Dry floodproofing
Dry floodproofing systems are intended to keep water from entering and can be temporarily deployed or permanent. They can be part of the original site design or incorporated into flood management plans for existing facilities. Sandbags have traditionally been used as a temporary barrier system in advance of storms to limit moisture infiltration. Temporary barrier systems can be flexible or rigid.
Flexible systems include water-filled flexible tubes in multiple configurations, self-inflating barriers, and barriers that rely on flood water pressure to open the barrier system completely and hold it in place. These products have multiple sizes and configurations based on the level of flood protection anticipated to be required. However, these systems can be susceptible to puncture and other damage if large debris is present in flood waters.
Rigid barrier systems include temporary modular walls, panels, or blocks joined together with gasketed connections to limit seepage. They can be installed in multiple configurations and come in multiple sizes to provide different levels of flood protection. Permanent flood walls with openings for access can also be considered. Access openings in a permanent wall would then be protected through installation of a temporary system. Flood glazings, which are reinforced glass elements, can be used in flood walls to maintain sightlines and/or provide an aesthetically pleasing permanent flood wall. However, these glazings are anticipated to require more regular cleaning and maintenance than other permanent wall materials, such as concrete. The advantages and disadvantages of each material should be considered during the design phase.
Many different products are available for the various system types discussed herein. To assist building owners with the selection of reputable flood protection products, Factory Mutual Global (FM Global) has developed a standard for testing flood protection systems (FM Approvals 2510, ANSI 2510) and allows products which have been tested and passed to indicate their FM approval on marketing materials. However, some products with this seal of approval may only be tested and approved in certain configurations.
In addition to dry floodproofing products, sump pumps and other accessory products may be incorporated into the flood plan to reduce stormwater within the protected areas and seepage beneath or through protection systems.
Conclusion
It is critical to work with a project team focused on the development and implementation of a facility-specific FERP. This plan should include selection and maintenance of appropriate product(s) that work together as a flood mitigation system to protect against the agreed-upon flood protection design parameters. It is equally important to maintain this plan and periodically reassess the parameters and systems as the climate continues to change.
Notes
1 See the maps at msc.fema.gov/portal/home.
2 Visit the Boston Water and Sewer Commission (BWSC) storm app at www.bwscstormviewer.com/stormapp.
Authors
Kimberly A. Kilroy, PE, RRC, CDT is a project manager at Gale Associates, Inc. She performs roof, wall, and window evaluations, analysis, and design, including the development of technical specifications, drawings, and details.
Peter Spanos PE, CFM, LEED AP is a senior project manager at Gale Associates, Inc. He is responsible for project engineering related to site design and permitting, with a focus on flood mitigation.
