Getting Schooled: Floodproofing Existing Structures for Increased Resilience

28 May 2019
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  • What do you do when your existing structures — especially those you plan to renovate — don’t meet current flood regulations?
  • What do you do when your facility is historically flood-prone and you want to mitigate future damages?
  • How can you implement low-impact, cost-effective solutions for maximum protection?
  • What can you do to make your facility or your campus more resilient?

As peak storm season gets underway, these are likely some of the questions that facility owners and managers are asking about their properties in flood-prone areas. Each year, floods cause more than $40 billion in damage worldwide (OECD) and almost $8 billion in the United States (NOAA). Flooding is the most common and costliest natural disaster in the U.S., affecting every state (NFIP), and is a threat year-round, not just during peak season.

Houston, Texas is certainly no stranger to flooding, having experienced unprecedented flood events in recent years that wreaked havoc on many property owners and campuses, prompting new, increasingly restrictive floodplain regulations and re-mapping of flood zones. With NOAA issuing new rainfall frequency probabilities across the U.S., many urban areas are seeing significant increases in the rainfall frequency probabilities, adding to the concern of being adequately protected.

YES Prep Gets a Big ‘NO’
When YES Prep, a Houston open-enrollment public charter school system, purchased an existing commercial office building to house their Yorktown campus, they were initially unaware that repurposing the building from commercial to institutional would change their requirements for flood protection.

As an office building, it met the floodplain development criteria, but because it was being redesigned and renovated as a school, which is deemed a “critical” facility, the building was required to be protected 12 inches above the 0.2% Chance (500-year) floodplain instead of 12 inches above the 1% Chance (100-year) floodplain. The YES Prep new Northwest Campus building was about 14 inches shy of meeting that requirement, so their initial plans to renovate the space into a school were rejected by the floodplain management office.

Getting to ‘YES’
With renovations stalled and an opening date that simply wasn’t flexible, YES Prep’s Director of Operations Keith Weaver contacted Walter P Moore for guidance. Experts from the firm’s Civil Engineering, Water Resources Engineering, and Diagnostics Groups teamed up with Element Architects to quickly evaluate the conditions and devise a flood protection solution that was elegant, simple, and cost-efficient to implement.

A combination of both active and passive measures, the resulting flood protection system consists of an 18” poured concrete curb within the wall cavity around the entire structure (passive element) and an overhead “drop-down gate” system (active element) designed to meet YES Prep’s unique campus needs while preserving aesthetics of the new school building.

Structural flood protection measures are generally classified as active or passive. According to the Federal Emergency Management Agency (FEMA), active measures are systems that require human intervention or power to operate correctly and need sufficient warning time to mobilize the necessary labor and equipment in order to implement. The drop-down flood gate is considered an active protection measure. Passive measures do not require any human intervention, and because of this, can be thought of as 24/7 flood protection. The new curb wall meets the definition of passive protection.

Walter P Moore worked closely with PS Flood Barriers™ to design and fabricate the overhead door system to be unobtrusive and easy to deploy and operate. The “gate” is a flood log that is attached to a guiderail concealed within the door jam. The “gate,” when open, is hidden above the ceiling; you can’t tell it’s there unless you know about it. The doors are deployed manually with a hand crank, similar to a tire tool. Because they are manually operated, the doors can still be operational in the event of a power outage. This custom, one-of-a-kind design is a good example of innovative, low-impact flood mitigation.

A Campus Approach
When managing a campus of facilities, one of the best measures for mitigating flood damage and increasing resilience is moving all critical infrastructure and building systems out of basements and ground-floor levels. This was perhaps one of the most crucial components of our flood mitigation plan that we devised for the University of Texas Medical Branch (UTMB) at Galveston, following the devastating Hurricane Ike that flooded more than 1 million square feet of first-floor space in 2008.

In addition to elevating all critical equipment above first levels, we recommended connecting facilities at second levels to maintain critical operations and access. Relocating and protecting utilities and MEP systems were also imperative, as the breaching of these systems during Ike caused significant and prolonged damage. Physical plants were relocated to higher, safer ground and heavily protected with flood walls and doors, enabling the continued operation of UTMB’s campus during future large storms, including 2017’s Hurricane Harvey.

Similar flood protection measures were designed and implemented throughout the Texas Medical Center (TMC) campus in Houston, Texas. Protection systems included flood gates, doors and walls, flood marine doors to isolate buildings, training on the Rice-TMC early warning systems, waterproofing of electrical and mechanical systems, and increased sump pump capacities.

Working with Texas Children’s Hospital and other Texas Medical Center institutions connected to them, our team developed a multi-institutional protocol for shared operations to ensure that all the facilities would be engaged when specific conditions dictated closure.

Getting Your Facility to ‘YES’
A good place to start for floodproofing your facility or campus is to assess your property’s flood risk. While it’s best to engage engineering professionals in evaluating your property, here is a checklist to help you perform an initial assessment of your risk.. Floodwaters will always take the path of least resistance, which is why a thorough site evaluation is a critical first step for flood protection.

During a flood event, electrical power is typically lost, building personnel are often unable to get onsite due to rising floodwaters, or are simply unfamiliar with the flood emergency plan that has been put in place for the site. If any one of these occurs, active flood measures are prone to, and sometimes do, fail to get implemented. The best way to minimize that risk is the development of sound emergency protocol that is documented and practiced often.

Passive measures are a preferred course of action when protecting critical assets against flooding events. It should be understood, however, that passive measures cannot always be implemented when retrofitting a site for flood mitigation. This may be due to site constraints, accessibility, and operational constraints. Most flood protection systems are a combination of active and passive protection.

As owners become more cognizant of the effects flooding has on their long-term investments, they should partner with engineering design professionals, who can assess their property and design an efficient, low-impact, and cost-effective floodproofing system to best fit their needs. Whether for a single facility or an entire campus, each flood protection system — whether active, passive, or a combination of the two — is custom-designed to best fit the parameters of the site, the building(s), the owner’s budget, and operational staff.

FEMA National Flood Insurance Program (NFIP) -
Flood Safety Tips and Resources -
Organization for Economic Cooperation and Development (OECD) -
National Oceanic and Atmospheric Administration (NOAA) -
What’s Your Potential Flood Risk? A Checklist for Property Owners (by Charlie Penland) -

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