The subject site is located in Asse, Belgium and was used for fabrication and storage of glues and tar containing asphalt products. Due to a fire, a distillation unit of 30 tonnes and a filled storage tank of app. 40 m³ taroil were destroyed. The Public Waste Agency of Flanders (OVAM) is responsible for the clean-up of the site. An excavation of the superficial DNAPL contamination has already been executed. However, the DNAPL of tar products on the clay-layer at a depth of 14 to 15 m bls still needs corrective action. Commissioned by OVAM, a pilot for in-situ chemical oxidation (ISCO) with Fenton’s Reagens has been executed on the site. A reasonable reduction of the contaminant load (app. 90%) was obtained. In order to make a well-founded BATNEEC-evaluation, the DNAPL is further characterized in detail, as the exact volume/proportion and contaminant load will determine the final remediation costs. This characterisation is obtained by using the Rapid Optical Screening Tool (ROST™) of Fugro. ROST™ detects aromatic hydrocarbons by means of a Laser Induced Fluorescence (LIF) technique.

1. Localisation and remediation of a
DNAPL-contamination of PAH’s at
the former Asphaltco site
Karel Van Nieuwenhove, Koen Meskens
(Soresma nv),
Frank Pels (HMVT),
Koen Janssens (OVAM)

2. Summary of presentation
» Introduction
› Site description
› Characterization of the contamination
› Site Development Plans
› Already executed remediation
› Remediation of the second DNAPL
» Further characterization of the contamination: detection by ROST
› Principle
› Results:
› Hydro geological build-up of the underground
› Semi-quantitative determination of the contamination
» Site remediation: Pilot test
› Materials and methods
› Results
› Conclusions
» Future perspectives

3. INTRODUCTION
Site description
» Location: Belgium, Asse, Molenstraat 48-50
» History:
› < 1900: horticulture
› 1912-1920: production of glues
› 1920-1986: fabrication of glues and tar
containing asphalt products (Asphaltco)
› 1985-1997: several companies and illegal
dumps
› 2005: demolition of the site
» Calamity: fire
› 1942
› Destruction of distillation unit of 30
tonnes and filled storage tank of app.
40m³ tar oil
› Extinguished with foam containing
tetrachloromethane

4. INTRODUCTION
Characterization of the contamination
» Contamination in soil and
groundwater maaiveld
› PAH
› Mineral oil 7m
› Benzene pilot
12 -14 m
› Phenols and cresols
klei
» DNAPL’s of tar lid van Asse
14 m
› 7.0 m bgl (Lid Van Onderdijke)
› 14.0 m bgl (Klei van Asse)

5. Introduction
Site Development Plans
» Acquired by the local community
» Fire department, youth house, sport tracks,...
» Local depot for busses (De Lijn)
» Large parking lot for the train station
» OVAM will remediate the site

6. Introduction
Already executed remediation
» Demolition of the site (2005)
› Cost: 500.000 euro
» Remediation of the dumping ground (2006)
› Cost: 950.000 euro
» Excavation contamination until 5.0-6.0 m bgl (2007)
› Total cost excavation (removal and remediation of
contaminated soil): 8.150.000 euro

7. Introduction
Remediation of the second DNAPL
Remedial Action Plan originally said:
» Combination of steam injection and Electrical
Resistance Heating
» Followed by In-situ Chemical Oxidation
OVAM chose to directly perform a pilot study for ISCO

8. Further characterization of the
contamination
» Determination optimal location pilot test
» More detailed delineation of the DNAPL zone
By
» Camera probing
» ROST probing

9. Further characterization of contamination
Camera probing
» The camera probe is inserted in the
underground by means of regular
probing equipment.
» Simultaneously video-recordings are
made from the underground.
» The camera probe consists of:
• Stainless steel tubing (Ø 44 mm, ca 1 m)
• Saphire sight flow glass: 5 by 7 mm
• Behind which a lamp, a mirror and a camera are
placed.
• Viewed 100 times enlarged on the monitor
» Grain size and colour of the soil, oil
particles, gasbubbles but also
contamination like tar are visible
tar

10. Further characterization of contamination
Cameraprobing – examples

11. Further characterization of contamination
ROST probing
» Principle: ROST = Rapid Optical Screening Tool

12. Further characterization of contamination
Principle (2)

13. Further characterization of contamination
Results:
» Semi-quantitative determination of the contamination
DNAPL

14. Further characterization of contamination
Results:
» Geological cross sections
Dwarsdoorsnede AA' Dwarsdoorsnede BB'
Puntweerstand Puntweerstand
S 00
1 S3 S6 S9 S1
1 V B1
U A
S100 S3 S102 S103 S104 0,00
0,00
P S3
W
2,00 P S3
W
2,00 P S100
W
P S6
W
P S102
W
P S9
W
P S103
W
4,00 P S11
W
4,00 P S104
W
P S100
W
VUB1A
6,00
vermoedelijke verspreiding (niet af geperkt )
6,00 Zand van Buisputten Zandvan Buisputten
puur product in de klei van Asse
diepte (m -mvS4)
diepte (m-mvS4)
8,00 K van Zomergem
lei
8,00 Klei van Zomergem
zandige tussenlaag zandige tussenlaag
10,00 10,00
minder doorlatende laag minder doorlatende laag
Zand van Onderdaele Zandvan Onderdaele
12,00 12,00
minder doorlatende laag
14,00 14,00
K van Asse
lei
Klei van Asse
16,00 16,00
18,00 18,00

15. Further characterization of contamination
Contamination cross section

16. Site remediation
Pilot test : ISCO remediation
» Materials and methods:
› HMVT bvba. – Soresma nv.
› 2 stages (May and July 2007)
› Area: 10 x 15 m² - 12 injection points (screen depths of
13.0-14.0 m-gl.)
› Injection of Fentons reagens (conc. of 5 to 10 %)+ catalyst
(Fe2+-sulphate)
› Vapor extraction wells (14)

17. Site remediation
ISCO in action

18. Site remediation
Pilot test : ISCO remediation
» First results: Reduction of the contamination load with 80-95%
m inerale olie
30000
25000
20000 Reduction MO first step: 73%
15000
10000
2-8-2007
23-5-2007
23-4-2007
Reduction MO second step: 83%
5000
0
M1
M2
M3
M4
M5
M6
2-8-2007
M7
INJ 1
INJ 6
ug / l
INJ 9
INJ 12
punt e n
PAK 16
25000
2-8-2007
20000 23-5-2007
23-4-2007
15000
10000 Reduction PAH first step: 82%
5000 Reduction PAH second step: 94%
0
M1
M2
M3
M4
M5
M6
2-8-2007
M7
INJ 1
INJ 6
ug/ l
INJ 9
INJ 12
punt e n

19. Site remediation
Pilot test : ISCO remediation
» Conclusions :
› At first: reasonable reduction was obtained
› After 1 year: DNAPL contamination was restored
› DNAPL levelled out from upper layers (non-
treated)
Before start After 4 months After 1 year

20. Future perspectives
» Prior to ISCO a selective removal of the mobile
DNAPL will be performed by specially designed pure
product pumps => pilot test
» Final characterization of DNAPL by ROST probing
» Determination of risk based remediation values