Investigating the Construction and Demolition waste management practices in Kampala and their impact on the environment

Abstract

The construction industry is one of the major contributors to the development of countries. In developing countries especially, it is growing at a fast rate as there is need for infrastructure in the countries in order to ease the provision of services. The construction industry however is also linked to waste termed as construction and demolition waste which is a by product of the industry and it increases with the growth of the industry. This research is aimed at investigating the construction and demolition waste management practices in Kampala and their impacts on the environment. The methods used in this study are in line with similar studies on construction and demolition waste management. Five sites generating C&D waste in Kampala were selected as the study sites for this research. Interviews were used to collect information on the handling of waste on the various sites. The site managers and a few other workers on site were asked questions pertaining to C&D waste management on the various sites. Site observations were also carried out in order to observe the ongoing activities concerning C&D waste handling. Another method used in this study was direct sampling, sorting, and weighing. This method is particularly useful for obtaining information about waste quantities generated and their composition on the study sites. The waste on the sites was obtained through sampling on the site to get a representative sample. The components in the sample were sorted and weighed to get their composition in the waste. The materials used included the questionaires for the interviews, sampling container, weighing scale and personal protective equipment like gloves and safety shoes pn the sites. The results obtained from the study showed that C&D waste on the site is sorted into different components as it is generated and the debris is the only component that is mixed. After sorting, materials that are still in proper condition are salvaged and reused for other purposes or recycled to make other materials. Not all materials are reused or recycled so the remaining materials on site are disposed off the site in different areas. The quantity of waste generated on the construction sites amounted to 66.3 tons and 156.8 tons, on the demolition sites amounted to 2.4tons on both sites and 3.5tons was generated on the renovations site. The waste from the construction sites comprised of 79.5% wood, 19.5% concrete, 0% metal and 1% others. The waste from the demolition sites comprised of 40.7% concrete, 17.5% bricks, 16% metal, 13.5% ceramics, and 12.3% others including plastic, stone, mortar, paper, glass and polythene. The practices of C&D waste manangement observed were cutting across all sites. Sorting of waste as a first step in C&D waste handling helps to identify the materials that are capable of reuse and recycling. Reuse and recycling is an efficient method of waste management because it ensures sustainability of resources but it is not reliable on every site due to its dependence on the local market. The waste disposed mainly consists of unsorted debris. Different sites dispose their C&D in different areas due to lack of a common authorised place for C&D waste disposal. The composition of C&D waste from the different sites is directly influenced by the materials being used on the site at that time. The demolition waste amounted to those quantities because of the salvaging that takes place during demolition works. Most of the materials are salvaged and sold off to local buyers leaving debris on the site. The sampling was done on the remaining debris and hence it only comprised of mainly concrete. In order for all construction and demolition waste materials to be captured in the study, further studies should be carried out on the same topic, covering construction sites through all the stages of construction. This gives more conclusive results on C&D waste components and amounts generated. Contractors should develop a Site Waste Management Plan which can be used to track the waste components and their amounts and develop better C&D waste management practices in order to promote sustainability.