Hudson River PCBs Site Phase 2 Dredge Area Delineation Report A - - PowerPoint PPT Presentation

▶
hudson river pcbs site phase 2 dredge area delineation
SMART_READER_LITE
LIVE PREVIEW

Hudson River PCBs Site Phase 2 Dredge Area Delineation Report A - - PowerPoint PPT Presentation

Mar 15, 2023 19 likes •402 views

Hudson River PCBs Site Phase 2 Dredge Area Delineation Report A Summary for the Hudson River CAG Krissy Russell-Hedstrom, Ph.D. Technical Assistance Specialist E Inc. Ecology & Economics, Charlottesville, Virginia June 4, 2008 TASC

slide-1
SLIDE 1

Hudson River PCBs Site

A Summary for the Hudson River CAG

E² Inc. Ecology & Economics, Charlottesville, Virginia June 4, 2008

Phase 2 Dredge Area Delineation Report

Krissy Russell-Hedstrom, Ph.D. Technical Assistance Specialist

slide-2
SLIDE 2

TASC Background

  • Technical Assistance Services for

Communities

  • EPA sponsored program
  • Services provided by E² Inc.

– Information assistance – Community education – Technical expertise – Technical assistance plans – Superfund Jobs Training Initiative

2

slide-3
SLIDE 3

Services to Hudson River CAG

  • Explain the Phase 2 Dredge Area Delineation Report

in an understandable way

  • Focus on amount of sediment removed vs. amount
  • f PCBs removed

3

slide-4
SLIDE 4

Phase 2 Report

  • Third draft released

December 2007

  • Organized into seven

sections

4

slide-5
SLIDE 5

6. Conclusions and Summary

Report Sections

5

Background and Objectives Methods Results Conclusions

2. Data Analysis 3. Delineation General Methodology 4. Interpolation Methods 5. Delineation Results 7. References 1. Introduction

slide-6
SLIDE 6

Document History

  • ROD: February 2002
  • AOC between GE and EPA: August 2003

– GE agreed to conduct Remedial Design for the ROD selected remedy – Remedial Design in two phases:

  • Phase 1—1st year of dredging
  • Phase 2—remainder of project
  • Phase 1 Dredge Area Delineation Report: March 2005
  • Phase 2 Dredge Area Delineation Report: December 2007

6 Background and Objectives Section 1

slide-7
SLIDE 7

Area Covered by Phase 2 Report

  • Areas covered by ROD minus Phase 1

dredging areas

  • 37+ miles of Upper Hudson River

7 Background and Objectives Section 1

slide-8
SLIDE 8
slide-9
SLIDE 9

Project Objectives

  • Identify Phase 2 areas to be dredged
  • Identify depths of removal for those areas
  • Identify PCB concentrations within the delineated

sediments

9 Background and Objectives Section 1

slide-10
SLIDE 10

Methods Overview

  • Collect sediment data
  • Use data to determine areas to dredge

10 Methods Sections 2-4

slide-11
SLIDE 11

11 Methods Sections 2-4

Criteria for Removal

“Hotspots” 30 3 30 10 2 10 3 1

Other Top 12” PCB3+ Concentration (mg/kg) MPA PCB3+ (g/m2)

River Section

ROD Selected Remedy

All sediments removed to the 1 mg/kg PCB3+ concentration depth.

slide-12
SLIDE 12

Sediment Sampling Program

  • Sampling took place from 2002-2005
  • Collected a variety of sediment data including:

– Mass per unit area of PCBs with 3+ chlorine atoms in sediment cores (PCB3+) – Surface PCB concentrations – Depth of PCB-containing sediments – Other physical characteristics

  • Sampling primarily done at spaced intervals

12 Methods Sections 2-4

slide-13
SLIDE 13

PCB3+ Structure

13 Methods Sections 2-4

slide-14
SLIDE 14

Sediment Cores

14 Methods Sections 2-4

  • Column of sediment extracted from

river bottom

  • Collected in aluminum or plastic tubes
  • Several feet in length
  • Sliced into smaller columns and

analyzed for PCBs

  • GPS coordinates collected for each

core

  • Over 8,500 cores taken
slide-15
SLIDE 15

MPA: Mass Per Unit Area

15 Methods Sections 2-4

Length Core Slice x Concentration PCBs x Sediment Density

MPA =

slide-16
SLIDE 16

How New Samples Are Different

  • Over time PCB concentrations in sediment can change

– Buried – Redistributed

  • Older GPS data not as accurate (±1 m vs. ±1 cm)
  • Older PCB analysis methods may have been different

16 Methods Sections 2-4

slide-17
SLIDE 17

Additional Sampling Considerations

  • Sample contamination
  • Outliers
  • Incomplete Cores
  • Nondetects

17 Methods Sections 2-4

slide-18
SLIDE 18

PCB MPA PCB Sfc Concentration Depth of PCB Sediments Other Characteristics

How Was All This Data Used?

18 Methods Sections 2-4

Delineation Process

slide-19
SLIDE 19

What is Delineation?

  • To indicate or represent by drawn or painted lines

19 Methods Sections 2-4

slide-20
SLIDE 20

Delineated Parameters

  • Horizontal

– MPA – Maximum surface PCB concentrations

  • Vertical

– Total PCB concentrations

20 Methods Sections 2-4

slide-21
SLIDE 21

Phase 2 General Delineation Process

  • Based solely on the physical and chemical characteristics
  • f the river and sediment bed
  • Used interpolation to predict horizontal (Kriging) and

vertical (Inverse Distance Weighting) dredge area boundaries

21 Methods Sections 2-4

slide-22
SLIDE 22

What is Interpolation?

  • Determining the

value of an unknown quantity at an unobserved location from observations of its value at nearby locations

22 Methods Sections 2-4

15

River Section 2

5 15 5 5 5

MPA = 10 M P A = 1

Criteria for Removal: MPA = 10 g/m2

10 ft2

slide-23
SLIDE 23
slide-24
SLIDE 24
slide-25
SLIDE 25

Horizontal Delineation

  • Create contour lines on maps based on interpolation

for both MPA and Maximum Surface PCB Concentration

  • Overlay the maps
  • Locate outermost criteria values and recommend as

dredging boundaries

25 Methods Sections 2-4

slide-26
SLIDE 26

Vertical Delineation

  • First found horizontal dredge areas
  • Cores within those areas subdivided into 18 depth intervals
  • Average total PCB concentrations calculated for each interval
  • Interpolations performed to find more detailed depth profile
  • Deepest interval equal to or above 1 mg/kg assigned for

each core

  • Each 10 ft2 grid cell assigned the lowest depth value of all

cores

  • That depth was the depth of recommended sediment

removal

26 Methods Sections 2-4

slide-27
SLIDE 27

Additional Interpolation Considerations

  • Outlier points
  • Single, isolated points
  • Data gaps

27 Methods Sections 2-4

slide-28
SLIDE 28

Results

  • Areas to dredge
  • Depth of each area to dredge
  • Presented on a series of maps

28 Results Section 5

slide-29
SLIDE 29
slide-30
SLIDE 30
slide-31
SLIDE 31
slide-32
SLIDE 32
slide-33
SLIDE 33

Conclusions

  • 168 separate dredge areas delineated in Phase 2
  • 400 acres
  • 1,531,400 yd3 sediment targeted for removal
  • Average depth of contamination is less than 3 ft in most

dredge areas

  • Seven areas have contamination to depths of 5 ft or more

33 Conclusions Section 6

slide-34
SLIDE 34

34

24,000 95 3 28,500 86 2 60,600 310 1

kg of PCBs Removed Targeted Acres River Section

Phase 1 and Phase 2 Totals

Conclusions Section 6

slide-35
SLIDE 35

35

24,000 491,000 6,700 393,000 3

Phase 1 & 2 Targets ROD Estimates

2,450,000 565,000 1,492,000

yd3 Sediment

66,300 23,600 36,000

kg of PCBs

113,100 1,794,800 Total 28,500 364,000 2 60,600 939,800 1

kg of PCBs yd3 Sediment River Section

ROD Estimate Comparison

Conclusions Section 6

slide-36
SLIDE 36

How Can More PCBs Be Removed if Less Sediment is Dredged?

  • Comprehensive sampling program undertaken

after ROD was issued showed that PCB concentrations greater than 1 mg/kg are not as deep in the sediments as previously estimated

36 Conclusions Section 6

slide-37
SLIDE 37

37

1 2 1 5 15 10 20 15 25 20 Total MPA 91 30 Total MPA 83 30

DAD MPA ROD MPA

What Does This Mean?

Conclusions Section 6

slide-38
SLIDE 38

Questions?

Contact Information: Krissy Russell-Hedstrom TASC E² Inc. 719-256-5261 krissy@e2inc.com

38 Questions and Contact Information