Demolition

Abstract: The construction and demolition (C&D) waste generated by the Canadian construction industry accounts for 27 % of the total municipal solid waste disposed in landfills. However, it is evident that over 75 % of what the construction industry generates as waste has a residual value, and therefore could be recycled, salvaged and/or reused. The need for comprehensive and integrated waste management mechanisms, technologies, rating systems and policies is widely recognized. Owing to increasing C&D waste volumes, shortage of landfills and long-term adverse environmental, economic and social impacts of the disposed C&D waste, sustainable C&D waste management is becoming increasingly essential to protect public health and natural ecosystems. This paper proposes a conceptual C&D waste management framework to maximise the 3R (reduce, reuse and recycle) and minimise the disposal of construction waste by implementing sustainable and comprehensive strategy throughout the lifecycle of construction projects. In addition, a life cycle based C&D waste sustainability index is developed. This approach can be used to make decisions related to selection of material, sorting, recycle/reuse and treatment or disposal options for C&D waste.

Abstract: The construction industry is the major solid waste generator in Hong Kong. In 1998, it generated about 32 710 t per day of construction and demolition (C&D) waste. In the management of such a huge quantity of C&D waste, Hong Kong has adopted a strategy of depositing the inert portion (e.g. sand, bricks and concrete) of the waste at public filling areas for land reclamation and the non-inert portion (e.g. plastics, paper, wood) at municipal solid waste landfills. However, the C&D waste arisen is usually in the form of a mixture of both inert and non-inert materials. As a result, the waste has to be disposed of at landfills, aggravating the landfill shortage problem. There is a paramount need to separate the C&D waste into its constituent parts before it is delivered to either the landfills or the public filling areas for disposal. In order to study the feasibility of carrying out on-site waste sorting and the current situation of the building relating C&D waste generated in Hong Kong, a survey was conducted. This paper presents the results of the survey undertaken to evaluate three alternative waste sorting methods on building construction sites and to compare them with the use of an off-site central waste sorting facility. The results indicate source separation has the advantages of requiring less effort and resulting in better segregation of inert and non-inert wastes as compared with waste sorting centrally carried out at a designated area on- or off-site. In addition, the views of the building industry participants were also obtained through a questionnaire survey to give a better understanding of their attitude on on-site waste sorting. The results indicate that the building construction participants are reluctant to carry out on-site waste sorting. Even when high a tipping fee is imposed, they have little incentive to perform on-site waste sorting which is considered to be time and labour demanding. Only through contractual requirements or legislation can on-site waste sorting be fully implemented and becomes a long-term solution to the landfill shortage problem in Hong Kong.