The report includes an “Emerald City” green infrastructure scale to assess how each is doing.

The six-point scale identifies the primary actions every city can undertake to maximize its green infrastructure investment, including:

• A long-term green infrastructure plan for the city

• A retention standard

• A requirement to reduce existing impervious surfaces using green infrastructure

• Incentives for private-party action

• Guidance or other assistance in deploying green infrastructure

• A dedicated funding source.

Nashville is doing three of these things:

The city’s Green Infrastructure Master Plan was finalized and approved in 2009.

In addition to identifying various green infrastructure practices to be used within downtown’s 12.3-square mile stormwater planning district, the plan provides a detailed analysis of the impacts that four green infrastructure practices would have on the volume of stormwater runoff: rainfall harvesting, green roofs, urban trees, and infiltration practices such as permeable pavements and tree planters.

Metro also has a plan to implement green infrastructure within the city. In 2006, Nashville’s Department of Water and Sewage Services (MWS) updated its Stormwater Management Manual to incorporate green infrastructure practices as solutions to erosion and sediment control during site construction.

Practices included were green roofs, bioretention (the process in which contaminants and sedimentation are removed from stormwater runoff) and permeable pavement.

Also incorporated into the manual were post-development water quality and quantity requirements. Metro Nashville and MWS have implemented several other projects that engage and inform citizens of green infrastructure practices, such as partnering with the Army Corps of Engineers and a local nonprofit to develop an informational website and resource guide about rain gardens.

Also in 2009, Nashville completed a $4.5 million pilot “green street” demonstration project, converting a major downtown road into a pedestrian-friendly corridor using bioretention planters, bioretention curb bump-outs, a landscaped median, porous sidewalks and shade trees.

Nashville also has a dedicated funding source for green infrastructure. Metro’s stormwater business plan includes a dedicated user fee for stormwater drainage, with the rate structure based on a property’s total impervious surface area. The city also draws from its general fund, internal service fund, federal funds and private funding.