Monitoring of the Active Capping Demonstration Project in the - - PowerPoint PPT Presentation

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Monitoring of the Active Capping Demonstration Project in the - - PowerPoint PPT Presentation

Nov 12, 2023 234 likes •444 views

Monitoring of the Active Capping Demonstration Project in the Anacostia River Danny Reible 1 , David Lampert 1 , David Constant 2 , Yuewei Zhu 3 1 University of Texas 2 Louisiana State University 3 Horne Engineering Support : AWTA,

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SLIDE 1

Monitoring of the Active Capping Demonstration Project in the Anacostia River

Danny Reible1, David Lampert1, David Constant2, Yuewei Zhu3

1University of Texas 2 Louisiana State University 3 Horne Engineering

Support : AWTA, HSRC/S&SW, DoD ESTCP

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SLIDE 2

Anacostia River Site

Demonstration Area

Aerial Photograph

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SLIDE 3

Anacostia River Site

  • Contaminant Loadings

500 mg/kg Pb 4 mg/kg Cd 280 mg/kg Cu 80 mg/kg Cr 1000 mg/kg Zn 1000-4500 μg/kg Benzo[a]pyrene 800-3500 μg/kg Chrysene 1000-4000 μg/kg Phenanthrene Loading Contaminant

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SLIDE 4

Anacostia River Site

  • Project Objective

– To demonstrate on a field scale the ability to design and construct caps that combine containment and treatment of contaminated sediments

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SLIDE 5

Capping Materials

  • AquaBlok

– A bentonite material that forms a low-permeability barrier between the contaminated sediment and the

  • verlying aquatic ecosystem.
  • Apatite

– Mineral that sorbs metals through a surface precipitation reaction

  • Coke Breeze

– By-product of coal refining process that strongly sorbs

  • rganic compounds
  • Sand
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SLIDE 6

Anacostia River Site

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SLIDE 7

Evaluation Approach

  • Measure

– Cap sediment concentrations – Pore water concentrations – Accumulation in benthic organisms (lab)

  • Model migration through caps

– Pore water flow rates – Adsorption parameters – Degradation (if any?)

  • Compare effectiveness of different cap

materials

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SLIDE 8

Coke - Core 1 Total PAHs vs Depth October 2005

CB-C1-S-06 CB-C1-S-04 CB-C1-S-02 CB-C1-SD-04 CB-C1-SD-04-D

1 2 3 4 5 6 7 8 9 10 11 12 2000 4000 6000 8000 10000 12000 14000 16000

Total PAHs Concentration (ug/kg) Depth Below Cap-Water Interface (inches)

S - Sand Layer SD - Sediment Layer Month 18 Monitoring Event Coke Breeze Mat Native Sediment Sand

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SLIDE 9

18-Month Coring Results – Apatite Cap

Apatite Cap PAH Concentration Profile

1000 2000 3000 4000 5000 6000 34.5 35.0 35.5 36.0 36.5 37.0 37.5 38.0 38.5 39.0

Depth (cm) PAH Concentration (μg/kg)

Phenanthrene Pyrene Benzo[a]anthracene Chrysene Benzo[b]fluoranthene Benzo[k]fluoranthene Benzo[a]pyrene

Apatite-Sediment Interface

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SLIDE 10

Apatite-Sediment Interface

Percent Passing and C/C0 Versus Depth

34.5 35.0 35.5 36.0 36.5 37.0 37.5 38.0 38.5 39.0 0% 20% 40% 60% 80% 100%

% Depth (cm)

Phenanthrene Pyrene Benzo[a]anthracene Chrysene Benzo[b]fluoranthene Benzo[k]fluoranthene Benzo[a]pyrene % Passing

18-Month Coring Results – Apatite Cap

Apatite-Sediment Interface

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SLIDE 11

Better Indicator of Migration?

  • Pore Water Concentrations

– Peepers

  • Place core with 3 mL sample ports every 1 cm into

caps, then remove and analyze for metals/PAHs

– Solid-Phase Membrane Extraction (SPME)

  • Study aqueous-phase concentrations (not bound

to colloids)

  • Potential to determine concentrations at lower

levels (ppt)

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SLIDE 12

Peepers Sampling

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SLIDE 13

Peepers Sampling

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SLIDE 14

Solid Phase MicroExtraction Sorbent Polymer

  • PDMS (poly-dimethylsiloxane)

– Thickness of glass core: 114-108 µm – Thickness of PDMS coating: 30-31 µm – Volume of coating: 13.55 (±0.02) µL PDMS per

meter of fibre

x

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SLIDE 15

Slotted tube for SPME

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SLIDE 16

SPME Measured Porewater Profile

Depth cm

5 10 15 20 25 30

Concentration ng/L

100 200 300 400 500 600 Surface mean Pore water Concentration Surface mean

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SLIDE 17

Measured and estimated pore-water concentrations of PAHs (ng/L)

PAH Measured SPME Measured by LLE Theoretical* Phenanthrene 210 370 1810 pyrene 610 730 990 chrysene 7.1 7.8 83 B[b]F 2.1 5.3 70 B[k]F 1.8 2 55 B[a]P 1.9 2 68

* Estimated from log Koc= log Kow-0.21 (reversibly sorbed with KSW~ Kocfoc) Predicted BSAF ~ Ratio of measured to theoretical concentration Assumes Klipid~ Koc

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SLIDE 18

Measured and estimated pore-water concentrations of PCBs (ng/L)

PCB Measured Theoretical* #28 1.9 2.5 #52 2.0 2.0 #153 0.4 0.77 #138 0.45 0.60 #180 0.38 0.16

* Estimated from Log Koc= 1.03* log Kow-0.61

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SLIDE 19

Biota-sediment accumulation factors of PAHs and PCBs(Measured vs predicted)

0.05 0.1 0.15 0.2 0.25 0.3 0.05 0.1 0.15 0.2 0.25 0.3 Predicted BSAF Measured BSAF

PAHs

0.5 1 1.5 2 2.5 3 0.5 1 1.5 2 2.5 3 Predicted BSAF Measured BSAF

PCBs

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SLIDE 20

Lessons being Learned

  • Innovative cap materials possible to place using

conventional equipment with experienced contractor

  • Possible to apply thin (6”) layer of cap material using

clamshell techniques

  • A laminated mat provides opportunities for controlled

placement of light and/or high value materials (e.g. μ scale zero valent iron or activated carbon)

  • AquaBlok effectively diverted groundwater flow
  • Gas accumulated under AquaBlok but was released rapidly

and irregularly with no observable negative consequences

  • Contaminant profiles consistent with sediment-cap/sand

intermixing – no observed migration

  • Pore water assessments may provide more information