Environmental Assessment of Brownfield Rehabilitation Using Two Different Life Cycle Inventory Models
Part 2: Case Study
Part 1: Methodological Approach (DOI: http://dx.doi.org/10.1065/lca2006.10.279.1)
Preamble. Brownfield rehabilitation recycles land resources in an open loop. LCA has been used in the past to evaluate the reduction in site-specific impacts and the impacts of the rehabilitation service system itself, called primary and secondary impacts in this paper, respectively. The consequences of reintroducing the site in the economy have not, however, been considered. This last has been touted as an efficient way to counter environmentally destructive urban sprawl. This article is the first of two on how a consequential model allows the inclusion of the environmental consequences of reoccupying a brownfield, called tertiary impacts in this paper. The second paper provides an actual case study.
Abstract
Goal, Scope and Background. The principal aim of this paper is to evaluate the environmental attributes and consequences of a 'rehabilitation for residential redevelopment' scenario. It is contrasted to a non-intensive and low-cost 'exposure minimization' scenario, assumed to be the default intervention option to obtain compliance. This paper also aims to (1) quantitatively evaluate the relative environmental significance of primary, secondary and tertiary impacts, and (2) to compare conclusions obtained from attributional and from consequential LCA of the same decision.
Main Features. An attributional LCA (ALCA) and a consequential LCA (CLCA) are used to compare the two radically different intervention options. The rehabilitation for residential redevelopment scenario involves 'dig and dump' remediation, infrastructure material recycling and site backfilling. The 'exposure minimization' scenario consists in covering the site with clean soil and subsequently idling the site. The functional unit allowing this comparison is the 'legal and appropriate intervention on 1 ha of the tracked brownfield'. The inventory analyses are done following the proposals in Part 1. The LCIA is done using IMPACT 2002+ method.
Results and Conclusions. The ALCA results show no clear preference for either intervention option because of the trade-off between the benefits of decontamination and the impacts of the rehabilitation service system. The CLCA, on the other hand, unequivocally supports rehabilitation if it is followed by residential reuse, as long as the development of suburban sites is avoided. In these cases, tertiary environmental benefits dominate other types of impacts. It is concluded that, when brownfield intervention decisions can affect the fate of the site, the scope of brownfield management LCA should always be expanded to account for tertiary impacts
Perspectives. The methodology proposed was restricted to a single site and to residential redevelopment. It is suggested that the general approach could be used for other types of brownfield redevelopments and for decisions affecting multiple brownfields. |
