The 100-page report details findings from a survey of 52 public-sector stormwater management organizations across the U.S. that serve approximately 44.5 million people in total. It establishes a national-level dataset that illustrates how the public sector currently uses green infrastructure, identifies remaining barriers to further implementation, celebrates successes, and helps jurisdictions of all sizes unlock green infrastructure’s potential to meet multiple community goals.

“We are excited to provide these new insights into the state of green infrastructure implementation in the public sector,” said Barbara Hopkins, Green Infrastructure Leadership Exchange Executive Director, in a release. “We believe this report will be a valuable resource for communities looking to expand their green infrastructure efforts while centering community and ensuring long-term sustainability.”

Changing Regulations Drive Investment

Although the frequency with which public-sector stormwater organizations choose green infrastructure solutions over traditional pumps and pipes varies widely, report findings suggest that green infrastructure adoption is on the rise. In fiscal year 2022, capital expenditures on green infrastructure among survey respondents ranged from zero dollars to more than USD $90 million, with a median spend of USD $280,000.

Operations and maintenance costs for green infrastructure also ran the gamut, representing a median spend of USD $100,000, but as high as USD $5.3 million. About 61% of respondents indicated that their green infrastructure spending has increased at least somewhat during the last 5 years, with several reporting significant increases.

These organizations reported that meeting regulatory requirements for water quality was by far the most common driver for greater investment in green infrastructure. Nearly 90% of respondents ranked regulations that specifically promote green infrastructure as an acceptable compliance option as a “very important” motivator for investment. Meeting regulations outpaced such priorities as enhancing flood resilience, mitigating pressure on aging drainage and wastewater systems, and improving residents’ quality of life.

Report authors describe that this finding demonstrates that regulators are increasingly acknowledging the value of green infrastructure as a viable approach to water quality improvement. Likewise, stormwater organizations are eager to take advantage of this increasing regulatory flexibility.

Remaining Barriers

However, significant barriers to green infrastructure adoption remain in the regulatory space. Many respondents reported technical and institutional hurdles that decrease their confidence in green infrastructure, such as insufficient data on green infrastructure’s return on investment given its site-specific nature, a lack of design standards provided in codes and ordinances, and a lack of coordination among different types of green infrastructure-minded agencies. In some cases, state regulations did not explicitly specify green infrastructure as an acceptable approach to meet water quality requirements.

Survey results uncovered a range of additional insights, including that

• strong green infrastructure champions, such as elected officials and senior government/agency personnel, can play a critical role in unlocking funding for green infrastructure and supporting policy changes that support green infrastructure;
• innovative procurement approaches for green infrastructure planning, design, and delivery are growing in popularity, such as design-build contracts, public-private partnerships, and incentive programs;
• the broader U.S. green infrastructure sector suffers from a lack of standardization, including differing metrics to measure costs and performance, which hinders the usefulness of case studies and demonstration projects; and
• many respondents struggle to effectively incorporate environmental equity into their green infrastructure programs.

Poised for Further Growth

During the next 5 years, survey results indicate that public-sector green infrastructure is poised for additional growth.

73% of respondents predicted at least a modest increase in annual green infrastructure spending during the next 5 years as compared to the 2022 fiscal year, 16% of which predicted a significant spending increase.

Respondents also signaled efforts to expand green infrastructure coverage in specific areas in the coming years, due in part to the spread of emerging programs that incentivize green infrastructure development on private property.

In line with existing trends, publicly owned roadways are expected to be the most common location for new green infrastructure during the next 5 years, with 69% of respondents indicating plans to increase expenditures in these settings. Similarly, more than 50% of respondents expected to increase green infrastructure coverage on both public and private parcels through retrofit initiatives.

The report recommends a range of actions available to local stormwater agencies, nonprofit groups, governments, and other organizations to help promote public-sector green infrastructure adoption.

Public stormwater agencies of all sizes, according to the report, should focus on building green infrastructure-focused partnerships with other agencies in their region as well as elected officials. They should leverage these partnerships to influence simple policy actions that create new flexibility for green infrastructure. For example, working to classify green infrastructure as a capital investment in local codes can unlock new municipal funding sources, and requiring green infrastructure inclusion in new construction and redevelopment projects would spur its use.

Nonprofit groups should work to facilitate peer exchange regionally by supporting standardized performance metrics, units of cost, and terminology. State and federal governments can formalize this process further by codifying industry consensus around these standards into regulations and best practices.

Read the full report, The State of Public Sector Green Stormwater Infrastructure 2022, and explore additional insights from the survey via the Green Infrastructure Leadership Exchange’s State of the Field Data Dashboard.

Top image courtesy of Brigitte Werner/Pixabay

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Public-Sector Green Infrastructure on the Rise, New Report Finds appeared first on Stormwater Report.

Francine Kelly-Hooper, Ph.D., an Ontario, Canada-based expert in contaminant forensics, has devoted nearly 20 years of her career toward searching for a better solution. Since 2004, Kelly-Hooper has investigated stormwater pond sediments. Her research stretches across Canada and beyond to identify the substances sediments contain, the human and ecological risks these substances may present, and ultimately whether landfilling sediments is the only safe management option.

Her findings have shown that stormwater pond sediments often are not the unpredictable cocktail of contaminants they are often assumed to be. These sediments even may lend themselves to opportunities for beneficial reuse.

By demonstrating the safety of reusing sediments under the right circumstances, Kelly-Hooper and her partners have thus far earned regulatory approvals for five sediment reuse projects in Ontario — the only known approvals of their kind in Canada and beyond.

“When I started this work, the only question people had was ‘Can we avoid hazardous waste disposal?’” Kelly-Hooper said. “There was this assumption that stormwater pond sediments contained unpredictable contaminant mixtures, but what we found was that they typically contain road salt and asphalt pavement particles with low metal concentrations.”

A Hidden Financial Crisis

As stormwater ponds became a common tactic to sequester runoff and prevent urban flooding only around the 1990s, it took several years before the effects of sediment accumulation on their function became apparent. In the early 2000s, Kelly-Hooper’s home city of Waterloo, Ontario, became one of the first municipalities in Canada to investigate sediment removal logistics for its 40+ stormwater ponds. The city contacted Kelly-Hooper, then an independent consultant, to assess the substances these sediments contained as well as estimate total disposal costs.

“Once we got the results back, we realized that Waterloo was going to have to pay [CAD] $40,000 for just one pond, but the money was not set aside for it at that time,” Kelly-Hooper said. “The city managers did the math and realized they were going to lose about $10 million for all of their ponds combined, and it caused a big, chaotic reaction. I was worried about how this loss could affect the locally funded social programs in my city.”

Those kinds of numbers for a single, mid-sized city made Kelly-Hooper wonder about the magnitude of an imminent — and underrecognized — expense for cities elsewhere as more stormwater ponds began showing signs of impairment. She described her concerns in a letter to Ontario’s Ministry of Environment, Conservation, and Parks (MECP), who responded with a grant of $60,000 to further investigate the scope of the issue. Next, she called environmental representatives around the country, which resulted in 22 cities in five provinces providing matching funds to conduct a nationwide inquiry of sediment chemistry.

Ever since, Kelly-Hooper has been compiling a public database of contaminants discovered in stormwater pond sediments across Canada, as well as performing research to better understand the potential ecotoxicity of these contaminants. The database currently details findings from 371 sediment samples drawn from 121 urban stormwater ponds.              

Science Beneath the Surface

Particularly in the urban areas in which Kelly-Hooper typically conducts her research, roadways are a major source of the runoff that ultimately enters stormwater ponds. Her investigation illustrates that petroleum hydrocarbons (PHCs) from asphalt particles are consistently the most prevalent potential contaminant entrained in urban stormwater pond sediment. Previous research had established that asphalt PHCs often contain polycyclic aromatic hydrocarbons (PAHs). PAHs are a class of cancer-causing chemicals that are found in refined crude oil products such as gasoline, diesel fuel and asphalt as well as coal products such as coal tar pavement sealants. Kelly-Hooper’s work demonstrates that PAHs in stormwater pond sediments originate primarily from asphalt and coal tar sealant particles, but they are never high enough to require hazardous waste management.

In most cases, Kelly-Hooper’s research has found that PAHs account for less than 1% of the total petroleum hydrocarbon concentrations. Her sediment leachability data consistently finds non-detectable PHC and PAH concentrations, which indicates low toxicity risks for beneficial reuse in roadway environments.

Kelly-Hooper has also observed declining metal concentrations over the past 20 years. For example, while toxic metals such as cadmium used to be detectable in most samples, it is rarely detectable now. Today, only about 20% of ponds in her database exceed even the strictest regulatory limits on metal contamination, indicating gradual improvements in manufacturing processes that substitute potential contaminants with safer alternatives.

“Our stormwater ponds are really a wonderful barometer for the positive environmental changes we’ve made over past decades,” Kelly-Hooper said. “There were several common manufacturing processes, especially for brakes and rotors, that were introducing cadmium into almost every sediment sample collected 25 years ago. I started noticing over time that cadmium concentrations were decreasing, and it’s now extremely rare to find detectable cadmium in any of my sediment samples today.”

Translating Results into Regulations

Although Kelly-Hooper’s findings may indicate that most stormwater pond sediments are not hazardous as previously assumed, she acknowledges that beneficial reuse always entails some risk. However, as most of the contaminants in pond sediment originate from roadways, Kelly-Hooper’s work has demonstrated that sediments can be a valuable and sustainable soil amendment for landscaping alongside highways.

This “closed-loop” disposal scheme not only helps keep roadway contaminants out of the broader environment — it also can save cash-conscious municipalities millions in landfilling and landscaping costs.

In 2019, Kelly-Hooper worked alongside the Ontario Ministry of Transportation on a major highway reconstruction project outside Toronto. Plans called for the cleanout of a large stormwater pond, which project planners soon realized would entail approximately $3.3 million in sediment landfilling costs. After an in-depth analysis of the sediment in question, Kelly-Hooper and her team convinced environmental regulators to reuse more than 1,000 truckloads of sediment for landscaping alongside the new highway. The total cost of investigating, dredging, transporting, and applying the sediment was around $220,000, she said.

Much of Kelly-Hooper’s research has aimed to determine not only whether land-applied sediments are safe, but also whether they are productive. For example, in one experiment, her team grew small trees side-by-side in two types of sandy soil: one without any additives, and the other topped with 10 cm (4 in.) of dewatered stormwater pond sediments. After a year, trees growing in the amended soils reached about 0.3 m (1 ft.) taller than those planted in unamended soils, and also maintained more vibrant colors.

The new Ontario Regulation (O.Reg.) 406/09 Excess Soil management legislation is the first of its kind in Canada. The regulation includes rules for sampling and evaluating stormwater management pond sediment beneficial reuse versus disposal options. Kelly-Hooper estimates that about a third of the samples in her sediment chemistry database would qualify for beneficial reuse as “Excess Soil” due to PHC exceedances from asphalt sources. However, she has been able to obtain risk-based beneficial reuse approvals under the O.Reg. 208/19 Sewage Works Consolidated Linear Infrastructure Environmental Compliance Approvals (ECA) process. Each approval relied on PHC forensics and ecotoxicity weight-of-evidence to demonstrate that the asphalt contaminated sediment posed low groundwater leachability and bioavailability risks – in other words, the ability of plant roots, earthworms, and other soil-dwellers to consume or absorb these asphalt PHCs.

Still, these approvals represent a major milestone for sediment reuse, Kelly-Hooper said. Continued support for reuse possibilities from the Ontario MECP will enable more demonstration projects, which she is hopeful will open the door for additional regulatory flexibility in the future. “We’ve got some really great collaborative ideas,” she said. “I’m continuing to work with the MECP on developing new protocols and new ways of looking at stormwater pond sediment reuse.”

Navigating the Road to Reuse

To stormwater pond owners in Ontario and beyond interested in pursuing sediment reuse opportunities, Kelly-Hooper recommends approaching the process with realistic expectations. She stresses that the inherent characteristics of stormwater ponds make it unlikely that sediments will ever be considered “clean fill” — a term describing soil amendments acceptable for unregulated use based on their safety.

“You’re likely going to need an environmental compliance approval (ECA) for any offsite sediment reuse application,” Kelly-Hooper said. “To get those approvals, the first thing you’ll need is somebody qualified to perform sediment chemistry evaluations. Essential expertise includes the ability to determine if PHC concentrations originate from inert asphalt rather than highly toxic sources such as gasoline, diesel and other liquid PHC products.”

She challenges reuse-minded stormwater professionals conducting sediment evaluations to consider possibilities beyond the sediment-disposal status quo. While existing regulations in many regions restrict reuse in cases involving PHCs, for example, Kelly-Hooper’s research underscores that identifying the source and provenance of these contaminants is essential to these evaluations.
Regulators might assume, for instance, that an exceedance of PAH and/or PHC standards could indicate contamination by diesel or oil spills, when it likely results instead from asphalt with far lower toxicity risks. The right data and the right communication strategy — such as focusing on the economic and environmental advantages of reusing sediment in highway landscaping compared to trucking it to landfills — can convince regulators that additional options exist beyond landfilling.

“The absolute key to this is that you cannot get these regulatory approvals without showing that even though you may exceed a limit for PAHs or PHCs, there can still be safe beneficial reuse options,” she said.

In October 2022, Kelly-Hooper joined global professional services firm GHD (Waterloo, Ontario) as its Canadian Sediments Lead. While she is still working to advance local reuse regulations in her new role, she is also developing innovative ways to extend the reach of her research around the world. For the last few decades, she has had to investigate the makeup of each sediment sample manually, entailing significant time and cost. An effort currently underway by GHD Digital will create a tool to automate that analysis process, enabling professionals around the world to replicate her methodology. Although her role may be changing, however, Kelly-Hooper has no intention of slowing down the scientific investigation that has defined her career.

“I can’t help but to continue with my research,” she said. “The solutions we are currently designing can inform and help build action plans anywhere in the world.”

Top image courtesy of Pushok/Pixabay  

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Stormwater Pond Sediments: The Next Frontier for Beneficial Reuse? appeared first on Stormwater Report.

New research by environmental scientists from the University of Waterloo (Ontario, Canada) and University of Alabama (Tuscaloosa) shows that small, ephemeral wetlands are more effective at keeping nitrogen out of vulnerable waterways than their larger counterparts. At the same time, these smaller wetlands often receive the weakest legal protections, and are thus more vulnerable to loss.

The team’s conclusions, detailed in the journal Environmental Research Letters, have important implications for development-related wetland loss in the U.S. and beyond, explained Nandita Basu, study co-author and University of Waterloo Ecohydrologist.

Size Matters

In the U.S., larger wetland systems that act as a buffer between inland ecosystems and lakes, rivers, and oceans tend to receive the strongest legal protections under the Clean Water Act.

By contrast, smaller, more isolated wetlands — a broad classification that ranges from New England’s vernal pools, to midwestern prairie potholes, to playa lakes in the southwest U.S., and more — are typically overlooked during development planning processes. These inland wetlands often are ephemeral; they contain water for only part of each year and rarely connect to larger waterways. This means they do not receive protections afforded to “waters of the United States” under the Clean Water Act. The U.S. National Oceanic and Atmospheric Administration estimates that approximately 2,600 km² (1,000 mi²) of wetlands, most of them ephemeral, were lost in the U.S. between 1996 and 2016.

“If pollutants aren’t caught by small wetlands, then they’ll run into our lakes, beaches, and eventually impact our supply of drinking water and ability to use the beaches for recreation,” Basu said in a release about the study. “This is especially a concern in regions like southern Ontario, which has already lost more than 70% of its wetlands and is under threat to lose more from increasing population and developmental pressures.”

Overlooked and Understudied

Wetland soils typically contain large amounts of organic carbon and little to no oxygen, two factors that enable them to naturally strip reactive nitrogen from passing runoff. Previous research suggests U.S. wetlands reduce more nitrogen in runoff than all other aquatic ecosystems combined, and restoring wetlands is the most cost-effective way to target nutrient pollution at the watershed scale. Much of the existing body of research on wetland-based denitrification, however, focuses on wetlands adjacent to permanent waterways.

Because more water typically leaves ephemeral wetlands via transpiration than outflow, the denitrification process in these ecosystems is more complicated, authors of the new study write. Unlike in connected wetlands, nitrogen tends to remain in the soils of ephemeral wetlands even after water exits the system.

The researchers hypothesized that nitrogen’s higher residence time in ephemeral wetland soils would translate to a more thorough denitrification process.

“Being disconnected can actually be better because [disconnected wetlands] are catching the pollutants and retaining them as opposed to leaking them back to the stream waters,” said first author Frederick Cheng, now a postdoctoral researcher at Colorado State University (Fort Collins), in a release. 

To test their theory, the study team selected eight, 1,000-km² (385-mi²) patches of land in different U.S. regions. Each area contains high concentrations of different types of ephemeral wetlands. These included, for example, playa lakes in Texas, cypress domes in Florida, and sandhills in Nebraska. For each study area, researchers compiled 30 years of satellite imagery that detailed monthly changes in water levels in the ephemeral wetlands.

They used this imagery to estimate fluctuations in nitrogen-removal rates. They based these estimates on specially developed mathematical models to incorporate such additional factors as typical nitrogen concentrations observed in nearby runoff as well as the effects of vegetation, precipitation, and transpiration. According to the authors, this study represents the first-ever documented effort to derive data on nutrient retention from satellite imagery.

Finally, researchers compared their estimates of nitrogen retention in ephemeral wetlands to a “steady state” benchmark — a simulated wetland connected to a permanent water body. In these simulations, study authors modeled a wetland based on the median annual water contents of ephemeral wetlands in their study area, assuming no change throughout the year. They then applied the same calculations to derive comparable estimates of annual nitrogen retention.

Rethinking the Extent vs. Efficiency Relationship

Researchers discovered that longer residence times for nitrogen in ephemeral wetlands led to as much as 130% higher annual nitrogen-removal rates than their connected counterparts.

This difference was especially significant in smaller wetlands — a finding that turns conventional wisdom about the relationship between wetland size and nutrient retention on its head.

In connected wetlands, based on the steady state scenario, modeling indicated that wetlands with a maximum size smaller than 1,000 m² (10,800 ft²) retained approximately 38% of total nitrogen. The largest connected wetlands, defined as larger than 315,000 m² (3.4 million ft²), retained approximately 50%. The relationship flips in ephemeral wetlands — smaller ephemeral wetlands retained approximately 88% of total nitrogen while the largest retained approximately 71%. 

Temperature and climate also played a major role. The differences between nitrogen retention rates in connected versus ephemeral wetlands were largest in such semi-arid regions as North Dakota’s prairies, where ephemeral wetlands captured nearly twice the amount of nitrogen as connected wetlands. However, small, unconnected wetlands outperformed connected wetlands even in more humid areas.

The research team acknowledges that their methods have inherent weaknesses that could lead to uncertainty in the results. These include the relatively low temporal and spatial resolution of the satellite imagery as well as the mathematical model’s assumptions underscoring the relationship between wetland area and nutrient retention. However, the researchers report confidence in their approach and the resulting data. The team describes in a release that they are now planning to test these principles in Canadian watersheds, supported by a grant from Environment and Climate Change Canada.

Read the full study, “Disconnectivity Matters: The Outsized Role Of Small Ephemeral Wetlands in Landscape-Scale Nutrient Retention,” in Environmental Research Letters.

Top image courtesy of U.S. Fish and Wildlife Service

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A growing number of U.S. cities are leveraging green infrastructure to transform dilapidated alleyways into attractive and functional community spaces. Among them is Los Angeles.

A joint initiative by the city, the Trust for Public Land (TPL; San Francisco), and other partners is finalizing the third phase of a long-term campaign to distribute green alleys across the city’s most socially vulnerable and flood-prone areas. These green alleys focus on safety and accessibility in addition to stormwater management. They add lighting and signage as well as permeable pavers, bioswales, and dry wells, described TPL Los Angeles Parks for People Program Manager Pamela Soto.

“These urban alleys are multiple-benefit projects that incorporate urban greening, create safer passages for walking and biking, and connect important community assets,” Soto said. “There are 900 linear miles [1,450 linear km] of alleys in Los Angeles that are typically ignored, and we’re working to make these spaces into vibrant, outdoor areas for pedestrian travel with improvements.”

Rethinking Los Angeles’ Alleyways

Residents of South Los Angeles have few local options when it comes to green spaces. In 2015, the region contained less than 0.2 ha (0.5 ac) of park space per 1,000 residents — about 93% lower than the average ratio of parks to people throughout the rest of Los Angeles, according to TPL estimates. At the same time, South Los Angeles contains as much as 30% of the city’s alleyways. Sensing an opportunity, TPL collaborated with the City of Los Angeles’ Community Redevelopment Agency, Los Angeles Sanitation and Environment, the University of Southern California (Los Angeles) Center for Sustainable Cities, and others to develop the South Los Angeles Green Alley Master Plan in 2015, Soto said.

For their first green alley demonstration project, the partnership looked to Los Angeles’ South Park neighborhood. Focusing on six city blocks surrounding an existing park, the team sought to redesign six alley segments that would work together to create safe and convenient pedestrian access between the park and local homes, schools, and businesses. Project partners redesigned alleyways covering a total of 0.7 ha (1.8 ac), adding permeable interlocking pavers supplemented by underground infiltration trenches and dry-well systems. The revitalized alleys also feature educational signage, artwork, lighting fixtures, as well as extensive native vegetation, including nearly 150 new street trees. Since its completion in October 2016, the South Park green alley network has captured, treated, and infiltrated more than 7.5 million L (2 million gal) of stormwater per year from its surroundings. The alleys discourage flooding and keep pollutants out of the nearby Los Angeles River.

Shifting their focus further north, the partnership completed its second green alley project in the Pacoima neighborhood in October 2020. The Bradley Green Alley project was designed to redirect runoff to help replenish the San Fernando Valley Groundwater Basin. The plan redesigned a 244-m (800-ft) -long, 8-m (25-ft) -wide artery with similar green infrastructure elements to the South Park project as well as new bioswales on either side of the alley. It also added new seating, play areas, fitness facilities, picnic tables, and public art.

Today, the Bradley Green Alley infiltrates approximately 7.5 million L (2 million gal) of stormwater per year into local aquifers while providing new community amenities, according to Los Angeles Sanitation and Environment.

Now project partners are finalizing two additional projects in South Los Angeles: the Central-Jefferson High and Quincy Jones green alley networks. Reconstruction of the 11 alleyways included in the projects are already largely complete, with a ribbon-cutting scheduled for March, Soto said. Like the other green alleys, the Central-Jefferson and Quincy Jones networks will feature permeable pavers, infiltration trenches, bioswales, and dry wells, in addition to community amenities and other green infrastructure elements. Preliminary monitoring by TPL shows that the new alley networks already are proving their worth, mitigating flooding during an especially rainy wet season in late 2022.

“For our Central-Jefferson and Quincy Jones projects, we have recorded data on how much stormwater each has been able to capture,” Soto said. “For Central-Jefferson, it has captured 1,300,000 gallons per year and for Quincy Jones, 263,000 gallons per year.”

Alley Transformations Meet Multiple Goals

Los Angeles follows the example of several other U.S. cities that regard alleyways as opportunities to improve social and environmental well-being.

Chicago is perhaps the earliest adopter of the green alley concept among large U.S. cities. The Chicago Department of Transportation (CDOT) built the city’s first green alleys in 2001. This experiment matured into an organized program resulting in the redesign of more than 300 alleys citywide.

In 2010, CDOT released The Chicago Green Alley Handbook, that summarizes lessons from the city’s green alleys campaign and provides a roadmap for other cities interested in the concept. The guide provides an in-depth investigation of the technical aspects underlying green alleys as well as ways to tailor their design according to community needs. Through various Chicago case studies, it details how cities can construct green alleys across a range of different sites and contexts. The handbook also touches on financing, operations, and maintenance concerns.

In Austin, Texas, a partnership between the University of Texas at Austin, nonprofit Community Powered Workshop (Austin), and the Guadalupe Neighborhood Development Corporation underway since 2005 is pioneering the alley flats concept. These small, detached residential units focus on sustainable design. They incorporate permeable pavers, native vegetation, and other green infrastructure elements and provide new, affordable housing units in areas where homelessness is high.

Meanwhile, the Alley Network Project underway in Seattle works to make better use of the city’s alleys by turning them into safe and attractive event spaces. In Seattle’s historic Pioneer Square, the Alley Network Project has designated two large alleys — Nord Alley and Pioneer Passage — as festival streets. This allows for their temporary closure to traffic for events. The surfaces of both alleys were reconstructed using permeable, clay-based pavers, enabling them to infiltrate stormwater while still accommodating limited vehicle traffic. Since their redesign, the alleyways have hosted such events as art shows, poetry readings, pet adoption events, and viewing parties.

Top image courtesy of layacarlos16/Pixabay

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Los Angeles ‘Green Alleys’ Promote Safety, Stormwater Management appeared first on Stormwater Report.

Mounting evidence that green infrastructure can be used to not only manage stormwater, but improve the health, value, and attractiveness of its surroundings, is convincing more and more U.S. cities to recommend green infrastructure as a preferred alternative to conventional pumps and pipes. The next question that must be answered, argues a recent study that appeared in the journal Landscape and Urban Planning, is how cities can best position green infrastructure as a force for environmental equity. In other words, how can cities maximize the potential for green infrastructure to address longstanding disparities among different neighborhoods related to such quality-of-life factors as exposure to environmental risks and access to green spaces?

Researchers behind the new study, who analyzed plans and guidelines for green infrastructure implementation issued by the governments of 20 U.S. cities, contend that the municipalities that develop zoning and building codes and control city budgets have the most power to ensure green infrastructure can promote environmental equity. However, while their analysis shows that most U.S. cities understand and acknowledge that potential, none have yet developed plans that fully realize it.

“Many U.S. cities use green infrastructure to comply with stormwater regulations in the Clean Water Act,” said lead author Zbigniew Grabowski, who worked on the study as a postdoctoral researcher at the Cary Institute of Ecosystem Studies (Millbrook, New York) and now performs water quality research for the University of Connecticut (Storrs). “Significant investments are being made — often without scrutinizing how the benefits and burdens are distributed. Who gets jobs? Who is displaced? Whose voices are heard in the planning process? These are among the questions we need to address.”

Making the Equity Connection

The research team members began their exploration of the degree to which cities regard the scope and intentions of green infrastructure by focusing on how they define it. One city, for example, might consider green infrastructure primarily as a means to address flooding — largely ignoring its co-benefits — whereas another might see its ability to manage stormwater as secondary to its socioeconomic uses.

After gathering more than 360 documents with potential implications for municipal green infrastructure policy concerning cities of varying sizes and climates, the team decided to focus only on official planning documents authored by municipal agencies rather than community or nonprofit groups, narrowing the field to 122 plans from 20 cities that specifically defined the term “green infrastructure.”

“This limited our analysis to those plans that are explicit about planning for green infrastructure, which excludes some plans that focused on parks or trees or neighborhood master-planning but did not actually use the term ‘green infrastructure,’” Grabowski described. “Our intention was to bring attention to how green infrastructure as a planning concept can be used to coordinate diverse planning processes, [and] more importantly, how it interacts with urban equity issues.”

According to the study, about 45% of these plans use the word “equity” as part of their definition of green infrastructure — however, only 13% of the plans elaborated on the term’s meaning or offer specific guidance on how green infrastructure can help achieve it. Only 10% of plans contain language requiring opportunities for participation in green infrastructure planning decisions by the residents who will benefit from them.

The U.S. Environmental Protection Agency (EPA), in response to Executive Order 12898, requires plans intended to address combined sewer overflows to assess how prescribed measures might affect local environmental justice concerns. The analysis found that the majority of plans that mention “environmental justice” did so only in reference to combined sewer overflows without elaboration, which the researchers describe indicates a “box-checking approach” to meet EPA’s directives rather than proposing a substantial vision for addressing environmental justice concerns.

The Displacement Question

While the analysis shows that many plans fall short with regard to environmental equity, several cities stand out as more equity-minded than others in the ways they frame green infrastructure, Grabowski said. Among those with the most comprehensive plans include Atlanta; Austin; Baltimore; Milwaukee; and Portland, Oregon.

Portland’s 2015 Climate Action Plan, for example, includes extensive language about the link between green infrastructure and environmental equity and also acknowledges that using green infrastructure to add value to a neighborhood may have unintended consequences for its most vulnerable residents. Chief among those consequences is the idea of green displacement.

In the past, the exercise of eminent domain — the right of cities to seize private property after compensating the owner — was a more common way to facilitate the establishment of large-scale green spaces. Today, displacement tends to occur more gradually, Grabowski said. In some cases, cities install highly visible green infrastructure measures such as large parks or expansive streetscape improvements with the explicit goal of increasing local property values. Property taxes, as well as rents and costs of ownership, also tend to rise in these cases, potentially forcing lower-income residents to relocate. 

“This economic pressure cannot be separated from the legacies and ongoing realities of discriminatory lending, policing, and structural disadvantage that make some communities more vulnerable to economic and environmental pressures than others,” Grabowski said. “While no city examined had a robust anti-displacement plan in place, several refer to the need to create one, namely Atlanta and Portland.”

Extending a Hand Without Extending the Timeline

One key takeaway from the research team’s analysis is that one of the best ways to foster equity is to perform extensive community outreach at every stage of a prospective green infrastructure project. This means more than simply holding public meetings to educate locals about a plan already in progress — the researchers challenge urban planners to involve neighbors early in the design process, valuing their feedback just as highly as input from technical experts and city agencies. The community also should be part of the conversation regarding where a project will be built, who will construct it, and who will maintain it during its lifespan.

The researchers acknowledge, however, that outreach on this scale both extends the project’s timeline and enlarges its price tag. Particularly in smaller cities with tighter budgets, urban planners may struggle to strike a balance between effectively involving locals and minimizing project-delivery costs.

“We would argue that making investments in community capacity to be engaged in greening keeps city money circulating within the local economy,” Grabowski said. “For example, a city that has limited resources could be tempted to employ external consultants to create a greening plan, who would then see community engagement as an extension of a project timeline. Money spent on the consultant is gone from the city, and a plan that has had no community input and may not be aware of relevant, on-the-ground issues, is delivered. Now it needs to be implemented, and as it gets implemented, it leads to protest and public outcry.”

This resistance may add more to the project’s bottom line than the extra outreach might have cost, he describes. It is not unusual for protests to necessitate additional, ad hoc planning meetings or even interfere with construction. On the other hand, extensive outreach may pay greater dividends over the long term, Grabowski said.

“If the community had been engaged — if local institutions such as high schools, community colleges, and universities had been engaged in developing a community-led planning process — money would stay in the community, skills would be developed which will speed up future planning and projects, and the community would have ownership of the resultant plan.”

Nature by Numbers

The study proposes a new framework to help cities determine how well their green infrastructure plans promote equity as well as identify opportunities for improvement. It provides specific criteria as well as a 0-4 scoring system to rate a green infrastructure plan’s attention to equity based on three broad categories: vision, process, and distribution.

Vision refers to how each plan defines the concepts of green infrastructure, equity, and justice, as well as the scope of the relationship between them. A plan scoring a 0 in vision would not include equity considerations in its framing of green infrastructure while a plan scoring a 4 would not only fully address the link between the two concepts, but also discuss green infrastructure’s potential to help address the underlying, location-specific issues leading to environmental inequity.

The process category gauges the extent to which members of the communities receiving a new green infrastructure measure can participate in its development, construction, maintenance, and evaluation. As the study describes, a plan created for a community might score low in the process category; a plan created with a community might achieve a moderate score; and a plan created primarily by the community with input from technical experts would score highest.

Distribution mostly concerns the placement of new green infrastructure — i.e., whether the installation will offset environmental hazards, whether it will increase local property values without displacing vulnerable populations, and whether the plan contains long-term provisions to ensure the installation continually operates as intended. A high-scoring plan will not only contain thoughtful and comprehensive attention to siting but also feature avenues to increase the wealth of locals, such as providing new, well-paying jobs in infrastructure operation and maintenance.   

Read the full, open-access study, “Transforming US urban green infrastructure planning to address equity,” in Landscape and Urban Planning.

Top image courtesy of Architect of the U.S. Capitol

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Study: Green Infrastructure Underutilized as a Socioeconomic Tool appeared first on Stormwater Report.

The renovation at Coles, completed Oct. 28, 2022, resulted from a year-long design and construction process informed by extensive outreach to students, teachers, parents, and neighbors.

The Space to Grow program is orchestrated by Chicago-based nonprofits Openlands and the Healthy Schools Campaign as well as the Chicago Department of Water Management, Chicago Public Schools, and the Metropolitan Water Reclamation District of Greater Chicago (MWRD). The outreach process aims to produce a schoolyard design that directly responds to the stated needs of community members while also enhancing the neighborhood’s resilience against flooding and combined sewer overflows, described MWRD President Kari K. Steele.

“The new schoolyard at Coles School offers students a dynamic place to play, learn, and grow, while allowing the neighboring community to benefit from the green infrastructure elements that mitigate flooding and improve water quality,” Steele said in a release. “We hope students and families enjoy all the features that have been included in this beautiful schoolyard.”

A New Classroom at Coles

Unlike many parts of Chicago, sand constitutes a major proportion of the soil beneath Coles. Project planners sought to unlock the potential of these sandy soils. Sandy conditions slow the flow of runoff and maximize retention rates compared to other soil types. But before the project, an impervious asphalt playlot blocked the soil.

The redesign project replaced the playground’s asphalt with a permeable alternative, adjacent to an artificial-turf field that provides a setting for sports while allowing runoff to infiltrate into the soil below. Throughout the property, Space to Grow partners installed a collection of sloped rain gardens seeded with native plants that not only retain precipitation, but also provide new green spaces for students and new habitat for pollinators. A series of kid-friendly signs at each of the new installations teach students the basics behind what they do and why they are necessary.

Coles Principal Charlie McSpadden told the Healthy Schools Campaign that the redesigned schoolyard will provide “a place where students can learn about ecosystems and gardens, release stress, actively play, and exercise using safe equipment.”

The benefits of these new green infrastructure elements will extend far beyond the bounds of the Coles campus. The installation will discourage local flooding which has long caused basement backups and combined sewer overflows in the densely populated neighborhood during heavy storms, describes an MWRD fact sheet about the redesign.

Providing Space to Grow

From its unique method of identifying schoolyards to redesign to its way of engaging all parts of the school community during the design and construction process, the Space to Grow partnership focuses on environmental equity.

From the 649 campuses managed by Chicago Public Schools, program partners identify candidates for schoolyard redesigns based on their degree of access to safe and functional outdoor spaces as well as other socioeconomic factors, such as childhood obesity rates and average household income. They consider this information alongside hydrological factors, such as the neighborhood’s vulnerability to flooding and the site’s geographic potential to affect it. Schools that score highly in these need-based categories and have a buildable area of at least 2,800 m² (30,000 ft²) are invited each year to apply for $1.5 million each in Space to Grow funding.

Once schools are selected, partners lead a consultation process that involves surveys and site visits with students, school staff, parents, and community members to identify specific priorities. These could include, for example, specific amenities like new fields or playgrounds, or specific elements that designers should keep intact, such as landmarks or artwork with sentimental value to the community. All major elements of the design undergo a community vote to ensure they address both environmental and social needs.

With the completion of this year’s four Space to Grow redesigns, the partnership describes that its schoolyards now boast a collective rainfall storage volume of 24.6 million L (6.5 million gal) per precipitation event. This capacity is roughly equal to 10 Olympic-sized swimming pools. In the process, these redesigns have engaged more than 900 educators and at least 11,000 students, as well as thousands of parents, neighbors, and school staff.

Learn more about the Space to Grow program at its website.

Top image courtesy of Metropolitan Water Reclamation District of Greater Chicago

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Chicago Partnership Cuts Ribbon on 34^th Stormwater-Focused Schoolyard Redesign appeared first on Stormwater Report.

The team’s study, which appeared in the journal Ecology and Society, produces the first publicly available, citywide dataset of green roof distribution throughout New York City. Guided by findings from this analysis, authors write, governments and nonprofit groups can plan more effective initiatives to spur green roof adoption, ensuring they benefit neighborhoods most prone to urban heat-island effects, combined sewer overflows, and lack of access to green spaces. The methods the researchers use to develop their analysis also can help planners in other cities assess green roof coverage as well as provide a means to track green roof adoption over time, the researchers write.

“If we are going to meet our goals for climate adaptation, sustainability, and equity, we have to invest more in our green roofs alongside other green spaces,” said co-author Timon McPhearson, professor of urban ecology at The New School, in a release. “The unmet opportunity to transform the flat roof space in New York City is vast. Mobilizing city resources to expand green roofs, especially in underserved neighborhoods, could go a long way towards cooling the city, improving stormwater resiliency, and providing new recreation spaces.”

Satellites and Artificial Intelligence

Previous studies have attempted to quantify green roof coverage in New York City on a neighborhood-by-neighborhood basis, the researchers describe. But for a truly citywide assessment of green roofs, the study team turned to New York state’s rich database of publicly available satellite imagery, which covers virtually all parts of New York City at resolutions as high as 15.2 cm (6 in.).

From this record, the researchers identified images depicting a birds-eye-view of 155 buildings that clearly featured green roofs. They used these images to train a machine-learning model that would pore over the millions of other overhead shots of New York City rooftops in search of buildings that looked similar to the ones the team identified.

“Companies and building owners have installed green roofs in an effort to retain stormwater, but there is no central registry of these installations,” study co-author Greg Yetman from the Columbia University Climate School said in a release. “Detecting the roofs from imagery was an ideal way to locate both large and small installations without having to survey building owners.”

In selecting these “training rooftops” the machine-learning model would use, the team had to exercise caution to ensure that the vegetated structures they were looking at were truly part of the roofs on which they sat rather than, for example, arrangements of potted plants or artificial turf, they describe in their study. They also trained the model on approximately 1.3 ha (3.2 ac) of regular, non-green roofs to teach it what not to look for.

Although authors caution that their analysis likely missed some green roofs existing in 2016 and that the number has likely fluctuated significantly since the imagery was gathered, they found that green roofs occupied only about 25 ha (62 ac) citywide. These existing roofs were unevenly distributed, with more than 50% concentrated in Manhattan. Citywide, neighborhoods identified as most vulnerable to urban heat-island effects were notably underserved by green roofs, with 22 of these neighborhoods containing less than 10 green roofs and four containing none at all. Neighborhoods with the highest number of green roofs were typically served by combined sewer systems, providing evidence that minimizing runoff volumes in areas prone to flooding — rather than lowering surface temperatures — is the primary environmental driver for green roof adoption in New York City, according to the study.

A Function of Policy

The rate at which cities adopt green infrastructure, as well as where they choose to install it, largely depends on the extent of municipal development policies, the researchers write. In New York City, for example, study authors believe green roof coverage in 2016 was largely a product of two mayoral initiatives: PlaNYC, a set of incentive programs including one specifically for green roofs introduced in 2007 under Mayor Michael Bloomberg; and OneNYC, a measure introduced under Mayor Bill de Blasio which included a tax abatement program for green roofs.

Researchers believe the number of green roofs built since their 2016 analysis likely is significant. This is due to several recent New York City green infrastructure initiatives including a set of grant programs targeting urban heat-island effects established in 2017 as well as NYC Local Laws 92 and 94, a pair of measures enacted in 2019 that require green roofs or solar panels on all newly constructed or substantially expanded or renovated buildings.

While these types of programs go a long way toward making green roofs a more attractive option for developers, described lead study author and Nature Conservancy scientist Mike Treglia, heeding the findings of studies like this one can help New York City legislators and urban planners carry out targeted efforts to ensure the areas most in need of the benefits green roofs can provide receive them. Planners in other cities can also use the combination of satellite imagery and machine learning the team used in this study to assess green infrastructure needs in other settings, he said.

“This information, as well as insights on the types of buildings we see green roofs on … is ultimately invaluable in working with policymakers, advocates, and researchers to expand green roofs, particularly in areas where they are most needed,” Treglia said in a release.

Read the full study, “Examining the distribution of green roofs in New York City through a lens of social, ecological, and technological filters,” in Ecology & Society.

Top image courtesy of Aloha Jon/Creative Commons

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Less Than 0.1% of New York City Buildings Feature Green Roofs, Study Finds appeared first on Stormwater Report.

While executive-level green infrastructure positions are growing increasingly common at utilities and watershed organizations, England is thought to be the first such administrator to carry out green infrastructure policy for a major U.S. city. As Boston’s Director of Green Infrastructure, England has the authority to develop long-term green infrastructure implementation plans across city departments, furthering Wu’s vision of the city’s Green New Deal.

England described that the creation of the new position demonstrates a growing recognition of green infrastructure’s effectiveness — both as a tactic to control stormwater quality and quantity as well as improve public health, the local economy, and residents’ quality of life.

“We don’t just see green infrastructure as a stormwater tool,” England told Stormwater Report in September. “We see it as a tool to make the city more resilient, to address some of our urban tree canopy issues, to address some of our equity issues, to build opportunities for new jobs, to help with air quality issues. The list goes on.”

Familiar With the Big Picture

With previous roles at the Boston Water and Sewer Commission (BWSC) and Massachusetts Department of Conservation and Recreation (MDCR), England has experience in leading far-reaching green infrastructure initiatives.

England led BWSC’s green infrastructure program from 2015 to 2019, where she spearheaded the authorship of several manuals and design handbooks still in use by the city. She also convened Boston’s first interdepartmental working group focusing on green infrastructure. The informal group, who met once each month to discuss planned projects, incorporate green infrastructure elements into broader city initiatives, and identify opportunities to collaborate across agencies, included representatives from Boston’s public works, parks, and transportation departments, among others.

As an engineer for MDCR, England oversaw the design and construction of countless green infrastructure projects throughout the state before transitioning to a role in longer-term regional planning. Her work on climate change preparedness — which included co-leading MDCR’s statewide Climate Change Vulnerability Assessment and chairing one of the department’s Climate Action Teams — caught the attention of Mayor Wu. Wu approached England and asked her to build a broader green infrastructure program for the city with the authority to make progress quickly, working above the bounds of the various city departments rather than within them.

“Most cities and towns have a separation of labor where your public works department has one lane and they stay in it, while your parks department has another lane that they stay in,” England described. “I think the fact that these silos are still so prominent in city government is part of why green infrastructure has taken so long to really catch on.”

Extending the Professional Pipeline

England is perhaps proudest, she says, of her work with Boston Public Schools on behalf of BWSC. Collaborating with Boston science teachers and educational consultants, England developed a series of green infrastructure-focused curricula targeting 5^th– and 7^th-grade students. These lessons are already being taught annually at five Boston public schools, an initiative she plans to scale up citywide.

For 5^th-graders, these lessons mesh with existing curricula on environmental science and the value of healthy ecosystems. The 7^th-grade program is more hands-on. It tasks students not only with learning about different green infrastructure designs, how they function, and their purposes, but with demonstrating these concepts on their campuses. After identifying flooding vulnerabilities around parking lots and schoolyards, students are split up into small groups, who are each assigned a different category of green infrastructure — rain gardens, subsurface features, mixtures of green and gray infrastructure, etc. — to study. The unit, which culminates in a range of fully developed, purpose-built infrastructure proposals, intends to teach students how the flexibility of green infrastructure can accomplish multiple goals — as well as provide students with a memorable experience that makes a long-lasting impression about career possibilities in sustainable design.

“Education is a huge component of understanding and acceptance of green infrastructure implementation,” England said. “The sooner we can get it up and running in the classroom, the more likely we are to have parents hearing about it, teachers telling their colleagues about it, and students learning about it. That builds a whole population of people that, in theory, already understand the value of green infrastructure.”

That philosophy extends beyond the formal schooling process, she described. One of England’s priorities as Director of Green Infrastructure is to extend the reach of existing green infrastructure workforce and certification efforts, such as the National Green Infrastructure Certification Program (NGICP), within the city. An NGICP graduate herself, England praised the program for its accessibility and the comprehensiveness of its curriculum, as well as its ability to equip students without extensive education with the skills to secure high-paying, in-demand jobs.

“An idea that Mayor Wu thinks is very important and that I absolutely agree with is that we really want people in the city to have the skills and knowledge they need to improve their own neighborhoods,” England said. “My hope is to create a pipeline to get individuals from the various neighborhoods where we’re building green infrastructure features to get trained up and certified.”

Laying a Flexible Foundation

While England says she is still in the process of establishing the relationships and resources that will underpin her new role, she has already begun making moves. She is reforming and formalizing the working group she convened at BWSC, for example, involving upward of 40 people that include local experts on climate change, environmental justice, and workforce development. The group’s first meeting is scheduled for later this month.

She is also finalizing a new engineering policy that will require projects on public lands citywide to incorporate green infrastructure elements like bioretention planters, permeable pavers, or subsurface features into new curb extensions and bump-outs. The new policy emphasizes flexibility, England said, offering a range of applicable green infrastructure elements for developers to choose from rather than prescribing a single, “cookie-cutter” design. She says she intends for this type of flexibility to be a hallmark of her work as a policymaker.

“There’s a good amount of creativity involved in this kind of work,” England said. “I’m trying to make sure that the policies and manuals I put forward are giving people enough latitude to design what works best for a site rather than requiring something very specific that maybe is not the best fit for a particular location.”

An Engineer’s Administrator

As a career engineer rather than a public policy expert, England described her affinity for a bottom-up approach to leadership, emphasizing the needs of individual engineers and field staff just as much as broader mayoral directives and the priorities of agency commissioners.

“You have to engage designers and engineers and help them understand why we’re doing things and how we’re doing them,” she said. “Acknowledging that they’re the ones who are going to have to do a lot of this work we talk about among upper management I think is really important.”

Maintaining accessibility between the city government and its water professionals will create a more effective working relationship and ultimately facilitate green infrastructure adoption, she described. 

“I want the various city departments to view me as a resource,” England said. “I want them to know that if there’s a barrier or a question or a concern, and I can find a solution for it, I’m happy to do that. We’re going to do everything that we can to give you the resources you need to implement green infrastructure in your own department.”

Top image courtesy of City of Boston

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Boston Leadership Embraces Green Infrastructure With First-of-its-Kind Cabinet Position appeared first on Stormwater Report.

Consider the Alabama Department of Environmental Management (ALDEM), for example, which recommends a standard bioretention media mix based on the state’s precipitation characteristics. The mix contains about 85% sand, 11% fine grains of silt and clay, and 4% organic matter, such as hardwood mulch. Numerous applications have demonstrated that this mixture excels at stripping heavy metals, such as zinc and copper, from runoff and can reduce phosphorus concentrations by as much as 95% or more. However, the mixture is far less effective at controlling nitrogen, mostly relying on vegetation to compensate. Particularly in areas where nitrate pollution is a major concern in Alabama and beyond, such as agricultural regions where fertilizer usage is rampant, green infrastructure professionals are searching for ways to strike a better balance with their choice of bioretention media.

New research from Auburn University (Alabama) demonstrates how including zeolites — a group of common minerals featuring forms of aluminum and silicon — in Alabama’s standard bioretention mixture can dramatically improve nitrogen mitigation rates. The team’s open-access study was recently published in the journal Agricultural & Environmental Letters.

Side-by-Side Soil Comparison

Zeolite-based soil amendments are well-known for their ability to help soil retain water while maximizing its potential to provide plants with accessible nutrients. However, study authors write that previous research has not thoroughly investigated zeolite amendments within the context of bioretention. Additionally, little is known about the minerals’ ability to treat the broad spectrum of contaminants typically found in stormwater runoff.

To bridge the knowledge gap, the researchers began by filling a row of five, 60-cm (24-in.)-long columns with bioretention media containing increasing proportions of a commercially available zeolite-based soil amendment containing the mineral clinoptilolite. Beside one column containing ALDEM’s mixture and a control column containing only sand, the other columns contained variations of the ALDEM mixture replacing 2%, 10%, and 20% of its sand contents with the zeolite amendment. Each column was topped with 5 cm (2 in.) of peat moss with a small layer of aquarium gravel at the bottom.

Next, they created synthetic stormwater runoff rich in phosphorus, nitrate, ammonium, copper, and zinc. Then, they poured the solution into the five columns at a constant rate of 42 ml (1.4 fl oz) per minute to simulate the effects of a heavy rainstorm. Simulating four such storms over the course of a week, the researchers analyzed the effluent from each column after each storm to examine how well the different bioretention mixtures sequestered each contaminant.

Ideal for Agricultural Settings

In most cases, performance differences among the four non-control columns were subtle. Regardless of whether the mixture contained zeolite, each bioretention medium reduced phosphorus in the synthetic runoff by at least 95% after each trial, compared to only a 20% reduction observed in the sand-only column. The four non-control mixtures also demonstrated similarly effective removal of heavy metals, each remediating at least 84% of zinc and at least 98% of copper.

The first key difference was regarding ammonium. The ALDEM mixture typically reduced ammonium by about 70%, whereas the mixtures containing at least 10% zeolite captured at least 16% more. The most striking difference, however, was in nitrate mitigation. Mixtures containing at least 10% zeolite sequestered as much as 46% more nitrate than the ALDEM medium, according to the study.

“Nitrate is a compound that is not typically held or retained by soil, so it was surprising that the nitrate reduction was higher with added zeolite,” said Thorsten Knappenberger, Auburn University professor of soil physics and study co-author, in a release about the recent paper.

Study authors hypothesize that including vegetation in the experiment would have driven nitrate removal rates higher, as would including an internal water storage layer, which could provide the anaerobic conditions necessary for the denitrification process.

Analysis of the soil in each column also revealed that increasing zeolite contents caused slight decreases in the media’s overall density. Rather, it increased the soil’s hydraulic conductivity, processing the water faster than the ALDEM standard without compromising its treatment performance.

However, these advantages do not come without considerable cost that could hinder their adoption for bioretention, the researchers caution. Each cubic meter of the ALDEM-recommended mixture costs about $50 to implement, the study describes. Replacing just 10% of sand in the mixture with commercially available zeolites increases that cost to as much as $115 per cubic meter. For that reason, zeolite amendments are perhaps best suited for strategic, small-scale deployment in bioretention infrastructure designed specifically to target nutrient pollution, researchers write.

Read the full study, “Zeolite amended bioretention media improves nitrogen removal from stormwater,” in Agricultural & Environmental Letters.

Top image courtesy of Ngo Minh Tuan/Pixabay

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Common Minerals Maximize Nutrient Capture in Bioretention Media appeared first on Stormwater Report.

Master Plan Winner: University of Maryland

In the Master Plan category, student teams developed long-term strategies to integrate green infrastructure concepts throughout their entire campuses.

The student team representing UMD described their 27-ha (66-ac) project area in submission materials as “car-centric,” located alongside a major entryway into campus for approximately 15,000 commuting students and home to a busy UMD athletic complex. Approximately one-third of the neighborhood, which straddles two tributaries of the sensitive Anacostia River, is covered in impervious parking lots. Currently, these parking lots are served only by inlets that redirect untreated runoff into the tributaries and, in turn, the Chesapeake Bay.

The winning Master Plan from the UMD team proposes to update and relocate parking for the athletic complex. Additionally, it lays out a 40-year, $300-million USD green infrastructure timeline that aims to reduce the area’s runoff generation rates by more than half and achieve a range of co-benefits.

First, the plan calls for consolidating five existing, surface-level parking lot into a new, multi-tier parking garage. The spaces formerly occupied by parking lots that currently generate motor oil, tire rubber, and other potential runoff pollutants would become new recreational fields, able to accommodate students, athletes, and tailgaters. On rainy days, cisterns beneath the fields would capture up to 28,000 L (7,500 gal) for irrigation and other non-potable uses, the team describes in a video about their proposal. Meanwhile, the new parking garage would feature a green roof and sit next to a “multi-modal transportation plaza,” providing convenient bicycle, scooter, and skateboard rentals as well as access to shuttle buses and other public transportation options.

Recent UMD initiatives to encourage and expand public transportation — including five new light-rail stations currently being built throughout campus — have already caused a notable decrease in on-campus vehicle traffic since 2018 even despite an increase in enrollment, according to data cited by the project team. The plan envisions taking advantage of this trend by restricting non-emergency vehicle traffic to the periphery of campus, replacing most inner roadways with new, permeable walkways geared toward pedestrians and cyclists. Lined by a suite of new bioswales and native trees, the plan calls for 700 m (2,300 ft) of new bicycle lanes.

By 2060, the plan accounts for a new basketball stadium as well as a new academic building elevated above the floodplain by stilts, both equipped with green roofs. It also describes extensive stream revitalization efforts, including a 62% increase in streamside riparian buffer coverage in addition to a new walking trail along Campus Creek. All told, project documents describe that the improvements could enable the site to fully treat a 6-cm (2.5-in.) rain event, mitigating flooding while drastically cutting Anacostia River water pollution. The team notes in their submission that the project’s goals, approaches, and location would make it eligible for a host of local, state, and federal grant programs to help subsidize construction and maintenance costs.

Watch a video about the UMD team’s Master Plan, titled “Future Flows,” on YouTube:

Demonstration Project Winner: Florida International University

Demonstration Project entrants submitted plans for smaller-scale green infrastructure projects that provide innovative solutions to local environmental, social, and economic challenges.

Within the FIU campus in North Miami sits the Marine Academy of Science and Technology (MAST@FIU), a public high school that cooperates directly with FIU to offer its students specialized education in marine and environmental research. The FIU team focused on MAST@FIU for its winning Demonstration Project submission, tailoring green infrastructure interventions according to U.S. National Oceanic and Atmospheric Administration (NOAA) predictions for Miami-area sea-level rise by 2050.

During the Florida coastline’s infamous downpours, rain that falls on the 6-ha (15-ac) MAST@FIU campus is currently collected and diverted into a retention pond that allows it to infiltrate the area’s porous limestone substrate and recharge groundwater supplies. In low-lying Southeast Florida, the project team contends that the existing approach may be unsustainable. According to NOAA data, the level of the sea lining the coast of campus has already risen by at least 15 cm (6 in.) within the last 30 years and is poised to continue at an accelerating rate. As the sea level rises, underground capacity for groundwater aquifers shrinks and could exacerbate flood risks, the team describes in project documents.

Interventions recommended by the team focus on decreasing runoff generation by increasing opportunities for evapotranspiration, a process that began by identifying the specific points on campus most prone to coastal flooding and the effects of sea-level rise. The team first focused on a 400-m (1,300-ft) stretch of the main access road serving both the FIU and MAST@FIU campuses, which modeling showed as particularly susceptible to storm surge compounded by sea level rise. The team found that elevating this stretch of road by just 25 cm (10 in.) would eliminate flood risks from storm surge under a 2050 climate scenario.

For the main MAST@FIU building, the project team designed a 1,850-m² (20,000-ft²) green roof capable of retaining up to 107 cm (42 in.) of precipitation each year, dramatically slowing runoff generation. Additionally, modeling by the team demonstrates significant benefits for heat mitigation — installing a green roof could cool indoor temperatures at MAST@FIU by as much as 3.5°C (6.3°F). The green roof would join a retrofit for the 2-ha (5-ac) of on-campus parking lots utilizing native vegetation and permeable pavement.

Finally, the team’s proposal calls for a series of uniquely designed “multipurpose smart pavilions” scattered throughout campus. The pavilions would consist of small basins for water collection connected by sharply curved, geodesic shelters inspired by leaves. The shelters, fabricated from steel, concrete, and bamboo, sport a double-layered, bioplastic-based outer shell equipped with injectors capable of spreading micro-algae throughout the shell subsurface. Sustained by sunlight and oxygen, this micro-algae mimics photosynthesis and naturally sequester carbon from the pavilion’s surroundings. The modular pavilions would provide comfortable gathering places for students while also capturing and retaining stormwater.

According to submission documents, the project would cost approximately $3.5 million in capital as well as around $60,000 USD in annual maintenance costs. It would increase stormwater infiltration on the site by 68%, reduce runoff generation by 73%, and reduce total suspended solids loading into Biscayne Bay by 75%.

Watch a video about the FIU team’s Demonstration Project, titled “Resilient MAST@FIU,” on YouTube:

About the Challenge

Student teams represented 35 U.S. colleges and universities across the nation. They devised in-depth plans to bring green infrastructure into their communities.

Technical experts from the Water Environment Federation (WEF; Alexandria, Virginia) provided support for this year’s Campus RainWorks Challenge alongside counterparts from the American Society of Civil Engineers (Reston, Virginia) and American Society of Landscape Architects (Washington, D.C.).

“Green infrastructure is essential to building dynamic and thriving communities,” said Radhika Fox, EPA Assistant Administrator for Water, in a release announcing the winners. “When we apply green infrastructure strategies — like those exemplified by the Campus RainWorks winners — projects can meet community needs while supporting clean water goals.”

Top image courtesy of U.S. Environmental Protection Agency

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ABOUT THE AUTHOR
Justin Jacques is editor of Stormwater Report and a staff member of the Water Environment Federation (WEF). In addition to writing for WEF’s online publications, he also contributes to Water Environment & Technology magazine. Contact him at jjacques@wef.org.

The post Maryland, Florida Teams Win 10th Campus RainWorks Challenge appeared first on Stormwater Report.