1. BoRit Asbestos Superfund Site
Remedial Overview of USACE Reservoir Report
January 15, 2014
Jill Lowe, EPA
Travis Fatzinger, USACE

2. BoRit Asbestos Superfund Site Overview
USACE Report on BoRit Reservoir
Reservoir Hydrology
Berm Stability
Options Reviewed

3. 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

4. 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

5. BoRit Asbestos Superfund Site
Legend
Monitoring Well, Transducer
Monitoring Well, No Transducer
Staff Gauge, Transducer
Staff Gauge, No Transducer
Pennsylvania
BoRit
Figure 3.1
Monitoring Locations
BoRit Asbestos Superfund Site
Ambler, PA
August 2013

6. 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
Identified 2-Non-potable production wells

7. BoRit Asbestos Superfund Site USACE Report

8. 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

9. Zone of Weak Material in SW Berm
Figure 2.2
Zone of Weak Material in SW Berm
BoRit Asbestos Superfund Site
Ambler, PA
August 2013

10. 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

11. Locations of BOB-1, BOB-2, and BOB-3
Figure 2.4
Locations of BOB-1, BOB-2, and BOB-3
BoRit Asbestos Superfund Site
Ambler, PA
August 2013

12. Slope Stability Model GeoStudio 2012 Survey Profiles Soil Profiles
Seep /W
Slope /W
Survey Profiles
Soil Profiles
Lab Results

13. BOB-2 Current Geometry High Head
Layer
Material
γ (lbs/ft3)
φ(°)
Cohesion (lbs/ft2)
Region 1
Sandy SILT (Drained)
115 22
Region 2
Poorly Graded SAND (Drained)
120 33
Region 3
Bedrock
N/A
Region 4
Region 5
Clean Silty Sand FILL (Drained) 34
Region 6
Dense Silty SAND (Drained)
125
Region 7
Loose Silty SAND (Drained) 29
Legend
FS= 0.93
Pennsylvania
BoRit
Figure 4.5
BOB-2 Current Geometry High Head
BoRit Asbestos Superfund Site
Ambler, PA
August 2013

14. Current Condition Slope Stability Results
Current Geometry
Boring
Factor of Safety1
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

15. 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

16. BOB-2 Proposed Geometry Normal Head
Layer
Material
γ (lbs/ft3)
φ(°)
Cohesion (lbs/ft2)
Region 1
Sandy SILT (Drained)
115 22
Region 2
Poorly Graded SAND (Drained)
120 33
Region 3
Bedrock
N/A
Region 4
Region 5
Clean Silty Sand FILL (Drained) 34
Region 6
Dense Silty SAND (Drained)
125
Region 7
Loose Silty SAND (Drained) 29
Region 12
BACKFILL
110 30
Legend
FS= 1.63
Pennsylvania
BoRit
Figure 4.8
BOB-2 Proposed Geometry Normal Head
BoRit Asbestos Superfund Site
Ambler, PA
August 2013

17. Proposed Geometry Slope Stability Results
Boring
Factor of Safety
Normal with Fill
High Head
with Fill
BOB-1
3.87
3.44
BOB-2
1.63
1.62
BOB-3
1.57
1.47

18. 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

19. 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

20. BOB-2 GCL Normal Head Legend FS= 1.500 BoRit Asbestos Superfund Site
Layer
Material
γ (lbs/ft3)
φ(°)
Cohesion (lbs/ft2)
Region 1
Sandy SILT (Drained)
115 22
Region 2
Poorly Graded SAND (Drained)
120 33
Region 3
Bedrock
N/A
Region 4
Region 5
Clean Silty Sand FILL (Drained) 34
Region 6
Dense Silty SAND (Drained)
125
Region 7
Loose Silty SAND (Drained) 29
Region 12
BACKFILL
110 30
Legend
FS= 1.500
Pennsylvania
BoRit
BOB-2 GCL Normal Head
BoRit Asbestos Superfund Site
Ambler, PA
January 2014