ENVIRONMENTAL DREDGING PILOT STUDY IN THE LOWER PASSAIC RIVER: UPDATED RESULTS

摘要

An environmental dredging pilot study was conducted in the Lower Passaic River in Newark, New Jersey in December 2005 led by NJDOT along with the USACE and USEPA. The pilot study was performed as part of the Feasibility Study for the Lower Passaic River Restoration Project (LPRRP), which is being conducted by the partner agencies - USEPA Region 2, USACE, NJDOT, USFWS, NOAA and NJDEP under joint CERCLA and WRDA authorities. The LPRRP is also being performed as a pilot program under the Urban Rivers Restoration Initiative to develop a comprehensive plan to restore this 17-mile long, highly-degraded industrial waterway.Using an 6.1 m~3 [8- cubic yards (cy)] Cable Arm~R mechanical clamshell dredge bucket approximately 3,173 m~3 [4,150 cy] of contaminated sediment were dredged from a 6,070 m~2 [1.5 acre] area in 3.0 to 4.6 m [10 to 15 feet] of water in the Harrison Reach just west of the New Jersey Turnpike Bridge over a five day period. The two primary goals of this pilot study were (1) to evaluate dredging productivity and equipment performance and (2) to measure the amount of sediment that is resuspended and subsequently transported downstream as a result of a dredging operation in the Passaic River estuary. A third goal of this pilot study was to evaluate the technical feasibility and economic viability of two full-scale decontamination technologies to treat the dredged Passaic River sediment.A comprehensive and elaborate water quality monitoring program utilized a combination of six fixed moorings in conjunction with shipboard monitoring using four boats and associated instruments including Differential Global Positioning Systems (DGPS), Acoustic Doppler Current Profilers (ADCP), Laser In-Situ Scattering and Transmissometry (LISST) probes, Conductivity-Temperature-Depth (CTD) probes, Optical Back Scatter (OBS) sensors, Trace Organic Platform Samplers (TOPS) and Instrument Specialty Company (ISCO) samplers. Preliminary results from the pilot study were presented at the WEDA XXVI conference in San Diego (June 2006).This paper presents updated results of the water quality monitoring measurements including a detailed characterization of the hydrodynamics of the estuarine system before, during, and after the dredging and the chemistry of the sediment released by the dredging operation in the suspended and dissolved phases. The paper also compares these results with predictive modeling that was performed prior to execution of the study using a focused three-dimensional (3-D) hydrodynamic and sediment transport model using Computational Fluid Dynamics (CFD).