MAGAZINE HILL: A WEATHERED CONTINUUM
See introductory short film available at: http://www.youtube.com/watch?v=MVnn-sDfR_U
This project is rooted within a process of unification, a personal struggle to understanding the fragile relationship that exists between opposites. This affiliation between juxtaposed thoughts is explored within the realm of architecture in relation to time, focusing on architecture’s potential to adapt according to the passage of time, through the process of aging and weathering. This study is thus grounded in the aim to re-establish architecture’s connection to the continuum of time.
The proposed historical site (Magazine Hill) forms a comprehensive construct of different layers of time and influence. This mysterious, abandoned and isolated site consist of 2 underground ammunition magazines, 5 bomb shelters and ammunition factories, all structures that represents an era of unrest in South Africa. The site was utilised for the production and storage of military ammunition from the 1890’s up to 1960. This was also the first site in South Africa where military-industrialism was formalised for ammunition production, which provided 45% of ammunition used by the Allied forces in the Second World War (DENEL, 2011).
A mysterious explosion of one of the ammunition magazines (Sentraalmagazynhad) in 1945 led to massive destruction in Pretoria where damages were reported as far as 3 kilometres from the detonation point (Panagos, 2006: 5). This intense explosion left a physical scar in the hill, which is the only remaining witness of the tragic event. Currently, parts of Magazine Hill are still covered with live ammunition and unexploded ordnance that reappears with each rain season (personal communication Du Plessis, 14 November 2010). There is an inherent tension locked within the site, hidden in mystery and untold stories. In the author’s experience the isolation of the site forms part of a negative mental construct relating to the site’s history– a sense to forget the tragic past. It is as if the site doesn’t want to be found, remaining imprisoned in its own misery.
The project places contemporary commemorative architecture under the limelight, criticising the static notion of heritage commemoration through the typologies of museums and memorials. These typologies often evolve into static monuments, where the relevance in contemporary society can be questioned. The architectural response of this dissertation is thus focused on commemoration through everyday use.
The proposed program forms part of the conceptual premise of mediation, unifying different opposites inherent in both Magazine Hill and the South African context. A Brass foundry is proposed that recycles the South African National Defence Force’s spent ammunition shells to introduce brass artists and a public interface to Magazine Hill. Where ammunition was once produced, ammunition is now reduced. This program can form mediation between the public and the Military, and different layers of time, reinstating architectures connection to the continuum of time.
Within the context of Magazine Hill this project explores an architecture of alter egos, where multiple identities and layered memories define spaces that is simultaneously physical and metaphysical. The physical character of space present in the decayed fabric of Magazine Hill relates to the experience of abandoned space, the weathered building elements, ruination and the smell of decay that only manifests with the passing of time. The physical character of space on Magazine Hill thus relates to experiential time that focuses on the experience of the present, therefore weathered space is left unaltered in the design.
Its alter ego, the metaphysical character of space present on the site, relates to the historic activities that accompany a timeframe passed, where the memory of past activities and use is constantly provoked through experience. This character of space thus responds to referential time, where physical attributes of weathered space refers to previous use and historic occupancy. It is within the alter egos of space where the architectural experience of the site and the brass foundry is explored.
The structural investigation of the proposed foundry focuses on the theoretical premise of Gottfired Semper (1803-1879) that explores the tectonic relationship of architectural materiality. In his Die Vier Elemente der Baukunst (Four Elements of Architecture), the German architect argues that architectural composition can be divided into two opposite material procedures: the stereotomic that relates to solidity, and the tectonic that defines dematerialisation (1995:3). Kenneth Frampton (1990: 518) states that these inherent opposites in architectural materiality forms cosmological opposites of each other, where the stereotomic mass symbolises earth, while the tectonic forms an analogy for the sky. It is argued that the transition from the materiality of the stereotomic, to the immateriality of the tectonic, constitutes the basic poetics and essence of construction (ibid).
All existing structures on Magazine Hill form part of an impervious military aesthetic that is steriotomic of nature. This impenetrable built fabric of existing structures on site consists mainly of hardened sement bags, natural stone retaining walls, concrete bunker walls and vernacular Kirkness brick buildings. The steriotomic character of built fabric thus relates to the existing, that which belongs to the site. In contrast to the existing steriotomic aesthetic, a tectonic response implies new built form. In the design of the foundry, both aesthetics are utilised to anchor the new proposal within the historical arena of Magazine Hill.
The design of the brass foundry integrates an industrial process of ammunition reduction with an experiential route that unveils the rich history of ammunition production on Magazine hill. The experiential quality of this journey is governed by a series of foundry processes that is revealed along the route as the visitor progresses through the site. It is within this subtle integration of site and program that the past, present and future of Magazine Hill can be experienced and imagined.
A tower structure is proposed that is detached from the remaining part of the building, connected only with a steel bridge that distributes brass ingots and billets to the rest of the building. Integrated with the existing bunker retaining wall, the tower weaves together form, angle, materiality and function, while providing a visual experience of the first process of foundry mechanics.
Spent ammunition shells is brought via old wagon routes to an ammunition pit located in front of the furnace tower, where a vertical crane system hoists the raw material into the foundry. This process acts as a permanent kinetic exhibition in the existing open air bunker. From this point raw material is sorted, dismantled and distributed to the washing and drying department located behind the ammunition bunker wall. The western portion of the tower accommodates the hot shop, where the raw material is melted in 100 l crucible induction furnaces. This submerged workshop space ventilates vertically through an interlocking louver system, for when raw material is cooled in water after the casting process, great amounts of steam escapes through the roof. Because of the submerged character of the hot shop, the natural ground line is set on the same vertical height as the louvered roof, for when steam escapes vertically, the landscape is perceived as being ablaze, smouldering within the grass. This experiential quality commemorates the aftermath of the devastating scene after the 1945 explosion, where Magazine Hill smouldered for several days after the accident with numerous explosions still occurring days after the tragic event. In this instance, commemoration is not reduced to an isolated memorial frozen in time, but is celebrated on an hourly basis through active experience.
EXISTING FLAME TRACER BUILDING
The Flame Tracer building was built in the late 1930’s for the production of amour piercing ammunition on Magazine Hill, and is designed and compartmentalised according to the process of ammunition production. Process descriptions on the weathered walls guide one through the series of decayed and derelict spaces that had been neglected shortly after the explosion in 1945.
In the foundry design the Flame Tracer building is adaptively reused as the public’s main circulation space, also accommodating an indoor sculpture gallery, information access, ablutions and viewing pavilions. The north facade windows had been removed, leaving a series of excessive openings in the wall. In the design, artist studios are arranged along the north facade of the Flame Tracer building, projecting over the new courtyard space. A translucent studio facade ensures visual translucency into studio spaces, where artist work can be viewed from the confinement of the existing building. Within the strict safety regulations of foundry design legislation, public circulation is diverted through the existing building that acts as a “safety capsule” for viewing metal castings and sculpture processes that occurs in the artist studios.
This design element allows the visitor to experience the art of ammunition reduction within the context of ammunition production, commemorating the large scale production lines of Magazine hill. The act of commemoration is thus focussed on the interpretation of old (ammunition production) and new (ammunition reduction) processes as an ongoing activity, as stipulated in Principle 1 of the Ename Charter (ICOMOS, 2005) Again commemorative design is not encapsulated within a static memorial or monument but rather experienced as an active construct that does not only relate to the past, but also the future of Magazine Hill.
The weathered state of the building in left unaltered, while allowing the process of ruination to continue with the passing of time. This design approach stresses the mortality of architecture and distinguishes clearly between old and new fabric. It is within the Flame Tracer building where one escape from reality to memory.
Forming a spatial extension of the Flame Tracer building, the artist studios are designed according to the “cire perdue” or lost wax method of sculpture production that was used by bronze artists in ancient Rome (CPA, 2011). The studio is divided vertically in 3 storeys, with the top floor forming a continuation of the Flame Tracer building space, the middle floor extending out onto the courtyard where studio practice can be observed from the north, and the bottom storey accommodating sculpture storage. Each artist studio is further divided into 4 secondary studios. The modelling and wax studios define the middle floor space while the ceramic works and hot shop are located on the top floor. The artist studios thus functions as permanent exhibitions in the new courtyard space that capitalise on the future projections of Magazine Hill, enforcing the statement that ruination can inform creation.
From the initial developmental stage of Magazine Hill (Fort Commeline, 1881) the site had been designed to function as a secretive entity within the natural hilltop landscape. In 1894 when the underground ammunition magazines was constructed on site as part of the second fortification plan for Pretoria, the same concept of veiled architecture concluded a new typology for hidden military infrastructure. The design of the ammunition bunkers with internal production facilities followed the same construction methodology after Magazine Hill was labelled as one of the first sites for military industrialism in the country. This inherent typology of built form on Magazine Hill forms a conceptual platform for space that reveals and space that conceals.
Throughout the design of the route through the site and foundry, this concept of revealing and concealing space is utilised to enrich spatial experience. The old wagon routes that form circulation platforms between the exhibition bunkers define concealing space, while the interiors of the bunkers itself identifies revealed space, revealing exhibited sculptures. The different foundry processes are also experienced to be revealed and concealed along the route through the foundry.
The structural aesthetic on Magazine Hill combines a series of building materials. For the purpose of the dissertation, it was not only important to study the composition and arrangement of existing materiality on site, but also the weathered state of building elements that contribute to the mysterious and abandoned quality of the terrain. In the opinion of the author all new proposed building materials should not compromise the unique deteriorated state of the site, but rather enhance this quality, expressing architecture’s mortality through the process of ageing. The use of contemporary materials is therefore specified to form analogies of deteriorated fabric, where structural detailing is executed to promote weathering and staining of contemporary materials. By implementing this technical concept, the new foundry does not only commemorate the history and past of Magazine Hill, but also the site’s inherent physical qualities of the present.
Proposed brickwork in the use of the super- and substructure had to comply with existing Kirkness and red brickwork aesthetic of Magazine Hill, therefore a Firelight Travertine Imperial FBX brick by Corobrik is specified. This face brick is manufactured in Gauteng, therefore minimising transportation costs of material distribution. The Firelight Travertine brick has a slight efflorescence rating which means that a white crystallised deposit occurs on the surface of the brick as water evaporates and the salt is trapped in the brick pores (Corobrik, 2011). This quality of the brick implies that the Travertine is semi porous, therefore the material can absorb the oxidation deposits of the weathering steel roof, promoting staining and weathering of the new foundry building.
The existing ammunition bunkers consist of 3 m high hardened cement bags that form slanted retaining walls, which is hand packed on a mortar less natural stone core. These stereotomic walls define the submerged bunker space in the natural landscape. New landscaping walls are constructed from loose packed natural stone, therefore forming an analogy of the existing bunkers walls. Proposed reinforced gravity type retaining walls define the new courtyard, further incorporating the existing structural syntax.
The existing Flame Tracer building roofing system consists of s-profile corrugated iron roof sheeting, laid to a 15 degree fall, fixed to 75x50 timber battens. This building is to be reused in the foundry design as public circulation space, where artist metal castings can be viewed from a confined existing space. The corrugated iron sheets are severely weathered, with oxidised deposits covering the exterior surface. A 3mm SA 588 grade A corten steel roofing system is proposed to be installed on the adjacent artist studios, symbolising an extension of the existing weathered roof. The weathering steel produces an oxidised deposit that stains the porous substructure, creating the illusion of a building bleeding into the landscape.
Many existing buildings on Magazine Hill, including parts of the Flame Tracer building, are in a critical condition due to the removal of the roofing material. This aspect results in exposed roof trusses that cast deep shadows into interior spaces. This interior light quality of existing buildings on site is translated into the design by means of a translucent roofing system, defining studio and foundry spaces vertically. The Translucent Opening Roof interlocking aluminium louvre and gutter system with Naturelite UV treated top infills is proposed to be fixed to the primary support frames. When closed, the roof forms a weatherproof surface, while allowing for light penetration through the Naturelite panels (LouvreTec: 2010). This design element integrates existing and new spatial and light qualities while adhering to programmatic requirements.
As mentioned in Chapter 7, the foundry tower process incorporates the sorting, dismantling, washing, drying, melting and casting foundry procedures. All mentioned processes functions as separate systems that form integrated water harvesting, heat transfer and ventilation strategies. The first recycling system focuses on water management, where the spent ammunition cartridges are washed in soap less water to dispose of cordite remnants in casing cavities. A series of washing tables also serve as drying baths as bottom plugs are removed for water drainage. These multi functional tables alternate between washing and drying processes within the production period of 60 minutes, based on the processing time of the melting furnaces. As the plugs are removed, water accumulates down a screed to fall into a grey water storage tank, located in the basement. From this point grey water is distributed through a biofliter system located in the existing ammunition bunker, which comprises of natural boulders and nitrate absorbing hydrological vegetation. As water filters through the system, rising water levels trigger the submersible pump to distribute recycled water to the storage tank located on the stair apex. Water is recycled three times before it is utilised for secondary purposes on site. Recycled water is only utilised for washing and sanitary purposes.
A heat transfer strategy is incorporated to enhance the drying process of raw material after washing. The existing composite retaining wall is adaptively reused as a trombe wall system because of the wall’s northern orientation (exposure to solar radiation) and massive characteristic. A 7 meter wall strip is fitted with a clear glass facade to form a pressure cavity between the glass and existing wall. Openings that connect the cavity with the adjacent basement interior are core drilled through the existing bunker wall. External openings are provided in the basement for fresh air intake. As the trombe wall heats up, air pressure differences allows air to circulate from basement interior into trombe wall cavity where the air temperature rises drastically, therefore ventilating the basement while providing hot air that is utilised in the drying process.
ENVIRONMENTAL CONSIDERATIONS AND PASSIVE SYSTEMS
• The building program specialises in a reduction process of obsolete ammunition, forming a catalyst in the SANDF environmental program called Green Soldiering. The proposed foundry forms an environmental statement of the SA Army.
• Brass ingots and billets are produced from recycled ammunition cartridges and distributed to Denel PMP for ammunition production. A portion of raw material is kept on site for the production of art, thus forming a horizontal integration program between local artists that contributes to social sustainability.
• The foundry creates work opportunities for prison inmates and the SA army, thus contributing to a skill transfer process.
• The foundry is dependent on the public as a tertiary source of raw material, therefore providing the public with a financial benefit and awareness of recyclability potential.
• The topography of Magazine Hill is utilised to harvest rainwater in the Red Magazine crater, forming both a commemoration pool and water body to supply building with water for foundry use and sanitation purposes.
• A water harvesting strategy is implemented in the furnace tower that harvest water from washing and cleaning tables and send grey water through a biofilter pit for secondary use.
• The existing massive bunker wall in the furnace tower is converted into a trombe wall system that ventilates the storage basement and provides a hot air system to dry washed ammunition cartridges.
• Passive ventilation systems in the tower hot shop is developed as a commemorative steam feature in the design.
• The series of artist studios is orientated north for maximum day lighting and sufficient thermal comfort control.
• Sliding eastern wall panelling provide the artist studios with adjustable options, optimising passive ventilation, natural day lighting, and extending spatial qualities beyond the limited workshop space.
• An interlocking louvered roof system allows studio workers to ventilate hot shops vertically, control natural light quality for working purposes and allow for rain water penetration if open studio space needs to be cleaned.
• Sufficient insulation is provided in roof structures that are exposed to direct solar radiation, strengthening thermal comfort in studio spaces.
• Water harvesting strategies in artist studio space is defined by sloping floors diverting water flow to catchment areas in the public courtyard where bio filter pits purify grey water for foundry use.
• Dual flush sanitation systems is stalled, with CFL and LED lighting panels utilised for lighting strategies in studio ablutions and kitchenettes. Sufficient day lighting allows for lighting systems only to be active at night.