Geotechnical Project Detail

Cherry Island Landfill

Location

Wilmington, Delaware

Client

Delaware Solid Waste Authority

Services Provided

Slope Stability
Filling Plan
Deep Mixing Methods: Soil Stabilization
In Situ Testing and Instrumentation Monitoring
3-D ArcView GIS
Data Management
Modeling

Project Overview

Schnabel performed a complete review and assessment of the geotechnical issues related to this landfill constructed over soft dredge spoils. This included stability of the embankments, long term consolidation and strength gain evaluation, and development of a filling sequence and a site drainage system. Schnabel evaluated stability of the landfill that had been constructed on 342 acres of marshland and dredge spoils up to 80 feet deep. Field vane shear testing, static piezo and seismic cone penetrometer and dilatometer testing, along with laboratory testing on undisturbed samples, were used to estimate shear strength parameters for slope stability analysis.

Earthquake time history records from selected events were modified to reflect the site-specific seismic hazard and were input into the SHAKE computer program to estimate the site amplification and response. Pseudo-static seismic slope stability was evaluated to determine the yield acceleration, and permanent slope displacement analyses were performed using the Newmark Method.

Given the results of our analysis, concerns for the long term stability of the site led us to provide recommendations for modifications to the operation plan and augmentation of the subsurface conditions. Stability and deformation analyses of the proposed use of deep mixing methods to create a structural cutoff wall around the site were performed with FLAC Two-Dimensional Finite Difference software.

Schnabel was subsequently awarded the three year instrumentation monitoring contract for this facility as a continuation of our ongoing assessment of the site performance.

:: Return to list