WSP is the prime engineering contractor for the demolition and remediation of a 1,000-acre phosphate chemical plant in Central Florida. After completion of the first phase of the remedial investigation, WSP evaluated soil and sediment removal technologies under the Engineering Evaluation/Cost Analysis (EE/CA) process of the National Contingency Plan to address the imminent risk to public health and safety. Chemicals present in site media include mining and chemical processing constituents including arsenic, boron and technologically enhanced radioactive material (TENORM).
To address the site contamination, we proposed remedial action to consolidate contaminated soil and sediment under the cap of a process lagoon which would be converted for use as a disposal cell. WSP gained acceptance from the Florida Department of Environment (FDEP) and the U.S. EPA to utilize the existing process pond before installing an impervious cap and groundwater hydraulic control system.
The process pond selected as the on-site consolidation cell was a 60-acre mining pit filled with phosphatic clay, a semi-solid sludge exhibiting low shear strength. WSP’s design called for reinforcement of the sludge by placement of a high-strength woven geotextile over the sludge. The geotextile was seamed on-site and deployed in four 15-acre panels, providing a platform for placement of lifts of contaminated soil and sediment from the site. The design was reviewed and approved by the Corps of Engineers, and the implementation, which was the largest single deployment of geotextile at the time, was awarded the Outstanding Achievement Award by the Industrial Fabrics Association International.