Phase 1 Cumulative PCB Load

These bar charts represent the results of project Resuspension Performance Standard calculations to estimate dredging-related PCB mass loads. The PCB mass load numbers represents the Phase 1 pro-rated portion of the total mass load that was established for the full dredging program. While a mass load figure was established for each of several downstream sampling locations, it was primarily established to limit the mass being transported into the Lower Hudson, beyond the furthest downstream sampling station (located at Waterford).

The data and associated calculations were approved and agreed to by EPA and GE as part of the Phase 1 Remedial Action Monitoring Quality Assurance Project Plan. By mid-season the annual number of 117 kg/258 lbs total PCBs had been exceeded at the Thompson Island Dam and Lock 5 (Schuylerville) monitoring stations, however, Waterford remained under the annual target until the final weeks of dredging. Another measured parameter is the heavier fraction of PCBs (commonly referred to as Tri+). Similar conditions were observed for the Tri + load levels. The annual Tri+ load is 39 kg/86 lbs for the 1st year.

Exceeding this target number at any of the stations is important as it requires that evaluations be performed and actions taken to try to reduce the mass being transported. Evaluations were performed and numerous modifications to dredging operations were implemented. It is important to recognize that the load standard represents an overall requirement for the project and not for a single year. It may be necessary to re-evaluate the load criteria after Phase 1. The occurrence of higher loads during Phase 1 will be addressed through lessons learned and associated improvements to be made in Phase 2.