development and in situ application of sorbent/reagent ...adriaens/site/dioxin... · anacostia...
TRANSCRIPT
![Page 1: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/1.jpg)
Development and In Situ Application ofSorbent/reagent-amended “Active” Sediment Caps
for Managing HOC-contaminated Sediments
Greg LowryCarnegie Mellon University
Civil and Environmental Engineering
Technology Benchmarking Workshopfor Sediment and Floodplain Remediation
Ann Arbor, MI
March 25-26, 2004
Support: HSRC, NSF, Alcoa
![Page 2: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/2.jpg)
Outline
• Technology Description• Development and Application• Observations/lessons learned• Future Directions
![Page 3: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/3.jpg)
Concept
Degradable Products
qRiver Water
Contaminated Sediment
Active Layer(s)Bioturbation Layer
-Degradation-Sequestration-Treating porewater
Z=0
+Z
CzCD
zCu
tC
n ezdb k
K−
∂∂
+∂∂
−=∂∂
+ 2
2
1ρ
![Page 4: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/4.jpg)
Proposed Placement Method
Anacostia River Sediment Profile
![Page 5: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/5.jpg)
Proposed Placement Method
RCM
Anacostia River Sediment Profile
RCM unrolled and placed by divers
RCM=Reactive Core Mat
![Page 6: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/6.jpg)
Proposed Placement Method
RCM
Sand
15-25 cm clean sand placed over RCM
1. Provides Containment2. Protects Benthic organisms3. Reduces PCB flux4. Eliminates exposure pathway
![Page 7: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/7.jpg)
Development and Application
• Suitable “Active” Materials– Degrade or sequester PCBs
• Placement Techniques– Clam shell, geotextiles
• Demonstration of technology (ongoing)– Effectiveness of placement method and risk reduction– Performance evaluation
Data Gaps Addressed
![Page 8: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/8.jpg)
Identifying Suitable Sorbents
• Treatability Study Goals– Determine reactivity of PCBs with Fe0
– Compare performance of different sorbents– Provide design criteria for demonstration
![Page 9: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/9.jpg)
Rationale for Fe0 and Sorbents• Fe0
– Proven dechlorination potential– Removes meta and para chlorines
• Potential to decrease toxicity of PCB mixtures
• Sorbents (Coke, AC, soil, sand)– Sequester PCBs and decreases bioavailability– Coke is inexpensive (~$100/ton)– Soil (OC) is inexpensive and previously tested– Sand is standard cap material
![Page 10: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/10.jpg)
Approach: Fe0
• Batch experiments monitoring PCB loss and byproduct formation– Commercial Fe(0), Pd/Fe(0), Nano-Fe(0)– Individual PCB congeners– Rate constants (k) based on byproduct formation
![Page 11: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/11.jpg)
Fe0 MediaNano Fe(0)Nano Fe(0)Size: ~50 nmSize: ~50 nm
Fisher Fe(0)Fisher Fe(0)Size: 150 Size: 150 µµmm
Peerless Fe(0)Peerless Fe(0)Size: 0.4 Size: 0.4 -- 2.4 mm2.4 mm
0.05% Pd/Peerless Fe(0)0.05% Pd/Peerless Fe(0)Size: 0.4 Size: 0.4 -- 2.4 mm2.4 mm
![Page 12: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/12.jpg)
Pd/Fe0-0.05% k~21 yr-1
![Page 13: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/13.jpg)
2,2’,3,5’-Nano Fe0
![Page 14: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/14.jpg)
PCB Dechlorination Patterns
0
0.01
0.02
0.03
0.04
0.05
0.06
22' 34' 234 22'35' 22'45'
Parent Congeners
µmol
o/m/p
-Cl r
emov
ed /
µm
olo o/m/p
-Cl ortho
metapara
Cl Cl
ClCl
ClClCl
Cl Cl Cl
Cl
Cl ClCl
Cl
00.050.1
0.150.2
0.25
33'44'
ClClCl
Cl
![Page 15: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/15.jpg)
Fe0 Reactivity Summary
0.01-6Dechlorination rates variable
Meta and Para chlorine dechlorination favored
Nano Fe(0)
21Rapid dechlorination
not sustainablePd/Fe(0)
(500 ppmw Pd)
0No Observable Reaction
(6 months)Commercial Fe(0)
k (yr –1)
RESULTSMEDIA
![Page 16: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/16.jpg)
Approach: Sorbents
•
• Isotherms/column breakthrough with 1,2-DCB• Estimate Kd for PCBs• Assess coke toxicity
– Leaching tests-Heavy metals, PAHs, VOCs
Kd (L/kg)
Activated Carbon
Sediment (low)
Fly Ash
COKE??
Sediment (high)
5.6E+914,000 1.9E+6180
Krauss et al. 2001Jonker et al. 2002
![Page 17: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/17.jpg)
Properties of Sorbents
1.8 x 1072.3 x 1051.6 x 1056 x 102R (retardation)
<1
2.5
~0.3
0.29
~0
Sand
6.6
2.0
0.4-2.0
0.47
3.8%
Soil
2-12
1.5
0.4-2.0
0.48
92
Coke
919BET SA (m2/g)
1.4Particle Density (g/cm3)
0.3-2.0Size (mm)
0.53Porosity (eff)
90Carbon (%)
AC
![Page 18: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/18.jpg)
0
20000
40000
60000
80000
100000
120000
140000
160000
0 0.5 1 1.5 2 2.5 3Cw (mg/L)
Cs
(mg/
kg)
Coke Activated Carbon
0
100
200
300
400
500
600
0 0.2 0.4 0.6 0.8
Coke
Activated Carbon
Isotherms with 1,2 Dichlorobenzene
0.9452.49308Farm Soil
0.9812.57375Anacostia Sediment
0.9552.79616Coke
0.9594.8062950Activated Carbon
(L/kg)(L/kg)
R2Log KdKdSorbent
![Page 19: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/19.jpg)
Log Kd = 0.9355Log Kow - 0.3792R2 = 0.9675
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7 8
Log Kow
Log
Kd
(L/K
g)
8.557.8Activated Carbon
5.025.15Coke
Jonker and Koelmans
Extrapolated from 1,2 DCB
Measured-1,2Dichlorobenzene
Extrapolated
Data from Jonker and Koelmans
Jonker and Koelmans. Environ. Sci. Technol. 2002, 36, 3725-3734
![Page 20: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/20.jpg)
Sorbent Performance and Capacity
0
0.5
1
0 5 10 15 20 25
Time (hours)
C/C
oCoke Farm Soil Sand AC
NeglibleSand
0.7Farm Soil
250.8Activated Carbon
0.6Coke
(mg DCB /g sorbent)
1,2 DCB CapacityMaterial
Co = 35 ppm 1,2-DCB, Vx=1.4 m/d
Assumptions:
•1,2 DCB Capacity = PCB Capacity
•1.25 cm thick cap
•60 cm uniform contaminated sediment
![Page 21: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/21.jpg)
Coke Toxicity Evaluation• Solid Coke
– 11 Heavy Metals, 16 PAHs, 33 VOCs, CN-, N, P
• Leachate (DI and Sediment Pore Water)– Heavy Metals, PAHs
• Comparison with Sediment Quality Guidelines (e.g. ERL1) and WQ standards (e.g. CMC2)
1 Effects Range Low (NOAA)2 Criterion Maximum Concentration (EPA)
![Page 22: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/22.jpg)
Heavy Metals in Solid Coke
1505.82ZincNA0.560.5SeleniumNA10.11.5Manganese46.70.740.3LeadNA250010Iron3420.22.5Copper811.51ChromiumNA11.45Barium8.21.71ArsenicNA46620Aluminum0.150.0340.033Mercury
ERL2
(mg/kg)Conc.
(mg/kg)Rept. Limit
(mg/kg)Metal
![Page 23: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/23.jpg)
PAHs in Solid Coke
665100Pyrene240120Phenanthrene16048NaphthaleneN/A42Indeno (1,2,3-cd) pyrene600110Fluoranthene63.432Dibenz (a,h) anthracene384110ChryseneN/A68Benzo (k) fluorantheneN/A68Benzo (ghi) pyreneN/A70Benzo (b) fluoranthene43083Benzo (a) pyrene26181Benzo (a) anthracene85.331Anthracene
ERL(µg/kg)
Result (µg/kg)PAH
![Page 24: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/24.jpg)
Metals Detected in Leachate
5ND10.67.6Se40481368419Fe676.158.453.7Ba
200249279228B(µg/L)(µg/L)(µg/L)(µg/L)
Rept. Limit
Anacostia Porewater
Leachate PW
Leachate DI
Metal
![Page 25: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/25.jpg)
PAHs in Leachate
30010ND2Pyrene30101.23.2Phenanthrene
398010ND1.7Fluoranthene30010ND1.9Chrysene30010ND1.6Benzo(a)pyrene30010ND1.4Benzo(a)anthraceneµg/Lµg/Lµg/Lµg/L
CMCReporting Limit
Leachate (PW)
Leachate (DI)PAH
![Page 26: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/26.jpg)
Predicting Performance in the Anacostia River
1.25cmRCM
-2-6 cm/dUz (seepage)
0 yr-1k (assumed)
260 m3/minFlow rate5.6 mDepth
CzCD
zCu
tC
n ezdb k
K−
∂∂
+∂∂
−=∂∂
+ 2
2
1ρ
![Page 27: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/27.jpg)
Sorbent Performance (v=1 cm/d)
Sand
Coke Sediment
Sand
Sorbentx
Assumes capacity not exceeded and no attenuation
![Page 28: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/28.jpg)
Cap Placement and Concerns
• Methods of placement– Particle Broadcasting– Reactive Core Mat (RCM)
![Page 29: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/29.jpg)
Particle Broadcasting
![Page 30: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/30.jpg)
Potential Problems with Particle Broadcasting for Sorbents
• Difficult to place thin layers• Variable settling velocities• Floating material• Fines
![Page 31: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/31.jpg)
Release of Fines From Coke
1.6 kg Coke~ 6 L Water
Release of fines during placement could be an issue!
![Page 32: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/32.jpg)
Coke SettlingVs~12-24 cm/s
Uneven distribution
6 Hours after release~13% of material does not sinkSome fines still suspended
![Page 33: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/33.jpg)
Reactive Core Mat (RCM)
![Page 34: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/34.jpg)
Reactive Core Mat II
![Page 35: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/35.jpg)
Mat Properties and Costs
• Thickness– ~0.5 in. (1.25cm)
• Loading– ~0.8-1.0 lb/ft2 (3.4
kg/m2)
• Twelve 10’ x 100’ rolls produced– ~6.5 tons of (10 x 40
mesh coke)
• Costs– Materials ($2700)– Lamination ($1750)– Labor ($2850)– Coke ($950)– Shipping ($2900)
– Total ($11,100)($1.11/ft2)
Coke-filled polyester corePolyester laminate
11.5 mils1.25 cm
![Page 36: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/36.jpg)
Comparative Materials Costs
010203040506070
0 2 4 6 8 10 12 14 16
Depth of Contaminated Sediment (ft)
Mat
eria
ls C
ost
($/y
d3)
Activated Carbon ($1/lb)
Coke ($0.07/lb)
![Page 37: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/37.jpg)
Factors Affecting Suitability of Approach
• Types of contaminants• Site characteristics• Geotextile properties
![Page 38: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/38.jpg)
Types of Contaminants
• Hydrophobic organics– PCBs (log Kow=4-8)– PAHs (log Kow=3-6)– PCDD (log Kow=4-8)– PCDF (log Kow=4-8)
• Other contaminants– Metals– Less hydrophobic organics
![Page 39: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/39.jpg)
Favorable Site Characteristics
• Diffuse contamination• Low energy
depositional and stable environment
• Minimal surface roughness/debris
• Minimal seepage rates
L/kg5.15Log Kd
cm/sec0.5Dispersivityg/cm30.78Bulk Density
0.48Effective PorosityParameters (coke)
Time=100 yrs
![Page 40: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/40.jpg)
Geotextile Properties
• Strength– Placement and integrity
• Permeability (gas and liquid)– Seepage and burping potential
• Susceptibility to pore plugging– Changes in permeability with time
• Density– Placement and stability
![Page 41: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/41.jpg)
Observations/conclusions• Most Promising Aspects
– RCM technology is simple– **Provides ability to accurately place thin layer caps– Will work with AC as sorbent, less expensive sorbents may be
effective if natural attenuation occurring– High potential for future development of reactive media– Technologies with modest reaction rates (<1 yr-1) can be effective
• Concerns– Sorbents do NOT directly provide PCB mass reductions– Sorbent capacity– Fe0 may NOT be cost effective (lifetime unknown)– Further research needed to develop reactive media for RCMs– Effect of NOM and colloids on sorptive properties– Geotextile/cap integrity
![Page 42: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/42.jpg)
Open Scientific Questions?
• What should design lifetime be?• How will NOM affect performance?• Cap Stability• What geotextiles properties are needed?• Can contaminants effectively be degraded
in situ?• Who will fund development/testing?
![Page 43: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/43.jpg)
Ongoing Research
• Column studies-long term performance– Evaluating the effect of DOM and colloids in porewater
on sorbent/mat performance (lower Kd, competition, ...)
• Anacostia River Pilot Demonstration (April 04)– Mat placement and performance
• Evaluate alternative geotextiles• Develop “reactive” media for PCBs and other
contaminants
![Page 44: Development and In Situ Application of Sorbent/reagent ...adriaens/Site/Dioxin... · Anacostia River RCM 1.25cm Uz (seepage) -2-6 cm/d k (assumed) 0 yr-1 ... • Floating material](https://reader034.vdocument.in/reader034/viewer/2022042909/5f3c6a90a9661150b219f966/html5/thumbnails/44.jpg)
Questions/Comments?