA 70517
États-Unis
Hazard
Identify the likelihood and frequency of this hazard
Explain how vulnerable the community is to this hazard
List the potential affects of this hazard
Identify how sensitive the community is to these affects
Preparedness Goal
Implementation Actions
The Buoyant Foundation Project is a formalization and adaptation of the successful grassroots solutions developed from the bottom up by the inhabitants of Old River Landing in Point Coupee Parish, Louisiana. Using their own ingenuity, scrounged materials, and roughly $5000 in buoyant foam blocks and steel for guidance posts and structural underpinning, homeowners in Old River Landing have adapted their structures to cope successfully with seasonal flooding in their community. The Buoyant Foundation Project seeks to apply that spirit of individual initiative and low cost to a design suitable for retrofitting on a large number of existing homes increasingly endangered by flooding. Initially, focus has been on how to adapt a particular long and narrow type of vernacular architecture known as the ‘shotgun house’, as this typology is common in the bayou communities most threatened.
An amphibious foundation retrofit is comprised of a structural subframe built within the crawlspace underneath a house, underpinning and reinforcing the existing structure to support the house. Buoyancy is provided to the structure by EPS foam blocks or empty recycled barrels. Outboard of the house are fastened telescoping steel guidance posts, which ensure that when floating above its foundations the building moves only vertically and does not drift laterally, guiding it back down to its solid foundations as floodwaters subside. Sewer and gas lines have self-sealing breakaway connections, while typical electrical and water lines are replaced with long, coiled ‘umbilical’ lines. This system allows a home to detach from its solid foundations and rise dynamically with the water level, floating above the flood until the waters drain and the house can return to its original position. Crucially, an amphibious retrofit functions entirely passively, ensuring that it operates as intended even during secondary flood effects like power outages.
Describe Your Solution
A house that can float when floodwaters rise keeps household possessions and water-sensitive equipment from being submerged, prevents structural damage caused by the lateral forces of water, wind and debris, will function even during power outages, and will adapt dynamically to a large range of flood levels. Compared to static elevation (the principal flood-mitigation strategy promoted by US government agencies), it is half the cost, does not hinder access to the home or disrupt lifestyle, will keep the house above water even at flood levels above design height, and does not increase the structure's vulnerability to other factors like hurricane winds.
Inhabitants of houses with amphibious retrofits still need to evacuate until floodwaters subside (currently the design is not intended for continued occupation of the house while floating), but after the flood, residents can return to find their homes and possessions intact. This provides a low-cost option that protects the most valuable assetsof those who live in areas beyond the defensive lines defined by government agencies. Individuals are no longer dependant on government infrastructure megaprojects. Community members can affordably protect their homes against the possibility of regional flood defences failing. Damage control on flood plains can be decentralized. Flooding is no longer a catastrophic event of ever-increasing frequency, but a common but survivable inconvenience.
Above all, amphibious construction suggests how to sit lightly on the land and live with flooding, rather than attempting to obstruct this natural process. Amphibious foundations make homes resilient, and resilient homes lead to resilient communities.
Economic?
For the low-income homeowner in a vanishing delta community, an amphibious foundation retrofit may be among the very few solutions within his or her financial means. Replacing one’s possessions and rebuilding one’s home every year is impossible. Spending more than the value of the house to raise it up on stilts does not make economic sense. Retreating to higher ground is difficult and expensive, particularly if the land left behind has suffered a severe devaluation. If the homeowner wants to continue a traditional way of life on lands inhabited for generations, then adaptation to the flooding may be the only economically, socially and culturally viable option.
Environmental?
Flood cycles in a river delta are a natural occurrence. Before human settlement it was the annual deposition of sediment that kept pace with natural subsidence in the delta. The old solution of building levees and canals to control flooding has robbed the wetlands of their ability to replenish soils lost to the sea. The fresh water and nutrients brought by floods were essential to maintaining the delta’s marsh ecology, which is now in rapid decline. If no longer dependent on massive levee and diversion systems to protect themselves, communities can coexist with the natural annual flood cycle, and help restore their vanishing ecosystems.
Coastal communities must also learn to live with sea level rise. Amphibious housing presents intriguing possibilities in the quest for sustainable responses to the impending global climate change crisis.
What were the negative or unintended impacts (if any) associated with implementing this solution?
Amphibious foundation retrofits can be aesthetically unappealing. Visually, the guidance posts located on the outside of a retrofitted structure can look out of place on a traditional style of home. The visible steel of guidance posts and other structural components may not match the material palette of wood-and- shingle vernacular architecture. In new construction, the guidance posts can be integrated into the design so that they are unobtrusive. For retrofits, it is entirely possible to reduce the visual impact of the guideposts by installing them to telescope out of the ground, but this design feature is more expensive than the exterior static post.
Return on Investment: How much did it cost to implement these activities? How do your results above compare to this investment?
One of the main focuses of the Buoyant Foundation Project is that its capital costs be manageable for a typical homeowner, especially those with a fixed or low income as they are often the most sensitive to disaster damage. In the community of Old River Landing in Point Coupee Parish, individuals were able to improvise retrofits on modest homes with about $5,000 in materials (primarily steel and buoyant foam blocks). The prototype built at the LSU Hurricane Centre in 2007 cost $5,200 in materials, with mostly volunteer labor. For a fully engineered solution applied to a 1000-square-foot, single-storey home, the cost to implement is estimated at roughly $20,000-$25,000 if installed by a general contractor, or $10,000-$15,000 if installed by the homeowner.
What are the main factors needed to successfully replicate this solution
As global climate change causes sea levels to rise and weather events to become more extreme, severe flooding will become more commonplace around the world. The large populations living in deltaic or riverine floodplain regions will be particularly severely affected, especially those living at the lowest levels of income. Amphibious housing presents a sustainable and affordable response to the climate change crisis at a global scale.
For the Buoyant Foundation Project to succeed elsewhere, its design must be adapted to fit the local conditions, culture, materials and labor. Keeping the capital cost down requires a considered approach to the entire system, as regional differences in cost and supply may make one material a logical choice in some areas but prohibitively expensive in others. For example, in less industrialized regions around the world, large blocks of foam may be unavailable or cost-prohibitive. Barrels or even bundles of recapped empty bottles could be suitable substitutes. Design elements can be altered to suit the homeowner’s skills and ability to construct the retrofit themselves. The Buoyant Foundation Project intends to make buildings adaptive, but it must be adaptively applied in and of itself.
Our goal is to improve the well-being of populations around the world that are currently facing the choice between leaving their traditional homelands or living with the disruption and devastation of repetitive seasonal and/or severe occasional flooding. Amphibious solutions could provide a much-needed answer.