Assessing the Feasibility of Using Navigation-Dredged Material ...
The Industrial Waste Site (IWS)
FA D
I WS
Approximate area of high barrel density
MBDS-G !( MBDS-D
A MDA08 Buoy
!(
MBDS-C !(
MBDS-E !( MBDS-F
MBDS-B
!(
!(
MBDS-A !(
2
D
ea
y
ap
Ar
ar
C
o
nd
8 00
em
MB
DS
u Bo
S
Nuclear Waste Site at the IWS
1958 Saturday Evening Post
Container Density
Photos: The Massachusetts Bay Industrial Waste Site: A Preliminary Survey of Hazardous Waste Containers and an Assessment of Seafood Safety. NOAA 1996.
Potential Boston Harbor Deep Draft Project Approximately 10 million cubic yards of improvement material
Potential for Use
Concerns for Use
•
Large volume of material
•
Highly consolidated Boston Blue Clay
•
Close to IWS
•
Capping cannot interfere with dredging and disposal operations
Conceptual Model
Capping Approach
Capping Demonstration Project
Objectives •
Assess the ability to precisely direct material placement at the IWS from a production–level dredging project
•
Assess the impact of the disposal process on ambient seafloor sediments
•
Assess any differences in impact disturbance between disposals placed on ambient seafloor and those placed on a berm of disposal material.
Sequential Disposal and Monitoring Disposal Operations •
Directed placement of split‐hull scows
•
Individual placements and sequential, overlapping placements
Monitoring Operations •
Bathymetry/Backscatter/Side‐Scan Sonar
•
Sub‐bottom Profiling
•
Sediment‐Profile & Plan‐View Imaging
•
Sediment Coring
Placement
88
5
•
Single placement impacts were measureable on the seafloor
•
Impact points were very close to target coordinates (often within the length of the scow)
•
Targeted placement did not affect disposal operations
.5
e0
88
87.
n Li
87 8 6 .5
86
Single impact ~250 ft diameter
85.
5
85
85
83.5
84
84.5
Crater Characteristics
Disposal Profiles Ambient Seafloor
Berm Material Bathymetric Profile (25X Vertical Exaggeration) -82.2
-83.0 Elevation (m)
Bathymetric Profile (25X Vertical Exaggeration) Elevation (m)
-83.5 -84.0 -84.5 -85.0
-84.0
-85.0
-85.5 0
100
200
300
-85.4
0
100
200
Distance (m)
300
Impact Analysis
O
e ob ct
r
0 20
8
Ba
ym th
ri c et
rv Su
ey
t Ex
t en
n Li
e0
n Li
e1
Lin e 6 Lin e 2 Lin e 3 Lin e 4 Lin e 5
Lin e 9 Lin e 7 Lin e 8
MBDS Ambient 210Pb (dgpm/g)
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
0
10
Depth (cm)
20
30
40 y = 43.576e-0.398x R² = 0.6483 50
60
70
80
6.00
Conclusions •
Individual placement events were highly discernible on the seafloor—based on their location it was concluded that it was possible to accurately direct placement of material at this site.
•
Horizontal spread from individual placement events were focused within 650 ft (200 m) of the impact center. Vertical displacement of the ambient seafloor ranged from 1.5 to 5 feet (0.5 to 1.5 m).
•
The buildup of a berm of “flank” material over the ambient seafloor with limited impact can be observed after multiple, overlapping placement events.
Next Steps •
Develop a model of impact potential from Boston Blue Clay disposal at the IWS
•
Use the model and empirical data to develop minimum thickness dimensions for the berm area to successfully mitigate impact forces from disposal
•
Turn those dimensions into a useable capping plan for potential full‐scale implementation using Boston Harbor Deep Draft Project material
Thanks for your attention – questions?
FA D
I WS
Approximate area of high barrel density
MBDS-G !( MBDS-D
A MDA08 Buoy
!(
MBDS-C !(
MBDS-E !( MBDS-F
MBDS-B
!(
!(
MBDS-A !(
2
D
ea
y
ap
Ar
ar
C
o
nd
8 00
em
MB
DS
u Bo
S
Nuclear Waste Site at the IWS
1958 Saturday Evening Post
Container Density
Photos: The Massachusetts Bay Industrial Waste Site: A Preliminary Survey of Hazardous Waste Containers and an Assessment of Seafood Safety. NOAA 1996.
Potential Boston Harbor Deep Draft Project Approximately 10 million cubic yards of improvement material
Potential for Use
Concerns for Use
•
Large volume of material
•
Highly consolidated Boston Blue Clay
•
Close to IWS
•
Capping cannot interfere with dredging and disposal operations
Conceptual Model
Capping Approach
Capping Demonstration Project
Objectives •
Assess the ability to precisely direct material placement at the IWS from a production–level dredging project
•
Assess the impact of the disposal process on ambient seafloor sediments
•
Assess any differences in impact disturbance between disposals placed on ambient seafloor and those placed on a berm of disposal material.
Sequential Disposal and Monitoring Disposal Operations •
Directed placement of split‐hull scows
•
Individual placements and sequential, overlapping placements
Monitoring Operations •
Bathymetry/Backscatter/Side‐Scan Sonar
•
Sub‐bottom Profiling
•
Sediment‐Profile & Plan‐View Imaging
•
Sediment Coring
Placement
88
5
•
Single placement impacts were measureable on the seafloor
•
Impact points were very close to target coordinates (often within the length of the scow)
•
Targeted placement did not affect disposal operations
.5
e0
88
87.
n Li
87 8 6 .5
86
Single impact ~250 ft diameter
85.
5
85
85
83.5
84
84.5
Crater Characteristics
Disposal Profiles Ambient Seafloor
Berm Material Bathymetric Profile (25X Vertical Exaggeration) -82.2
-83.0 Elevation (m)
Bathymetric Profile (25X Vertical Exaggeration) Elevation (m)
-83.5 -84.0 -84.5 -85.0
-84.0
-85.0
-85.5 0
100
200
300
-85.4
0
100
200
Distance (m)
300
Impact Analysis
O
e ob ct
r
0 20
8
Ba
ym th
ri c et
rv Su
ey
t Ex
t en
n Li
e0
n Li
e1
Lin e 6 Lin e 2 Lin e 3 Lin e 4 Lin e 5
Lin e 9 Lin e 7 Lin e 8
MBDS Ambient 210Pb (dgpm/g)
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
0
10
Depth (cm)
20
30
40 y = 43.576e-0.398x R² = 0.6483 50
60
70
80
6.00
Conclusions •
Individual placement events were highly discernible on the seafloor—based on their location it was concluded that it was possible to accurately direct placement of material at this site.
•
Horizontal spread from individual placement events were focused within 650 ft (200 m) of the impact center. Vertical displacement of the ambient seafloor ranged from 1.5 to 5 feet (0.5 to 1.5 m).
•
The buildup of a berm of “flank” material over the ambient seafloor with limited impact can be observed after multiple, overlapping placement events.
Next Steps •
Develop a model of impact potential from Boston Blue Clay disposal at the IWS
•
Use the model and empirical data to develop minimum thickness dimensions for the berm area to successfully mitigate impact forces from disposal
•
Turn those dimensions into a useable capping plan for potential full‐scale implementation using Boston Harbor Deep Draft Project material
Thanks for your attention – questions?
