Emerging Trends in Contaminated Sediment Cleanup

Transcription

1 Emerging Trends in Contaminated Sediment Cleanup Presented to Best Practices Group Presented by Clay Patmont Anchor Environmental, LLC August 28, 2008

2 Presentation Outline Overview of emerging trends Regulatory and industry initiatives Key technical developments Dredging technology limitations Monitored natural recovery and capping case studies Low cost in situ treatment Adaptive Management

3 Regulatory and Industry Initiatives EPA s s 11 Sediment Management Principles National Academy of Sciences (NAS) A Risk Management Strategy for PCB-Contaminated Contaminated Sediments Sediment Dredging at Superfund Megasites: Assessing Effectiveness Sediment Management Work Group (SMWG) EPA Contaminated Sediment Guidance EPA Contaminated Sediments Technical Advisory Group (CSTAG) State Programs

4 EPA s 11 Sediment Management Principles 1. Control Sources Early 2. Community Involvement 3. Coordinate With Other Stakeholders 4. Sediment Stability Model 5. Risk-Based Framework 6. Carefully Evaluate Data 7. Site-Specific Specific Risk Management 8. Risk Driven Goals 9. Maximize Institutional Controls 10. Risk-Driven Remedies 11. Monitor Remedy

5 National Academy of Sciences (NAS) A Risk Management Strategy for PCB- Contaminated Sediments Overall risk reduction focus No presumptive remedy Sediment Dredging at Superfund Megasites: Assessing the Effectiveness Site conditions determine dredging effectiveness Risk reduction focus (not mass removal)

6 Sediment Management Work Group year history 2. Industry lessons learned 3. Adaptive management framework 4. Collaboration with EPA and Corps Joint technical conferences Sediment Remediation Guidance

7 EPA Contaminated Sediment Guidance 1. Focus on risk reduction, not simply removal 2. Realistic, site-specific specific evaluation of options 3. Comparative net risk reduction evaluation 4. Combined remedies at complex sites 5. Adaptive management based on new data 6. Compare costs and benefits Disproportionate cost analysis

8 EPA Contaminated Sediment Technical Advisory Group (CSTAG) Site monitoring and advisory role Large, complex, or controversial sites Limited number of sites currently in program EPA regional and headquarters interactions

9 State Regulatory Initiatives Existing State programs Washington, Florida and California Disproportionate cost analyses Emerging State programs Interstate Technology & Regulatory Council

10 Key Technical Developments Case studies of biological recovery Monitored natural recovery Capping Dredging Dredging technology limitations Low cost in situ treatment

11 Biological Recovery Case Studies Monitored natural recovery Bellingham Bay, WA (20+ years) Grasse River, NY (15+ years) Capping St. Paul Waterway, WA (15+ years) Eagle Harbor, WA (15+ years) Dredging Commencement Bay, WA (25+ years) Duwamish Waterway, WA (30+ years)

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14 Bellingham Bay Site Conditions and Natural Recovery Timeline Chemicals of Potential Concern Mercury & Wood Waste Source Control Implementation Mercury - 70 Wood - 72, 78, 99 Log Pond Cap 00/ 01 Monitoring Record 30+ Years RI/FS - 96, 98 Pre-RD 02

15 Mercury Release and Source Control: Bellingham Bay 8 7 Chlor/Alkali Source Mercury Loading (kg/day) Nooksack River Background Data Source: Patmont et al. (2004)

16 Temporal Change in Core Profiles: Inner Bellingham Bay 0 Sediment Mercury (mg/kg) Sediment Depth (cm) Data Source: Patmont et al. (2004)

17 Natural Recovery Biological Endpoint: Sediment Toxicity Toxicity tests: Amphipod: acute toxicity Larval: acute toxicity & abnormality Polychaete: chronic toxicity & growth 2002 Data Source: Patmont et al. (2004)

18 Safe Seafood Mercury Levels FDA Guidelines 1.0 ppm tissue EPA Guidelines 0.30 ppm tissue Site-Specific Screening Level 0.18 ppm tissue Seafood Tissue Mercury Concentrations Bellingham Bay Crab Testing Ecology Studies (1991) 0.06 to 0.15 ppm PSDDA Program Studies (1991) 0.03 to 0.09 ppm Log Pond Monitoring (2002, 2005) 0.01 to 0.03 ppm

19 Monitored Natural Recovery: Grasse River, Massena, NY

20 Natural Recovery Biological Endpoint: Fish Tissue PCB Levels Brown Bullhead PCB ppm lipid 1000 ROPS Dredging (26,000 cy) Source Control Data Source: Alcoa (2007)

21 Commencement Bay Superfund Site, WA

22 St. Paul Waterway Capping and Habitat Restoration, Tacoma, WA

23 St. Paul Waterway Sediment Remediation & Restoration Timeline Site Discovery and Hazard Assessment Wood Waste (phenolics), PAHs, Cu RI/FS and Cleanup Plan Sediment Toxicity Targeted Containment Remedy Identified Remedial Design and Permitting Source Controls Implemented Integrated Cap and Habitat Restoration Design Post-Construction Monitoring & NRD Settlement Physical Integrity and Chemical Stability Biological Productivity/Enhancement

24 St. Paul Cap After 1988 Construction

25 St. Paul Cap Biological Monitoring Primary measure of project success Rapid recolonization by benthic, epibenthic, and macrophyte communities Indistinguishable from reference areas within a few years

26 St. Paul Cap Performance Metrics PHYSICAL Cap Integrity Confirmed Following Initial Placement Final Bathymetric Monitoring in Year 15 (2004) Storm/earthquake contingency monitoring, as needed CHEMICAL Chemical Stability and Source Control Confirmed Final Verification Sampling in Year 10 (1998) BIOLOGICAL Primary Criteria Biological Recovery Within 2 Years of Construction Biological Enhancement/NRD Restoration Final Biological Sampling in Year 10 (1998)

27 Cap Performance Example: Eagle Harbor, WA Trawl

28 Cap Performance Biological Endpoint: Flatfish Liver Lesions 60% English Sole Liver Lesion Trends Bainbridge Island, WA Age-Adjusted Liver Lesion Frequency 50% 40% 30% 20% 10% Nisqually/Carr/Colvos Reference Eagle Harbor East Harbor Capping 0% Year Data Sources: Myers et al. (2001) & WDFW (2002)

29 Sediment Concentrations and Flatfish Liver Lesions 40% Liver Lesion Prevalence 35% 30% 25% 20% 15% 10% 5% Puget Sound Background Eagle Harbor Pre-Cleanup (1993) Eagle Harbor Post-Cleanup ( ) 0% Area-Average Sediment PAH Conc (mg/kg dry wt) Data Source: Anchor (2002)

30 Commencement Bay Superfund Site, WA

31 Blair and Sitcum Waterways PCB, PAH, and metals Navigation needs important dredging and disposal Trawl

32 Sitcum Waterway Dredging: 93-94

33 Hylebos, Middle & Thea Foss Waterway Dredging and Disposal:

34 Commencement Bay Dredging Performance: Fish Tissue PCBs 500 English Sole Muscle PCB Trends Commencement Bay, WA Total PCBs (ug/kg wet wt; +/- 2 std. err.) Nisqually/Carr Reference Commencement Bay ROD Blair & Sitcum Waterway Dredging (~400,000 cy) Miscellaneous Brownfield Projects Hylebos, Middle & Thea Foss Waterway Dredging (~1,100,000 cy) Year Data Sources: TetraTech (1985), West and O Neill (2007) & WDFW (2007)

35 Duwamish Waterway and Harbor Island Superfund Sites, WA Trawl

36 East Waterway Dredging 2003 to 2005

37 Duwamish Waterway Performance Biological Endpoint: Fish Tissue PCBs Total PCBs (ug/kg wet wt; +/- 2 std. err.) 7,000 6,000 5,000 4,000 3,000 2,000 1,000 English Sole Muscle PCB Trends Duwamish Waterway, WA Nisqually/Carr Reference Duwamish Waterway Duwamish/Diagonal, East Waterway, Lockheed & Todd Shipyard Dredging (~600,000 cy) Data Sources: Miller et al. (1977), Malins et al. (1982), Metro (1983), EPA (1988), West & O Neill (2007), WDFW (2007) & Stern et al. (2007) Year

38 Ecological Recovery Lessons Learned Documented ecological recovery from monitored natural recovery and completed capping projects Little evidence to date of net ecological recovery from completed dredging projects Dredging technology limitations

39 Dredging Technology Limitations Environmental dredging and processes 4Rs 2008 Report Management implications

40 Conceptual Illustration of Environmental Dredging and Processes

41 Estimating Residuals What are Residuals? 1. Undisturbed Residuals: Contaminated sediment that remains after dredging below the design interface (i.e., the neat line ) 2. Generated Residuals: Contaminated sediment dislodged but not removed by dredging Neat Line Residual Sediment

42 Primary Sources of Residuals Nepheloid Layer Nepholoid layer flows Slight turbidity Clay Contaminated Sediment Slope Some failure Sand material into bite left behind Bedrock

43 Estimating Residuals Residual mass balance using database of completed projects Range of 2 to 9% by mass (Avg. 5%) Residual conc. equal to average of sediment dredged Turbid Water Nepheloid 3.5 cm Residuals 1.5 cm Z-layer

44 Case Study Summary of Generated Residuals Generated Residual (% of last production cut) 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% Little Debris or Rock/Hardpan Debris and/or Rock/Hardpan 0% Average In-Situ Dry Density of Last Production Cut (gms/cm 3 )

45 Residual Management Options Monitored Natural Recovery Residuals Cap or Sand Cover Engineered Isolation Cap Additional Dredging (Production or Cleanup) Decision Tree

46 Decision Tree Considerations Nature of residuals (undisturbed vs. generated) Characteristics of residuals (thickness, density, concentration) Site conditions Environmental benefit and effectiveness of additional dredging

47 Low Cost In Situ Treatment Activated Carbon Addition Laboratory studies (Stanford, Univ. Maryland) Field-scale pilot studies San Francisco Bay (CA) Grasse River (NY) Results to date very promising Satisfies CERCLA preference for permanence Engineering considerations Cost comparisons

48 Activated Carbon Pilot Study Area

49 Activated Carbon Placement Techniques Roto-Tiller

50 Activated Carbon Placement Techniques Tine Sled

51 Field and Lab PCB Bioaccumulation Studies In-river deployment of field exposure cages with L. variegatus for baseline study L. variegatus Laboratory exposure test with L. variegatus

52 Activated Carbon Pilot Study Results to Date 1. Activated carbon successfully delivered to sediments using a range of different methods 2. No construction water quality impacts 3. All of the activated carbon added in fall 2006 remained in sediments in fall 2007; declining spatial variability 4. Activated carbon bound most of the PCBs in surface sediments and rendered them unavailable to biota 5. Minor change in erosion potential of treated sediments 6. No measureable changes to benthic community 7. Additional work underway: Follow-on testing in August 2008 Potential applications to Grasse River sediment cleanup remedy

53 Sediment Delivery System Concept 1. Agglomerate containing AC delivered from water surface 2. Sinks to sediment surface and resists resuspension Water Column Biologically Active Zone Deep Sediment 3. Breaks down slowly Time 3. Breaks down slowly 4. Mixed into sediment by bioturbation

54 Activated Carbon and Sand Application

55 Potential Activated Carbon Applications 1. Potential substitute for caps 2. Direct application to surface sediments Typical unit cost < $50,000/acre 3. Incorporate activated carbon into cap 4. In situ treatment remedies supported by EPA guidance 55

56 Adaptive Management Grasse River Case Study Early source control and long-term monitoring Pilot studies of dredging, capping, and in situ treatment technologies Fox River Case Study New data drove ROD Amendment Combined dredging and capping remedy Value engineering and cost reduction