State of the art, challenges and upcoming techniques regarding investigation and

remediation of chlorinated solvents

Tom Heron, Executive Director Charlotte Riis, Expertise Director

NIRAS

2

Source versus Plume

Governing Parametres

Distribution and Risk

• Contaminant Characteristics

• Geology

• Hydrogeology

• Soil/GW chemistry; redox

• Time

Source zone • Free Phase (DNAPL) and high

sorbed and dissolved concentrations • mg/l or mg/kg • >95% of the mass

Plume •Dissolved components • Low concentrations;

µg/l or µg/kg

3

Challenges DNAPL and/in Low permeable Soil

4

Backdiffusion and Scale

Few cm to decimetres

1 – 100 cm

5

V = -k ∙ dh/dx

Challenges Permeability Contrasts

6

Residual fri fase; 2 fase flow

V = -k ∙ dh/dx

Boks 2. Beregning af reduceret gennemstrømning som følge af residual fri fase.

F = 2 kr/(1 + kr) hvor

F er reduktionen af gennemstrømningen

kr er den relative permeabilitet i området med residual fri fase (kr =

1 ved uforurenede forhold)

Anderson, M. R. The dissolution and transport of dense non-aqueous phase liquids in saturated porous media, 1988. OHSU OGI School of Science & Engineering, Beaverton, OR

7

Challenges

• Understand the system at the relevant scale - Characterization

• Extreme demands: 10.000 to 1 µg/l

• Ensure CONTACT (X-Y-Z, mass, time)

‐ Flow by-pass

‐ Diffusion in/out

‐ Reactions in water phase

‐ Incapsulation

‐ Density driven flow

8

Understand the system at the relevant scale

Characterization

• Contaminant Composition and 3D Distribution

• Geology

• Hydrogeology

• Soil- and Water Chemistry; Redox

9

Characterization

High quality sampling, depth specific; Coring

Non-/Less disruptive; Probing

Site specific combination of tools

Dynamic Approaches, Rapis SA; TRIAD

10

Data presentation

11

Source Zones Continous sampling with Dual-Tube system

• Continous sampling (1,25” cores) in 2,25” casing

• Ground Water Sampling in selected depths (SP22)

• Small diameter screened permanent sampling points for gas or water

12

Source Zones DNAPL Detection using MIP, Coring and Sudan-IV Dye tests

76 1,4

6,6 0,03

21.000 79,0

250 0,78 270 0,42

450 2,70

Soil samples mg/kg TS PCE TCE Sand

Moraine clay

Sand

Moraine clay

M412 og K401 (80 cm apart)

13

Source Zones MIP with GC/MS

• MIP-system and on-site GC/MS for detection of VOC’s in carrier gas. Appr. 1 sample/meter

Probing DK

14

Source Zones FLUTe FACT liner, MIP and Coring (PCE)

MIP M5

PID [µV]

0

1

2

3

4

5

6

7

8

9

10

0,0E+0 2,0E+6 4,0E+6 6,0E+6

MIP M5

FID [µV]

0

1

2

3

4

5

6

7

8

9

10

0,0E+0 2,0E+6 4,0E+6 6,0E+6

MIP M5

XSD [µV]

0

1

2

3

4

5

6

7

8

9

10

0,0E+0 2,0E+6 4,0E+6 6,0E+6

Kerneprøve K3

Sum chlorerede

[mg/kg-Wv]

0

1

2

3

4

5

6

7

8

9

10

0 1 10 100 1000

Kerneprøve K3

PID

[ppm]

0

1

2

3

4

5

6

7

8

9

10

0 1 10 100 1000

FLUTe liner F3B

Sum chlorerede

0

1

2

3

4

5

6

7

8

9

10

0 2000 4000

Liner MIP Core

15

Source Zones Laser Induced Fluorescens (LIF) for in-situ detection of LNAPL (UVOST system, Dakota)

• Aromatic components floures, Aliphats don’t

• Different respons from different UV-wave lengths

• Real time respons

• Used in combination with GeoProbe

• Detection level; 10-50 ppm in soil

16

Source Zones Dye-LIF for detection of DNAPL (Dakota Tech.)

• Injection of hydrophobic dye 30 cm ’in front’ of UV-Source/detector

• Induces Flourescens from DNAPL by preferential dissolution of dye into the DNAPL

17

Ground Water Plumes Dissolved Concentrations

18

Ground Water Plumes Depth specific sampling using Geoprobe

19

Ground Water Plumes EnISSA system (Belgium)

• In-Situ measurements; MIP & GC-MS; detection of 14 VOC pr. 30 cm (1 min./analyses)

• Detektion limit for VOC i ground water ~ 20 µg/l

20

Ground Water Plumes Waterloo profiler with Geoprobe

• Waterloo profiler modified (Stone Environmental)

• Water sampling, hydraulic head and K estimation

• Continuous extraction from probe and on-line analyses of redox-parametres

PCE TCE TCA 1,2-DCE Head K

21

Ground Water Plumes Low detection limit MIP

• Sensitivity enhanced > 10 times, using XSD detector

Responstest with 0,5 ppm TCE

Standard system

New system

Standard

New

22

Geology and Hydrogeology

Coring, depth specific, detailed sampling

Probing, Non-/Less disruptive

• Physical

• Electrical

• Optical

• Chemical

Less permanent piezometres

23

Geology and Hydrogeology Estimation of K and vertical gradient by HPT

• HPT pressure yields trustworthy hydraulic conductivity data. Values from 10-4 -10-6 m/s

• Conductivity log for indication of geological composition

24

Hydrogeology Pneumatic slugtest for estimating K-values and simultaneous water sampling

• K-values validated by HPT

• Basis for flux estimates (M=A*v*C)

0

1

2

3

4

5

6

7

0 10 20 30

De

pth

(m

ete

rs)

Hydraulic Conductivity [K] (m/day)

Est. K (m/day)

Slug Test K (m/day)

24.16 m/day

18.06 m/day

0.43 m/day

0.90 m/day

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Geology and Hydrogeology CPT, Electrical Conductivity-logs & Photos

• CPT (Tip & Sleeve, Hydraulic Head)

• Electrical Conductivity, tracing ZVI/Guar injektion with tracer

• Optical log

0,3

0,8

1,3

1,8

2,3

2,8

3,3

3,8

4,3

4,8

5,3

5,8

6,3

6,8

7,3

0 200 400 600 800 1000 1200

Dyd

be (

m u

.t.]

EC [mS/m]

E314

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Summary

• High Resolution data on

Contaminant Distribution

Geology

Hydrogeology

Redox Conditions

• In Situ measurements

• High Quality On-Site, On-line, Real-time data

• Supplementary Accredited Analyses

• Dynamic Approach for Rapid Site Assessment

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Remediation

• Choose the right technology/-ies

‐ Contact / Non-contact issues

‐ Flow by-pass

‐ Density driven flow

‐ Stoichiometric delivery

‐ Incapsulation issues

‐ Diffusion in/out

‐ Reactions in water phase

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Flow bypass,

dilution & dispersion kinetics

Desorption, diffusion

Contact sport

• Air Sparging

• Soil Vapor Extraction

• In Situ Chemical Oxidation

• Biological methods

• Flushing

• Pump and Treat

29

Courtesy of Gorm Heron, TerraTherm

Non-Contact

• Excavation

• Mixing

• Thermal Enhanced

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Technologies and key parametres

ERD ISCO SVE IAS Ther-mal

DPE, etc

Smolde-ring

Mixing

Surfac-tants

Fracturing

EK

Contact dependent √ √ √ √ % √ % % √ √*

Sufficient mass deliv. √ √ % % % % √ √ √ √

Specific concentration √ √ % % % % √ (√) √ √

Contact time requirements

√ √ √ √ √ √ % √ √ √

Extr. pathways require. % % √ √ √ √ % % √ %

Risk of spreading √ √ √ √ √ % % (%) √ √

Soil structure changes % (%) % % (%) % (%) √ % %

Enhancement methods So

il V

apo

r E

xtra

ctio

n

En

han

ced

Red

uct

ive

Deh

alo

gen

atio

n

Slo

w In

Sit

u C

om

bu

stio

n

In S

itu

Air

Sp

arg

ing

Th

erm

ally

En

han

ced

Te

chn

olo

gie

s

Du

al P

has

e/M

ult

i Ph

ase

Ext

ract

ion

In S

itu

Ch

emic

al O

xid

atio

n

Hyd

rau

lic o

r p

neu

mat

ic

Ele

ctro

Kin

etic

Tra

nsp

ort

Ph

ysic

al m

ixin

g o

f so

il et

c.

En

han

ced

Dis

solu

tio

n b

y su

rfac

e ac

tive

am

men

dm

ents

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Fighting the contact challenge

• Slow Release; Chelated Iron, fast/slow substrates

• Mixing

• Fracturing

• Circulation

• Surfactants

• Pulsed injection

• Changing injection pressure and re-injection

• Installation/over-injection

• Osmosis/ion-migration/foreses (EK-Bio)

32

Sand

Volatile/semi-volatile

components: Light oils,

chlorinated solvents etc.

‘Homogenous’ sand

> 95 %

Thermal: Steam, ISTD, ERH, RF

Radical oxidation: Fentons, persulfate, Regen-Ox

ZVI-Clay/Soil Mixing

Smoldering

(Direct Ox/ERD/S-ISCO/S-ERD)

< 25 % Pump & Treat

50 – 75%

Oxidation: KMnO4, Persulfate, ozone, H2O2

Enhanced biological degradation

(Air Sparging/SVE)

Surfactant Flushing

< 50 %

Air Sparging/SVE

Free phase pumping, DPE

(Surfactant flushing)

Realistic removal

33

? ?? ?

Clay and silt

> 95 %

< 25 %

Air Sparging/SVE

Free phase pumping, DPE

Smoldering

Pump & Treat

Phytoremediation

Natural attenuation

50 – 75% Radical oxidation: Fentons, persulfate, Regen-Ox etc.

< 50 % Direct Ox/ERD/S-ISCO/S-ERD

Enhanced biological degradation

Volatile/semi-volatile

componenter: Light oil

products, chlorinated solvents

etc.

Realistic removal Excavation

Thermal: ISTD, ERH, SEE, RF

ZVI-Clay/Soil Mixing

EK-Bio ?

34

That’s it!