A major grant to the Blackstone Parks Conservancy (BPC) for trail work in the Blackstone Park Conservation District will shore up our long-standing efforts to slow runoff and stop erosion. This welcome help arrives just in time to begin addressing a major challenge in a major way.
As we walk in the cool green of the park overlooking the Seekonk River, the ground beneath our feet feels solid enough. But in fact, every rainfall sends more of the thin topsoil sliding down to the foot of bluffs of glacial outwash created 10,000 to 12,000 years ago.
“It’s essentially a sand dune,” one BPC science advisor warns, waving photographs of the bluff that caved into the Seekonk River at Butler Hospital in the early 1990s. Such a collapse is probably not imminent here. Still, that image does concentrate the mind.
For years, volunteers lugging barrows full of woodchips and installing runoff-slowing water bars have struggled to stem the flow of topsoil off the central section of the Conservation District to the ground below and eventually into the river. With the Providence Parks Department and the Appalachian Mountain Club they built bluff-protecting fencing using small grants from the Rhode Island Department of Environmental Management (RIDEM).
Working with small numbers of our volunteers and, more recently, Friends of Blackstone Woods, we made some headway, especially above the eastern bluff. Greenery sprouted where there was only bare dirt not long ago. But at this pace, the struggle to slow runoff and stop erosion had little chance of lasting success, especially as super storms became more frequent.
The challenge of reducing the impact of stormwater is considerable. Even the level-looking parts of the plateau in the central section slope 5-15 percent, and the steep parts tilt as much as 40 percent. Without intervention, trails packed hard by walking and running feet are less and less able to absorb rainfall, becoming chutes for downhill-racing water. Aggravating the problem, visitors who ignore the “Please Stay on the Trails” signs trample plants, which then no longer can hold soil in place with their roots.
Both Blackstone parks face stormwater challenges. Though it is less noticeable on the Boulevard, erosion occurs there too, especially on the heavily used path. That problem is costly but manageable. In the Conservation District, however, an intense storm can undo years of effort in minutes, as happened in July 2012.
The three-inch downpour last July gave a foretaste of what to expect, overwhelming the coir “logs” and water bars laboriously installed by volunteers. Grasses that were beginning to repopulate the slope at Parkside with BPC encouragement were washed away. And the new garden of native plants recently installed at Angell Street by the Rhode Island Natural History Society and BPC volunteers was pierced by a small gully.
Now, with the Providence Parks Department and a substantial grant from DEM and the Rhode Department of Transportation (RIDOT), the Blackstone Parks Conservancy can do a better job of keeping the park where it belongs. The grant will allow us to buy tough matting to hold steep slopes in place while native plants take root, more coir logs, and other materials recommended for slowing runoff. And concentrated resources can accomplish in weeks what would take volunteers years.
Meanwhile, volunteers will work to match the $67,320 grant with roughly $17,000 worth of labor and funds. A subcommittee is fine tuning the plan drafted last fall, selecting the best plants for bioremediation in bare areas and drawing up details for steps, or “cribs,” in one steep trail to capture water, as well as other erosion control measures. Our charge is to “first, do no harm.” We want to ensure that neither the money nor the work is wasted. Soon we will solicit competitive bids, and work in the woods should begin in September.
The project will be phased to allow time to intervene in one area, then step back and monitor results before proceeding to the next phase. Later this summer and early fall, look for tables at Parkside Avenue where you can see the refined plan (also on the BPC website) and make comments and suggestions. We will need volunteers to help with many aspects of the project.
Some say, “Erosion is natural. Let nature take its course.” Erosion is natural. But human beings have altered the natural course of things. Now, thanks to the trail grant, we can give nature a chance to heal as we move toward our vision of healthy urban green space for all.
Jane Peterson
