- THE MAGAZINE
The award, given for a highly innovative slime remediation project, was presented to Ed J. Garbin Jr., chief engineer of Hayward Baker’s southern region, Feb. 23 during the ASCE Ridge Branch’s annual awards banquet in Lakeland, Fla.
In being selected for the award, Hayward Baker was cited for its technical leadership in employing highly effective and cost-efficient Rigid Inclusions (RI) technology in the construction of a major road extension in Lakeland, Fla. The East-West Connector project involved extending Edgewood Boulevard to the west, from Harden Boulevard to South Florida Avenue.
The project’s scope included constructing a new roadway embankment through an area formerly strip-mined for phosphate ore. A portion of the proposed roadway alignment was situated over settling ponds remaining from the former mining operation. These ponds contained up to 40 feet of very soft waste phosphatic clay (slime). This very weak and unstable material needed to be modified in order to make the land suitable to support the roadway embankment.
Hayward Baker’s solution was an innovative RI ground improvement system, proposed as the most effective and cost-efficient way to ensure long-term stability in an environment of poor soils beneath the new roadway embankment. As a proven solution in Europe for supporting embankments on soft soils, RIs reinforce buried soft compressible soils by transferring stresses from a near-surface granular soil to a deeper competent stratum. Compared to alternative stabilization methods, they often are a significantly less costly solution.
Employing RI technology for ground improvement involves using high-modulus columns constructed through compressible soils to reduce settlement and increase bearing capacity. These are arranged in a grid pattern, and extended to the competent bearing stratum. As part of the system, Hayward Baker designed a reinforced earth bridging layer directly atop the grid of RI elements to ensure uniform stress distribution to all elements. Kimmins Contracting Corp. of Tampa, Fla., constructed this geosynthetic-reinforced, compacted aggregate platform. Arching within this layer distributed all overburden stresses to the RI elements.
The work was completed within five months’ time. Due to thorough pre-planning and the RI design calculations conducted by Hayward Baker, the project proceeded smoothly according to plan, with no unforeseen developments or project delays encountered.
James Hussin, a director at Hayward Baker, says, “We’re pleased that the ASCE has cited this project for special recognition. Rigid Inclusions technology was ideally suited for the construction requirements of the East-West Connector at a large cost savings to the owner. RI elements represent an increasingly popular ground modification method for projects of this type.”
Kimmins Contracting served as the primary contractor on the East-West Connector project. In addition to Hayward Baker, other project participants included a pair of Tampa-based firms – Atkins North America for engineering consulting, and Tierra Inc. for geotechnical/materials testing and environmental consulting.