Arkema EECA

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• Arkema EE/CA
• Draft Work Plan Meeting

June 26, 2007 Seattle, Washington
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Outline

• Mass Removal Approach
• Why Mass Removal ?
• What constitutes Mass Removal ?
• How do we benefit from Mass Removal?
• Where does Mass Removal fit into the PH RI/FS ?
• General Comments on EPA revised EE/CA Work Plan

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Why a Mass Removal Approach?

• Significantly reduces risk
• Risk decreases with decrease in contaminant
  mass/concentration
• Remediates most significant mass in sediment
  associated with Arkemas former operation
• Highly effective
• Proven technology
• Consistent with NTCRA Guidance and LWG RI/FS
• Recommended by EPA team members
• Precedence
• Greens Bayou, Fox River, Grasse River, Great Lakes

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Why a Mass Removal Approach? (cont.)

• Public support
• Majority DDx mass in discrete area
• Addresses other Portland Harbor COIs
• Consistent with EPAs iterative, adaptive
  management approach
• Engineering-based removal action
• Consensus approach expedites project

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What is the Mass Approach?

• Compile 230 data points
• All sediment data
• Establish model domain
• Convert from mg/kg to mass per unit volume
• Perform 3D kriging with C-Tech EVS Software
• Calculate volumes with ArcGIS

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Still of Grid Etc
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What is the Mass Approach? (cont)

• Establish isovolumes to identify the distribution
  of DDx in sediments
• Approx. 1000, 100, 10, 5, 1, 0.1 and 0.035 mg/kg
  (EPAs stated objective 0.035 mg/kg DDx SLV
  x1000)
• Calculate total mass per concentration level

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EVS Model Plan View
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EVS Model View to NW
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EVS Model View to N
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What is the Mass Approach? (cont.)

• Calculate preliminary dredge volumes per each
  isovolume contour
• Calculate Total DDx mass removed per volume
  dredged
• Compare Total DDx mass versus volume
• Estimate different mass removal scenarios
• Establish breakpoint between mass of DDx and
  sediment volume

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Dredge Prism Calculations
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1,000 mg/kg 7 DDx Mass 3,500 cu yds
100 mg/kg 56 DDx Mass 19,000 cu yds
10 mg/kg 89 DDx Mass 73,000 cu yds
5 mg/kg 92 DDx Mass 110,000 cu yds
1 mg/kg 96 DDx Mass 280,000 cu yds
0.1 mg/kg 99.7 DDx Mass 830,000 cu yds
0.035 mg/kg 100 DDx Mass 1,300,000 cu yds
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1,000 mg/kg 7 DDx Mass 3,500 cu yds
100 mg/kg 56 DDx Mass 19,000 cu yds
10 mg/kg 89 DDx Mass 73,000 cu yds
5 mg/kg 92 DDx Mass 110,000 cu yds
1 mg/kg 96 DDx Mass 280,000 cu yds
0.1 mg/kg 99.7 DDx Mass 830,000 cu yds
0.035 mg/kg 100 DDx Mass 1,300,000 cu yds
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Dredge Volume v. Mass Removal
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Break Point Graph
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1,000 x SLV Total DDx - Surface
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1,000 x SLV Total DDx - Subsurface
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1,000 x SLV All COIs - Surface
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1,000 x SLV All COIs - Subsurface
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How Do We Benefit from Mass Removal?

• Significantly reduces DDx mass
• Significantly reduces associated risk
• Expedites removal action
• Measures effectiveness
• Frees up resources
• Meets RAOs
• Meets 11 principles
• Meets guidance
• Public support
• Residual risk addressed by RI/FS
• Resolves dispute

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Where does Mass Removal fit into the Portland
Harbor RI/FS ?

• Remediates Arkema DDx hotspot
• Compatible with PH RI/FS and RA
• The NTCRA is one of a series of response actions
  where a completed RI will be available
• Advances the goal of the Superfund Accelerated
  Clean Up Model to include substantial,
  prioritized risk reduction
• An integral part of an adaptive-management
  approach at a contaminated sediment megasite
  where dredging is the preferred alternative

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