Blending Green and Gray
One major issue with current asset management practices is their focus on manmade (gray) infrastructure to the exclusion of green infrastructure. The maturation and strengthening of asset management programs for gray assets provide an opportunity to extend the principles and practices to green infrastructure. For many communities, green infrastructure will be a complement to gray infrastructure rather than a replacement. By blending gray and green infrastructure provides opportunities to save money, improve the environment, or increase operational efficiency.
Different departments, entities, or governmental agencies, within a community may manage, design, and/or operate green and gray infrastructure. This segmented approach can create barriers to widespread implementation of green infrastructure and might prevent utility staff and the community from seeing benefits of green or natural projects. Communities and systems should consider the holistic picture of gray and green infrastructure to achieve the greatest financial, environmental, and social benefits from their water infrastructure.
There are a wide variety of definitions for green infrastructure. To effectively implement the integrated asset management framework, here are the definitions that will be used for green and gray assets in this guide.
GREEN ASSETS
Natural and engineered green assets. Green assets range in scale from single tree site applications, such as stormwater planters or rain gardens, to large-scale approaches using constructed wetlands or a forested watershed.
GREEN INFRASTRUCTURE
Any practice that uses or replicates the functions of natural systems to achieve the desired outcome and often provides multiple community benefits. Green infrastructure does not exclusively mean vegetation. For example, permeable surfaces are considered green infrastructure because they handle rainfall the same way natural landscapes do.
GRAY INFRASTRUCTURE
human-engineered water resource infrastructure made from concrete, plastic, metals, and stone. Gray infrastructure includes pipes, treatment plants, water meters, culverts, pumps, storage tanks, and many others that typically have a single purpose.
The goal of a blended green and gray framework is to enable utilities to make better, more efficient, effective, and environmentally friendly decisions. It can move individuals away from the belief that only concrete and steel solutions can work to create a more holistic view of the available options. It can provide a more expansive view of the types of alternatives that can yield the desired results and the co-benefits that can be achieved.
By considering both approaches together from the beginning, communities can incorporate green infrastructure early enough to potentially reduce the amount of gray infrastructure needed to meet water quality objectives cost-effectively and on schedule. The main intent is to enable the consideration of a full range of choices so that each community can make informed decisions.
Green Asset Resource Database
This green infrastructure database serves as an introduction for those looking to learn more about green and natural assets that are used in water, wastewater, and stormwater systems. It will give users a basic understanding of the design, construction, O&M, costs, and benefits associated with each of these assets. It also provides some relative comparisons between the different infrastructure types related to construction and maintenance. If there are any assets you think should be added, please contact Hayley Hajic.
Other Resources
- Green Infrastructure Overview – American Society of Landscape Architects, Green Infrastructure Overview: Benefits, Forests & Nature Reserves, Wildlife Habitat & Corridors, Cities, Constructed Wetlands, Green Streets, Green Roofs & Walls
- Green Stormwater Infrastructure Asset Management Resources Toolkit, page 37 – Story: Portland, Oregon – Incorporating Streams into Asset Management.