Construction and Post-Construction Construction Monitoring of a Landfill MSE Perimeter BackfillPerimeter Berm over Soft Mine BackfillPerimeter Berm over Soft Mine BackfillPerimeter Berm over Soft Mine Backfill

摘要

A former sand and clay mine in the northeastern United States is the site of an operating municipal waste landfill containing a mechanically-stabilized earth (MSE) berm around the perimeter of the disposal area. A portion of the site contains an appreciable thickness (5 to 8 meters) of mine spoils consisting of a heterogeneous mix of clay, silt, and fine to medium sands which were placed in an “unengineered” manner. Geotechnical investigations were performed to determine the in-situ shear strength of the fill and natural soils for use in design of the liner system subgrade and MSE berm. To evaluate the impact of coarse fragments (>2.5 cm) in the proposed reinforced fill for the MSE berm, a test fill was constructed in the field during the design phase using geogrid products of various tensile strengths to determine the appropriate reduction factor for installation damage. The test fill resulted in adjustments to the assumed reduction factor and allowed for a modification of the gradation specification of the reinforced fill to accommodate available fill sources. A geotechnical instrumentation program was implemented during construction and subsequent operation of the landfill, and included slope inclinometers to monitor for horizontal displacements within the MSE berm and vibrating wire piezometers to measure pore pressures in the foundation soils. Data collected to date indicate that movements within the MSE berm and pore pressures in the foundation soils have been within anticipatable ranges and landfill development and waste placement operations have continued with no disruption.