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andora Dumping Site was the largest dumpsite in sub-Saharan Africa, located 8 km from the CBD of Kenya’s capital city - Nairobi. The sprawling dumpsite, with an extent of over 46 acres, receives over 1500 metric tonnes of solid waste from the greater Nairobi daily, was designed to be saturated in 2001 yet it is still in operation. The dumpsite was uncontrolled and was once the place where the 6000-10000 households from nearby slums make their income by scavenging at the site without any protection against the toxins in the waste from unrestricted source. Despite the government had sensed the problem and proposed a new dumping ground catering to the growing demand on refuse management associated with the robust economic growth and urban development, the plan was banned by the Airport Authority due to the scavenging birds (i.e. Marabou Stork) attracted by the dumping ground would pose dangers to the flights. There were a few reports on using other abandoned quarries in the city as new dumping site to replace the old one. Prior to constructing the building of a segregation plant and a waste recycling plant and an electricity generating plant as claimed by Nairobi’s government in early 2010s an incineration plant was proposed on the existing as an immediate remedial strategy to the site and prevent the people from the toxins of the waste. According tho the architect, through multi architectural treatments on the design of the NIMBY facility, the life of the nearby slum inhabitants could be dignified while the uncontrolled sprawl can be halted. A sustainable operation model with concern of environmental, social and economic issues would be addressed in PROJECT DANDORA as well.
andora Dumping Site The dumping site was launched in 1981. It is located 8km away from the CBD and it is the only official dumping site (there are over 70 illegal dumping sites scattering in town as well) in the city receiving 1500-1700 tonnes of solid waste from the city. Part of it occupies an old quarry with an area of about 2 ha. The site was designed to be closed and replaced by the new one at Ruai in 2001. However, due to the opposition from the Airport Authority, as the birds (i.e. Marabou Stork) attracted by the new dumping site might pose dangers to aeroplanes, the proposal was on hold and Dandora Dumping Site is still in operation after saturation and keep sprawling to the neighbouring informal settlements causing health problem to the dwellers in Dandora and Kongocho Slum. According to NJS Consultant Co., the depth of the quarry is about 20-30m and the average height of the waste landfill is 3m.
Project Overview
Pollution Around 220,000 tonnes of waste was brought to the site every year and a total amount of approximately 3,550,000 tonnes of solid waste were reclaimed from 1981 to 2009. Over 50 % of the waste in Dandora Dumping Site was food waste and it also contained untreated industrial and medical waste. Soil in the site was polluted by heavy metal and toxic chemical. Due to primitive management, the leachate water from the dumping site also contaminated the nearby streams. The heavily polluted site causes health problems to the adjacent dwellers. Scavengers searching for valuable materials and food with bare hand were highly prone to toxins. NIMBY/ PIIMBY ? Despite the site was the main source of income to the slum dwellers, especially to the 1500 active pickers, they actually suffered at long term risk and this way of livelihood should be viewed as the infringement of human right and immoral. The dumping site literally was the waste treatment amenity yet it is both environmentally and socially
unsustainable and creates even more nuisance which was particularly unfair to the low income class while the city is enjoying the fruit of rapid economic growth since 1980s. PROJECT DANDORA suggested alternative options for the government in waste management and to a larger extent it was an urgent urban planning issue in the contemporary. Remediation strategy was proposed with interventions of different scales (XL, L, M, S, XS) including construction of incineration and waste treatment plant as the mean to put a halt in the immediate environmental and health problems. The project is never a one-step solution, a holistic plan with a multitude of social interventions in regard of economic operation is stressed. The repercussion of the project was also considered. The technology of using incineration to produce energy and use of incineration bottom ash (IBA) as materials for capping, road paving and building was applied as well.
blueprint of project dandora phasing strategy phase 01 - present
STAGE ZERO Preparation Education on recycling as the first step to reduce the amount of waste and thus the pressure to the dumping site since a large amount of the waste disposed of is reusable and recyclable. Scavengers should be provided with protection gear to avoid direct exposure to toxins and heavy metal. Waste with potential dangers (medical and industrial waste) should be separated as well.
phase 02 - 2017-2018 Site fromation
Milestones
- commencement of the project - bio-remediation at the edge of the site by greening
Physical Construction
- construction of recycling plant at the buffering belt at the south of the dumping site to collect recyclable waste from adjacent community - excavation at the old quarry to prepare a proper site to place the incineration facility for the following stage - pad foundation to be constructed at the quarry
Socio - economic
- new job opportunities including labour for construction and staff at the recycling plant
Environmental
- put a cap to the environmental hazard on site - control the sprawling extent of the dumping site
other interventions
- funding and techniques from UNEP, UN Habitat and Asian Infrastructure Investment Bank (AIIB) - education on waste reduction and recycling - a number of recycling plants are established around the city
phase 03 - 2019-2023 critical construction
Milestones
- incinerator complex completed and in operation - building material plant established - bio remediation applied on the site
Physical Construction
- incinerator with special architectural design in response to the context is placed at the former quarry - waste at the site are being incinerated with consideration on the level of urgency, it is managed in a centripetal sequence so that the impact of the solid waste to the adjacent informal housing and streams could be ameliorated first - building material plant is constructed near the incinerator collecting Incineration Bottom Ash (IBA) to produce capping and building materials for the plant itself - part of the IBA is used to repave the road in poor conditions - construct a trail along the stream and improve the connectivity - pilot housing project to experiment with the IBA building material
Socio - economic
- scavengers are trained into semi skilled construction labour - new job opportunities from the plants - building materials composed of IBA to improve the building conditions of the informal housing at the slums
Environmental
- use of IBA as the capping material on the polluted soil - bio remediation with vegetation and bacteria is applied on the site to detoxify the soil - leaching of waste water to the streams is under control and water quality is improved - improper combustion of solid waste is halted - greenery penetrates from the site to the surrounding
other interventions
- workshops on construction using recycled IBA blocks - all illegal dumping sites in Nairobi are suppressed
phase 04 - 2024-2030 remedaition
Milestones
- all solid waste on the site has been incinerated - the site is covered by vegetation and left idle in the remediation period - recycling plant constructed near the incinerator
Physical Construction
- new highways and roads across the site are constructed in improve the accessibility - IBA building blocks are mainly used to improve the building conditions of the informal housing - extension of riverside trail to enhance the connectivity - relocate the slum dwelling (especially those at the floor-prone region) to new public housing construct with IBA material -former waste collection point for recycling is converted into a new community centre
Socio - economic
- building materials composed of IBA to improve the building conditions of the informal housing at the slums - new business opportunity for IBA materials - waste-to-energy serving the community
Environmental
- expansion of greenery to neighbourhood - water quality of the river imporved
other interventions
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- workshop on construction using recycled IBA blocks - investigation on innovative use of IBA
phase 05 - 2031urban regeneration
Milestones
- the site is recovered after long period of bio remediation and converted into a park of over 30 ha - the project serves as a pilot scheme on waste management to other cities in Africa and globally - urban regeneration at slums
Physical Construction
- expansion of the plant (only if applicable) - slums replaced by social housing project which is constructed with latest IBA material at the south of the park - walking trails form a loop - the trail is extend to form a network
Socio - economic
- job and business opportunities in associated with the auxciliary amenities are created - people of the community is dignified
Environmental
- the site beome the nodal point linking patches of greenery along the stream - water quality improved - green patches are expanding along the streams and trail
other interventions
- new visiting route for tourist in Nairobi - a precedent is set up for other cities in Africa and the world
esign Strategy The building proposed in PROJECT DANDORA was based on the extrapolation from the principles learnt from the precedent NIMBY projects while new strategies were applied on the design addressing different parameters of issues on site. The building is not only merely an incinerator to burn off all the solid waste as it is only a section of the entire waste management in the Project. The pursuant of long term sustainability was considered in the project, therefore the output from the incineration process was taken into account in the building design as well. Additional space for landfill for storing the Incineration Bottom Ash (IBA) was usually required for an incinerator. Rather than depleting extra land resources and
leaving the IBA buried, the complex also consists of a building material manufacturing plant making use of the IBA to produce materials for paving, capping and construction, i.e. IBA construction, blocks and hence, a production line was created within the complex which reduce the extra burden on land while more economic revenue can be generated. The new social housing - Dandora Estate was constructed with the use of this recycled materials while the ferrous particles were sent to the metal plants in the neighborhood to be molten for production of metal members, generating a recycling circle in which different stakeholders were engaged in the process.
A recycling plant is located at an adjacent building plant to the incinerationmaterial manufacturing complex in response to the composition of solid waste sent to the Dandora Dumping Site in the past. Since a majority of the waste was recyclable and could be reused in other ways besides being incinerated, the recycling plant is, thus, provide a more environmentally responsible way in waste management in which the recyclables are processed and compressed into smaller volumes and then transported to other local recycling establishment (e.g. Chandaria Industries Ltd.). The waste producers and waste treatment procedures are then made more cling to each other. Apart from the waste treatment facilities, programs for public visitors (e.g. park, gallery, roof garden, etc) were considered since public awareness on waste reduction could be raised through demonstration and exhibition, while these programs also allow public inclusion to the project.
Stack Treatment According to the international standard, the height requirement of an incinerator stack is highly determined by the microclimate, air flow and the context for the sake of dilution. The minimum stack height is 75m or at least double to the taller buildings within 1km diameter. The stack of an incinerator is always accused as the culprit which leads to negative visual impact from the incinerator with its contrast in height to the plant. Smart strategies were applied to “hide� the stack by a sloping building mass and blending the stack into the building. In the proposed design, the stack will be blurred into the administrative building with a profile tapering upwardly. The treatment on the stack crown also echoes to the massing strategy subtly.
esign of the Massing The building form was derived based on various rationale and the lessons learnt from the precedents. Due to the building bulkiness caused by the three-step waste treatment programs accommodated in the complex, strategies were needed to resolve the monolithic bulk. Instead of breaking down the building mass into smaller entities, the building is kept as one single volume as there were technical hindrances in decomposition of the production process in the building and more land resources would be devoted to the building. Utilization of the natural landform The design made use of the old quarry as a massive space for seating the space demanding trash pit, IBA pit and other massive machinery required. It acts as the natural barrier towards any dangers that may occur and the hard bedrock provides stable footing for the pad foundation. Architecture Camouflage The stack (80m high) is hidden into the tower. The strategy, thus, gets rid of the contrast in building height as the stack is part of the building.
Respect to the neighbourhood To avoid hostility to the adjacent living quarters and the river stream, the building has a building profile sloping down to the edges. The tallest elevation with the administrative tower will be facing to the park (Dandora Dumping site after bio remediation) where a distance between the settlements and the plant is allowed. The building mass was generated based on these consideration on the built context. Punching-out space The roof of the complex serves multi purposes, the one on top of the building material manufacturing plant is used as the drying space for the IBA blocks where the shadow casted by the tower is minimum. The other side of the roof surface is dedicated to the public. The public terraced spaced was obtained through a punch on the surface where adequate headroom was left for the tall machinery in the incineration plant. The geometry of the whole building was kept consistent by aligning the edges of the terraced to the building footprint.
Design Development
Schematic Designs Scheme 01 - arranagement following the sequence of production - three separated plants to reduce the sense of bulkiness - part of the incinerator (footprint: 80X110m) is located on ground level
Scheme 02 - increased irregualrity to reduce the bulkiness and rigidity - architectural treatment to hide the stack into the building mass - sloping down towards the river and show respect to the neighbourhood
Scheme 03 - continuous roof surface - strong visual impact from the stack - waste recylcling plant as the second phase of development
Scheme 04 - curvelinear form - merge into the adjacent landscape - stack located at the centre and the building mass acts as a shield
Scheme 05 - building mass scale up vertically to accommodate the stack (height: 80m) - steep slopes are fromed and may not be accessible - waste recycling plant with similar architectural language - sloping gesture
Scheme 06 - further development of scheme 01 & 02 - notion of three masses connected to form a interconnected production chain
Scheme 07 - continuous slope from incinerator to building material plant - pyramidal tower accommodating the stack and administrative programs
Scheme 08 - re-oriented waste erecycling plant to from a semi open courtyard layout - lifting up the tip of recycling plant to create a more undulating slope and introduce skyplight
Scheme 09 - re-oriented waste erecycling plant to from a semi open courtyard layout - lifting up the tip of recycling plant and building material plant to create a more dynamic roof and introduce skyplight - identity of three key processes
Scheme 10 - waste erecycling plant oriented to form a L-shape layout and have an extrovert interface to the park - two masses merged into one structure - more undulations on the rooftop carpet slope
Scheme 11 - retreat of the recycling plant to reduce the bulkiness - more undulations on the rooftop carpet slope and potential for opening skylights
Scheme 12 - the complex split into 2 masses to reduce building bulkiness - busy transport controlled in the gap between the 2 volumes - re-oriented waste erecycling plant to from a L-shape layout and have an extrovert interface - tower taper from the bottom gentle slope to the top
esign Rationale Besides the design on building mass, the way of construction was a highlight in the project. After replacing the dumping site with the incineration complex and a park after bio mediation, the livelihood of the scavengers from the nearby informal settlements was seemingly be erased. It is critical to maintain the economic sustainability to these people relying on the dumping site while dignifying their life in this Project. They were hired as the construction labour after training. The building methodology and its associated materials were primitive so that local people could easily engage in the building process. Materiality Selection of materials is particularly important in the project as it determines the degree local people could involve in the construction and how the building would react to the context sensitively. There were numerous precedent projects that empower the indigenous people to involve in the building project through fabrication and assembly process that can be easily executed, e.g. projects done by Mass Design Group and Carin Smuts’s CS Studio. Rather than extensive use of glass and steel members, the major material adopted should be capable of responding to the large pool of low tech labour and the primitive technology available in Nairobi. Rammed earth Rammed earth was chosen as the key building materials in the project at first as it is just available in the backyard. It can be easily carried out by the local people. Rammed earth can be moulded into bricks of multiple forms easily with
simple tools like mixer and presser. The labour intensive building process with primitive technical requirement does suit the context in Nairobi. Rammed earth is ideal for the program as it can moderate the interior micro climate. However, direct exposure to the intense sunlight would lead to damage of the rammed earth members. It is undesirable for application of protective coating on the rammed earth as it affects the material characteristic.
Incineration Bottom Ash (IBA) IBA is the residual ash left after solid waste being burnt out. Currently, IBA is mostly used for road paving and capping. Meanwhile, there is robust investigation and development in the use of IBA for building and construction. IBA is used to replace the concrete aggregate and then moulded as light weight construction blocks. IBA blocks can be used for building as it is proved that the harmful substances
are destroyed under high temperature. With a bid to make the building more specific to the situation, rather than making it very local, IBA was selected as the major building materials instead of rammed earth which would only be used for constructing the wall at the bottom part of the building.
Construction Sequence - Original attempt (Rammed Earth as the main building material)
Phase 01: timber formworks are made for constructing the 1000mm thick rammed earth wall and the foundation, the quarry is used as the trash pit and Incineration Bottom Ash (IBA) pits.
Phase 02: timber formworks used for building the rammed earth are converted into working platform and perforated rammed earth bricks cast on site are placed on the wall, machines for incineration are installed in the excavation
Phase 03: vechicular ramp and floor plates are constructed, large entry is left for logistics purpose
Phase 04: large brick members are placed on the upper level and roof structure are constructed
Phase 05: completion of the plant while the administration block is in progress and the recycling plant is completed
Phase 06: completion of Plant Dandora
Construction Sequence - Final Decision (IBA blocks as the main building material)
Phase 01: timber formworks are made for constructing the 1000mm thick rammed earth wall and the foundation, the quarry is used as the trash pit and Incineration Bottom Ash (IBA) pits.
Phase 02: machineries for the incinerator and building material manufacturing will be seated on site propoerly at this stage so as to allow earlier operation even during the building construction
Phase 03: concrete roof will be constructed for the the protection of the machinery, the srtack will be erected and the operation commence
Phase 04: IBA blocks are produced and used as the main construction material for the building complex
Phase 05: completion of the plant while the administration block is under progress to hide the stack
Phase 06: completion of Plant Dandora
Ground Floor Plan
esign of facade system In the design of the facade system, not only the ease of execution should be considered for the sake of public engagement in the construction, the aesthetics should be by no mean be compromised. As the massiveness of the plant complex is a dominating design issue need to be addressed, the facade system will be used for breaking the massive volume. On top of the rammed earth wall are the weatherproofing clerestories for introduction of natural ventilation, the patterns vary on different elevations so that the view into the plant will change from different angles and the elevation porosity is higher at the elevation facing the dwelling. On the administrative tower, larger IBA blocks members are applied for natural lighting for the office and lab programs. The facade, therefore, shows a gradient of disintegration from the solid wall to the pixelated pattern on top.
Front Elevation
Back Elevation
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