A CASE HISTORY OF SETTLEMENT AT THE FLORENCE LANDFILL BEFORE AND AFTER REMEDIATION

摘要

The Florence Landfill is a Superfund site located in Burlington County, New Jersey. The actual refuse area covers 11.7 hectares (29 acres) in roughly an L-shape. The landfill operated from late-1973 through late-1981 as a solid waste disposal facility. Waste fill thickness ranged from 6 meters (20 ft) to 18 meters (59 ft). Environmental concerns at the site were focused on the reported deposition of approximately 86 metric tons of hazardous chemicals. The site was supposedly capped with 0.6 meter (2 ft) of low hydraulic conductivity soil. However, the thickness of the cap varied from less than 0.15 meter (6 inches) in some areas to the required"0.6 meter (2 ft). The Record of Decision for the site included the installation of a multilayer cap. As part of the multilayer cap design investigations, historical data concerning settlement were gathered. Four topographic surveys (information and maps) of the site prior to the remediation were collected. Observed topographic changes were documented, and these values were used to back calculate the compression index of the waste fill materials and the potential settlement under the new cap loading. In 1993, the 2-meter (6 ft) multilayer cap was completed and initial survey measurements were made at 32 locations (permanent monuments) on the landfill surface. Comparisons are made between settlement before the multilayer cap and the settlement experienced since the cap has been placed. The possible effects that geosynthetics may play in reducing the observed settlement are discussed. The historical data prior to remediation and the post remediation surveys provide hard data upon which one can evaluate predictive values against actual settlement.