Appropriate System of SWM for Wenchi

This project sought to evaluate and design an appropriate solid waste management system for the Wenchi Township in the Brong Ahafo regio of Ghana from May 6 to June 4,2001. The specific objectives of this study are: (1) To assess the adequacy or otherwise of the current Solid Waste Management system in Wenchi in the light of: • Equipment type and adequacy, • Service coverage and disposal method, • Institutional arrangements, • Service cost and financing. (2) To investigate solid waste properties in order to properly assess the current system by determining: • Generation rate, • Density and • Characteristics of solid waste. (3) To prescribe an appropriate system of Solid Waste Management based on the findings of the assessment of the current system by using financial cost analysis. Methodology Information on the equipment type and adequacy, service coverage and disposal method, institutional arrangement and service cost and financing was obtained by interviewing the Head of the Environmental Health and Management Department (EHMD). The EHMD also provided information on the population and housing types. The driver of the refuse collection vehicle and his assistants also provided credible information on the general working condition. Although the EHMD provided basic information on the current system, the communities were interviewed to have their views on the current system. In order to investigate solid waste properties, thirty (30) houses were selected at random from each income group for the study. This gave a total of ninety (90) houses from which in all nine hundred (900) samples were taken and analysed. Available Solid Waste Data did not specify the standard deviation, error and confidence interval. Therefore two preliminary samples were taken from each house for the determination of the required sample size for each income group on a pilot basis. Sampling was done over a period of four weeks from May 6, 2001 to June 4, 2001 and between 5.30 am and 7.30 am. As already stated, ninety houses, thirty from each income group were chosen at random from the three zones for the exercise. The selected houses were first animated to gain their interest in the exercise. As one would expect of a place where refuse piles up and is not collected as and when it should, the exercise was very much welcome by the people of Wenchi. Ten houses from each income group were visited each day. This gives the total number of houses visited in a day as thirty. It goes without saying that it took three days to visit all the three zones in one sampling cycle. In other words, each house was visited every three days in one sampling cycle. For the entire project period, each house was visited ten times. The Weight Volume Analysis method was employed. This method involves weight and volume measurements of waste generated in a house over a period of time. In Wenchi, waste is disposed off daily, implying that any measurements taken were for particular days and not for a certain number of days. Feasibility studies of the project area revealed that standard refuse bins were not being used in the township. Waste was stored in things like polyethylene bags, cane baskets, sacks, and buckets of all types. It therefore became necessary to carry along a 30 cylindrical bucket so that all waste from a particular house could be emptied in and weighed. After measurements were taken, the wastes were emptied into two 240 litre bins for transportation to the communal disposal site. This refuse collection method had to be employed because it would have been difficult to give back each household its right quantity of waste after measurements were taken. Also, because waste was disposed of very early in the morning so that the children could get to school early enough since they do the dumping, the use of the 240 litre bins for refuse collection was a very thoughtful approach. The use of the 30 litre bin was also meant to standardise the empty weight and base area of the bin. Solid waste densities were determined for each house by noting the weight of the wastes generated and the volume it occupied in the primary collection bin. Weighing was done with a standard platform balance scale graduated in pounds. The weight of waste was found by subtracting the empty weight of the bin from the combined weight of the waste and bin. The volume of refuse was determined by noting its height in the bin and multiplying this height and the base area of the bin. The density of waste was then determined by dividing the weight of the waste by its volume. The population of each house was ascertained by interviewing the landlords or their representatives who gave the population of each household from which the total population was determined. Knowing the population of a house, the generation rate was determined by dividing the weight of waste measured by the population. The sampling procedure was repeated ten times for each house, with the first two as basis for selecting sample sizes. Below are the units in which the various parameters were determined: • Weight in kg/day • Volume in m3/day • Density in kg/ m3 • Generation rate in kg/capita/day It is important to state here that the Load Count Analysis method was not used for the density and generation rate determinations because there was no means of knowing the weight of the refuse in the secondary containers as there was no weighing bridge at the final disposal site for that purpose. Solid waste was characterised by using the quartering method. In this method, truckloads are divided into four quarters and a quarter further quartered until a weight of about 200 pounds is obtained. Sorting is then done to characterize the waste on weight basis. The following are the characteristics that were considered with two truckloads of waste: • Greens/Vegetables/Fruits • Plastics • Fabrics/Textiles • Paper/Cardboard • Bottles • Metals • Rubber • Miscellaneous -, Results of costing criteria collected from both Kumasi Metropolitan Assembly (KMA) and Accra Metropolitan Assembly (AMA) were used for the financial costing of the current and proposed solid waste management systems. Results The Weight-Volume analysis method for the determination of the physical parameters of solid waste gave the following results for the various income groups: • Solid Waste Generation Rates for the Low, Middle and High Income Groups of Wenchi Township are 0.803, 0.8 14 and 0.923 kg/capita/day respectively. The average Generation Rate for the township is 0.847 kg/capita/day. • The average Solid Waste Density determined for Wenchi is 439 kg/rn3.day. Recorded densities for the Low, Middle and High Income Groups are 627, 403 and 287 kg/m3.day respectively. • Solid Waste Characteristics investigated are listed below together with their percentage compositions by weight. > Greens/Vegetables/Fruits 58.31% > Paper/Cardboard 1.23% Plastics 0.91% > Glass 0.54% Metals 1.86% > Rubber 0.29% > Fabrics/Textiles 0.26% > Miscellaneous 36.6% > Total 100% The miscellaneous is composed mainly of a mixture of sand, ash and food waste making it organic in nature. The high percentage composition of the organics and miscellaneous suggests a high potential for composting of the waste. This will invariably increase the lifespan of any landfill designed for the Township. Using financial cost analysis the current solid waste management system costs ¢121,774.00 per ton of waste collected, which would have resulted in a tariff of ¢268,553.00 per month per house. This is of course unacceptable and unaffordable. Reasons for this are that the refuse collection vehicle is available only once in six days for refuse collection whilst for the remainder of the days it is used for other purposes not beneficial to the Assembly. From the analysis, 66,160 tons of refuse is generated annually with only 300 tons being collected leaving a deficit of 65,860 tons. This implies that only 0.45% of refuse is collected annually, a situation that is completely unacceptable. This alone shows how inappropriate the current system is and also explains why there is almost always a pile of refuse in the Wenchi township. In order to propose an appropriate system of solid waste management for the Wenchi Township, three alternative systems were considered. System 1 consists of 3 Skip Loaders, 12 Power Tillers and 9 Secondary Containers. System 2 has 4 Compactor trucks. System 3 comprises 2 Roll-on-off trucks, 12 Power Tillers and 6 Secondary Containers. Each of the three systems has a Bulldozer, Pickup and Motorcycle. Financial cost analysis for the three systems considered gives the cost of waste collection per ton as ¢26,359.00, 026,774.00 and ¢25,087.00 for systems 1, 2 and 3 respectively. The corresponding tariffs are ¢42,809.00, 043,484.00 and ¢40,743.00 per month per house respectively. System 3 gives the least cost per ton of refuse collection of ¢25,087.00 and a tariff of ¢40,743.00 per month per house. In addition to environmental factors, maintenance, employment generation, suitability of internal road network and aesthetics, system 3 is proposed for Wenchi Township. Total annual waste to be generated is expected to be 68,212 tons while the system has the capacity to collect a maximum of 69,300 tons. Conclusions (1) The current Solid Waste Management system is inadequate in the sense that: • It makes use of one skip loader in good condition and ten secondary containers which have outlived their usefulness. • Out of the 66,160 tons of refuse generated annually, only 300 tons is collected leaving a deficit of 65,860 ton. This implies that only 0.45% of refuse is collected annually, a situation that is completely unacceptable. • Solid waste is disposed of at the final disposal site in a crude and haphazard manner on a site that has not been legally acquired for that purpose. There is nobody supervising activities at the final disposal site and as such there is no record keeping. • The institutional arrangement for the management of solid waste is unclear. Thc Environmental Health and Management Department, which is supposed to be responsible for managing waste but lacks capacity to do so in terms of expertise, has been sidelined in the management of waste. Reasons for this are difficult to establish. • The Assembly’s book expenditure on solid waste service cost and financing was not made available for comparison with that computed by this research. The fact that the Assembly would not make its book expenditure available suggests that the inadequacies cannot be financial. • From the analysis, the Assembly spends ¢121,774.00 per ton of refuse collected as compared with ¢2,087.00 for the proposed system. If the service cost of the current system is transferred to the citizenry it would result in a tariff of ¢268,553.00 per month per house. The proposed system on the other hand would require a tariff of ¢40,743.00 per month per house. This comparison clearly shows the inadequacy of the current system. (2) Analysis of refuse gave the following results: • The Solid Waste Generation Rates for the Low, Middle and High Income Groups of Wenchi Township are 0.803, 0.8 14 and 0.923 kg/capita/day respectivcly. The average Generation Rate for the Township is 0.847 kg/capita/day. • The average Solid Waste Density determined for Wenchi is 439 kg/rn3.day. Recorded densities for the Low, Middle and High Income Groups are 627, 403 and 287 kg/m3.day respectively. • The Solid Waste Characteristics investigated are listed below together with their percentage compositions by weight. > Greens/Vegetables/Fruits 58.31% paper/Cardboard 1.23% Plastics 0.91% Glass 0.54% > Metals 1.86% Rubber 0.29% > Fabrics/Textiles 0.26% > Miscellaneous 3 6.6% Total 100% The high percentage composition of the organic fraction and miscellaneous, which is generally organic, suggests a high potential for composting of the waste. This will invariably increase the lifespan of any landfill designed for the Township. (3) An appropriate Solid Waste Management system has been proposed in which the private sector would take an active part to ensure efficiency of service. The system is a combination of communal and house-to-house collection, making use of power tillers for pre-collection and dumping of waste in communal containers located at vantage points within each community. Recommendations It has been recommended based on the findings of this research that: (1) To ensure a smooth transition from the current to the proposed system the Assembly must as an interim measure: • First meet with all Assemblymen to sensitise them on the need for the new System, • Hold community meetings together with the Assemblymen to educate the communities on the importance of the new system. It should be made clear to the communities that it is likely problems may arise and that if they do arise solutions would be found, • Select contractors for registration of houses, • Agree on a takeoff time with the communities. (2) The Assembly should franchise the solid waste management service and play a role by supervising the service provide. Privatisation of the system would ensure: • Improved solid waste collection service, • Health improvement and • Savings in waste collection and a potential for savings in waste collection since any subsidy to be provided by the Assembly cannot meet the cost of refuse collection. (3) The Assembly should subsidise the solid waste collection service by providing ¢20,743.00 of the service cost. Each house would then pay just ¢20,000.00 per month for refuse collection. This would encourage the citizenry and also ensure full participation. The subsidy however should be withdrawn gradually as would not be felt by the community. (4) It is possible to provide a house to house or kerbside solid waste collection service in Wenchi Township. This is because there is proper layout of buildings, except that the access roads are not good enough. If these roads are at least graded, house to house service would be most ideal for the Township. (5) A willingness to pay survey should be conducted for the house to house or kerbside waste collection service. (6) There is no written agreement or legal acquisition of the landfill site by the Assembly which situation can result in undesirable conflicts and consequences in future for the solid waste management of the District Assembly. Efforts should therefore be made to acquire the site legally and proper landfill designs and management work programmes implemented. (7) Composting, which is a Solid Waste Treatment option based on decomposition, is highly recommended since the climatic condition is satisfactory for microbiological activity that leads to decomposition of the high organic component of the solid waste into compost. This presupposes that a market survey of the compost should be made before any attempt at composting is made. Composting increases the lifespan of landfills.

Source: KNUST