GE's Monitoring Program for the Dredging Project
In 2004, EPA established eight engineering and quality-of-life performance standards — the strictest ever developed for an environmental dredging project — to govern the Hudson River Dredging Project. The standards include three engineering standards — the migration of PCBs into the water during dredging (resuspension), the level of PCBs left on the river bottom after dredging (residuals), and the rate at which dredging was performed (productivity) — and five quality-of-life standards — air quality, noise, lighting, odor and river navigation. It required that dredging meet these standards consistently and simultaneously.
Despite the use of the best available dredging technology, daily oversight by regulatory agencies, and multiple modifications in the dredging process, the standards could not be met consistently and simultaneously because they are in conflict with one another. For example, attempts to achieve the Productivity Standard led to exceedances in the Resuspension Standard. Attempts to limit resuspension or to meet the Residual Standard inhibited productivity.
GE's evaluation is based on its analysis of more than 18,000 air, water and sediment samples that were collected during and after dredging. These data are described in more detail below.
PCBs in Water During Dredging (Resuspension)
EPA established two Resuspension Standards to ensure that dredging did not cause exceedances of the drinking water standard and did not release more PCBs into the river than would have happened over time without dredging. The first standard requires that during dredging the concentration of PCBs in the water not exceed the federal drinking water standard of 500 parts per trillion. The second standard requires that the total mass of PCBs resuspended during dredging not exceed 117 kilograms (258 pounds).
Both standards were exceeded during Phase 1: The federal drinking water standard was exceeded 10 times. And, dredging released 200 kg (440 pounds) of PCBs, as measured at Waterford 30 miles downstream, in exceedance of EPA's maximum allowable limit.
Dredging released 3 percent to 4 percent of the PCBs dredged, a rate experienced at other environmental dredging projects. PCB levels in water increased from 30-50 parts per trillion before dredging to 100-400 parts per trillion during dredging.
Click here to view water quality data from Thompson Island
Click here to view water quality data from Schuylerville
Click here to view water quality data from Waterford
PCBs in Sediments After Dredging (Residuals)
EPA established the Residual Standard — the amount of PCBs left on the surface sediments after dredging — to reduce the amount of PCBs that are or may become bioavailable. EPA's goal for five-acre dredge areas was less than 1 part per million PCB. Sampling was required after each dredging pass to measure the mass of PCBs left behind.
To meet EPA's standard, multiple additional dredging passes were required at most dredging locations, even though 90% of the PCBs present were successfully removed in the first two passes in all but one of the areas dredged. In addition, capping (or putting down a clean layer of soil over parts of the area) was necessary in parts of all but one of the dredge areas.
The Rate of Dredging (Productivity)
Nearly 290,000 cubic yards of sediment, containing approximately 35,000 pounds of PCBs, was dredged. EPA's goal for the first phase of the project was to dredge 265,000 cubic yards.
EPA's Productivity Standard required removal of 89,000 cubic yards of sediment in a single month during Phase 1, the rate needed to complete Phase 2 in five years. This standard was not met. In the best month for productivity in Phase 1, 77,300 cubic yards of sediment was removed.
Only 10 of the 18 areas scheduled for dredging in Phase 1 were dredged because more PCBs than forecast were found buried beneath the large volumes of debris in the Upper Hudson. About 120,000 cubic yards more sediment was removed than anticipated in those 10 areas.
Air Quality
PCB concentrations in air were analyzed near dredging activities and near the processing facility. Samples were collected from upwind and downwind locations. Even with the best dredging technology available and constant oversight by EPA and New York State, PCB levels in air during Phase 1 exceeded the project's quality standard 105 times.
Noise
Lighting
Odor
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