PCB mass loads are monitored during the dredging process so that PCB sediments traveling downstream do not exceed pre-established load limits. Load limits were established primarily to limit the mass being transported into the Lower Hudson, beyond the furthest downstream sampling station (located at Waterford/Troy) and are defined in the Resuspension Standard.
The Phase 2 cumulative net load criteria of the Tri + PCB mass removed during the dredging season is 2 percent at the first far-field water monitoring station (located at the Schuylerville [Lock 5]/Stillwater Station) and 1 percent as monitored at the Waterford/Troy Station. Tri + is the common term that refers to the heavier fraction of PCBs. If river flows are elevated, the load criteria will adjust to 3 percent at the Schuylerville [Lock 5]/Stillwater Station and 2 percent at the Waterford/Troy Station. The Phase 2 load criteria were adjusted to take into account upstream river flows based on Peer Review Panel recommendations as well as knowledge gained during Phase 1.
Phase 2 Year 4 dredging operations occurred between May 7 and November, 2014. The following table (Table 1) indicates that the PCB mass load is in compliance with pre-established load criteria at the Schuylerville (Lock 5)/Stillwater and Waterford/Troy monitoring stations. Phase 2 dredging operations will resume in spring 2015.
Schuylerville (Lock 5)/Stillwater Far-Field Station
|Waterford Far-Field Station||In-Compliance|
|Date of Last Data Collected: October 5, 2014|
If the PCB load targets are exceeded for multiple consecutive days at any of the stations (non-compliant), evaluations must be performed and actions taken to try to reduce the mass being transported downstream. The standards, particularly the load at the Waterford Station, will be re-evaluated and may need to be adjusted and updated as dredging operations move downstream.