Seattle Spotlight: Creative Outfall Protection for School Safety

As a code requirement, nearly every stormwater design must include outfall protection, including several of Seattle’s Public Schools. Where water is released from a system, outfall protection, sometimes called a “splash pad” such as gravel or cobbles must be used to dissipate the force of water and prevent erosion. While working with Seattle Public Schools on several design projects, the stakeholders identified a need to secure the splash pad materials to prevent students from injuring themselves or others.  

AHBL was challenged to find a solution which balanced the technical and aesthetic needs, while creating a safe environment for students. At Ingraham High School, cement was poured over existing cobbles as an emergency solution to the perceived safety issue of loose rocks on a school ground. However it minimized the splash pad’s ability to dissipate water and therefore didn’t provide a long-term solution. For future development, our Civil Engineering and landscape teams worked toward an intentional, well-thought-out solution.  

Currently, there are no “Best Practices” for this design challenge, Civil Engineer,  Bethany Steadman, toured the nearby Magnolia Elementary School which had utilized some creative methods to secure loose materials.  

Our in-house Landscape Architects and other design professionals designed slate “steps” to slow water, pervious paving splash pads and intentionally cemented cobble stones. AHBL is utilizing these potential solutions among several Seattle Public Schools projects out to bid, to determine which solutions work best. Through collaboration and creative thinking, our Civil Engineering and Lanscape teams were able to provide a variety of options to the client and balance the unique needs of the projects.