GeoStructures Inc.

GeoStructures Inc., based in Purcellville, Va., designs and builds foundation support and soil reinforcement for large commercial, industrial and residential structures throughout the eastern U.S. They joined PDCA earlier this year and couldn't be happier with the decision to become a member.
"We felt this was an important step to advancing the capabilities of our group in the U.S. since we had recently become part of the Terratest Group, which has a great history in deep foundations around the world," said Michael Cowell, PE, president and CEO at GeoStructures.
Cowell who previously was vice president of the Reinforced Earth Company and general manager of the Tensar Corporation formed GeoStructures in 1995 because he found that every time an innovative solution or product was developed, a contractor was needed who was willing to build it, or it wouldn't happen.
"I wanted to develop a design-build company that would challenge conventional solutions and provide customers with innovative solutions to their foundation and grade separation challenges. The test against which success was measured was that every solution needed to provide customers with value in terms of cost savings over conventional methods, a shorter schedule and a seamless project delivery by a team focused on customer service through the design/build delivery. It was believed that anyone can bid specs and plans, but real value occurs by improving the plan and providing a design that is easier to build, lowers cost, improves the schedule and is accomplished with great customer service."
History and today
GeoStructures began as a design and marketing firm selling tieback and cantilever pile solutions to contractors in 1995. In 1997, the company obtained the Geopier® license for the mid-Atlantic area and formed a construction arm GeoConstructors to design and build Geopier ground improvement systems. The growth of ground improvement in the region led to numerous contracts on projects in North Carolina through New York, including support of embankments for the 11th Street Bridge project in D.C., the I-495 HOT Lanes, Capital One Building in Tyson's Corner, Pittsburgh Penguin Arena, Tappan Zee Bridge Abutment and office buildings, data centers and warehouses along the I-95 corridor.
As the company grew, the company expanded into piling options to compliment the ground improvement. In 2010, GeoStructures worked with the Fluor-Lane JV on the I-495 HOT Lanes project designing and building all the sound walls, MSE walls and several soldier pile and tieback walls. Overall, this was a $45 million contract.
"It was in January of this year that the Geo Group was sold to the Terratest Group, which will enable Geo to expand its footprint in the U.S. and provide more design-build capabilities in piling, support of excavation, diaphragm walls and tunneling," said Cowell.
GeoStructures and its affiliated construction companies (including GeoConstructors) have approximately 90 employees serving customers in New York, New Jersey, Delaware, Pennsylvania, Maryland, Virginia and North Carolina.
GeoStructures specializes in providing design-build construction services for foundation support (precast concrete piles, pipe piles, H piles, full displacement columns, ductile iron piles (DIPs) and diaphragm walls), ground improvement (aggregate piers, rigid onclusions and rapid impact compaction) and structures (microtunneling, diaphragm walls, SOE, sound walls, retaining walls, MSE walls, post and panel walls, concrete arches and bridges).
"These technologies are used to solve problems such as settlement control of buildings, tank and MSE wall foundations, liquefaction mitigation, support of load transfer platforms for walls and embankment, economical grade separation options and repair and replacement of utility tunnels," said Cowell.
He adds that over the past 20 years, a great deal of the design-bid-build work with drilled shafts and piles has switched to design-build with ground improvement.
"Recently, in the last three years, we have been promoting design-build for pile foundations and combinations of piles and ground improvement. This seems to be taking hold and allowing more innovation with piles."
Notable projects
While GeoStructures has a number of impressive projects under its proverbial toolbelt, two notable projects include the Adele in Washington, D.C., and Virginia Tech (Brodie Hall) in Blacksburg, Va.
The Adele is a redevelopment project that involved the construction of a new eight-story, mixed-use project located just three blocks north of the White House. The main challenge consisted of installing a cost-effective, low-vibration deep foundation on an extremely tight urban site.
"The geotechnical engineer considered numerous deep foundation options, including caissons extending to bedrock, auger cast piles and ductile iron piles," said Cowell.
"Ductile iron piles were selected because of the ability to work on the congested site, the modular and self-contained nature of the operation and the low-vibration levels during installation, which allowed us to work immediately adjacent to the property lines."
The piles were designed for a working capacity of 40 tons (compression). The DIP design consisted of a 4.6-inch diameter pile with a 0.3-inch wall thickness, which could develop a working capacity of 40 tons by driving through the terrace and residual deposits and terminated in partially weathered rock. In several locations, the piles were required to support 40-ton compression loads as well as five-ton tension loads. A modified installation approach was used on the tension piles using an oversized 8.6-inch conical grouting shoe, which allowed grout to be pumped through the pile and outside the pile to create a friction bond with the soil and weathered rock. The piles were driven to termination by achieving set in the weathered rock and resisted the tensile loads with a center bar inserted into the center of the friction pile.
"A compression load test was also performed at the site," Cowell said. "Deflection of the compression pile was less than a quarter-inch at the 80-kip design load. Following pre-production testing, a total of 145 piles were installed to terminate in rock at depths on the order of 25 to 30 feet below the working grade."
In Blacksburg, Va., the Virginia Tech Brodie Hall project included the construction of a new five-story dormitory with 234 dorm rooms with study and lounge space on each level. Project challenges included the following:
Heavily loaded mat foundations next to smaller footings
Excess settlement potential from adjacent footing stresses
Deep weak soil profile
Variable depth to a competent soil/rock layer
Tight settlement tolerances less than three-quarter-inch total
"A combination of systems proved to be the best method and consisted of Geopier rigid inclusions, Geopier Rammed Aggregate Pier® elements and Ductile Iron Piles," said Cowell.
"The DIPs provided an economical solution for areas where pier depths were 55 to 75 feet deep, which was beyond the depth capabilities for Geopier elements. The DIPs were able to transfer loads down to the weathered rock layer, thus eliminating adjacent footing stresses and controlling settlement to below less than three-quarter-inch."
What's next?
As for the near future, Cowell says over the next few years the plan is to move the needle on promoting design-build performance specifications for deep foundations.
"Currently, most deep foundation designs are prescriptive, with 'one size fits all' designs. Specialty contractors are only asked to provide a price for what is specified. By providing design-build specifications, we believe that owners and general contractors can benefit greatly from the many innovative solutions that specialty contractors can provide with pile foundations."

Posted in PileDriver Magazine. Tagged as Issue 5, 2018.

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