Green Infrastructure Guidelines for Corridor Projects: What You Need to Know  

Green infrastructure is most commonly used to help improve water quality and reduce sewer overflows in densely populated cities, but the concept has more recently been adopted by the transportation industry to help manage stormwater where it falls and keep it from entering stormwater collection systems in the first place. Some dense, urban communities are taking an area-wide approach, integrating their infrastructure plans to introduce elements like porous pavement and subsurface aggregate storage into their rights-of-way (ROWs). Others with more available space are using green parking lots and bioswales to convey their stormwater to retention basins downstream. Whatever the approach, the benefits of effective stormwater management, improved aesthetics and added resiliency can make the decision to implement green infrastructure a no-brainer.  

But green infrastructure is about much more than planting trees and building rain gardens. And the two most common questions that arise— ‘who will maintain it?’ and ‘how will we pay for it?’—must be addressed before any assets are built. 

Ginny Roach, PE, PMP, BCEE, CDM Smith’s national leader in green infrastructure planning and design, has helped municipal and private clients across the U.S. with their stormwater management plans. Thanks to decades of experience conducting site visits, interviewing staff, compiling design drawings, and reviewing historical documents, Ginny and her team have developed a list of guidelines to assist cities in operating and maintaining successful green infrastructure programs. Here they are. 

Guideline #1: Develop design standards 

Having a group of standard design details and specifications, as well as geotechnical investigation and ROW survey procedures, will help to save considerable planning and design costs, and make construction easier over time as contractors became familiar with and understand the designs. In addition, these design standards and procedures help make leaders and stakeholders feel confident that green infrastructure practices are being planned and constructed properly.  

Guideline #2: Utilize project prioritization tools to track success   

As one of the first steps in building a best-in-class green infrastructure program, cities should identify a system for quantifying, tracking and monitoring program benefits. A number of illustrative, interactive tools have been developed; many include mapping components that to help monitor program benefits such as water quality improvements or tree canopy coverage changes. Others include regulatory calculators so cities can ensure compliance on ROW projects with multiple types of green infrastructure installations. 

New York City Department of Environmental Protection (NYCDEP) and CDM Smith, for example, developed a dashboard and asset management system called GreenHUB to track the progress of green infrastructure construction, as well as to provide a digital ‘file cabinet’ for storing design drawings, reports and other submittals over the life of each asset. The system includes an interactive map to help keep the community engaged and show them what’s happening in their neighborhoods.

Guideline #3: Access available funding  

There’s a wide variety of funding methods that can be used for green infrastructure programs. Here’s a look at how some cities are maintaining their assets: 

• Water and sewer rates: San Francisco, New York City and Toronto  
• Parcel tax: Los Angeles  
• Stormwater utilities: Detroit, Philadelphia, Columbus, Cleveland, Harrisburg and Tucson  
• Grants and incentives: Milwaukee, New York City and Houston  

Guideline #4: Design with maintenance in mind  

As one of the first steps in the program management process, cities should explore how different types of green infrastructure assets can help them problem-solve. If the project area has problems with trash buildup, hardscapes (rather than planted areas) can lessen flooding impacts when debris inevitably collects in infiltration basins and street gutters. If you’ve already predicted that maintenance is going to be an issue, opt for grasses instead of plantings to minimize upkeep.  

It’s also a good idea to prepare for continued upkeep. Cities like San Francisco have created youth programs that offer opportunities for students at local high schools and elementary schools to rehabilitate green infrastructure sites and help with general maintenance. Others, including Syracuse and Hartford, CT chose to implement green job training programs that target underemployed demographics in the area. Maintenance agreements can also be “baked in” to construction contracts to give municipalities time to get a dedicated department up and running.  

Guideline #5: Foster community engagement  

Community input and active involvement from local residents, businesses, district leaders and artisans promotes acceptance, integration and ownership, explains Roach.  

Done right, green infra­struc­ture sites should not serve only as stand-alone free spaces, fenced off, and utilitarian in nature. They should be designed as restorative inter­ven­tions into blighted communities, prior­i­tiz­ing aesthetics, community-specific amenities, and passive recreation space. “Rather than taking the space to fix issues downstream, they give space back,” Roach says.  

Take, for example, the Northeast Ohio Regional Sewer District (NEORSD), that included the work of local Cleveland artists in its Union Buckeye project. Poetry was inscribed in plaza seating areas surrounded by rain gardens (and located above subsurface storage and infil­tra­tion systems), with custom-fabricated trench drains, a water tower sculpture and a bike rack symbolizing the water treatment practices within and under the plaza. This community engagement helped to beautify a previously downtrodden area while also spreading the word about the importance of water quality. 

Guideline #6: Branding = buy-in 

Program branding helps garner both internal and community-wide support. Cities have used program-specific logos, promotional videos, native-language speaking brochures, interactive maps, and other program materials to familiarize the public and keep stake­hold­ers abreast of the program’s progress and success.  

As Roach reminds clients, not all green infra­struc­ture is created equal, so munic­i­pal­i­ties with well-established guidelines can place a greater priority on instal­la­tions that fulfill the specific orga­ni­za­tion’s goals. “We also recognize that one size certainly does not fit all with regard to imple­men­ta­tion. That’s why our approach is tailored to the specific needs of each urban community, as well as the regulatory require­ments, zoning, rainfall patterns, soil types, topography, hydrology, and public interests of each project area,” she adds.