SESSION B3-B Look up! Vegetated roofs for urban stormwater management

A resilient southeast relies on the profession of landscape architecture, and it’s cross-disciplinary, collaborative process to deliver solutions that balance competing interests, design goals, budget, and jurisdictional requirements. Our role is particularly important when managing stormwater and responding to the impacts of climate change, which requires us to supplement or replace single-purpose grey infrastructure with resilient natural infrastructure. 

In urban areas and other constrained sites where stormwater infiltration is infeasible, vegetated roofs can perform valuable water management functions by retaining rainfall, detaining runoff, and increasing evapotranspiration. Although these qualitative stormwater benefits are commonly accepted, there is little guidance for designing the quantitative hydraulic performance of green roofs during individual storm events. As a result, design professionals are reluctant to claim stormwater management benefits for projects and regulatory officials are reluctant to allow green roofs to satisfy stormwater requirements. 

Fortunately, the state-of-the-practice is shifting towards a view of green roofs as infrastructure and is supported by NC DEQ which recognizes green roofs as a Primary SCM. The presentation builds the case for green roofs in conjunction with, and sometimes in place of, single-purpose grey infrastructure for economic and environmental reasons. The presentation will outline methods to quantify hydraulic performance during design storm events, share how to design a green roof for maximum performance, provide case studies of green roofs that meet state stormwater requirements, and identify characteristics of suitable projects to use green roofs to satisfy state requirements. We will outline a successful path to utilizing green roofs for stormwater requirements. 

Learning Objectives:

• Understand the North Carolina requirements for stormwater and provide examples of green roofs that meet North Carolina stormwater quality and quantity control standards.

• Understand the characteristics of suitable projects for using green roofs to satisfy stormwater requirements and the barriers to utilizing green roofs as an approved Stormwater Control Measure. 

Presentation/lecture supported by a slideshow of images, infographics, and local and regional case studies. We will provide ample time for question and answer/discussion following the presentation.