by Fred P. Rohe
The city of Detroit is in the process of reclaiming its river
front. Over the years the area has been dominated by business and
industry but the area has become an embarrassment. The Detroit
Riverfront Conservancy was created with the mission of revitalizing
the waterfront area. The first phase of this undertaking was the
Louis Arena to the Douglas MacArthur bridge to Belle Isle. People
are to run, walk, bike and roller-blade on the new RiverWalk, which
will also include places for people to sit and take in the scenery.
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A portion of the RiverWalk passes directly between the General
Motors (GM) Renaissance Center buildings and the Detroit River. GM
retained Albert Kahn Associates to design a suitable plaza and
promenade to blend as part of the RiverWalk project. The plaza
includes a granite world map showing the GM facility locations world
wide. John Carlo, Inc. was selected as the prime contractor to build
the plaza as a showpiece for the GM Center.
The area selected for the plaza has seen many varied uses over the
past century. There are many unknowns regarding the soils and other
materials deposited there. It was known that the area had
experienced some subsidence and the fill in the area was over soft
soils. The area is bounded on one side by a service areaway and on
the other by a concrete sea wall at the river’s edge. The site’s
close proximity to the Windsor Tunnel under the Detroit River to
Canada was another important consideration.
The plaza area needed to be raised approximately four meters above
the existing parking lot area it is replacing. The designers
selected expanded polystyrene Geofoam for use as fill material. The
1.5 pounds/square foot density Geofoam would save weight, reduce
lateral pressures on the adjacent structures, and speed construction
at the congested work site.
Hydrocarbons have a devastating effect on contact with expanded
polystyrene foam. In order to protect the Geofoam from damage by an
accidental spill of fuel or other hydrocarbon materials, the
designers utilized a geomembrane.
8130 XR-5 was selected to cover the top of all areas where Geofoam
was installed. XR-5 is a PVC coated fabric formulated using Elvaloy,
a chemical resistant polymer which imparts flexibility to the
The GM Renaissance Center Plaza and Promenade is a public area in
downtown Detroit. GM will be displaying vehicles at the plaza as
well as hosting many outdoor events in the area. The plaza will also
be heavily landscaped to provide an enhanced look to the park like
setting. The plaza is also directly adjacent to a busy city street
with all types of vehicles all types of vehicles traveling in the
congested area. There is legitimate concern for a possibility of an
accidental fuel spill. Therefore it was necessary to take
precautions to protect the Geofoam from any adverse exposure to
chemicals that would dissolve the foam.
Environmental Protection, Inc. (EPI) was selected to provide over
4,700 square meters of XR-5 geomembrane liner for this project. Over
one acre of XR-5 was prefabricated to fit the varying shapes of the
plaza and the many planter boxes and planting areas that were
incorporated into the design. Each area of the plaza where Geofoam
was installed had to be covered with geomembrane. The XR-5 material
was installed directly over the foam, or over a sand cushion that
was installed on top of the foam in some areas.
The liner extended up vertically 30 to 50 centimeters on the
perimeter concrete walls. The geomembrane was secured to the
concrete using an aluminum batten bar 0.3175 centimeters by five
centimeters. The batten was anchored to the concrete wall using
Ramset three centimeter long powder-actuated fasteners located
approximately 15 centimeters centre to centre.
Since the geomembrane now acts to collect any fluid, including
rainwater, a drain age system had to be implemented above the liner
and drain piping to direct the water away from the plaza. The liner
was sealed to these drain pipes using prefabricated EPI Tapered Pipe
Boots. Boots were custom fabricated of XR-5 for each pipe diameter
used on the project. EPI also prefabricated inside and outside
corners to simplify the installation of the XR-5 around the many
column foundations and intricate corners in the planter areas.
Installation of the XR-5 had to be coordinated with the many other
subcontractors working on the site. The area was so congested that
the installation had to be done in phases in order to allow enough
area for everyone to operate efficiently.
The XR-5 geomembrane provided an excellent solution for protection
of the EPS Geofoam on this project. The material was easily
fabricated to fit the unusual shapes and dimensions of the plaza and
its many planters. Installation was rapid, with very little field
While unlikely, it is possible that an accidental spill could cause
serious damage to the Geofoam underlying the GM Renaissance Center
Plaza and Promenade. The foresight to provide protection for the EPS
foam will ensure that this area will be use-able and useful to the
visitors to the Detroit river front for many years to come.
Curtis, R., Page, D., Peaslee, G. “EPS Geofoam Technology
Project”, The Bridge, April/June 2004, Michigan Technological
University, Houghton, MI 49931.
“Reclaiming The Riverfront.”
“GM Riverfront Plaza & Promenade”, The Liner Letter, Vol. 4 –
Issue 5, July 7, 2004.
Wehrmeyer, S., “Geofoam: Providing new solutions to old
challenges”, Geotechnical Fabrics Report, June/July 2001.
Nystrom, J., “Applications: Geofoam takes a new track”,
Geotechnical Fabrics Report, September 1999.
Reuter, G., Rutz, J., “Applications: A lightweight solution for
landslide stabilization”, Geotechnical Fabrics Report, September
Environmental Protection, Inc.
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