Soft Landing

A historic airfield in Massachusetts is transformed into a haven for biodiversity.

By Jane Roy Brown

Seating decks on the edge of the marsh invite bird-watching. © Charles Mayer Photography.

“Are you folks from the parks department?” asked a white-haired man in hiking clothes.

It was an early summer morning, and he approached a small group standing in a path at 1st Lt. Arthur E. Farnham Jr. and SSgt. Thomas M. Connolly Jr. Memorial Park, which covers 12 acres on the 338-acre site of a former regional airport in Canton, southwest of Boston. The group did not include anyone from the park’s managing agency, the Massachusetts Department of Conservation and Recreation (DCR). But it did include the park’s designers, Deneen Crosby, ASLA, and Daniel Norman, ASLA, from the Boston firm Crosby | Schlessinger | Smallridge (CSS). With them was the consulting biologist Ingeborg Hegemann, the senior vice president of ecological sciences and principal at BSC Group, a Boston-based environmental services firm. Hegemann worked with CSS to evaluate the soils, review proposed grading, and select plants and seed stock for the park, which includes extensive restored wetlands.

The park visitor, a retired Canton resident who identified himself as “Mike,” described a woman he had spotted digging up plants and stashing them in her trunk. “She had a shovel in the car, so it wasn’t the first time,” he said, pulling a notebook from his day pack. He read out a plate number. Norman jotted it down. “I come here almost every day,” said Mike. “I love this park, and I don’t want to see it destroyed.”

It was the kind of gratifying feedback professionals who work on public projects rarely get firsthand, and it left the team smiling. The park opened in the summer of 2014, and the design team had recently completed the public amenities—interpretive signs, an entry pavilion, and a final stretch of path. The finished design recognizes the site’s rich natural and cultural history with an almost minimalist aesthetic. Stone “ghost walls” outline the rectangular footprints of two former hangars that stood on the property’s north side. The low, flat walls also provide seating.

One of those walled spaces contains a grove of young poplars, the other a stand of paper birch. The trees will eventually form a shady, rooflike canopy over their respective spaces. Atop a knoll, a performance pavilion with two up-tilting sections of roof seems poised for takeoff. Two seating decks built of narrow wood slats are tucked into separate spots along the edge of the marsh, offering quiet places for bird-watching or just gazing out at the waving grasses. All the structures in the park, which were designed by Touloukian Touloukian Inc. of Boston, evoke some aspect of aircraft—the slender metal ribs of a hull, the tapered elliptical section of a wing.

Other segments of stone wall, the same comfortable seating height as the “ghost walls,” provide places to stop along the path that loops through the developed upland area of the park—only three acres, surrounded by another 12 acres of restored wetland. All the stone walls, dry-laid by the Tibetan monk and stonemason Lobsang Gyaltsen, are made of a mica-flecked schist quarried in western Massachusetts. Norman points out that the absence of mortar allows the walls to absorb shifts in ground level as the site, which is built on fill, settles over time. The walls also gesture to the land’s agricultural and aeronautical history. “It was important that the walls evoke both stories, and this traditional building method does that,” he says.

The farms here long ago gave way to residential neighborhoods, but the more recent history of the Boston Metropolitan Airport, which operated from 1931 to 1954, still lives in local memory. Its four grass runways launched many dreams and adventures, including those of the Canton native Dorothy (Dottie) Shaw. After graduating as valedictorian of her high school class in 1926, Shaw could not afford to go on to college. Working at an office job, Shaw scrimped to pay for flying lessons and took her first solo flight in 1933, at age 23. She later joined the Ninety-Nines, the female pilot’s organization cofounded by Amelia Earhart, and eventually married a fellow pilot.

Other stories touched the wider world. The dirigible Hindenburg took its first daytime flight in Canton in 1936, and it passed through again on its final flight, on May 6, 1937, which ended in a catastrophic fire in New Jersey. The two servicemen for whom the park is named, 1st Lt. Arthur E. Farnham Jr. and SSgt. Thomas M. Connolly Jr., met and became friends while working as mechanics at this airport. During World War II, they served heroically on the crew of the same B-24 when it was shot down over Serbia. Aided by resistance forces, they hid behind enemy lines for two months before being rescued in a daring airlift. These stories and others appear on interpretive panels installed around the performance pavilion.

Today, it is hard to imagine that this sea of wetlands and meadow with an eastern edge of wetland and upland forest once supported either agriculture or aviation. In the wetland, the breeze tosses joe-pye weed, goldenrod, boneset, rushes and sedges, grasses, swamp milkweed, and asters. Blackbirds flit among the low branches of elderberry, witch hazel, blueberry, dogwoods, and winterberry. These and dozens of other species of herbaceous and woody species, selected by CSS and Hegemann after in-depth study, have succeeded in repopulating the diverse habitats here. Hegemann says the property is unique in New England, where red maple swamps tend to dominate, because it showcases the full range of wetlands plant communities: the alluvial red maple swamps adjacent to the Neponset River, with patches of cottonwood and gray birch; open-water floodplain emergent marshes and wet meadows that support cattails, water lily, pickerelweed, meadowsweet, and wool grass; scrub-shrub species including willows, highbush blueberry, and dogwood; and finally the wetland and upland forests of red maple and oak.

Crosby | Schlessinger | Smallridge
Plan of 1st Lt. Arthur E. Farnham Jr. and SSgt. Thomas M. Connolly Jr. Memorial Park. Credit: Crosby | Schlessinger | Smallridge.

“It’s exciting, scientifically, to have such vertical and horizontal diversity in one place,” Hegemann says. Not only can the eye take in the full sweep of the floodplain, but “vertically, the change from flat, open water to shrubs and trees is dramatic,” she says. “And the ecological diversity makes great wildlife habitat.” Bluebirds, for example, love wet meadows, and killdeer, a type of plover, have been spotted along the river. The open and emergent wetlands are especially inviting to migratory birds such as geese, ducks, herons, and warblers. There is also plenty to feed four-legged animals such as fox and coyote. Amphibians breed in the standing water left after spring flooding, and for at least three species of turtles, this place is paradise. Damselflies and dragonflies shelter among the alluvial swamps. Between these ancient insects flitting about and the prehistoric visages of snapping turtles that crawl up the banks to nest, it’s easy to envision the place as a soupy evolutionary lab.

But decades of disturbance have also primed it for the invasion of exotic species including purple loosestrife, common reed, and reed canarygrass. Hegemann is attacking them with a nontoxic liquid: water. “By providing varying water levels across the areas of restored wetland, we are hoping to check the spread of invasive species or the growth of monocultures such as cattails across the site,” she says. “In flood conditions, some areas could be as deep as five feet. We also created peninsulas that will be seasonally underwater, an idea that CSS came up with.” That will help interrupt noninvasive plants, such as cattails, from forming single-species swaths.

The Federal Emergency Management Agency has designated the entire site as a floodplain, and the agency’s regulations prohibit displacing water on the site, so Hegemann had to choose plants that could survive a fluctuation in water levels of three to four feet a month during the spring high-water season. “Not all the plants will survive,” she explains, “because they are fresh from the nursery and may not have time to adapt before seasonal flooding. Eventually, our goal is to allow species to self-select areas most suitable to them.”

Nursery-fresh plants also must adapt to the highly acidic organic soils (pH: about 5) uncovered during site excavation. These had been buried for decades under fill used to build the airport. Since these long buried “relic” soils were first exposed, however, the air and floodwaters have taken the edge off the extreme acidity.

BEDIT_F3-Canton_Norman_Wetlands and Black-Eyed Susans
The planting design knits the re-created wetlands (foreground) with the existing landscape. Credit: Daniel Norman, ASLA.

Though it is no longer surprising to learn that a sea of thriving wetlands is the result of a designed restoration, such transformations are particularly powerful when they amplify the capacity of other important sites and systems. This site is a small but important part of a regional system that includes the 8,350-acre Fowl Meadow and Ponkapoag Bog, a state-designated Area of Critical Environmental Concern—a place recognized for the quality, uniqueness, and significance of its natural or historical/archaeological resources.

What also makes the former airport land significant was its state of contamination and the chance to clean it up. When the DCR bought the tract, in 1995, the agency discovered toxins including polychlorinated biphenyls (PCBs) and heavy metals, mainly lead from hunting shot. The contaminants remained not only from the airport, but also from later occupants, especially a scrap-metal business that left pockets of PCBs in and around the hangars. (PCBs also turned up in the riverbed, but these likely flowed downstream from an EPA Superfund site in neighboring Norwood, one of two in the Neponset watershed. The second site is in Walpole.)

The ruins of a 1930s airport and pockets of toxic waste were not the only incursions into the floodplain. Interstate 95 and the Neponset River form the northwest boundary of the roughly triangular site. Building the highway included filling in wetlands and diverting the river through a dredged channel, which have contributed to flooding ever since. “During a severe rainstorm in 2012, fish swam up the I-95 ramp,” Hegemann says. A commuter rail line (which also claimed wetlands), a residential neighborhood, and an office-industrial park border the site on the east. The south side abutters include a busy street, another DCR tract, and two commercial properties. The land is also laced with sewer lines and mosquito ditches, and an easement for the state water authority’s maintenance road runs north–south through the site.

The DCR project manager Ruth Helfeld, ASLA, explains that the project consisted of two major components: remediating the site and creating a naturalistic and usable landscape. “The remediation, while a separate effort, fundamentally affected the parkland design,” she says. “It entailed complete clear-cutting of the site, extensive soil excavation, and depositing huge quantities of soil to form a three-foot-thick cap in the upland area.”

Visitors can glimpse the knoll and performance pavilion from this welcome kiosk near the parking lot. Credit: Daniel Norman, ASLA.

CSS started the master planning on both prongs of the project concurrently. (The master plan received a 2011 Merit Award for Landscape Analysis and Planning from the Boston Society of Landscape Architects.) GEI Consultants, Inc., the company in charge of cleaning up the site, analyzed the soils, came up with the remediation plan, and provided geotechnical surfaces to keep the new structures from sinking into the spongy ground. Hegemann coordinated with CSS and GEI to evaluate the soils and the frequency of flooding to plan the wetlands restoration plantings.

The park needed to occupy the limited upland above the floodplain that comprised most of the property. Twelve acres disturbed during park construction and remediation would be restored to wetlands. “During the public meetings, there was a group that wanted to develop ball fields in the park,” Crosby says. “But when they heard about the potential for flooding, they opted for passive recreation.”

That choice required minimal facilities: a lawn with a picnic shelter, a universally accessible trail for walking, opportunities to connect with nature, and interpretation of the site’s history, plants, and wildlife. The DCR also wanted to provide canoe and kayak access to the river and explore possible connections to hiking trails that passed through adjacent conservation areas.

Crosby says her team “wanted the park to be comfortable, with gentle enclosure to allow for more intimate spaces, places to really observe the texture and color of the plantings, and different experiences as you walk around, yet generally open and safe.” With design proceeding in tandem with the cleanup, the landscape architects saw opportunities to turn artifacts of the remediation into design features: The capped toxic mound, which, Crosby says, topped out at about 58 feet high, became a naturalistic knoll in the upland park. Curving around the base of the knoll is one of three stormwater-treatment swales, one of which drains into a wetland re-created to manage stormwater. “Two wetlands along the southern and southeastern edges of the park pick up about two-thirds of the stormwater from the site,” Crosby says. “All of the bank plantings help to filter stormwater, and the remaining stormwater flows through those into re-created wetlands surrounding the three developed acres.”

Stone walls evoke the agricultural past and ground the structures’ abstract geometry. Credit: © Charles Mayer Photography.

The knolls and swales in this area were sculpted through precise grading, which proved to be one of the project’s biggest challenges. In spite of extensive advance testing to determine the quantity of contaminated soils to be capped, “that amount kept increasing throughout construction, all within a tightly defined footprint, and we could not reduce the thickness of the cap,” Crosby explains. “There was only one direction in which the grading could change—up.” In the end, the cap consumed 14,000 cubic yards of soil. “The result was that the slopes are steeper than I would have liked, but the precise grading kept paths easily accessible and preserved the minimum depth of soils.”

During the master planning, the landscape architects recognized that several nearby conservation areas could be linked to the new park by building feeder trails to long-standing regional trail networks. Should this come to pass, hikers here could not only walk to a neighboring reservation, they could take a new spur of the existing 30-mile Warner Trail to the Bay Circuit Trail, which stretches 200 miles, from the state’s southeastern coast to Boston’s North Shore. Or, using other new and existing links, they could hike east from Canton to the 47-mile Boston Harborwalk, north to the Blue Hills Reservation, or south to Rhode Island. Eventually, some of these trails could be wrapped into the East Coast Greenway, a continuous Maine-to-Florida pedestrian corridor. The park, in short, could become not only a day-hiking destination, but also a hub for long-distance hikers traveling in all directions.

Within the park, the designers created different kinds of paths to reflect the varied environments, cuing walkers to their surroundings. A universally accessible, stabilized path runs from the park entrance to the north end of the property. Shorter, winding trails intersect the main corridor, leading to two observation decks, each tucked away at the edge of the wetlands. Although the canoe launch on the river has yet to be built, Norman says, it is one of several additional phases of work, which also include boardwalks and a canopy walk that have been schematically designed but not yet funded.

Crosby says that even before they began construction, the long-abandoned open space was a favorite haunt for local hikers and birders. “I assumed that the people who were coming here prior to the redesign would continue to do so regardless of what we did,” she says, “but I hoped that the design would also invite people in who had never thought of visiting. If the man who reported the plant poacher is in that category, I think there’s a new constituency for this part of the Boston Metropolitan Park System.”

Jane Roy Brown is a contributing editor based in Massachusetts.

Project Credits: Client Commonwealth of Massachusetts Department of Conservation and Recreation, Boston. Landscape Architect Crosby | Schlessinger | Smallridge, Boston. Design Engineer and Environmental Consultant GEI Consultants, Woburn, Massachusetts. Architect Touloukian Touloukian Inc., Boston. Wetlands and Ecological Assessment BSC Group, Boston. Structural Engineer Richmond So Engineers, Inc., Watertown, Massachusetts. Interpretative Signage Main Street Design Inc., Cambridge, Massachusetts. General Contractor Phase 1: CRC Company Inc., Quincy, Massachusetts; Phase 2: NELM Corporation, Carver, Massachusetts. Landscape Contractor ValleyCrest, Boston. Stonemason Tibetan Stoneworks by Gyaltsen, Shelburne Falls, Massachusetts. Steel Fabricator GG’s Custom Metals, South Hadley, Massachusetts. Electrical Engineer Architectural Engineers, Inc., Boston.

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