Slope inspections were conducted for the city of Burlington, Vermont, as the first of an inspection program.
According to a study presented to the Public Works Commission, the program is being established to inspect, monitor, and identify prioritize projects as a proactive maintenance plan to address slope stability issues.
Hoyle, Tanner & Associates worked with Terracon to perform inspections of four identified slope locations including: Northshore Natural Area, Manhattan Drive at Route 127 Beltline, Manhattan Drive at North Champlain Street, and Riverside Avenue, according to Burlington’s Public Works. The visual inspections were completed in the Fall of 2019 and Summer of 2020.
Based on the results of the study, there are urgent repairs needed to prevent destructive landslides along portions of Riverside Drive in Burlington. This risk first became known when a large landslide in the area occurred on Oct. 31, 2019, reported The Burlington Free Press.
These locations also experience surface erosion, active slope movement and some of the recommendations include monitoring vegetated slope stability and erosion around drainage pipes and swale, according to the study. Slopes will be “armored” with crushed rock and boreholes will be drilled to find out what lies beneath thin topsoil.
The locations also experience loose soil, which is compounded by storm water erosion and threatens buildings and parking lots, according to consultants Terracon and Hoyle, Tanner & Associates, reported the study.
Steps to repair the least stable parts of those slopes are already underway, according to the Public Works Department in the study.
Riverside Avenue in particular served as a city dump for decades. Loosely packed brush, construction materials and car parts are shifting downhill, according to the study. A landslide in 1955 exposed hundreds of junked cars.
Vermont State Geologist Marjorie Gale warned that landslides on Riverside Avenue pose a threat, reported The Burlington Free Press.
"If it's happened here once, there's a very good chance it's going to happen again," said Gale to The Burlington Free Press. "A landslide will not stabilize itself."
