A Vision of Hillside Regeneration
Keith Zaltzberg and Josiah Simpson traveled to Montville, Maine to oversee the construction of slope-stabilizing, water harvesting earthworks on a 60-acre parcel known as the Halldale Hillside. This was the second phase of a multi-year plan to transform a denuded and eroding hillside into a stable landscape that protects local waterways, provides wildlife habitat, and produces fruits, nuts, herbs and flowers.
The Halldale Hillside is the site of a failed subdivision. The parcel was clear-cut, the topsoil bulldozed (exposing the mineral subsoils), and a poorly engineered dirt road was built. When we first visited the site in Fall 2013, the exposed soils and road were rapidly eroding. Because the topsoil had been removed, the ground was devoid of plant life and a seed bank.
Phase One of the Halldale Hillside repair began in the spring of 2014 and involved planting over 100 pounds of pollinator and pasture seed mix across the site to help stabilize the soil and begin nurturing the development of topsoil. The seed mixes germinated successfully and by July, wildflowers like rudbeckia, vervain, and blazing star were blooming and native grasses had established a firm root mass. To overcome the drainage issues that were continuing to compromise the hillside, we designed a network of diversion and infiltration swales.
These simple swales are engineered to slow the flow of water, spread it out and distribute it across the hillside, and infiltrate it into the ground. This network of swales simultaneously diverts water from erosion channels and creates a passive irrigation system to support the future vegetation of the hillside.
Over 1000 linear feet of swale were formed using a bulldozer, excavator, and 10 volunteers from the Waldo County Permaculture Community. Using a transit to check elevations, the team was able to pitch the swales just off contour at .5%-2%, which allows water to infiltrate in the swale basin but still move across the landscape very slowly. The spillways for each swale were hand graded into level spreaders that evenly overflows water downhill to the next swale. After construction, the swales were seeded with cover crops to help with soil stability and nutrient improvement. A surprise thunderstorm dumped an inch of rain in twenty minutes, but the swale network held together with no breaches.
Phase Three, scheduled for Spring 2016, will involve a forestry style planting of native and productive species such as hybrid chestnuts and hazels across the Halldale Hillside.