Case Study / Waterline

Atlas EPS Geofoam Leaves Grand Rapids Waterline Undisturbed

When the Michigan Department of Transportation (MDOT) decided a road-widening project along a 6.75-mile stretch of Lake Michigan Drive (M45) through the town of Allendale would be necessary, it meant leveling several hills and valleys along the two-lane rural road to create a divided four-lane boulevard.

An expansion of the busy rural artery could not happen until the load on a nearby buried water main — that supplies up to 45 million gallons per day to the greater Grand Rapids area — was also lessened. A traditional sand fill would exert a 2,000-pound-per-square-foot load on the 1939 waterline and that would present too much of a rupture risk to the 46″ diameter, wire-wound reinforced concrete waterline. So road engineers turned to a less traditional, more innovative fill for the job.

MDOT specified geofoam ⎯ the generic name for large blocks of Expanded Polystyrene (EPS) ⎯ which is manufactured by Atlas EPS, a division of Atlas Roofing Corporation that specializes in developing and manufacturing quality, HCFC-free EPS insulation products.

This wasn’t the first time geofoam ⎯ an environmentally responsible fill option that doesn’t contaminate ground water or soil ⎯ had been used in Michigan. MDOT had found many applications for geofoam on its road building projects. Geofoam is also used in road projects over underlying soft soils that cannot carry the design loads and is installed alongside bridge and foundation walls as a soil substitute to reduce horizontal loading. In some cases, geofoam can also reduce the amount of steel reinforcement and concrete needed to build bridges because of a lateral load reduction.

For the M45 project, geofoam greatly reduced the weight over the waterline. For example, a 20-foot tall by 1-square-foot geofoam column weighs just 31 pounds, an equal volume of sand would have weighed about 2,000 pounds! Over the entire project, the foam blocks weighed a combined 533,000 pounds and represented just 1.5% of the nearly 36 million pounds of sand fill that the geofoam replaced. For perspective on how much foam was placed under Lake Michigan Drive, the 4,100 geofoam blocks used would cover a football field stacked over 87’ high.

Geofoam blocks can carry the enormous weight of a four-lane boulevard and the traffic it carries because the blocks have impressive compressive strength, in spite of their light weight, and the load is spread over a large surface area. The blocks for the M45 project were at 1.54 pcf density EPS, but density can be adjusted to specifications.

Each block was molded at the Atlas EPS Byron Center, Michigan plant and cut to size before being delivered. Field cutting was easily achieved, with a chainsaw, on-site, especially to fit around manholes. The foam blocks left the factory and arrived at the jobsite in August 2001 by flatbed truck consisting of 36 blocks per delivery. Each block on the M45 project weighed 130 pounds and was 32″ x 48″ x 96″, making installation easily accomplished with two workers.

Before the road could be surfaced, the sides and tops of the blocks were wrapped in a PVC liner to prevent degradation if a petroleum spill occurred on the highway. Dirt was moved to road level to secure the blocks from side-to-side movement and a minimum 3’ layer of sand and gravel was placed on top of the blocks to keep them below the frost line.

Bruce Morren, project manager with Nagel Construction Inc. of Wayland, Michigan, the project’s general contractor, said he enjoyed working with Atlas EPS, which delivered enough geofoam to cover a nearby 10,000-square-foot yard, where it was covered to prevent UV light degradation. “They made it faster than anybody else could in the area,” Morren said.

The advantage of geofoam was safety, according to Morren. “The labor cost is probably about the same, but the safety factor is key.”

As the geofoam was laid, about 40 to 45 million gallons of water per day flowed through the City of Grand Rapids waterline, Morren noted. A heavier fill or dirt moving equipment could have punctured the line and it would have taken two to three hours to shut off the water. “When you put the foam over the line you know you are not going to disturb it,” Morren said.

Morren also noted that geofoam is the more cost-effective choice of fill when sand fill requires long-distance transportation. Other benefits include a reduction of labor costs and project schedules and the fact that geofoam can be constructed easily in limited right-of-way areas and in adverse weather conditions.

Installation of the geofoam was a snap, according to Morren. Each foam block was fastened into place with 4″ by 4″ galvanized steel connector plates. The blocks were laid perpendicular to the previous layer with the vertical joints offset to the greatest extent practical.

The multi-layered foam blocks were placed in trenches that had been cleared of vegetation and any large sharp-edged soil particles prior to placing a geotextile and/or sand-bedding layer. The plastic liner was installed in 20’ lengths and overlapped by 18”. The foam was then covered by 5’ of sand and gravel and the road surfaced with bituminous asphalt.

This was the second road project incorporating geofoam that was successfully completed by Nagel Construction. Their first application of Atlas EPS geofoam was in 1996, for a bridge approach in northern Michigan.

According to the U.S. Department of Transportation’s Federal Highway Administration, geofoam has been used on high profile jobs in the United States, including the Interstate 15 project in Utah and the Big Dig in Massachusetts. Both projects turned to EPS geofoam to complete large embankment sections under extremely tight construction schedules that would not have allowed enough time for conventional embankment construction.