Sustainability and Remediation - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 936

20.5.3 Sustainable Reuse of Contaminated Sediments

Sediments of the Old IJssel River system in the east of the Netherlands are severely
contaminated due to historical industrial activities. The rivers are regularly dredged,
and their sediments are contaminated. The dredged sediment is usually stored in a
temporary depot for dewatering. After dewatering, which may take a few months to
a year, the drained sediments are excavated and transported to a landfill.
These sediments have been re-used by a local authority project to substitute for
a primary resource (sand) for a 3,700 m 2 car park at a recreational area, in the
province of Utrecht. 1,500 m 3 of dredged sediment were dewatered in a temporary
landfill leaving a volume of 1,000 m 3 drained sediment which were then mixed with
a proprietary stabilisation amendment Megatrax R . The pavement met the leaching

criteria of the Dutch Building Materials Decree
The re-use of the sediment avoided the use of 1,000 m 3 of a primary resource
and resulted in a CO 2 emission reduction of 15 % compared with the use of primary
raw materials.

20.5.4 The Use of the REC Method to Select a Remediation
Strategy

The REC (Risks, Environmental Merits and Costs) method was used in the reme-
diation strategy development for a large chemical production plant in the province
of Zeeland in the Netherlands, where historical incidents have led to multiple soil
contamination hotspots, including aromatic hydrocarbons and chlorinated solvents.
These hotspots have resulted in several groundwater contaminant plumes, which are
partly intermingled.
The following remediation alternatives were compared, the using REC method:

• complete removal of contaminations, i.e. a multi-functional approach (referred to

as “complete removal alternative”);

• monitoring Natural Attenuation in combination with local hot spot removal

(referred to as “buffer zone alternative”)

• hydrological containment including removal of mobile light non-aqueous phase

liquid (LNAPL) contaminants (referred to as “IBC+ alternative”);

• hydrological containment (referred to as “IBC-alternative”).

The buffer zone alternative is a risk-based remediation approach and consists
of monitored Natural Attenuation in combination with local hotspot removal. The
buffer zone is defined as the zone at the site boundary in which Natural Attenuation
is able to reduce the contaminant concentrations at the site boundary to the values
accepted by the local authorities (Dutch T-value) so that the potential off site migra-
tion of the contamination does not cause any risks outside the site. The hydrological
containment strategy would involve pumping groundwater at a rate of 25 m 3 /h with
18 deep wells on site.