PROJECT OVERVIEW: HOW A LANDFILL ADDED 3 MILLION CUBIC YARDS OF VOLUME WITH NO ADDITIONAL LAND, THANKS TO SMART ENGINEERING AND GEOSYNTHETICS.

Situation:

The Donzi Lane Landfill in Atlanta, GA was near capacity but the need for landfill space was urgently increasing due to population growth and development. There was no additional land to expand the landfill outward. A new landfill would be too costly and take too long to develop. The Donzi Landfill needed an innovative way to expand, quickly.

The answer was to build up. But how do you construct sides for a landfill that rise up vertically that are strong enough to hold millions of cubic yards of volume and withstand the constant activity of dump trucks?

Further, vertical expansion created a serious complication. High-tension lines traversed the center of the landfill. Height limitations were so severe that dump trucks would no longer be able to lift their beds to discharge waste without hitting power lines. The lines had to be relocated and raised to allow dump trucks to travel across the site. But the foundations for the new power line supports needed to be located within the reinforced fill. How could the fill be made strong enough to hold the power line supports?

Solution:

The answer was the StrataSlope System, which comprised geogrid-reinforced steep slopes with wire-basket facing. The reinforced slopes created sturdy sides that provided increased landfill volume and created a strong enough foundation to hold the power line supports.

Vegetated reinforced steep slope was also considered. However, the reinforced steep slope with rock-filled wire-basket facing provided more expansion capacity. It was also the best option for staged construction, which would permit vertical expansion to proceed, as additional landfill capacity was needed. The planned finished height of the structures reached 40 feet.

The foundation conditions and waste currently on-site were competent enough to allow the increase in loading from both the steepened slope and additional waste. Stability analysis was performed using design programs, which analyzed internal stability, compound stability, direct sliding and deep seated analysis. Seismic stability analysis was also performed, completing the geotechnical analysis of the site structures.

The primary reinforcement layers consisted of Stratagrid SG500 and SG550 with maximum embedment lengths of 26 feet. Vertical spacing of the primary reinforcement varied. The vertical spacing for the initial 6 feet of slope construction was 1.5 feet, while 3 feet vertical spacing was utilized for the remainder of the slope up to the maximum vertical height of 40 feet. The facing detail utilized Stratagrid SG150 for secondary reinforcement and 90-degree welded wire baskets for facing support. Since aesthetics was not an issue and the owner did not want to maintain a vegetated slope, the baskets were filled with stone. This facing detail also provided long-term erosion control.

Results:

The design and construction of a Stratagrid-reinforced retaining structure around the existing Donzi landfill provided a safe, highly engineered method of expanding this tightly-restricted landfill. It was constructed with the landfill operator’s own crews, and the completed project resulted in more than 3 million additional cubic yards of volume. Performance today is still excellent. The StrataSlope system has performed as designed, and the wire form face using SG150 face wrap and 1-inch clean stone is performing as designed, as well.

To learn more about StrataSlope, visit www.geogrid.com or call 800.680.7750.

Strata Systems (www.geogrid.com) is a leader in the production and distribution of advanced geogrid soil reinforcement and composite geosynthetic products under the Stratagrid®, Microgrid™, StrataTex™, StrataWeb™ and StrataDrain™ brands. Additionally, the company’s Sleeve-It product line affords designers and civil engineers a code-compliant system for integrating fencing into engineered retaining walls. High performance Strata products are designed to meet complex engineering and construction challenges relating to retaining walls, reinforced slopes and embankments. Strata Systems state-of-the-industry manufacturing and R&D capabilities are an extension of its commitment to growth through innovation. Strata Systems is an operating unit of Glen Raven, Inc. (www.glenraven.com) the leader in performance textiles and fabrics, recognized globally for its Sunbrella® brand.