Green Infrastructure Guidance: Making LID in the Right-of-Way Standard Practice

Variations in Green Infrastructure (GI) Low Impact Development (LID) Best Management Practices (BMPs) within the right-of-way have resulted in problems with construction, maintenance, and durability. GI implementation guidance documents, standard details and specifications provide uniformity in planning, design, construction, and maintenance. By standardizing how LID is placed in the Right-of-Way agencies can reclaim valuable space for people to enjoy, turn a burden into a resource, reduce irrigation demand and stormwater runoff, and provide for a sustainable and resilient transportation corridor. When green stormwater infrastructure is integrated with complete street concepts numerous co-benefits strengthen the three pillars of sustainability; the environment, social equity, and the economy. San Diego County is one agency that implemented GI guidelines and standards. Green Infrastructure Guidelines are an outreach tool and are also intended to serve as a companion to the rest of the Green Infrastructure publications. They include an introduction, strategies, procedures and design examples for implementing Green Infrastructure projects. The strategies include tree wells, rain gardens, rock gardens, and permeable pavement. Green Infrastructure Design Criteria lay out general definitions, general policy, and landscape design criteria for Green Infrastructure strategies. Green Infrastructure Design Standard Drawings includes construction details which may be referenced in improvement plans. Green Streets Maintenance Schedules include a list with maintenance tasks, frequency, and time of year for initial, routine, and as-needed maintenance of each strategy. Green Streets Specifications include detailed construction material and installation requirements for strategies including aggregates, geosynthetics, underdrains, permeable pavement, engineered soil media, mulch, overflow risers, check dams, and tree grates. Building on the GI guidelines and standards developed within the Southern California region, these concepts were integrated into a Climate Resilient Infrastructure Guidebook for Riverside and San Bernardino Counties in southern California including climate resiliency strategies related to stormwater. The Guidebook complements city-level, climate-related transportation hazards and evacuation maps and other products developed as part of a larger resilient infrastructure initiative. The Guidebook serves as a guide to help educate local practitioners in making the transportation system more resilient to these changes. It is intended as a practical resource for jurisdictions and includes strategies, best practices, and methods for overcoming challenges and using climate resiliency tools to address changing patterns of extreme temperatures, heavy precipitation and flooding events, and drought. It was tailored to address the diverse climate, terrain, and needs of the region to ensure the long-term viability of the transportation system. Stakeholder groups and agency staff are instrumental in identifying implementation priorities and correcting procedural barriers to implementation. There is typically limited surface and underground area available within the right-of-way to accommodate often competing needs for travel lanes, parking, bike lanes, pedestrian sidewalks/paths, and utilities. In constrained right-of-way areas, this often leads to limited availability for implementation of green/climate resilient infrastructure strategies. Another challenge to implementing strategies within the public right-of-way includes often conflicting jurisdiction regulations, codes, ordinances, and standards from various levels (local through Federal) due to differing priorities of various project elements. Standardizing the implementation, design, construction, and maintenance of green stormwater infrastructure provide multiple benefits for the public and stakeholders. Integration of green stormwater infrastructure elements into transportation planning, resiliency studies and guidelines provides effective tools for planners and engineers to address changing patterns of extreme temperatures, heavy precipitation and flooding events, and drought.