Remedial Overview of USACE Reservoir Report
January 15, 2014
Jill Lowe, EPA
Travis Fatzinger, USACE
BoRit Asbestos Superfund Site
Overview
USACE Report on BoRit Reservoir
Reservoir Hydrology
Berm
Stability
Options Reviewed
BoRit Asbestos Superfund Site
USACE Report
Remedial Inter Agency Agreement (IA) with U.S. Army
Corps of Engineers (USACE)
Tasks
Analyze Hydraulics of Reservoir
Assess
Berm
Stability
Investigations Performed
Geotechnical Investigations
Water Level Investigation
Berm
slope stability and seepage
BoRit Asbestos Superfund Site
USACE Report
Hydraulics Study
Transducers
–
March
-
August 2013
3 transducers in wells MW
-
01a, MW
-
02, and MW
-
03
1 in Reservoir
Transducer
–
July 2013
-
August 2013
1 transducer in background well, MW
-
07
Monitoring Locations
BoRit Asbestos Superfund Site
Ambler, PA
Figure 3.1
August 2013
Legend
Monitoring Well, Transducer
Monitoring Well, No Transducer
Staff Gauge, Transducer
Staff Gauge, No Transducer
Pennsylvania
BoRit
BoRit Asbestos Superfund Site
USACE Report
Hydraulics Study Conclusions
Reservoir
No direct correlation between groundwater and Reservoir
Water levels correlate to rainfall and evaporation
Known seep is not significant
Groundwater
Significant drawdown Monday through Friday
o
Identified 2
-
Non
-
potable production wells
BoRit Asbestos Superfund Site
USACE Report
Geophysical Investigation
Multi
-
channel analysis of surface waves (MASW)
Characterize Soil
Self
-
potential (SP)
Water flow
EM61 Metal Detector
Ground Penetrating Radar (GPR)
Probable pipe locations targeted based upon drawings from
Whitpain
Township and removal work
Known pipes likely filled in with sedimentation
8
Zone of Weak Material in SW Berm
BoRit Asbestos Superfund Site
Ambler, PA
Figure 2.2
August 2013
Geotechnical Investigation
Boring locations based on survey cross
-
sections,
geophysical results, and seepage locations
Three Borings
Continuous Split Spoon Sampling
Advanced until bedrock refusal
Lab testing on Samples
Included sieve analyses,
triaxial
consolidated
-
undrained
, unconfined compression
10
Locations of BOB
-
1, BOB
-
2, and BOB
-
3
BoRit Asbestos Superfund Site
Ambler, PA
Figure 2.4
August 2013
Slope Stability Model
GeoStudio
2012
Seep /W
Slope /W
Survey Profiles
Soil Profiles
Lab Results
12
BOB
-
2 Current Geometry High Head
BoRit Asbestos Superfund Site
Ambler, PA
Figure 4.5
August 2013
Legend
FS= 0.93
Pennsylvania
BoRit
Layer
Material
γ (
汢猯晴
3
)
φ(
°
)
Cohesion (lbs/ft
2
)
Region 1
Sandy SILT (Drained)
115
22
0
Region 2
Poorly Graded SAND (Drained)
120
33
0
Region 3
Bedrock
N/A
N/A
N/A
Region 4
N/A
N/A
N/A
N/A
Region 5
Clean Silty Sand FILL (Drained)
115
34
0
Region 6
Dense Silty SAND (Drained)
125
34
0
Region 7
Loose Silty SAND (Drained)
115
29
0
Current Condition
Slope Stability Results
Current Geometry
Boring
Factor of Safety
1
Normal Water Level
Factor of Safety
High Head
Level
BOB
-
1
3.28
2.70
BOB
-
2
1.12
0.93
BOB
-
3
1.46
1.26
1
Factor of Safety = material strength/design load. USACE target is 1.4
14
BoRit Asbestos Superfund Site
USACE Report
USACE Options to cover ACM and stabilize
berm
Option 1
Flatten exterior slope
Add stability
berm
to exterior toe of slope (
Wissahickon
side)
Option 2
Sheetpile
Option 3
Increase
berm’s
cross
-
sectional width
Flatten interior slope to 3H:1V =18
°
Material stable to 30
°
resulting in Factor of Safety of 1.7
BOB
-
2 Proposed Geometry Normal Head
BoRit Asbestos Superfund Site
Ambler, PA
Figure 4.8
August 2013
Legend
FS= 1.63
Pennsylvania
BoRit
Layer
Material
γ (
汢猯晴
3
)
φ(
°
)
Cohesion (lbs/ft
2
)
Region 1
Sandy SILT (Drained)
115
22
0
Region 2
Poorly Graded SAND (Drained)
120
33
0
Region 3
Bedrock
N/A
N/A
N/A
Region 4
N/A
N/A
N/A
N/A
Region 5
Clean
Silty
Sand FILL (Drained)
115
34
0
Region 6
Dense Silty SAND (Drained)
125
34
0
Region 7
Loose Silty SAND (Drained)
115
29
0
Region 12
BACKFILL
110
30
0
Proposed Geometry
Slope Stability Results
17
Proposed Geometry
Boring
Factor of Safety
Normal
with Fill
Factor of Safety
High Head
with
Fill
BOB
-
1
3.87
3.44
BOB
-
2
1.63
1.62
BOB
-
3
1.57
1.47
Option 3 with GCL
Supplement clay fill with Geosynthetic Clay Liner (GCL)
GCL consists of
bentonite
between layers
of Geotextile
“Self Healing” Properties
Benefits
Reduced berm width
Homogenous, uniform installation
Less fill and haul trucks required
Sand and Clay fill geotechnical properties testing complete
GCL FS for Bob
-
2 Normal head conditions 1.50, High head
1.41
GCL/ Backfill placement
Backfill material Sandy Lean Clay
Clay material placed on inside slope compacted in lifts
to 90% standard Proctor
GCL placed on top
-
then covered by 2
-
3 ft additional
compacted clay
Existing berm will be dry and compacted from
additional weight
BOB
-
2 GCL Normal Head
BoRit Asbestos Superfund Site
Ambler, PA
January 2014
Legend
FS= 1.500
Pennsylvania
BoRit
Layer
Material
γ (
汢猯晴
3
)
φ(
°
)
Cohesion (lbs/ft
2
)
Region 1
Sandy SILT (Drained)
115
22
0
Region 2
Poorly Graded SAND (Drained)
120
33
0
Region 3
Bedrock
N/A
N/A
N/A
Region 4
N/A
N/A
N/A
N/A
Region 5
Clean
Silty
Sand FILL (Drained)
115
34
0
Region 6
Dense Silty SAND (Drained)
125
34
0
Region 7
Loose Silty SAND (Drained)
115
29
0
Region 12
BACKFILL
110
30
0
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