Environmental Engineering Reference
In-Depth Information
three times more than the in situ option. For the in situ option, electricity consumption
was considered to be the main environmental cost of the biosparging process. However,
as hydroelectricity is the major source of electrical power, negligible amounts of CO
2
were
emitted. Material consumption was equal in both cases but differed in origin. Iron and
manganese were required for excavation machines, whereas nickel and copper were used
for the air injection pipes and electrical materials. Biosparging was thus selected as the
remedial option. The area is used for parking and storage facilities and will be used in
the future for housing and parks. Other environmental assessments in the future will be
performed using this approach.
A follow-up report by Ellefsen et al. (2005) indicated that the cleanup was completed in
2003. The area will become a green area with reserves for nature. Another challenge of the
area was the management of the asphalt and sub-base contamination from PAHs from an
old runway. Instead of transporting the waste to a hazardous waste facility, bitumen at a
level of 3% was added to 20,000 tonnes of the soil via a cold mix process. The stabilized
mixture was then used as a road foundation in the area. Leaching tests with water and
road salt indicated that the material was appropriate for reuse. Another 80,000 tonnes of
the contaminated soil were used without stabilization in the same road, whereas 60,000 m
3
were used for other road construction and 80,000 tonnes for new terrain construction. In
total 200,000 m
3
of PAH contaminated soil were used with only 15,000 m
3
requiring haz-
ardous waste disposal.
Materials from the demolition were also used for recycling at an onsite recycling plant.
The onsite plant enabled a reduction of 80,000 truckloads of materials during construc-
tion. A test road built with recycled asphalt and concrete showed better behavior than
natural aggregates. Overall, 50,000 m
3
of C&D waste, 120,000 m
3
of old runways, 150,000
m
3
of excavated material, and 300,000 m
3
of blasted rock were used for 450,000 m
3
of
roads, buildings, and ditches. Another 60,000 m
3
of composted sludge, 120,000 m
3
of
excavated materials, and 150,000 m
3
of sand were for 400,000 m
3
of new soil and green
areas, whereas 888,000 m
3
of the 1,050,000 m
3
excavated material went to landill. For
energy, energy in seawater was exploited by heat pumps. The target was to supply 50%
of the energy by renewable energy. Wetlands were conserved for migrant birds, and
other landscaping for aesthetics and public recreation. Low impact transport such as
public transportation, footpaths, and cycle paths was prioritorized. The entire project is
to be completed in 2015 (Statsbygg, Norwegian Directorate of Public Construction and
Property [Statsbygg, 2014]).
13.5.1.1 Sustainability Indicators: Observations and Comments
There are several indicators that can be used to determine whether a remediation project
meets the aims or principles of
sustainability
. These include
• Land use
: The results show that if one uses the contaminated land as a starting
point, the original plan for remediation and rehabilitation of the land to permit
usage as parking and storage facilities is a step forward, i.e., better land use. The
subsequent report indicating use of the rehabilitated land as green space is a posi-
tive step toward sustainability goals. We need to note that the land-use indica-
tors here are not in reference to the initial airport land use. Because of the new
intended green space land use, the sustainability indicators can now be cast in
terms of “return to nature” indicators.
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