New York Container Terminal - Howland Hook Marine
Staten Island, NY
Subsurface Environmental Investigation
Waste Characterization and Material Management
Field Data Laboratory Analysis
This commercial container terminal was built on a marginal site (dubbed moonscape) that was previously a disposal site for gypsum waste that is prone to dissolution with sink hole and crater topography.
The Port Authority of NY and NJ (PANYNJ) developed the area to a commercial terminal by installing fill with two layers of geogrid. Subsequent to service initiation, problems of craters and sinkhole continued to persist leading to concerns about potential catastrophic failure of the loaded 4-6 stacks of containers and tipping of equipment of heavy Top Loaders and Stackers.
The investigation program consisted of a GPR survey to help locate voids, testing for gypsum to verify historic data, digging test pits to see the condition of the geogrid and measure its geometry, and conducting a detailed 3-D finite element analysis to assess the performance of the geogrid as placed under the action of stacked containers with hardened corner, Top Loaders, Stackers and other pieces of equipment.
The paving blocks, the soil and geogrid were modeled using available data and actual testing on geogrid samples retrieved from the test pits. After the detailed analysis, it was concluded that the failure of the supporting subgrade was expected and could have been predictable had the mechanics been modelled realistically. A tolerance of 2 inches was considered appropriate for safe operation.
A monitoring program was recommended to attempt anticipate collapse and remediate it before it occurs but the frequency of repairs may be disruptive to the operation of the terminal operation. Consequently, the criteria were provided for the design of a CSE (Column Supported Embankment) or a pile supported concrete platform.