Residential Slope Stabilization | South Hadley, MA
Collaboration with the Regenerative Design Group
This project stabilized a severe slope failure caused by a clogged storm drain pipe during a heavy rain event. The top of the slope failure was located just 12 feet away from this house’s rear deck support. The failed slope measured about 50 feet across by 60 feet in height with a 1:1 or steeper gradient. Wetlands located at the bottom of slope put the site within the wetland buffer zone requiring a wetland permit to complete the work.
The terraced bioengineered solution included a combination of hard structural retaining walls, softer bio-degradable coir tube structures to tie in the ends to existing woods, and substantial planting and seeding secured with bio-degradable blankets. Openings through the retaining walls allowed surface and groundwater to drain freely from behind walls and be directed into reinforced channels down the slope face. Preserving stable existing patches of existing native willows within the slope failure area proved important to the project’s success. Native planting techniques featured live staking of native willows and dogwoods, and hundreds of native grass, fern and wildflower “plant plugs.” At top of slope adjacent to rear lawn, a showy flowering strip was included to enhance views from the house and further stabilize the upper slope.
Plantings and seeded area established quickly and this slope has proved stable through extremely wet periods such as the 2018 season (two years after construction), and also through successive drought years.