Assessing effects of site characteristics on remediation secondary life cycle impact with a generalised framework
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Assessing effects of site characteristicson remediation secondary life cycleimpact with a generalised frameworkDeyi Houa, Abir Al-Tabbaaa & Jian Luoba Department of Engineering, University of Cambridge,Trumpington Street, Cambridge CB2 1PZ, UKb School of Civil & Environment Engineering, Georgia Instituteof Technology, Mason 226, 790 Atlantic Drive, Atlanta, GA, USA30332-0355Published online: 16 Jan 2014.
To cite this article: Deyi Hou, Abir Al-Tabbaa & Jian Luo (2014) Assessing effects of sitecharacteristics on remediation secondary life cycle impact with a generalised framework, Journalof Environmental Planning and Management, 57:7, 1083-1100, DOI: 10.1080/09640568.2013.863754
To link to this article: http://dx.doi.org/10.1080/09640568.2013.863754
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Assessing effects of site characteristics on remediation secondary life
cycle impact with a generalised framework
Deyi Houa*, Abir Al-Tabbaaa and Jian Luob
aDepartment of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ,UK; bSchool of Civil & Environment Engineering, Georgia Institute of Technology, Mason 226,
790 Atlantic Drive, Atlanta, GA, USA 30332-0355
(Received 13 July 2013; final version received 5 November 2013)
The sustainable remediation concept has been broadly embraced by industry andgovernments in recent years in both the US and Europe. However, there is a strongneed for more research to enhance its practicability. In an attempt to fill this researchgap, this study developed a generalised framework for selecting the mostenvironmentally sustainable remedial technology under various site conditions. Fourremediation technologies were evaluated: pump and treat (P&T), enhanced in situbioremediation (EIB), permeable reactive barrier (PRB), and in situ chemicalreduction (ISCR). Within the developed framework and examined site conditionranges, our results indicate that site characteristics have a profound effect on the lifecycle impact of various remedial alternatives, thus providing insights and valuableinformation for determining what is considered the most desired remedy from anenvironmental sustainability perspective.
Keywords: sustainable remediation; life cycle assessment; groundwater remediation;contaminated land
Land contamination is a major challenge to modern society; with an estimated 294,000
contaminated sites in the US (USEPA 2004) and over 300,000 ha of potential
contaminated land in the UK (EA 2005). The land contamination issue can deteriorate
due to other environmental-friendly practices such as recycling (Hou 2011; Hou et al.
2012). Land remediation requires the investment of a significant amount of resources.
The US Superfund clean-up programme alone is spending approximately $1.2 billion
annually in the federal budget; and the requested reinstating of the Superfund tax would
add over $20 billion in funding over the next decade (USEPA 2013). Historically,
remediation was considered to be an inherently sustainable practice because it restores
contaminated land and reduces urban sprawl and greenfield development. Modern green
design standards, such as the Leadership in Energy and Environmental Design (LEED)
programme, recognise brownfield remediation as a major credit towards sustainable
development (USGBC 2011). However, remediation operations are also associated with
adverse environmental effects throughout its life cycle. It is only in recent years that
researchers and industrial practitioners have started to examine these secondary
environmental impacts from a sustainability perspective, and using a life-cycle
approach (Ellis and Hadley 2009).
*Corresponding author. Email: email@example.com
2014 University of Newcastle upon Tyne
Journal of Environmental Planning and Management, 2014
Vol. 57, No. 7, 10831100, http://dx.doi.org/10.1080/09640568.2013.863754
Sustainable remediation is an emerging field, with its concept first adopted by several
organisations which are sponsored primarily by the industry. These organisations include
the Network for Industrially Contaminated Land in Europe (NICOLE, founded in 1995 in
Europe), the Contaminated Land: Applications in Real Environments (CLAIRE, founded
in 1999 in the UK), and the Sustainable Remediation Forum (SURF, founded in 2006 in
the US). Sustainable remediation, or its variant green remediation, is also increasingly
supported by governments (CLARINET 2002; ITRC 2011; USEPA 2010a). Various US
federal agencies, e.g. USACE (USACE 2010), AFCEE (AFCEE 2010), NAVFAC
(NAVFAC 2011) and state governments, e.g. California-DTSC (DTSC 2009), have
developed guidance, protocols and software packages in this field in the past few years.
A number of research studies have been conducted relating to this field, and they have
used life cycle assessment (LCA) (Lemming, Hauschild, and Bjerg 2010; Morais and
Delerue-Matos 2010), multi-criterion analysis (Harbottle, Al-Tabbaa, and Evans 2008;
Sparrevik et al. 2012) and footprint calculators (USEPA 2010b; Lubrecht 2012) in
sustainability evaluation for remedy selection. Several early studies laid the foundations
for conducting life cycle assessment (LCA) in the field of remediation, primarily to
account for secondary impacts in order to support informed decision making (Diamond
et al. 1999; Volkwein, Hurtig, and Klopffer 1999; Blanc et al. 2004). Two review paperspublished in 2010 summarised the findings and challenges based on a review of over 10
remediation LCA studies (Lemming, Hauschild, and Bjerg 2010; Morais and Delerue-
Matos 2010). Since 2010, over a dozen more LCA studies have been published
(Owsianiak et al. 2013). These studies have rendered a wide range of findings and
implications to assist researchers and industrial practitioners in taking a holistic view in
remediation decision-making processes.
As an International Organization for Standardization (ISO) standardised method,
LCA can be used with other factors, such as cost and performance data, to select the most
appropriate remedial alternative. However, performing an LCA can be resource and time-
consuming (USEPA 2006), and may not be affordable by most remediation projects.
Moreover, the incorporation of sustainability in remediation decision making is a
continuous and iterative process (Holland 2011). As traditional LCA is a relatively static
process (i.e. requiring solid definition of the system), it may need adaptation to
accommodate the unique challenges in sustainable remediation decision making in a
project life cycle where sigificant changes may occur in the system. One of the
challenges is that most existing studies have used highly site specific data, which make it
difficult to extend the implications from these studies to other sites with different site
This study aims to explore the feasibility of using a generalised LCA model to derive
knowledge that can be more broadly applicable than what traditional LCA renders. Four
remediation technologies are assessed in this study: pump and treat (P&T), enhanced in
situ bioremediation (EIB), permeable reactive barrier (PRB), and in situ chemical
reduction (ISCR). This LCA has chosen chlorinated ethylene as the study subject because
chlorinated solvents are the most prevalent organic contaminants in soil and groundwater
(ATSDR 2007), due to their past extensive industrial use as cleaning and degreasing
solvents, adhesives, coating solvents and as feedstock for other chemicals (Stroo and
Ward 2010). Unlike most existing remediation LCA studies that are limited by highly site
specific conditions and thus rendering mixed results (see Table S1 in the Supplementary
Material available via the article website), the present generalised remediation life cycle
assessment (GRLCA) studies the influence of broad-range varying site-specific
parameters, including site location, plume dimension, hydrology, chemistry and
1084 D. Hou et al.
geochemistry. The present study also represents the first LCA of ISCR with in situ soil
mixing, and one of only a few LCA studies on EIB.
2. Materials and methods
2.1. Generalised site conceptual model
A generalised site conceptual model (GSCM) was established based on a review of
remediation activities at four typical chlorinated solvent contaminated sites (see
Supplementary Material available via the article website, section B). These sites are
located in California, USA, with site size ranging from a few hectares to over 100 ha. The
plume dimensions and hydrogeological properties show moderate to strong variation
among these sites. A broad range of remediation activities have been conducted at these
sites to treat contaminated groundwater, ranging from conventional P&T to innovative
ISCR. The GSCM, as shown in Figure 1, was developed to encompass the site conditions
encountered at these sites. The system parameter ranges were expanded to account for a
wider range of site conditions (see Table 1).
In the GSCM, the contaminated area consisted of a treatment zone that was the target
of active remediation (e.g. chemical or biological treatment), and a monitored natural
attenuation (MNA) zone, where there was no active remediation, where instead risks
were managed through regularly monitoring the natural attenuation of the plume by
dilution and natural degradation. A series of parameters depicted the location of the site,
hydrogeology, extent and migration of contaminants, etc. The typical parameters
observed at these four sites were used to generate a range of parameters that were used in
the GSCM study. Section B of the Supplementary Material (available via the article
website) includes a diagram of the GSCM and simulated parameter range. In this study,
to simplify the analysis, tetrachloroethene (PCE) and its daughter products were selected
Figure 1. A diagram of the generalised site conceptual model (Denotation: W1 widthof treatment zone [40 m]; W2 width of plume area for monitored natural attenuation [270 m];L1 length of treatment zone [60 m]; L2 length of MNA zone [260 m]; D depth to upperlimit of contaminated aquifer [4 m]; B thickness of contaminated aquifer [6 m]).
Journal of Environmental Planning and Management 1085
as the modelled contaminants in the GSCM. The present GRLCA framework is a
parameterised LCA based on the GSCM.
2.2. LCA functional unit and LCA boundaries
The goal of the LCA was to compare the secondary life cycle impact from four
remediation options for the GSCM. The functional unit was to reduce the levels of PCE
and its daughter products (i.e. TCE, DCE and vinyl chloride) within the treatment zone of
the GSCM (see Figure 1) to levels below the California Maximum Contaminant Level
Table 1. Range of system parameters in the generalised site conceptual model.
Key system parametersRange of parameter
values Default values Basis
Plume dimensionWidth of treatment zone 4 m to 200 m 40 m A factor of 1/2 or 2 was applied to
the minimum/maximumvalues in Table S1 (in theSupplementary Materialavailable via the articlewebsite) to encompass andexpand the range of parametervalues being simulated in thisstudy, with the exception oftreatment zone width, forwhich the minimum value wasreduced to 4 m to encompass awider range of possible siteconditions. The default valueswere set at or near thegeometric mean of theminimum and maximumvalues.
Length of treatment zone 15 m to 300 m 60 mAquifer starting depth 1 m to 18 m 4 mAquifer thickness 2 m to 18 m 6 mMNA plume width 60 m to 1200 m 270 mMNA plume length 50 m to 1400 m 260 m
HydrogeologyHydraulic conductivity 0.5 to 100 m/day 7 m/day As aboveHydraulic gradient 0.0001 to 0.02 0.003 Reflect a wide range of
possibilities based onhistorical data at the typicalsites (i.e. accounting fortemporal variation).
Half-lives of PCE anddaughter products inZVI treatment
0.1 hour to 10 hour 2.4 hour (USEPA 2000; Rabideau,Suribhatla and Craig 2005;Muegge 2008).
ZVI longevity in PRB 5, 10, 15, and30 years
Native Electron AcceptorDemand (EIB)
0.002 to 0.2 kgH2/m
3 water0.02 kg
Information from typical sites.
Native demand of ZVIdosage in soil mixing
30 to 3,000 mgZVI/kg soil
280 mg ZVI/kgsoil
Information from typical sitesand Bozzini 2006; Sale andOlson n.d.).
Site locationSite worker travel
distance20 km to 500 km 100 km Information from typical sites.
1086 D. Hou et al.
(Cal-MCL) for drinking water (CDPH 2011), with a 30-year timeframe. The Cal-MCL is
5 mg/L for PCE, 5 mg/L for TCE, 6 mg/L for 1.1-DCE and cis-1.2-DCE, and 0.5 mg/L for
vinyl chloride. Groundwater monitoring and possibly supplemental remediati...