# Presentation: 180046

## Arkema EE/CA
Draft Work Plan Meeting

- Draft Work Plan Meeting

- June 26, 2007
- Seattle, Washington

## 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

- 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

- Outline

## Why a Mass Removal Approach?

- Significantly reduces risk
- Risk decreases with decrease in contaminant mass/concentration
- Remediates most significant mass in sediment associated with Arkema’s 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

## Why a Mass Removal Approach? (cont.)

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

**Notes:**
iterative/adaptive management approach (i.e., NAS Dredge Report and others)

## 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

**Notes:**
Model boundaries –OHW ~20 ft, eastern channel line, upstream boundary to BNRR bridge.

## Still of Grid Etc

## Slide 8

## Slide 9

## 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 (EPA’s stated objective 0.035 mg/kg DDx = SLV x1000)
- Calculate total mass per concentration level

## EVS Model – Plan View

## EVS Model – View to NW

## EVS Model – View to N

## Slide 14

## Slide 15

## Slide 17

## Slide 18

## Slide 19

## Slide 20

## Slide 21

## Slide 22

## Slide 23

## 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

## Dredge Prism Calculations

## 3,500 cu yds

**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**

## 3,500 cu yds

**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**

## Slide 28

## Slide 29

## Dredge Volume v. Mass Removal

## Break Point Graph

## 1,000 x SLV Total DDx - Surface

## 1,000 x SLV Total DDx - Subsurface

## 1,000 x SLV All COIs - Surface

## 1,000 x SLV All COIs - Subsurface

## 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

## 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