New Jersey Water Science Center
Great Falls of the Passaic River at Paterson, N.J.
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Particulate and Salt Distribution in the Harrison Reach of the Passaic River
Project Title: Particulate and Salt Distribution in the Harrison Reach of the Passaic River
To aid in assessing the impact of proposed dredging of contaminated sediments from the Passaic River, the US Geological Survey New Jersey District in proposing a program to monitor the suspended particulates and dissolved salt concentrations and distribution in the seventeen mile stretch of the river from Newark Bay upstream to the Dundee Dam.
Statement of Problem
As a result of the New Jersey Department of Environmental Protection Toxic Sediment Reduction Program, contaminated sediment in the Lower Passaic River has been identified as being an environmental problem that will require a substantial investment in a clean-up program. The proposed clean-up will include the dredging of contaminated sediment deposits from Dundee Dam (head of tide of the Passaic River) to the Newark Bay. There is a concern with the impacts of the dredging operation on the suspension of contaminants and the potential redistribution in the Lower Passaic and Newark Bay.
Strategy and Approach
Objective 1 - River Characterization
The first objective addressed by this work will be to characterize the river concurrent with the shipboard and moored surveys of the estuarine reach. In conjunction with the CTD surveys to be conducted by Dr. Chant, 6 of the approximately 12 surveys of the river will be made beginning in Newark Bay and ending upstream as far as possible towards the Dundee Dam. The sectional surveys, each anticipated to be 20 km in length, will be made from June 2004 through June 2005. At approximately 1 km intervals, 3 vertical profiles will be sampled at three depths (9 samples total) to characterize the particulate and salt distribution across the river. Samples will be collected at 1 meter below the surface, 1 meter above the bottom, and at the mid-point depth. The mid-river vertical profile will be made in the vicinity of the CTD tow, allowing the data to be used for instrument calibration as well as river characterization. Samples will be measured for suspended sediment, total dissolved salts, and conductivity. The total number of sampling locations for this objective is scoped at 1080. A subsection of these samples will also be measured for density in the USGS District Laboratory.
As part of the CTD surveys, Dr. Chant will be deploying mooring arrays, each consisting of a current profiler, conductivity and temperature, and a bottom OBS sensor. Six moorings will be deployed, two of which will be located in the Harrison Reach. The first deployment will be in late summer-fall 2004, and the second deployment will be late winter early spring 2005. We propose to collect a single vertical profile of suspended sediment, total dissolved salt, conductivity, and water density in the vicinity of each mooring, once when the moorings are deployed and again when retrieved. Up to 10 samples will be collected at 1 meter intervals. The total number of samples collected for this work is 240.
Objective 2 - Detailed Evaluation of the Harrison Reach
In conjunction with the proposed hydrodynamic evaluation of the Harrison Reach, we propose to collect data to characterize the cross sectional distribution of suspended sediment and dissolved salt in this reach of the river. The river will be characterized at 13 proposed cross sections, twice during neap conditions and twice during spring tide conditions. At each cross section we propose to collect samples at three verticals and three depths (1 meter below surface, one meter above bottom, and mid section, 9 samples total). These samples will be analyzed for suspended sediment, dissolved salt, and conductivity. This information can be combined with the hydrodynamic view of tidal and subtidal motion and cross-sectional circulation in the river section. Approximately 470 samples will be collected in total.
Objective 3 - Dye tracer test
At about the same time as the work for objective 2, four, one-day tracer-dye studies will be conducted by Dr. Chant. The USGS will assist in monitoring the distribution of the dye during the 8-12 hours following the release of the Fluorescein dye. In addition, a single vertical transect consisting of 10 samples will be collected in the preceding the release of the dye, to document the conditions of the river in the area of dye release. These samples will be measured for SS, dissolved solids, conductivity. These samples will also be measured for particle grain size using a Sedigraph III laser analyzer, available at the USGS Cascades Volcano Observatory in Vancouver, Washington. A total of 40 samples will be analyzed for this work.