In-situ management. The other approach to remediating contaminated sediments. SAO Environmental Consulting AB. Vattendagarna Oktober, 2012

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1 1 In-situ management The other approach to remediating contaminated sediments SAO Environmental Consulting AB

2 Managing (remediating) contaminated 2 sediments Reason Contamination poses unacceptable risks to ecological and/or human receptors, risks that need to be managed in some way Goal Reduce risks to acceptable levels (& maintain)

3 Approaches to sediment remediation 3 ex-situ displaced removal (dredging) treatment disposal

4 Removal, treatment and disposal 4 Description Removing contaminated sediment by dredging or excavation, followed by transport and disposal (with/without pre-treatment of sediment and/or water phases)

5 Approaches to sediment remediation 5 ex-situ displaced removal (dredging) treatment disposal

6 Approaches to sediment remediation 6 ex-situ displaced removal (dredging) in-situ in place capping treatment treatment disposal

7 In-situ capping Description Placing clean, conventional or innovative material of different thicknesses overtop contaminated sediment for the purpose of meeting performance objective(s) 7 Biologge Biologge CETCO Birchenough et al., 2010

8 In-situ treatment 8 Description Placing treatment agents into or overtop contaminated sediment to reduce COC mass, toxicity and/or bioavailability within the sediment s biological zone. Classic method Inject agents into sediment mass Mechanically mix in

9 Approaches to sediment remediation 9 ex-situ displaced removal (dredging) in-situ in place capping treatment treatment disposal

10 Approaches to sediment remediation 10 ex-situ displaced in-situ in place removal (dredging) treatment treatment disposal

11 Approaches to sediment remediation 11 ex-situ displaced in-situ in place removal (dredging) treatment treatment disposal

In-situ treatment 12 Description Placing treatment agents into or overtop contaminated sediment to reduce COC mass, toxicity and/or bioavailability within the sediment s

12 In-situ treatment 12 Description Placing treatment agents into or overtop contaminated sediment to reduce COC mass, toxicity and/or bioavailability within the sediment s biological zone. Classic method Inject agents into sediment mass Mechanically mix in New method Place agents overtop sediment surface Natural bioturbation activity mixes in Ghosh, 2010

13 Approaches to sediment remediation 13 ex-situ displaced in-situ in place removal (dredging) treatment disposal treatment MNR monitored natural recovery

14 Which remediation approach to use? 14 Project-/site-specific decision, depends on Rate and degree of risk reduction needed COC(s) Site conditions Sediment characteristics Cost Combination of approaches often attractive e.g. removal followed by capping of residuals

15 In-situ capping Strategy, design and materials 15 Most appropriate strategy, design and material(s) depends on Cap performance objectives COC(s) Site conditions Sediment characteristics Construction equipment/placement technique Cost

16 Cap performance objectives 16 Key factor in selecting appropriate strategy, design and materials Objectives differ depending on strategy

17 Isolation capping 17 Cap thickness > bioturbation depth total cap thickness > ~10 cm COCs sediment bioturbation depth ~10 cm (typical) not to scale Performance objectives: Reduce risks by 1. Isolating sediments from bioturbating organisms 2. Stabilizing sediments against erosional losses 3. Minimizing COC migration up into bio zone

18 Thin-layer capping 18 Cap thickness < bioturbation depth total cap thickness < to << 10 cm not to scale cap material and sediment become mixed over time Performance objectives: Reduce risks by 1. Diluting total COC concentrations in bio zone 2. Lowering porewater concentrations by dilution 3. Lowering porewater concentrations by sorption TLC also considered in-situ treatment (or emnr)

19 Isolation vs thin-layer capping Selecting the best strategy 19 Factors to consider Site s depositional vs erosional character Degree and spatial extent of contamination COC(s) Rate and degree of risk reduction needed Cost Project-/site-specific decision Type of cap material another big factor

20 Capping strategies Expand to include the material factor 20

21 Conventional capping materials Inert, variable grain size & permeability 21 LWG, 2010

22 Conventional isolation capping Design components 22 Total cap thickness T t T b T e T i T c T o bioturbation / habitat layer erosion layer chemical isolation layer cap + sediment consolidation layer operational / mixing layer contaminated sediment

23 Conventional isolation capping Use of approach 23 Appropriate, adequate in many situations Used successfully at many sites, worldwide Will continue to be widely used migrating COCs sand cap

24 Conventional (isolation) capping projects, 24 worldwide ( ) from Fox River ROD, 2007

25 When conventional capping may not be adequate 25 COCs don t bind (partition) strongly to sediment s solid phase Groundwater upwelling occurring Partitioning processes variable or uncertain e.g. tributyltin (TBT) Non-aqueous phase liquids (NAPL) involved Need to manage ongoing inputs over time

26 Innovative capping materials 26 Different from conventional Physically, mineralogically and/or chemically Various composition, grain size, permeability More effective than conventional at Lowering porewater COC concentrations by strong partitioning to solid phase Reducing COC migration by different processes (use of low-permeability clays) Binding NAPLs Promoting in-situ degradation of some organic COCs in (and below) capping layer

27 Innovative capping materials with 27 proven, unique attributes Reactive (sorptive) Activated carbon (AC) Topsoil Coke Organoclay Apatite Zeolite Bauxite Fine-gr. crushed rock Magnetite most relatively permeable Zero-valent metals Reactive (degradation) Nutrients (solid, liquid) ORC and HRC Low-permeability (very fine grained) Phyllosilicate clays, e.g. Bentonite Palygorskite

28 Ease of placing innovative materials in their natural state 28 Material characteristics larger (granular) particles with density of >> 1 g/cm 3 seconds Material characteristics smaller (fine) particles of variable density hours (if ever) vs currents

29 Innovative capping products 29 incorporating innovative materials Higher-perm + reactive Reactive Core Mats, RCMs Organoclay (granular) Bioblok Gate P-control products Lower-perm + reactive BioBlok+ SediMite Lower-perm + inert Geosynthetic clay liners, GCLs Bentonite chips, pellets BioBlok Clay/cement composites BioBlok in Scandinavia AquaBlok in North America

30 AquaBlok or BioBlok particles 30 Clay-based AquaBlok PAC-based BioBlok Courtesy AquaBlok, Ltd. or Biologge AS

31 Selected innovative capping projects: USA and Norway

32 Anacostia River, Wash. DC., USA 32 site handling, placement cap design monitoring From Reible et al., 2005; USEPA, 2007

33 Aberdeen Proving Grounds, Md., USA 33 site handling, placement cap design monitoring Courtesy AquaBlok, Ltd.

34 Sandefjord Harbor, Norway 34 site handling, placement cap design monitoring Courtesy Biologge AS

35 Bergen Harbor (Kirkebukten), Norway 35 site cap designs handling, placement monitoring Courtesy Biologge AS

36 Leirvik Sveis, Norway 36 site placement monitoring cap designs From Biologge AS

37 Estimating capping costs: Involves weighing several variables 37 A = Minimum thickness of material or product X required to achieve acceptable long-term protection B = Material costs (delivered, offloaded) C = Placement costs Cost/m² seabed = f(a, B, C)

38 General costs for sediment management 38 Qualitatively Remove (dredge) > in-situ cap > MNR Quantitatively (but very roughly!) SGI, Malmö 14 September, 2012

39 39 Thanks for your attention!

In-situ capping of contaminated sediments

In-situ capping of contaminated sediments Overall summary Joseph Jersak, Gunnel Göransson, Yvonne Ohlsson, Lennart Larsson, Peter Flyhammar, Per Lindh SGI Publication 30-7E Linköping 2016 Cite as: SGI