Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
Closing PresentationClosing Presentation
Peer Review MeetingPeer Review MeetingMay 4May 4‐‐6, 20106, 20101
1. Redistribution of suspended sediments during dredging
2. Post‐remediation risks –Upper & 2. Post remediation risks Upper & Lower RiverR d t t hi h l d d i 3. Remedy targets high value dredging areas
4. Improvements
While it is important to consider While it is important to consider suspended sediment redeposition,
only limited redeposition is expected outside of the dredging footprintoutside of the dredging footprint
1 0Sediment Trap Data Downstream of CU‐18
d
0 8
1.0
7/22‐8/18Downstream CU‐18 Boundary
0.6
0.8
mm/d) 10/15‐22/09
0.4osition (m
0.2
Dep
o
0.0
0 200 400 600 800 1000 1200Distance Downstream (ft)
1000
East Rogers
100
East Rogers Island Transect
Backfill Operations
50 ft downstream duringBucket Decant Study100
(mg/
L)
Bucket Decant Study
10
SS C
onc
1
T
5/20/2009 6/17/2009 7/15/2009 8/12/2009 9/9/2009 10/7/2009 11/4/2009 12/2/2009
Sample Date
All available data support conclusion Sediment trap data below CU‐18
Near‐field TSS data Bucket decant study
Consistent with Consistent with field team observations
Result: Limited TSS redistribution beyond dredging y g gfootprint
8.0
FishRand MNR and Dredging Predictions vs. Monitoring Data1998-2009
6 0
7.0
et w
t)
5.0
6.0
(mg/
kg w
e
MNR
Black Bass
B llh d
3.0
4.0
CB
Con
c. Bullhead
Yellow Perch
1.0
2.0
Fish
P
0.0
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
10.0Composite Fish - River Section 2 (RM 184)
kg
Original MNA
Remediation with No Resuspension
No long term impacts to fish at 500 ng/L
PCB
mg/
k pTotal PCB 350 ng/L (sr04)
Total PCB 500 ng/L
1.0
Mea
n Tr
i+ P
M
0.1Risk –Based Targets
2005 2010 2015 2020 2025 2030 2035 2040Year
Thompson Island = 212 ng/Lp g/
Lock 5 (Schuylerville) = 153 ng/Loc 5 (Sc uy e e) 53 g/
Waterford = 74 ng/L Waterford 74 ng/L
10.0Lower Hudson Fish Tissue Forecasts - RM 152
10.0Original MNA
Remedy with No Resuspension
600 kg Tri+
No long term impacts Even at twice the proposed
1.0
B m
g/kg
600 kg Tri
800 kg Tri+
1,200 kg Tri+
standard
n Tr
i+ P
CB
0.1
Mea
n
0.02005 2010 2015 2020 2025 2030
Risk –Based Targets
2005 2010 2015 2020 2025 2030Year
Phase 1 data showed small increases in fish body burdens in downstream regionsbody burdens in downstream regions
Modeling was completed to predict fish body b d i d i d d i f burden increases during dredging for a range of concentrations
Forecasts indicate negligible changes in time to risk‐based targets
ROD selected priority areas for dredgingdredging
“REM 3‐10‐select” effectively uses 30‐90‐90 mg/kg criteria by river sectionriver section
Sequestered inventory will remain in RS 3
4. Improvements Use larger buckets where feasible (> 5 CY) Scow unloadingg Minimize time dredged areas left openNear field monitoring PCBs & TSS Near‐field monitoring – PCBs & TSS
Monitoring diagnostics Address DoC uncertainty Re‐examine dredging tolerancesg g Practicable improvements found in Field Oversight ReportOversight Report
Resuspension shown to be associated with controllable operational factors
Adjusted load standard more realistic for actual PCB inventory; acceptable risky; p
Provision of alternate public water supply alleviates need for automatic shut‐downsalleviates need for automatic shut downs
Fixing scow availability issue will increase productivity and reduce resuspensionproductivity and reduce resuspension
Increasing scow loads will reduce vessel traffic and dredging time and thus resuspensiondredging time…and thus resuspension
Residuals standard was effective at minimizing residuals and undredged inventoryresiduals and undredged inventory
Address DoC uncertainty for more efficient dredging (fewer passes)( p )
Streamlined residuals standard will result in faster CU closure