سهم سیستم های مدیریت زیست محیطی برای مدیریت مواد زائد ساخت و ساز و تخریب : در مورد جامعه خودگردان مادرید (اسپانیا)

The construction industry has both positive and negative repercussions on the environment. One of the main negative impacts is the generation of waste. Various types of instruments exist to manage construction and demolition wastes (C&DW). These include voluntary agreements between economic agents, planning, and technological development applied to specific projects. The present state of C&DW management is different in each country and/or region, and is determined by the management instruments used and the degree to which their content has been developed. As elsewhere, the rise of the construction sector in the Community of Madrid in recent years has brought about a notable increase in the generation of C&DW. In order to deal with this situation, the Autonomous Government has initiated several management instruments, including the Plan for Integrated Management of C&DW in the Community of Madrid (2002–2011). At the same time, some construction companies have implemented an environmental management system (EMS) in accordance with ISO Standard 14001, with a view to controlling the main environmental aspects associated with their activities, such as the generation of waste. These companies have established practical measures for the appropriate management of waste generated in their work centres and sites, whether permanent or temporary. This paper presents results of an analysis and evaluation of the application of ISO Standard 14001 to construction sites in the Autonomous Community of Madrid, with specific regard to practices of control and management of wastes generated on site, and to the fulfilment of legislation on waste management. The study aims to detect the deficiencies of EMS and current waste management instruments, and to determine the measures which may be necessary for improvement at all territorial levels (autonomous, national and supranational). In addition, some recommendations are made for promoting management of C&DW based on reuse and recycling in construction companies.

Construction and demolition wastes (C&DW) are generated on active building sites (Stein, 1996) and include a wide range of materials depending on the source of the waste: excavation materials (e.g. earth, sand, gravel, rocks and clay), road building and maintenance materials (e.g. asphalt, sand, gravel and metals), demolition materials (debris including earth, gravel, sand, blocks of concrete, bricks, gypsum, porcelain and lime-cast), as well as other worksite waste materials (e.g. wood, plastic, paper, glass, metal and pigments) (Fatta et al., 2003). These wastes are problematic not so much for their hazardous nature as for the sheer volume generated. However, between 50 and 80% of construction waste is reusable or recyclable (Bossink and Brouwers, 1996). Accordingly, many countries are presently directing their efforts towards adopting the necessary measures to promote waste minimization, as well as to reduce the quantities of waste disposed in landfills or eliminated illegally (CICA, 2002). Among measures to minimise C&DW are reusing, recycling and reducing generation through control of aspects such as design quality, applied technology and habitual construction methods (Ekanayake and Ofori, 2004 and Huete et al., 1998). With regard to the origins of C&DW recycling, the practice arose in Europe and the United States in the mid-20th century, in response to the shortage of construction materials and the costs of disposal after the Second World War (Stein, 1996). Today, recycling techniques are applied not only in industrialized countries such as The Netherlands or Denmark, but also in developing countries such as Bangladesh and in countries in expansion such as Kuwait (Lauritzen and Hahn, 1992). Generally speaking, recycling is competitive in situations where both raw materials and adequate disposal sites are scarce (Lauritzen, 1998). In addition, recycling helps to preserve areas of land for future urban development, and to improve the general state of the environment (Kartam et al., 2004). An alternative to recycling is reusing C&DW. To give just one example, the inert portion of C&DW may be used as filling material in land destined for reclamation (Poon et al., 2001). Finally, given that present-day society is directing its efforts towards environmental sustainability, it is interesting to note that United Nations Agenda 21 defines sustainable waste management as the application of the concept of integrated lifecycle management to the management of waste (Nilsson-Djerf and McDougall, 2000). This stresses the importance of adopting a lifecycle perspective when evaluating waste management measures (Klang et al., 2003). In this respect, various models and criteria have been studied and defined for evaluating sustainability in C&DW management (Chung et al., 2003 and Klang et al., 2003). Similarly, systems analysis tools for C&DW management have been developed (Wang et al., 2004), and studies have been carried out to establish a methodology for evaluating the environmental impact of recycled materials in construction (Petkovic et al., 2004). This paper presents the results of an evaluation of the management of wastes on sites in the Autonomous Community of Madrid. Specifically, the paper compares construction waste management on sites with and without environmental management system (EMS), with a view to analyzing both waste management and the effectiveness of current EMS.

Application of EMS in worksites contributes to a gradual enhancement of environmental awareness on the part of all personnel. At the same time, it promotes fulfilment of the relevant current legislation and the appropriate management of solid, inert and hazardous wastes. However, not all the companies who implement this type of management system observe the applicable legal requirements, or manage their wastes environmentally. Appropriate management involves higher costs for companies in the sector and at the present time promoters do not include specific budgetary allocations for C&DW management in project estimates. Similarly, promoters do not facilitate waste management plans by including them in technical specifications, nor do they make provision for the use of recycled materials and the establishment of models for demolition and selected collection at source. There is similarly a need for co-ordinated mechanisms to facilitate the reuse of surplus earth or stone materials in other sites in current or future operation in the area. Additionally, national and regional governments are slow to apply C&DW management plans which have been approved. As a result, there is no reduction in the quantities of C&DW eliminated in landfills, as may be expected in the absence of any effort to promote practices such as the prevention of C&DW generation, reuse and recycling, or to develop and stimulate the market for by-products obtained from C&DW. Similarly, no initiatives have been taken to launch information and awareness programmes for agents involved in the sector, and no agreements have been reached between government and the construction sector companies with a view to increasing recycling rates. At the same time, the technical standard regarding C&DW management and the production of recycled arid materials has not been fully developed. With regard to hazardous waste generated on worksites, the current legislation does not clarify aspects such as the moment from which the HW maximum storage period should be counted, and the obligations and responsibilities of main contractors and associated companies in relation to HW management. Similarly, there is a lack of definition concerning the specific requirements relating to HW storage facilities in the construction sector. Construction companies do not presently fulfil their obligations as producers of HW, due to the high cost of managing this type of waste and the imprecision of current legislation. Various options could be considered to reduce the costs of HW management. These might include permitting the admission of small quantities of HW from construction companies at Clean Points or Collection and Recycling Centres, exempting sector companies from the obligation to obtain authorization as HW Producers, and encouraging the use of environmentally non-aggressive materials, i.e. non-hazardous substances. In the course of the present study it proved difficult to find any reliable data regarding the quantities of wastes generated by construction companies. There is a similar lack of information regarding reuse and recycling rates, the costs of managing wastes generated on worksites (solid, inert and hazardous), and the final destination of such wastes. Obtaining this type of data could be a valuable objective for future research. Additionally, it would be of great interest to compile a review of current practices followed by construction companies to minimize and control the generation of on-site wastes, and to draw up guidelines for their widespread adoption.