Transcript The Riverside Avenue Landslide of 1955 Why is this area prone to landslides? Mark Leporati & Luella Strattner ABSTRACT:The purpose of this study.

The Riverside Avenue Landslide of 1955
Why is this area prone to landslides?
Mark Leporati & Luella Strattner
ABSTRACT:The purpose of this study is to understand why Riverside Ave. in Burlington, VT is prone to landslides. The Winooski River, which is ~43m wide and ~2.8m deep, has a discharge
of 21.7 m3/s at normal flow. We calculated Manning’s N to be 0.19. Our findings are that a combination of human impact and the steepness of the slope, on top of which Tortilla Flat now
stands, are responsible for the slope failure of 1955 in particular. The Winooski River at the foot of the slope continuously erodes sediment from the toe, weakening it. Humans have
impacted this area by constructing a road right on the edge of the Winooski river terrace, loading the top of the slide.
Then
Tortilla Flat,
indicated by a star,
is located on this
topographic map.
Note the close
contour lines at
Tortilla Flat and the
meandering
Winooski River.
View of December 8, 1955 transitional landslide
Damage from December 8, 1955
Now
Reasons for Failure:
Steep Slope
Human impact
~construction of buildings (loading top of slab)
~vibrations from vehicles on Riverside Ave.
Is this really a good spot for a restaurant?
Winooski River Erosion (removing mass from toe)
Tortilla Flat, October 19, 2005
Precipitation
Winooski River Facts:
Channel dimensions: width is 43 m, depth is 2.8 m, wetted cross sectional
area is 120.4 m2, velocity is 0.18 m/sec (at normal flow)
Discharge: 21.7 m3/sec (at normal flow)
Sediment type in river: all fine grained dark brown silt/clay
Channel type & geometry: The meandering Winooski River occupies an
alluvial, plane-bed channel.
Soils: At this site, the soils are not overly well developed, as this area is
prone to landslides. There is a distinct organic layer, as there is a lot of
riparian vegetation. Below that there is a mixed zone of river sediments and
debris from the slope above, including parts of trees, some chunks of cement
and building materials.
Chemical analysis of water sample: Units = g/mL
0.03~Al, 0.00~Be, 15.60~Ca, 0.03~Fe, 0.93~K, 3.55~Mg, 9.83~Na, 0.00~Ti
This diagram shows the basic components
of the area under study. The inset
photograph, taken in 1930, shows that this
slope has been in need of stabilization since
humans began developing this area.