5 Ways To Improve Green Infrastructure

By Peter Chawaga

There is a problem with the way that many communities deal with stormwater.

Conventional stormwater infrastructure simply moves runoff away from densely populated areas, oftentimes overwhelming sewer systems and contaminating local waterways in the process. Impervious concrete carries stormwater to streams and lakes, picking up urban pollutants along the way. This infrastructure also keeps the water from entering groundwater supplies, exacerbating drought issues.

That is why many communities are turning to green infrastructure for stormwater management, like rain gardens, porous pavement, and green roofs. It can play a vital role in meeting stringent stormwater regulations, managing volatile water supplies in the face of long-term drought, and creating more sustainable places to live.

“An increasing number of communities are exploring green infrastructure solutions in stormwater management,” a U.S. EPA spokesperson told Water Online. “Communities need to project long-term costs and effectiveness of green infrastructure as part of integrated water management solutions, looking across stormwater, wastewater, drinking water, and land conservation practices.”

To help them do so, the EPA is promoting its suite of digital models and tools for planning and implementing green infrastructure. The five applications included in the suite can help communities assess their needs for more sustainable stormwater management and figure out how to make it a reality.

“It is important to identify the most cost-effective practices to support sustainable solutions,” the spokesperson said. “These tools help water utilities address current and emerging issues affecting supplies of clean water.”

The Green Infrastructure Wizard (GIWiz) can be used to index the EPA’s websites, fact sheets, datasets, calculators, scientific papers, and other resources available to help make implementation decisions. Users can access the “explore” function, which serves as a searchable library, or the “quicklinks” function, which provides a pre-sorted list of resources for 12 objectives that the EPA considers most important for green infrastructure.

“Think of this as EPA’s ‘greatest hits’ for key decision objectives, such as finding out what other communities are doing or finding ways to pay for green infrastructure,” the agency spokesperson said.

The Watershed Management Optimization Support Tool (WMOST) is a graphical interface for identifying the management practices to consider for a given watershed, along with the implementation constraints they will bring. This covers land conservation, incentives to conserve water, leak repair in distribution systems, changes to existing infrastructure, aquifer storage, interbasin transfers, and more. WMOST has default costs plugged in, but if they have more accurate local data, users can enter it to get a more precise sense of the best practices for their community. The latest version of WMOST will provide a table showing which management practices are the most cost-effective, the level of implementation, and the sub-cost of each practice.

“WMOST represents the only free optimization tool supporting the application of green infrastructure within an integrated water management framework at the community and small watershed scales,” said the spokesperson.

The Visualizing Ecosystem Land Management Assessments (VELMA) Model has been used to estimate changes in water quality due to climate change and forest management over the next 100 years in Seattle’s Tolt River Watershed, according to the EPA. VELMA simulates water, nutrient, and contaminant cycling within watersheds to provide information on how they could be retained within plants and soils. It can identify where nutrients and contaminant transportation is concentrated and can give communities a better sense of where green infrastructure may be needed.

“Land use planners are using VELMA to identify where to locate green infrastructure, what type of green infrastructure would be most effective for those locations, and how much green infrastructure is needed to achieve a water quality target,” the spokesperson said. “VELMA currently simulates cycling and transport of nitrate, ammonium, dissolved organic nitrogen and carbon, and mercury within watersheds. Phosphorus, pesticides, and petroleum products are being added.”

With the Storm Water Management Model (SWMM), users can select the type of green infrastructure they want to install, input the physical characteristics and the area that generates the runoff, and receive a process model for the green infrastructure stormwater controls that can be added to intercept the runoff before it enters the sewer.

“Based on this information, SWMM can calculate the runoff reduction and the water balance in the green infrastructure stormwater control,” said the spokesperson.

Finally, the National Stormwater Calculator (SWC) produces stormwater runoff estimates in conjunction with SWMM, based on the project site size, land-cover, meteorological data, climate change scenarios, and the types of green infrastructure practices that the user selects.

Ultimately, these tools have been developed to give municipalities easier access to the breadth of information on green infrastructure that exists. By making it simple to do so, the hope is that more communities will implement sustainable solutions.