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Reassess Floodplain Models to Protect Your Facilities

It’s not just you; the seemingly nonstop news reports about extreme weather events are the due to the increase of such extreme weather in recent years. A 2018 report from Science Daily found that the number of floods and other hydrological events across the globe have doubled since 2004 and quadrupled since 1980. Plus, it’s not just coastal communities that are affected. Inland flooding events in the United State and around the world are on the rise.

 

As extreme weather becomes more common, owners and investors in various types of facilities need to ensure their buildings have the appropriate protection. Regardless of the type of structure, facilities in many parts of the United States in close proximity of a water body face a heightened danger of flooding.

 

Despite this significant risk, facility owners and managers may not be fully aware of the threat or have the most accurate information to assess their risk exposure.

 

If you own, operate, or invest in any facilities or other commercial property, the most logical question becomes how do I properly assess the flood risk for my facility?

 

Reassessing existing floodplain models for your buildings is the best place to start.

 

Carolyn Howard, Regional Manager for Site Development and Infrastructure with Draper Aden Associates, has worked on many floodplain models. She notes that reviewing current models will help facility owners and managers better assess their risk and have a more accurate picture of that risk.

“My best advice is to always check and verify the existing flood model for an area where a facility sits,” Howard says.

She adds, “Furthermore, for those who plan to renovate an existing facility or construct a new building in or near a mapped floodplain, taking a second look at approved flood models could save a lot of headaches and extra costs, and help to protect your investment in the future.”

 

Creating accurate flood models or maps for facilities is really all about proper risk management and cost management. For existing structures, it’s important for owners to protect their investment by understanding the extent of the risk present, so they can properly mitigate it. That mitigation can take various forms, including robust insurance policies to structural changes to a facility.

 

It’s important to remember that in most of the country flood elevations aren’t going to decrease over time. They’re going to keep rising as storm intensity increases.

 

For facilities that are under renovation or new buildings (either in the planning or construction stages), you need to make decisions about where to site a facility on a specific property. You also must consider and balance the finished floor elevation and its relation to the regulatory floodplain elevation with accessibility requirements. Many states and local governments require the finished floor elevations of new buildings to be one to three feet above the regulatory floodplain elevation. If your project is only required to be at or one foot above the base flood elevation, you might want to consider raising the finished floor elevation even more. The decision comes down to your risk tolerance today and into the future.

 

For all types of facilities – existing, under renovation, and under construction – insurance is vital and an accurate flood elevation can ensure you have the right amount and type of coverage.

 

Howard also notes that in addition to helping manage risk and preparing for proper flood proofing measures, updated flood models can yield cost savings for new facilities or those planning renovations. In many cases, approved regulatory flood models are not always accurate because they may underestimate the potential flood elevation. In some instances, older floodplain models have been shown to overestimate the threat of flooding, which could result in significant costs placed on facility owners.

 

“My best advice is to always check and verify the existing flood model for an area where a facility sits,” Howard says.

 

She points to an example from Clifton Forge, Virginia. A private foundation wanted to renovate and transform the Historic Masonic Theater back to its former glory as part of a broader revitalization effort in the downtown area. As in many historic communities, a creek runs along – or underneath – the town. In Clifton Forge, the west bank of Smith Creek is the east wall of the Masonic Theater.

creek theater wall

The regulatory Federal Rate Insurance Map (FIRM) showed the creek overtopping Main Street in the downtown area during flooding events and was based on a 1978 model that had not been updated. Anecdotally, no one could ever recall the creek overtopping the road, even during significant rain events. This led to further investigations into the accuracy of the existing model. A new model that incorporated updated topographic data for the area demonstrated that the actual flood elevation should be up to 5.5 feet lower upstream of Main Street than what was in the FIRM.

 

The foundation, which owns and manages the theater, presented this new information and model to FEMA. After a thorough review, FEMA accepted this updated model and adopted it as the approved regulatory flood model for the area. With the newly lowered flood elevation, the foundation saved significant costs on flood prevention and proofing of five feet along the building face. These cost savings were crucial to financing the project and bringing it to fruition.

 

This example highlights the upside of reassessing established floodplain models. This effort can yield significant savings. Updated models also can serve as a powerful risk management tool to protect the long-term viability of a facility. In either case, taking a second look pays off.

The regulatory Federal Rate Insurance Map (FIRM) showed the creek overtopping Main Street in the downtown area during flooding events and was based on a 1978 model that had not been updated. Anecdotally, no one could ever recall the creek overtopping the road, even during significant rain events. This led to further investigations into the accuracy of the existing model. A new model that incorporated updated topographic data for the area demonstrated that the actual flood elevation should be up to 5.5 feet lower upstream of Main Street than what was in the FIRM.

fema flood map

The foundation, which owns and manages the theater, presented this new information and model to FEMA. After a thorough review, FEMA accepted this updated model and adopted it as the approved regulatory flood model for the area. With the newly lowered flood elevation, the foundation saved significant costs on flood prevention and proofing of five feet along the building face. These cost savings were crucial to financing the project and bringing it to fruition.

 

This example highlights the upside of reassessing established floodplain models. This effort can yield significant savings. Updated models also can serve as a powerful risk management tool to protect the long-term viability of a facility. In either case, taking a second look pays off.

This blog post is part of a series exploring projects and services that have helped clients realize their goals in a cost-effective manner that saves time and money as well as help them manage risk. Click here for additional blog posts in this series, which covers a variety of engineering challenges.