Utilizing Geofoam in Foundation Design for Steep Sloped Lots

Foundation Design Layout

Foundation Design Layout

A custom high end home was built on a very steep hillside lot overlooking Lake Washington near Seattle.  The owner of this home owns an excavation/gravel business.  He has all of the heavy equipment and free soil he could ever want, yet he chose to backfill three foundation walls with geofoam.  This project was originally designed with a compacted soil backfilled MSE wall that would have to be trucked down 95′, through a country club and from the top of the hill.  The amount of concrete, reinforcement, tie backs and forming costs that were removed from the foundation design more than paid for the geofoam and reduced the total weight of the import fill material by over 2 million pounds.


Geofoam Installation, Lake Washington Residence

Geofoam Installation, Lake Washington Residence

Benefits that lead to overall project cost savings by using geofoam as an alternative to traditional soil fill:

  • Geofoam is easily installed and the lightweight nature of geofoam allows it to be maneuvered by hand and used on projects with tight construction access where the use of larger mechanical equipment may not be feasible.
  • Shotcrete, Gunite, or soil can be placed directly against geofoam eliminating the need for expensive forming.
  • Construction traffic and import costs are minimized, as 1 flatbed truck of geofoam is equivalent to approximately 12 dump truck loads of traditional fill.
  • Congestion on the roads or road closures leading in and out of a project site is minimized.
  • The construction time of a project is reduced as several feet of geofoam can be placed in a fraction of the time that it would take to the place and compact traditional soil fill in the required 8 to 12-inch lifts.  As an added incentive, geofoam does not require compaction testing like tradition fill.
  • Decreased maintenance costs as a result of less settlement issues from the low density geofoam.
  • Tight construction scheduling can easily be maintained using geofoam as it can be installed during any type of weather or site conditions.
  • Geofoam is extremely eco-friendly and geofoam blocks can be re-used in other projects or be recycled.
Geofoam Installation, Lake Washington Residence

Geofoam Installation, Lake Washington Residence

Geofoam Installation, Lake Washington Residence

Geofoam Installation, Lake Washington Residence

Slope Repair Problem & Solution

PROBLEM:  Infrastructure challenge, road creep slide in Santa Barbara, CA

CAUSE:  Gravity

SOLUTION:   InsulFoam Geofoam, a predictable & long lasting foundation for new pavement

Conejo Road

Conejo Road Geofoam Installation, Santa Barbara, CA

The City of Santa Barbara, CA had been experiencing continual maintenance concerns and costs due to a creep slide on Conejo Road. The project engineers and the city decided to permanently fix the problem by addressing the core cause of slope failure, gravity. During this 2012 project, the delivery of the InsulFoam Geofoam was delayed a few days because the contractor found that the asphalt pavement was up to 18″ thick due to continual settlement and repaving operations over the years.   John Madonna Construction of San Luis Obispo, CA was awarded the prime contract which included installing the EPS Geofoam. This was their 1st project using the ultra-lightweight large block fill material. Steve Alkyer of Insulfoam’s Chino, CA plant came to the jobsite to help train the installation crew on reading the shop drawings and hot wire cutting tools both provided by Insulfoam. This project utilized about 400 cubic yards of InsulFoam GF EPS19 which will provide a very predictable and long lasting foundation for the new pavement section in a difficult access residential neighborhood.

Time lapse video of the complete job install for the Conejo Road slope repair project in Santa Barbara.


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Geofoam Offers Performance and Efficiency for Bridge Reconstruction

Modern Contractor Solutions Magazine

Modern Contractor Magazine, April 2009

Originally published in Modern Contractor Magazine, April 2009

Full article (pdf)

Known as one of the Top 10 High-Tech metropolitan areas in the nation (as cited by Newsweek magazine), the city of Omaha, Nebraska, leads the nation by pursuing the most innovative technologies in virtually every field imaginable, not the least of which is road construction.  With more than 100 road construction projects currently under contract, the Nebraska Department of Roads (NDOR) strives to utilize the most effective and efficient construction products in its continuous improvement of the state’s road structures.

That is why, when NDOR officials decided to reconstruct the Pacific Street Bridge, they chose to use expanded polystyrene (EPS) geofoam for the below-grade void fill portion of the construction project.  By spring of 2008, Pacific Street, which provides commuters with convent access to and from downtown Omaha, was experiencing significant traffic congestion, decreasing the ease and efficiency of local commutes.

The Pacific Street Bridge, which spans Interstate 680, experienced the heaviest congestion, affecting the flow of both local and regional traffic.  It became apparent to NDOR officials that this situation required a remedy that would not only be effective in streamlining the flow of traffic, but could also be completed in a short time frame.

The NDOR decided to widen the bridge by adding one lane, while maintaining the current length of the bridge.  Construction, which was managed by Hawkins Construction Company, a local Omaha-based construction contractor, began in March 2008.

The existing 2:1 slope protection was removed and replaced by abutment walls allowing room for t he needed extra lane

Pacific Street Bridge, Nebraska:  The existing 2:1 slope protection was removed and replaced by abutment walls allowing room for the needed extra lane

In order to build an additional lane without lengthening the bridge, Hawkins had to first construct abutment walls at each end of the bridge.  To avoid creating excessive lateral pressures on the new abutments, a lightweight void fill material was needed for filling in the embankments.  Because of this requirement, the NDOR chose to use geofoam for this portion of the application.

After comparing a number of geofoam manufacturers, Hawkins Construction chose to use geofoam manufactured by Insulfoam, the nation’s largest manufacturer of block-molded expanded polystyrene.

“It was vital that we use a product that would not increase the amount of lateral load placed on the new abutments,” said Omar Qudus, NDOR Geotechnical Engineer.  “We chose to use geofoam because it would do just that, and would enable us to fill the embankments while still being able to build the additional lane.”

As this was the NDOR’s first specification of geofoam, Qudus and his team consulted multiple geofoam manufacturers in order to ensure that the geofoam was used correctly and in a way that would enhance both the performance of the bridge and the efficiency of the construction.

“We talked to a number of geofoam manufacturers,” says Qudus, ”because we wanted to make sure that we were using the geofoam product correctly. Insulfoam provided ample feedback and a detailed specification of how InsulFoam® GF can be used in this type of application.”

The construction project required a total of 2,045 cubic yards of type 15 EPS low-density geofoam blocks that were installed as void fill at the bridge abutments.

After pouring the abutment walls, the Hawkins crew installed the geofoam blocks, which not only provided easy handling, but also sped up the installation process. The use of geofoam eliminated both the need for surcharge and the settlement that is experienced with typical fill products, such as soil.

“We used geofoam for this project because we did not have enough time for both the surcharge and settlement that are typical with the application of traditional fill products,” says Qudus.


Pacific Street Bridge, Nebraska

Hawkins’ on-site supervisor, Lance Winkler, agreed that the use of geofoam significantly reduced construction time. “With traditional fill products, we typically backfill with sand at 8-inch increments and then compact; with geofoam, we just placed the blocks in position and then backfilled the minimal area that was left with sand. The InsulFoam® GF made installation easier and more efficient.”

Installation of a drainage mat was also necessary in order to ensure that any water that might collect around the abutment would drain properly and decrease the potential for any damage that might be caused by moisture penetration. By ensuring that water drained away from the abutment, the drainage mat would also eliminate the horizontal pressure that standing water would create.

The entire construction project was completed by September 2008, a short 6 months after it was started, and the bridge was re-opened to traffic. The use of geofoam in this project not only offered enhanced labor and cost savings, but also provided the increased, long-term stability and superior performance needed for the ever-moving technological hub of Omaha, Nebraska.

 Full article (pdf)



Nico Sutmoller, Insulfoam Geofoam Specialist

Nico Sutmoller, Insulfoam Geofoam Specialist

Contact Nico Sutmoller, Geofoam Specialist


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