|Emissions Reduction Toolkit||Climate Resilience Toolkit||Climate Resilience Guidelines|
Vulnerable building sites can be protected from floods through the use of levees and floodwalls. Levees and berms are structures made of compacted earthen materials with interior cores of impermeable soil (i.e. clay). Construction typically begins with excavation to ensure subsurface soil conditions are taken into account in design. Floodwalls are typically engineered structures made of reinforced concrete. Floodwalls can be built up to 20 feet in height and can be designed to be aesthetically pleasing architectural and landscape features. Floodwalls are typically more expensive to construct than levees, but require less space and landscaping and are more resistant to erosion. Construction of all floodwalls and levees should be undertaken by licensed engineers.
Due to the large amount of space needed for construction, the use of levees and floodwalls may be difficult and cost prohibitive in urban environments and may only be suitable for integration into new construction. In particular, levees and berms require a large quantity of earthen fill, and a lack of readily available, nearby fill may cause transportation costs to be prohibitive. Higher levees and floodwalls require significantly more support to withstand the greater water pressure exerted on the barrier. Strengthening levees and floodwalls requires increases in size, which may exceed the amount of space available on a building site and become impractical. Levees are typically limited to 6 feet in height and floodwalls to 4 feet to maintain cost-effectiveness. Sites with expected flood depths that exceed practical barrier heights should consider using alternate methods (e.g. elevation or floodproofing) instead of or in addition to permanent flood barriers. Barriers must be located a sufficient distance away from structures with basements to prevent damage to basement walls from the additional pressure from saturated soils. Regular maintenance is crucial to maintain service life.
With the reality of climate change threatening coastal security worldwide, it is essential to both proactively mitigate the effects, such as preparing against flooding from sea level rise, and combat the root causes by taking action to lower emissions, promote sustainability measures, and raise environmental awareness.
Potential regulatory touchpoints in Boston and Massachusetts include: