RECENT newspaper reports said that the Mid-East hospital in Clifton (Karachi) will be demolished and instead, a shopping mall will be constructed on the site. A lot of waste material would be available by the demolition of the structure that can be put into productive use.

At present, about 7,000 tons/day of solid waste is produced in Karachi, nearly 40 per cent of which is picked up by the informal sector. The rest is dumped at Jam Chakro and Gondal Pass—each of the dumping site comprising an area of 250 hectares. These sites are reported to have been filled up to their capacity. New dumping sites could not be developed because of land availibility. Locating new dumping sites at much greater distance will necessitate construction of transfer stations, to keep down the transportation costs.

Normally, landfills are built for the disposal of municipal solid waste. Well-maintained landfill operations involve spreading of solid waste and, then, covering each day’s operation with a layer of soil. This is not done in Karachi. The waste is simply dumped at the site and, in most cases, is burnt, impacting local air quality. Since, the system is not properly managed, a portion of the waste remains uncollected, which is then burnt by street sweepers.

In order to minimize such problems which are expected to be aggravated by rising city population, it will be wiser to adopt a strategy of rational management aiming at the prevention, minimization, recycling and re-use of the waste. Higher volumes of solid wastes will entail higher operational cost, imposing a financial burden on financially-starved municipal authorities.

The trend of demolishing old buildings and cinema houses and constructing shopping malls instead, is on increase and a number of such projects are underway in the city. However, a significant portion of solid waste, particularly that of buildings is proving to be troublesome, in the sense that it occupies relatively large space and, cannot be compressed, since the city does not have a crushing plant.

Construction and demolition waste is that portion of the solid waste stream, which results from excavation, construction and demolition, re-modelling and repair of buildings, roads and other utilities. It includes concrete, stones, asphalt, dirt, wooden material, metal parts and miscellaneous materials.

In addition to the inert materials, the demolition waste includes hazardous waste, like asbestos, lead and mercury from fluorescent lamps. Hazardous waste requires special handling and treatment procedures. For example, leachate (liquid portion from landfills), containing mercury and lead will pollute groundwater resources, if it is dumped at the dumping site. The city does not have any facility for handling of hazardous wastes.

Waste management strategy for reducing the construction and demolition waste focuses on three approaches. These are “reduce, reuse and recycle,” if the generation of waste cannot be prevented. Waste reduction or waste minimization aims at using less material, thereby reducing the pollution from its manufacture and transportation. This saves energy and water as well and, gives high environmental benefits. Waste reduction gets tops priority in the waste management programmes.

Waste re-use, the second approach, attempts to extend the life of existing materials and decreases the needs of new resources. Waste recycling, the third approach, converts waste into new products. For example, asphalt can be recycled to new paving, concrete and bricks can be crushed and used as alternative daily cover for municipal landfills.

Rational waste management has profound and major benefits. It saves money involved in the handling and transportation of solid waste. It generates wider environmental benefits, minimizing degradation of air quality, noise generation and even prevents water pollution.

Prevention of generation of waste and its re-use, lowers water and air pollution, including greenhouse gas emissions, associated with materials manufacturing and cartage. This in turn, saves energy. Adverse environmental impacts are largely reduced.

In Karachi, the city government needs to manage the building-related waste more economically and efficiently. It should educate the sponsors to minimize construction and demolition waste.

All private and projects should be required to achieve a recycling rate pf 75 per cent. For all multi-storey buildings (G+2 and above) or projects costing Rs10 million and above (construction or demolition projects), the developer should submit waste recycling plan to the building agency, along with the building plans.

A one-page form should be developed for this purpose. Based on the site conditions, the city government should assess the proportion of the materials intended to be recycled or re-used.