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)

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

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

INTRODUCTION

maaiveld

kleilid van Asse

12 -14 m

7 m

14 m

pilot

Characterization of the contamination

» Contamination in soil and groundwater

› PAH

› Mineral oil

› Benzene

› Phenols and cresols

» DNAPL’s of tar

› 7.0 m bgl (Lid Van Onderdijke)

› 14.0 m bgl (Klei van Asse)

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

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

Introduction

Remediation of the second DNAPL

Remedial Action Plan originally said:

» Combination of steam injection and ElectricalResistance Heating

» Followed by In-situ Chemical Oxidation

OVAM chose to directly perform a pilot study for ISCO

Introduction

Further characterization of the contamination

» Determination optimal location pilot test

» More detailed delineation of the DNAPL zone

By

» Camera probing

» ROST probing

Camera probing

» The camera probe is inserted in the underground by means of regularprobing 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, oilparticles, gasbubbles but alsocontamination like tar are visible

Further characterization of contamination

tar

Cameraprobing – examples

Further characterization of contamination

ROST probing

» Principle: ROST = Rapid Optical Screening Tool

Further characterization of contamination

Principle (2)

Further characterization of contamination

Results:

» Semi-quantitative determination of the contamination

DNAPL

Further characterization of contamination

Results:

» Geological cross sections

Dwarsdoorsnede AA'

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Puntweerstand

diep

te (m

-mvS

4)

PW S3

PW S100

PW S102

PW S103

PW S104

S100 S3 S102 S103 S104

vermoedelijke verspreiding (niet afgeperkt)

puur product in de klei van Asse

Zand van Buisputten

Klei van Zomergem

Zand van Onderdaele

Klei van Asse

zandige tussenlaag

minder doorlatende laag

Dwarsdoorsnede BB'

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te (m

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vS4)

PW S3

PW S6

PW S9

PW S11

PW S100

VUB1A

Zand van Buisputten

Klei van Zomergem

zandige tussenlaag

Zand van Onderdaele

Klei van Asse

minder doorlatende laag

minder doorlatende laag

S100 S3 S6 S9 S11 VUB1A

Further characterization of contamination

Contamination cross section

Further characterization of contamination

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)

Site remediation

ISCO in action

Site remediation

Pilot test : ISCO remediation

» First results: Reduction of the contamination load with 80-95%

M1

M2

M3

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2-8-2007

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minerale olie

2-8-200723-5-200723-4-2007

Site remediation

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2-8-2007

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PAK 16

2-8-200723-5-200723-4-2007

Reduction MO first step: 73%Reduction MO second step: 83%

Reduction PAH first step: 82%Reduction PAH second step: 94%

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)

Site remediation

Before start After 4 months After 1 year

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