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Designing an Effective Flood-Protection System

03 June 2024 Doug Coenen

This article originally appeared in the June 2024 issue of Informed Infrastructure


For decades, scientists have warned about extreme weather. Droughts, wildfires, oppressive heat and floods are frequently sweeping the globe. Such extreme weather is impacting communities in a major way from damage to properties as well as infrastructure. 

Floods alone have cost U.S. taxpayers more than $850 billion since 2000 and are responsible for two-thirds of the cost of all natural disasters, according to Flood Defenders, a nonprofit organization with the goal to make flood protection a top priority for elected officials. 

To help mitigate flooding and other natural disasters, the $1.2 trillion Infrastructure Investment and Jobs Act is designed to make the nation’s infrastructure resistant against the impacts of climate change and extreme weather events. So far, the funds trickling down for actual flood-related projects have been slow, and there are preventive measures that can be implemented now—design and planning—as they relate to infrastructure as well as structures. 

Although each have their own distinctive needs regarding flood protection, a properly designed and installed flood-protection system can prevent floodwaters from causing severe damage. The time to start planning for a flood is now—not after disaster strikes.

Determining Flood Risk

First, it is critical the design team and owner work together to create a system that ensures the proper flood protection. After the owner is informed about potential flood risks for their property, a flood-protection system must be designed to meet current needs, and it must be upgradeable to meet any future needs as conditions change. 

Defining the flood risk for a site contains many different considerations the owner must weigh to define the level of acceptable risk which, in turn, starts to define elevations and extent of protection. Risk is measured in the probability of flooding recurrence, cost of protection vs. cost of recovery, impacts to operations and reputation of a facility that experiences a flood, cost of insurance for a facility prone to flooding, and the emotional impacts of surviving a flood. If the cost includes potential loss of life, then the risk rises to an even higher level. Flood risk includes, but is not limited to, the property being mapped in a Federal Emergency Management Agency (FEMA) effective flood zone. The analysis includes how often and how high it floods. It also looks at other flooding source risks not identified in floodplain maps. This information is explained as part of an initial analysis that identifies flood exposure. 

Each property has unique flood risks based on a multitude of flooding sources, including natural and man-made occurrences. Understanding how water drains to and from a property is important in determining these risks. It’s helpful to know the history of flooding and how to look for information that may indicate risk, and every region has its own unique ways to handle and quantify drainage. 

Flood risk is one of the most difficult things to comprehend; water damage can be devastating and demoralizing. Ultimately, the owner should be provided the proper information to assess whether investment in flood mitigation is warranted. 

When an owner determines flood protection is necessary, the protection plan is developed from the initial designs based on a feasibility study conducted at the project’s onset. The study further identifies points of exposure to floodwaters, identifies potential levels of floodwaters, determines the protection system to address current and future points of exposure, and works through any other related issues with the system. The latter may include code requirements, agency interface requirements, anticipated costs, impacts to operation and project schedule. After issues are addressed in the feasibility study, the flood-protection system is moved to the design phase. 

The design phase, based on owner decisions, advances concept development from the feasibility study. Following the proof of concept, the design evolves to include schematic design, design development and construction process. Concurrently, the budget must be tracked and any design changes vetted with the owner.

Alignment Among Partners

A proactive owner can address flood risk by assembling a cohesive team that understands the specific flooding concerns of the facility and infrastructure to be protected to deliver a properly executed project. 

“The correct partners are important when defining and planning solutions, developing the design, and constructing the flood-protection project,” says Ray Drexler, a principal and project manager in the Diagnostics Group at Walter P Moore. “A diverse team for any flood-protection project is essential, as there are several different facets that must be addressed.” 

For example, in addition to knowing flood-protection design, team members must have a strong understanding of potential funding mechanisms, insurance impacts, flood risk to the surrounding community, and the impact of flooding on the infrastructure and surrounding areas. It is also important to have the ability to address code issues, architectural design elements, MEP design requirements and, where warranted, landscape architecture. 

After the team is selected, there should be alignment among all parties: a team leader is chosen, and each role must be clearly defined. Frequent communication among all team members, including the owner, leads to a better-defined, priced, and executed project. 

A flood-protection system must address myriad features, consider the various requirements for implementation, and provide requirements to keep the flood-protection system operational and maintained. In addition, if government funding is involved, the system should be designed and implemented with a FEMA consultant to meet any regulatory requirements. 

“A critical group beyond the owner and design team includes FEMA consultants as well as FEMA representatives themselves,” says Drexler. “FEMA and their consultants must be included from the onset of the project so they may be able to voice any concerns to the design team and owner.” 

A FEMA consultant’s feedback is critical to the design team because it may impact financial or regulatory issues. Regular meetings between FEMA and the design team are necessary early in the project to verify approaches and funding streams. A good FEMA consultant can help navigate some of the various bureaucratic processes to ensure reimbursement isn’t jeopardized by not correctly following procedures.

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