Green Infrastructure Toolkit

Effective Monitoring of Pilot Sites

A critical component of a successful pilot program is to demonstrate the performance of the green infrastructure installations. Monitoring a project’s performance (across goals and benefits) allows decision makers to make informed decisions about how to adapt the design of future projects based upon the performance of existing projects.^{See footnote 1}  This section of the toolkit describes the types of monitoring that local governments can perform for pilot sites to quantify co-benefits beyond stormwater management, meet regulatory requirements, create accurate performance standards, and use monitoring program to help make the transition from a pilot stage to jurisdiction-wide green infrastructure programs.

Local governments can use monitoring data to assess the feasibility of meeting their priority goals with green infrastructure projects, alone or in combination with traditional infrastructure.^{See footnote 2}  While goals for green infrastructure fundamentally include water quality, green infrastructure also offers an array of co-benefits that can add value and maximize the value of these investments across multiple sectors. Identifying and measuring these co-benefits through monitoring may contribute to positive cost benefit analysis and multi-sector/public buy in for green infrastructure programs. Known as a triple bottom line (TBL) approach, local governments can conduct an assessment of the co-benefits associated with green infrastructure, including environmental, social, and economic factors.^{See footnote 3} 

Regulatory Requirements

EPA guidance on Clean Water Act compliance encourages use of green infrastructure installations in local government plans, particularly to achieve water quality requirements.^{See footnote 4}  Permits and enforcement agreements that incorporate green infrastructure must include green infrastructure performance criteria and post-construction performance standards.^{See footnote 5}  To set these criteria, decision makers must first have designed their pilots to include a monitoring component that gauges their performance and sets those performance standards going forward.

The strength of green infrastructure, however, is in its ability to deliver more than just stormwater management and water quality benefits. The following discussion of the triple bottom line takes into account a variety of so-called “co-benefits” that green infrastructure can deliver on an everyday basis, not only during heavy precipitation events. Additionally, green infrastructure can be deployed more quickly than large-scale gray infrastructure projects, resulting in a shorter timeline to realize those benefits. While gray infrastructure is undoubtedly necessary for management of the most intense storms, gray and green infrastructure in combination may provide both protection against extreme events and many of the triple bottom line benefits listed below. By monitoring and quantifying those benefits, local governments may be able to build greater support in the community and among other partner agencies that might initially be skeptical.

Triple Bottom Line (TBL)

In monitoring pilots, collecting data to measure triple bottom line (TBL) goals provides important information on the co-benefits associated with green infrastructure programs. By quantifying these co-benefits in the pilot program stage of implementation, the broader eventual green infrastructure programs can integrate projections about TBL benefits.^{See footnote 6}  Because different green infrastructure types may achieve TBL values to varying extents, decision makers may choose pilot projects with particular TBL co-benefits that would best serve their communities’ interests.^{See footnote 7}  This section next discusses the economic, social, and environmental co-benefits that green infrastructure pilots can provide, and that local governments can monitor for achievement of those benefits.

Economic: Long-term projections based on economic co-benefits can assist decision makers in budgeting and maximizing capital investments. Project proponents can use data demonstrating economic savings in costs avoided (including gray stormwater infrastructure that would otherwise have needed to be built), economic gains in added green jobs, or higher property values, to build public and private support for green infrastructure projects. The Philadelphia Water Department’s Comprehensive Monitoring Plan, for example, analyzed its monitoring results from green infrastructure sites and found that the green infrastructure plan for Clean Water Act compliance was projected to be $7.8 million more cost effective than a gray stormwater plan alone.^{See footnote 8} 

Social: Monitoring for social co-benefits enables integration with other sustainability goals such as addressing environmental justice. Using pilot sites to design for and monitor social benefits may also boost community support where pilot sites are located.^{See footnote 9}  Social co-benefits of green infrastructure projects may include: reduced health risks associated with both urban heat islands and air pollution, increased recreational opportunities, lower localized crime rates,^{See footnote 10}  access to fresh produce via community gardens, safer traffic flow, and more.^{See footnote 11} 

Environmental: In addition to addressing stormwater runoff and associated pollution, green infrastructure sites add environmental value by supporting important ecosystem services in urban settings. Ecosystem services provided by green infrastructure sites may include: improved air quality from increased urban forest, new wildlife habitats, soil erosion control, decreased localized flooding, and more. These important features may help local governments contribute to reducing the coming impacts of climate change, and are quickly realized due to the short timeline for installing green infrastructure relative to large gray infrastructure projects.^{See footnote 12} 

Beyond triple-bottom line considerations, monitoring of pilot installations for a variety of outcomes can also help local governments achieve a variety of goals, including meeting regulatory requirements, creating accurate performance standards, confirming site selection, and scaling up from pilot stage to jurisdiction-wide green infrastructure programs.

Performance Standards

Local governments can use monitoring data to adapt management of green infrastructure projects and to model the projected benefits of larger programs.^{See footnote 13}   Performance standards can include rates of runoff, capacity for stormwater retention, reductions in pollution, and more.  Performance standards provide a scale to determine program success and to create accurate expectations for the future, as well as enabling decision makers to adapt programs based on performance as they go.^{See footnote 14}

Scaling Up

To successfully move from the pilot stage of a green infrastructure program to a jurisdiction-wide program, local governments need accurate, comparable data. Pilot sites can provide data sets by which decision makers can set goals for large-scale green infrastructure program.  Monitoring data can also be used to help decision makers anticipate both costs and benefits of projects and set targets for long-term implementation,^{See footnote 15}  including integrating green infrastructure plans into existing processes such as street design standards or zoning codes.