The document discusses a bridge project in California where the Dimension Foundation Improvement System by Tensar Earth Technologies was used to support heavy crane activity. The system was installed atop clay and silt soils with high groundwater levels to support crane weights up to 560,000 pounds. It has performed well with only 1/2 to 3/4 inch of settlement under 3,000 pounds per square foot of loading. The system was also able to support 740,000 pounds of crane load without needing temporary piles. The project has garnered interest from other contractors observing its success in supporting extremely heavy loads in difficult soil conditions.

1. Dimension®
System Hosts Colony of
Cranes at California Bridge Project
Issue 14.2 — fall 2004Tensar Earth Technologies, Inc.
geo
C
Geosynthetics Applications Newsletter
Crane watching in northern California isn’t for the birds – at least not at the site of a three-year interchange/bridge project
currently underway on Interstate 680.
The cranes there aren’t the feathered, water-loving variety; they’re a colony of Manitowocs busy with pile operations
and construction in the major expansion of the Benicia-Martinez bridge east of San Francisco. And they’re doing it atop
TET’s Dimension®
Foundation Improvement System.
The $42 million California Department of Transportation project, awarded to FCI Constructors in the summer of 2002,
specifies a new five-lane approach for northbound traffic. The approach will flare to 17 lanes through a new toll plaza
and return to four lanes on a new northbound bridge. The project site, described as “brackish marshlands” in an industrial
area, required construction of a working platform to support critical crane activity.
“We initially tried a coated polyester geogrid product with little success,” commented David Niese, P.E., senior project
manager at FCI North, a subsidiary of Netherlands-based HBG Constructors. About that time, Ron Illium, P.E., TET
business development manager for the Pacific region, submitted a value-engineered Dimension System proposal to FCI –
one that Illium felt was “a more cost effective and efficient way to handle the platform than FCI’s original solution.”
The Dimension System was developed to provide a stable foundation at a lower cost than conventional methods. The
system’s components include Tensar BX Geogrids and cohesionless soil, working together to create a stiffened platform
and distribute loads over weak, compressible soils. Among its benefits, the Dimension System increases bearing capacity
while it reduces differential settlement, undercutting, and backfilling.
“The foundation soil at the site included clay and silt, and groundwater was located at the bottom of the embankment,”
said Jong Lee, TET design engineer. To accommodate these conditions, the design featured two layers of BX1200 Geogrid,
with 1 foot of 1-inch aggregate sandwiched in between and 3 feet of 3-inch drain rock on top. The structure was designed
to support crane weights up to 560 kips and pick loading up to 150 kips. To date, the project has required more than
30,000 square yards of geogrid, according to Lynn Friesner, technical manager at Reed & Graham, TET’s regional distributor.
The majority of the installation took place over the first month and has continued as needed. FCI’s Niese, who had
worked with other Tensar Systems prior to the project, has been delighted with the results.
“I didn’t envision it performing as well as it has,” Niese said. “We’vehad no settlement or pumping issues. Settlement
has ranged from 1/2 to 3/4 of an inch with 3,000 pounds per-square-foot loads.
“The installation was originally intended for job access. But with load testing, we’ve been able to eliminate temporary
piles for supporting bridge formwork — it’s now supported on pads placed directly on the fill. We’re talking about 740,000
pounds of crane load.”
Located in sensitive wetlands, the Benicia-Martinez project may not
feature cranes from the animal kingdom, but it has garnered quite a bit
of interest -— and not just from other contractors who have come to
observe the work. The Discovery Channel’s Canadian outlet visited the
site to film the “Big Stan” drill rig for its “Monster Machines” series!
The Dimension Foundation Improvement System
was used to support extremely heavy crane loads
at the Benicia Bridge expansion project.
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