Category: Landscape Design

Landscape architects are working with the U.S. Army Corps of Engineers and building new networks through the Engineering With Nature program. The implications could be transformative for both.

By Jared Brey

A needle that falls in the southern reaches of the New Jersey Pinelands might find itself washed into the Maurice River and carried by its current to Delaware Bay. The Maurice flows south in tight coils, and before it reaches the estuary, it’s forced into one final wide bend around a long dike at Matts Landing, near the old bayside oyster towns of Bivalve and Shell Pile.

Gathered at the base of the dike one morning last spring was a group of engineers and researchers, milling about under a cloud-swept sky as they waited for Monica Chasten, a project manager for the U.S. Army Corps of Engineers Philadelphia District, who is overseeing the first dredging of the Maurice River in 20 years. They were also joined by Sean Burkholder, an assistant professor of landscape architecture at the University of Pennsylvania Stuart Weitzman School of Design and a member of the Dredge Research Collaborative, a loose affiliation of landscape architects who have been studying the movement and reuse of sediment since 2010.

The tide was out. Mudflats stretched out into the salty water on the bay side of the dike. Sanderlings and willets scampered and flocked. Slowly, the group walked out onto the dike, and began talking about how the mud from the bottom of the Maurice River might be used to create new marshland at its mouth. Could the dredging tube be laid across the dike to transfer sediment from one side to the other, or would that put the dike at risk of collapse?

“You could think about putting the dredge pipe, at least for a period of time, up on the marsh and letting [sediment] flow down into it,” Chasten said. “Which is kind of the Engineering With Nature approach, to let the landscape do the work.”

“Yeah,” Burkholder said. “It’s just a matter of making sure we have a baffle or something up there so we’re not blowing the marsh out while we’re placing.”

They talked this way for an hour, making their way down the dike. Should a Y-valve or a spreader be used for multidirectional distribution? They’d have to wait until after the horseshoe crab nesting season to do any major placement. And how would they manage people’s expectations about the future of the place? Dumping thousands of cubic feet of sediment into the mudflats would be sure to kill most of the existing vegetation before anything that looked like new, healthy land could be seen emerging.

By way of refocusing, Chasten proclaimed, “The primary mission of this project is to clear the channel.”

Over the past decade, the U.S. Army Corps of Engineers has begun purposefully incorporating natural processes and nature-based features into some of its flood-control and navigation projects through a program called Engineering With Nature (EWN). The corps, deeply committed to acronyms and bureaucratese, describes the program as “the intentional alignment of natural and engineering processes to efficiently and sustainably deliver economic, environmental, and social benefits through collaboration.”

Engineering With Nature is staffed by a small group of employees who act almost as internal consultants to the corps’s regional districts, which are tasked with actually carrying out infrastructure projects. It has published two atlases highlighting engineering projects in the United States and around the world that embody the EWN principles. But it’s still too early to know the program’s long-term impact, both on the corps and on coastal and flood-control infrastructure.

Landscape architects are playing a growing role in that negotiation. In 2017, the corps’s Engineer Research and Development Center (ERDC) and the Dredge Research Collaborative hosted a workshop at ERDC’s base in Vicksburg, Mississippi, to explore ways that landscape architects and engineers could work together. That workshop has led to a series of formal collaborations, including awarding research grants to a group of academics led by Rob Holmes, ASLA, an associate professor of landscape architecture at Auburn University (and a Dredge Research Collaborative member), along with Burkholder at Penn; Justine Holzman, formerly an assistant professor of landscape architecture at the University of Toronto, now studying for a PhD at Princeton, and others. Together they have produced a series of Engineering With Nature + Landscape Architecture (EWN + LA) reports, which outline design concepts for various sites of intervention by the corps, including a group of jetties in the Chesapeake Bay, the Comite Canal in Louisiana, and the New Jersey Back Bays that separate the mainland from the barrier islands and resort towns. The group has also published articles in the journal Integrated Environmental Assessment and Management describing their collaborations in recent months.

“What I find very intriguing with landscape architects, and why I value them so much, is that anything is possible,” says Jeffrey King, Affiliate ASLA, the deputy national lead and program manager for Engineering With Nature. “They’re not constrained in the purest sense of engineering, and they can think beyond a biological context.”

These collaborations have the potential to alter, however gradually, the way the corps plans its interventions in the landscape and its role in building infrastructure for an age of climate change and environmental fragility. And they have the potential to open new areas and methods of practice for landscape architects.

“Engineering With Nature is trying to help the corps see where the most valuable things it’s doing are and to disseminate that—to shift what the corps is doing as a whole,” Holmes says. “To me, supporting that work is probably the most valuable thing that we’re doing. In the long term, there’s an enormous amount of work that needs to be done for climate adaptation, and what we’re going to need is not just the desire to do that work…we’re going to need the expertise and the networks of practical knowledge about how to build nature-based infrastructure. That’s what we’re contributing to.”

The landscape architects who founded the Dredge Research Collaborative share a fascination with the transformative possibilities of displaced sediment (see “The Dredge Underground,” LAM, August 2014). The corps is the country’s chief displacer of sediment and builder of water infrastructure, and that infrastructure “is one thing that our society has agreed that everyone gets,” says Brian Davis, an associate professor of landscape architecture at the University of Virginia. So working with the corps is a way for landscape architects to design spaces that are typically outside their professional realm and that are threaded throughout the built environment differently than other types of public or private spaces.

“The scale of things they make and the impact on the environment [are] way bigger than park making or other types of landscape making,” Davis says. “That’s attractive to me in terms of its potential for impact and creating common ground and aesthetic values more broadly.”

Engineering With Nature was founded around the same time as the Dredge Research Collaborative. Todd Bridges, a senior research scientist with the corps who helped create the program and still leads it, says it was spurred by a confluence of factors. Among them was what the World Economic Forum estimated was a $100 trillion global need for infrastructure investment over the next several decades, and a desire on the part of corps leadership for innovation.

“When you consider how large the investments are, it begs the question: How could we expand the value from that investment?” Bridges says. “What are the ways we can diversify the value that can be produced through infrastructure investment?”

The program had an obvious ecological bent—Bridges has cited Ian McHarg’s Design With Nature among its foundational influences—but it was also justified as a way to make the corps’s work more cost-efficient. The EWN atlases highlight corps projects that have created environmental benefits, such as using dredged sediment to make new wildlife habitat, but those benefits have always been by-products of a broader engineering purpose. The program works by trying to create multiple benefits out of work that’s already going to happen. To gain purchase for EWN principles within the corps, Bridges faithfully speaks the language of “value.”

Some of the most elegant EWN strategies have in fact come from attempts to improve engineering efficiency. At the Horseshoe Bend Island in the Atchafalaya River, the corps placed sediment upstream, in midriver mounds, and allowed it to flow through the river’s current and accrete on the island over the past couple of decades, effectively allowing the island to “self-design.” In the process, it improved habitat for birds, invertebrates, and other organisms. Highlighted in the first EWN atlas, the Horseshoe Bend project actually predates the program. The concept for the sediment placement was created by one maintenance engineer in the corps’s New Orleans District who was just trying to make his job easier, Davis told me.

Similar strategies are being employed in the New Jersey Back Bays, where the Philadelphia District is charged with maintaining the navigability of the Intracoastal Waterway. There, the district is using dredged sand and mud to create and improve islands in the bays that are critical habitat for wading birds. At Gull Island in Cape May County, the district released sediment into open water to create a berm on the island’s edge that has helped protect the island from waves and wakes. Projects like those are conducted as experiments through the Seven Mile Island Innovation Laboratory, a partnership between the corps, the state of New Jersey, and the Wetlands Institute in Stone Harbor, New Jersey, which has consulted with Burkholder and some of his colleagues at Penn on design and monitoring strategies.

It’s yet to be seen how far the experiments will go. Partly because of the institutional culture of the corps, and partly because of the high-stakes, life-safety implications of its infrastructure work, EWN strategies tend to be negotiated add-ons to dredging projects. At the Maurice River, for example, the Philadelphia District has permission to build new marshland, but a mandate to clear the river channel to seven feet of depth. The role landscape architects can play in those projects is determined on a case-by-case basis.

The Environmental Modeling Lab, a project led by Burkholder and other landscape architecture faculty at Penn, recently received a grant from the corps to monitor the evolution of sediment placements at the Maurice River over several years. But Burkholder’s work with the Philadelphia District to design the sediment placement itself isn’t funded, strictly speaking. In some cases, the corps is just looking to landscape architects to make visual renderings of their design interventions as a means of better communicating its work. But for Burkholder and others, the real goal is to get a seat at the table where the infrastructure itself is designed. It’s taken years of relationship building to gain the small foothold they have now, and their collaborative role is still tenuous.

Burkholder says when working with the corps, “You have to demonstrate value. You’re never going to be in charge, and so you’re constantly fighting for agency in that process. There’s no reason you have to be there. They don’t need you. You’re always pushing that brick across the carpet: All the movement that happens is from your own hard work.”

Few people were more familiar with this dynamic, or worked harder to push the corps forward, than Heather Morgan, a landscape architect who died last year at the age of 44. At the time of her death, Morgan was the director of climate risk adaptation at AECOM. But prior to that, she had spent several years leading sustainability programs at the corps. Todd Bridges, who worked with Morgan, says it was her charge to develop a “comprehensive sustainability posture” within the organization, and she built a network of colleagues within the corps to help do it.

In October 2021, Morgan gave a presentation at the Courageous by Design symposium presented by the Cultural Landscape Foundation (TCLF). Her presentation was part of a panel on “Preparing and Adapting Bureaucracies for Our Future Climate.” She spoke at the time about the ways the corps has been constrained by politics, funding, and traditional approaches to engineering and environmental management.

“The Corps of Engineers has been asked for a very long time to put static measures on dynamic systems—not sustainable,” she said. “The corps has also been asked to put single measures on comprehensive systemic problems.”

To combat that paradigm, Morgan called on designers to build relationships with federal agencies like the corps and establish “advocate teams” of like-minded people within those agencies to push forward nature-based solutions. In correspondence with Charles Birnbaum, FASLA, TCLF’s president, Morgan once wrote that she was “trying to change the cultural identity of an agency, inch by inch” by focusing on transdisciplinary collaboration, bringing together landscape architecture with engineering, archaeology, geomorphology, biology, and ecology. A “collective response to climate change” demanded nothing short of that approach, she said.

Bridges says that he once woke up to a text message from Morgan the morning after she’d been through an eight-hour medical operation. She was sharing some thoughts about dam removal.

“She was full of ideas,” Bridges says. “She had a very creative intellect—probing and challenging and trying to move herself and her team and the organization forward. She got it that one of the ways we can increase the value through infrastructure investment is to bring more connection between infrastructure and people, which is at the heart of landscape architecture.”

The work continues.

At Matts Landing, as the group sorted through technical questions of sediment placement and management, Burkholder gradually nudged Chasten and the rest of the crew to the end of the dike, where a grove of red cedar trees was growing on a massive pile of oyster shells.

“Let’s go down into this grove of trees. It’s the coolest place here,” he said. “It’ll cheer us up.”

The Wetlands Institute was founded in 1969 when a businessman named Herbert Mills, who was then the executive director of the World Wildlife Fund, bought 6,000 acres of salt marsh with the intention of protecting it from development. Today it incorporates more than 15,000 acres of marsh in the bay behind Seven Mile Island, the barrier beach that’s home to Avalon and Stone Harbor, New Jersey. One morning in May, while I was waiting for a meeting with Chasten and Lenore Tedesco, the institute’s executive director, I walked down a sandy trail onto the boardwalks that hover above the mud. There were red-winged blackbirds screaming in the cedar trees, ospreys nesting on human-made stands, and a lone clapper rail stalking through the mud beneath the boardwalk. At the end of the boardwalk, I looked through my binoculars across the expanse of salt flats and noticed that, in fact, birds were swarming above the water by the hundreds—swallows, terns, ibises, egrets—as numerous as mosquitoes.

In a conference room upstairs, lined with decades-old volumes on marsh wildlife, Tedesco pointed a telescope at Great Flats, an island created with dredged sand to benefit beach-nesting birds, and one of the only elevated spots in the surrounding marshland. More than a quarter of the nesting wading birds in the state of New Jersey are found on Gull and Sturgeon Islands, two marshland sites built up with fill dredged by the corps, she says.

Tedesco has often described sediment—the nutrient-rich, larvae-filled mud at the bottom of the marsh—as the “currency” of wetland ecosystems.

“And Monica is the broker of sediment,” she told me.

Chasten is the EWN lead for the corps’s Philadelphia District, which is considered a “proving ground” for the program. That means the district can use some of its projects to test innovative sediment-placement methods, with the goal of producing multiple benefits. By bringing together the corps and the Wetlands Institute, along with permitting agencies and others, the Innovation Lab can link ecosystem needs with opportunities to beneficially reuse dredged sediment.

The need for marshland elevation is widespread. Tedesco showed me a rendering, which she said was made by Burkholder and Keith VanDerSys, a lecturer at Penn and a cofounder of PEG office of landscape + architecture, that depicted a projected high tide in future decades. Everything in the thousands of acres of marsh surrounding the Wetlands Institute was underwater, except for the institute itself and a few areas that had been elevated using dredged sediment. The founding of the institute had been a pioneering act of environmental protection, but protection status hardly matters in the face of sea-level rise, Tedesco says; you can’t buy or preserve your way out of it.

For reuse projects to be viable, sediment had to be placed reasonably close to where it was dredged. Chasten told me that a local nonprofit group had seen how the corps had used sediment to support habitat in the Back Bays and approached them for a project of its own. But the area it was interested in was nowhere near a dredging site.

“You can’t plan a project first and then try to force the corps into that project, because we have policies and regulations we have to abide by,” Chasten says.

The corps has no shortage of such regulations, most of which have been imposed in one form or another by elected lawmakers. In the early 1980s, Reagan-era rules required the corps, along with other federal agencies, to begin producing cost-benefit analyses for all its infrastructure projects. Those rules are focused on economic benefits and don’t allow for the consideration of environmental or social benefits—and some say they’ve sharply limited the types of projects the corps is able to take on. More recently, Congress has imposed, through the Water Resources Reform and Development Act, a so-called 3x3x3 rule, which says that planning studies may take no more than three years, cost no more than $3 million, and require concurrent review by three levels of corps oversight. The corps is also expected to build infrastructure to a 50-year standard of durability—an irrelevant target in the context of something as dynamic and mobile as a wetland. Rules like these have had the effect of limiting the ambition of the corps’s infrastructure projects.

For the corps to really evolve, says Billy Fleming, the Wilks Family Director of the Ian L. McHarg Center for Urbanism and Ecology at Penn, it would need to be able to evaluate the impacts of its projects in new ways. That would mean “moving away from a national economic benefit standard and into one that actually incorporates things like environmental impacts or ecosystem services or, God forbid, social justice or housing justice,” he says. But those things can only be changed through policy making, and not at the project scale, he says.

In the meantime, change comes gradually, partly because of institutional obstacles within the corps and the engineering profession more broadly. Bridges acknowledges a “tension point” in engineering between the need to build infrastructure using proven methods and the need to innovate in the face of climate and environmental changes. Chasten says that at the moment, interest in EWN is coming both from the bottom of the organization and the top brass—but that it follows political cycles. Persistence pays off, she says: Five years ago, the permitting agencies would have given a “hard no” on some of the work the Philadelphia District has done recently in the Back Bays. But innovation is still constrained by administrative rules: “The minute this gets more expensive, they’ll shut me down,” she says.

“This broader institutional shift is not something I think we’re going to see in two years or five years; I think it’s going to be a generational project, and I think it’s a very important generational project,” says Gena Wirth, ASLA, a principal at SCAPE and a member of the Dredge Research Collaborative. “The concern is that our institutions change very slowly, but our climate is changing very quickly, and our physical environment is changing very quickly, and our social environment is changing very quickly.”

The Maurice River was scheduled to be dredged in October. One benefit of working with the corps on a project like that, Burkholder says, is that it’s already funded and is going to happen no matter what. The stakes for experimentation are also relatively low, he says, because if the marshland project fails and the sediment escapes, it’s only returning to the same system it came from. So there’s a window of time for a landscape architect to influence the design of the sediment placement. By gradually developing networks and relationships with infrastructure-building institutions like the corps, landscape architects create those opportunities for themselves. And the stakes of that broader project, for landscape architects and for everyone else, are quite a bit higher.

“Engineers want to ensure that we survive as a species,” Burkholder says. “Landscape architects want to make sure that we enjoy surviving.”

Jared Brey is a freelance reporter in Philadelphia and a contributing editor to the magazine.