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environmental remediation

Dock Sud; to the left is the Exolgan container port, to the right is the Shell and YPF petrochemical facility; in the middle is the Canal Sur; to the far right on the edge of the Rio de la Plata is the Yarara confinement area for contaminated sediments; a tiny but noticeable breach is visible in the southern containment dike in the new cell; it is unclear if this cell is in use yet

While the fecund Reserva Ecologica is located on the northern side at the mouth of the Riachuelo, the southern side is seemingly its opposite.  Both, however, are the result of a major industrial city pushing into a silt laden estuary; the two faces of Janus.  The south side is known as Dock Sud.  It is the main petrochemical port and largest port in Argentina by operated tons.  In addition to gas and oil it supports containerized shipping as well as sand mining operations.  The port began in 1888 as a swampy, low-lying terminus to the Southern Railway which was British owned and operated until nationalization by Juan Peron in 1948.  The port was constructed as a public entity which it remains today- its shipping channels and bulkheads are maintained by the provincial port authority while the storage, unloading, and manufacturing facilities are constructed by the tenant companies.

There is pressure on the port to expand in the future, especially its container and petrochemical operations.  In addition, sediment dredging and the disposal of contaminated sediment is a significant cost to the port and a major area of concern for the residents in the densely populated surrounding area.  Each year the port must dredge approximately 1,100,000 cubic meters to maintain their facilities at the required 10.4 meter depth.  Fully one third of this is considered heavily contaminated, coming from the Riachuelo.  The other two-thirds (740,000 cubic meters) is dredged from the exterior of the port, mainly the entrance channel (Canal Sud) which connects Dock Sud to the trunk line in the middle of the Rio de la Plata.  While the clean sediment can be disposed of at sea, the contaminated sediment dredged from the Riachuelo and interior of the port must now be either treated or confined.  The issue is one of murky jurisdictions- the federal constitutional amendment mandates that the environment must be protected, the port is part of the Province of Buenos Aires, and much of the pollution in the port comes from the autonomous district of the city of Buenos Aires.

the action chart for the Tierra Plastic project shows the relationship of the Riachuelo to the port through sediment; in this case, the contaminated sediments are the instrumental aspect of the landscape, organizing the entire network around itself; the future Camalote disposal facility is indicated; capital dredging is shown in thicker lighter grey arrows, maintenance remedial dredging in darker with a darker arrow; the black boxes alongside the names of objects indicate their depth in relation to mean sea level

Objective

The sediments of the Riachuelo-port complex offer a fascinating and terrible situation.  The objective of this project related to the port will be the disposal of contaminated sediments.  The Riachuelo and Dock Sud are inextricably linked by geography, hydrology, the shared industrial history, and they share in the ambiguous and contentious jurisdictional morass.  This situation can be read through the common link that ties all of these themes together- sediment. Sediment pours down the Riachuelo, 640,000 cubic meters per year, half of which is dropped out in the port, the other half of which continues down out in to the Rio de la Plata.  All of it is considered heavily contaminated, affecting the lives of people nearby and the port’s operational costs.

The industries and urban settlements polluting upstream raise the sediment disposal costs of the port considerably.  Additionally, the pollutants from the port itself are flushed back in to low-lying neighborhoods during storm events and floods.  Given the projected expansion of the port within the next 20 years, deeper channels will be needed.  This will in turn require more dredging each year, a fact which projects future dredging of contaminated sediments to increase to 500,000 cubic meters annually.  Currently no dredging is done in the Riachuelo until it reaches the port zone that begins at the Exolgan logistics center.  This fact is evident in aerial photos and geo-soundings of the Vuelta de Rocha turning basin; it is no longer used and currently holds approximately 16 feet of contaminated sediments.  This sediment is then dredged and disposed of in the Yarara disposal facility on the eastern edge of the port next to the Rio de la Plata.  The facility is poorly constructed and filling up quickly.  It’s protection dike of 3 meters is subject to overtopping and wave battering and needs to be reinforced and safely closed.

The 2009 report on stormwater drainage for the Riachuelo basin noted that due to the high levels of contamination in the sediments, which would be dislocated and possibly released by dredging, a 1995 report recommended that no dredging occur.  However, this is being reconsidered due to necessities of using the canal for navigation and recreation (p. 134).

Proposal

diagram above illustrates dredge volumes in Dock Sud port by year; diagram series below just above illustrates different disposal structures considered for the new Camalote site; a near-shore confined disposal site is chose as it offers the best combination of secure containment, reduced costs, and fill for new port facilities

actual and projected increases in shipping, by tons operated; though Dock Sud is currently Argentina's busiest port, it is expected to triple the number of tons moved in the next twenty years; most of that growth will come in containerized shipping, though petrochemicals will continue to grow as well

The cost of the treating the 320,000 cubic meters of contaminated sediments is approximately ten times that of confining it (50 million to 6 million).  This cost would increase with additional dredging needed for channel deepening.  In addition, it is possible to reuse contaminated sediments as fill material for new port constructions if the disposal facilities are properly constructed.  For Tierra Plastica I am proposing a constructed near-shore disposal facility (see diagram above) to be constructed for confinement and use for new port facilities.  This proposal draws from and adapts the conclusions of the “Sustainable Management of Contaminated Sediment in Puerto Dock Sud” report by Kay Croonen of TU Delft/U of Buenos Aires.

This construction, named “Camalote” on the map below, will allow for the Yarara facility to be properly reinforced, protected from storm events, and closed, and for 90 hectares of territory to be reclaimed for port expansion.  The construction may be created from geotubes filled with mined sand, lined with local “tosca” clay, and reinforced with rip rap of construction and demolition rubble.  By providing a place for the contaminated sediments and logistical support in their transport, and allowing ACUMAR to concentrate funds on prevention of further contamination and the installation of sewer and industrial infrastructure, the port will limit the amount of time they need to pay for the disposal of contaminated sediment.

The remediation dredging will be carried out by multiple proposed tram dredges (number to be determined) and will continue for 5 years.  Further remedial dredging will likely be needed in the future due to the high number of industries and neighborhoods throughout the Riachuelo basin.  A system of monitoring will be needed to ensure the sediments are not contaminated beyond acceptable levels- if they can be maintained in a state clean enough to allow future interior port dredge spoils to be disposed of at sea then port operational costs could be reduced by up to 10 million dollars a year.

The Math

The Yarara site has an estimated capacity of 2,460,000 cubic meters.  It was estimated in 2008 to have only 200,000 cubic meters left and is likely now full or close to capacity, even with compaction due to dewatering.  The Camalote site will provide an estimated 10,000,000 cubic meters of capacity.  This will allow for storage of 1,000,000 cubic meters of dredge spoils from capital dredging in the Riachuelo, and provide capacity for confinement of contaminated spoils for the next twenty years.  At that point, institutional controls instigated by municipalities, agencies, and businesses through ACUMAR should be fully operational allowing for source control of pollutants.

However, given the dispersed nature, both temporally (spread over 200 years) and spatially (throughout the basin and spanning multiple jurisdictions) of the pollution sources, including residences, businesses, and industry, any future design should prove robust enough to mediate common pollutants.

geotubes may be filled, lined with local clay, and reinforced with rip rap including construction rubble to create a secure confinement dike fo the Camalote site

Implications

After the contaminated sediment is dredged and confined in the Camalote- or confined in place within the Riachuelo- and the new design depth obtained for the Riachuelo, maintenance dredging will be needed.  By confining the contaminated sediments so that they don’t contaminate groundwater or get flushed in to the city with sudestada floodwaters the health of the residents of the surrounding area will be greatly improved.  In addition, many plants and animals that currently suffer ill effects from the heavy metals and volatile organic compounds will have more space to grow and establish healthy ecological communities.

Regarding the future channel of the Riachuelo itself, the idea of “design depth” and “channel” needs to be rethought, considering that the future use primary uses of the Riachuelo will not be heavy industrial shipping but municipal transit, remediation, recreation, and light industry such as composting.  A monitoring system and catchment system must be developed to ensure that future remediation- likely to become necessary as hundreds of years of contaminated sediment make their way downstream- can be undertaken as part of a functioning industrial/recreational ecology within the city.

+ Where will the sediments be transferred from the tram dredge to the Port Authority?

+ How long will the remedial dredging take place?

+ What kind of ongoing dredging will occur after remedial dredging is finished?

+ How will the sediment monitoring system function?

+ How will the sediment catchment system function?

aerial showing context and limits of dredging program and creation of publicly accessible Camino de Sirga along the embankments of the Rio de la Plata; for scale the highlighted portion of the Riachuelo canal is almost exactly 1.5 miles long

Tierra Plastica is understood to be taking place under the purview of ACUMAR, the river basin authority of the Riachuelo.  ACUMAR (Autoridad de la CUenca MAtanza Riachuelo) is a decentralized interjurisdictional governmental agency with capital funds.  River basin authorities have developed into a relatively common device for dealing with the issues of pollution, economics, and politics in watersheds that span jurisdictional boundaries (as most do).  ACUMAR is unique in that it has capital funds to implement its decisions and recommendations thanks to a billion dollar loan from the World Bank.

One of the few precedents for this type of organization is the Tennessee Valley Authority which built dams, reforested hillsides, and constructed roads throughout the Tennessee Valley during the New Deal years of the United States (it still maintains a capital budget today, albeit a much less ambitious one).  ACUMAR differs from the TVA in that it is not a centralized planning organization accountable to an executive office and built according to the engineering/systems model as detailed by technological historians David Noble and Thomas P. Hughes.  Rather, ACUMAR is both part of and made of a network of administrative and technical experts, with its executive council consisting of local, state, and federal officials who work closely with the heads of state agencies such as Environmental Agency and Education Agency.

The organization itself is ultimately responsible to a federal court in nearby Quilmes, province of Buenos Aires, Argentina and works in concert with various local and municipal groups, non-governmental organizations, and municipal governments.  The nation of Argentina is responsible to the World Bank for showing progress according to the approved environmental remediation plan that was used to secure the loan.

inside the norris dam, built by the tennessee valley authority; at the norris dam the river basin authority created a landscape that is a massive piece of energy infrastructure and a publicly accessible recreation area; people come to walk through the forest and swim in the lakes, as well as to enjoy the technological sublime aspects of the landscape

a TVA shovel at work on a roadway at the Norris Dam site; note the "TVA" inscription on the shovel; as a river basin authority with capital funds ACUMAR like the TVA has the ability not only to pay contractors to build infrastructure, but also has the ability to buy its own instruments and undertake long-term projects and implement maintenance regimes

ACUMAR is responsible for executing the Integrated Plan for Environmental Remediation (PISA, by its Spanish Acronym), which it does by operating along four lines of action:  institutional, remedation, industry, planning and infrastructure.  There are certain aspects of both the plan and the institutional structure that are instructive and will ultimately be internalized as assumed parameters for the project.

1.  Efforts are being made to control the pollution point-sources upstream, including the construction of new sewage treatment plants, fining businesses disposing of chemicals and objects in the river, and controlling stormwater runoff.  Nonetheless, a robust and local system is needed for containing and cleaning the detritus and refuse carried downstream in the water column

2.  The system of levees and bulkheads that protect the urbanized area from floodwaters needs to be enlarged and reinforced, especially to withstand the sudestada storm events that occur several times per year and when combined with rain upstream and high tide lead to widespread flooding in the basin.

3.  As of April 2011 57 sunken or inoperable boats have been extracted from the river between the Pueyrredon Bridge and the Avellaneda Bridge.  In addition over 70 vehicles have been excavated from the canal bottom and there are no more in this zone.

4.  The Camino de Sirga (35 meter wide towpath) has been cleared of obstruction and structures in a first phase up to Dean Funes Street, with a second phase underway to clear up to Pueyrredon Bridge.  It is being cleared and designated as public space.  Sections further upstream are also being cleared with the final intent to unify a 35 meter wide swath on either side of the canal for public access.

5.  Dredging is being considered by ACUMAR in coordination with Port Authority at Dock Sud.  There are still some working port operations near the mouth of the canal and the section from the Vuelta de Rocha to the Canal Sur is still maintained and dredged by the Port Authority.  Any material that is dredged from the RIachuelo would have to be treated as contaminated and a treatment and disposal site would be needed.

6.  Two non-governmental organizations are currently advocating for the dredging of the canal; one in the interest of cleaning the watercourse, the other in the interest of making it navigable for a system of municipal transit boats.

2011, ACUMAR removes one of the 57 boats sunken and abandoned in the Riachuelo

Conclusions for the design of the Camino de Sirga

+ The physical limits of the site are defined as the outer edge of the Camino de Sirga on either side of the canal and all the space between, beginning at the new Avellaneda Bridge and going to the Pueyrredon Bridge, as this is the section where ACUMAR has worked to clear the Camino de Sirga of obstructions.  From there to the Victorino de la Plaza Bridge the project scope will be limited solely to the watercourse of the canal, as this area is desired for navigation but it is unknown when the Camino de Sirga may be cleared here.

+ Any design must include a strategy for dealing with the floodwaters of the Rio de la Plata, especially those occurring due to sudestada weather events.

+ The design should include a system that allows for constant monitoring of water level, sediment elevations, and enable the intermittent sampling of water and sediment chemistry.

+ Retention and filtration of stormwater along the banks of the canal in the urbanized area is necessary to reduce flooding in the basin.

+ Any design needs to provide a system for the filtration of contaminants and objects.  Major infrastructural and institutional investments by ACUMAR will help alleviate the situation.  However, given the heavily urbanized context the design of the canal should not suppose that all objects and contaminants will be removed.

+ For the purposes of this thesis project it will be assumed that ACUMAR has decided in favor of some type of dredging for the Riachuelo Canal.  A treatment and containment site is needed and should be coordinated with the Dock Sud Port at the mouth of the canal.  Creating a canal that is navigable for both recreation and municipal-scale transportation is desired by community groups and being considered by ACUMAR.  For Tierra Plastica it will be considered a necessary and ongoing process.

The Reserva Ecologica exists in the littoral zone between Buenos Aires and the Rio de la Plata; the greenish brown rectangular bar above the ecological reserve is a lagoon that was formally the municipal bathing area designed by JCN Forestier in 1918; the brown rectangular zone above that is the old port zone, Puerto Madero, which has recently been redeveloped as a high end residential neighborhood; downtown Buenos Aires is above that, with the Plaza de Mayo visible in the upper right portion of the image

The Reserva Ecologica is a testament to the potentiality of the Rio de la Plata biome and infrastructural projects gone awry.  Perched between Buenos Aires and the Rio de la Plata, with Puerto Nuevo on one side and the Petrochemical Port on the other, it is the liminal space between intentionality and potentiality.  And it is just to the north from the mouth of the Riachuelo canal.  Given its proximity and unique characteristics, it will serve as both a precedent and contextual situation to be dealt with for this thesis project.

The Reserva Ecological is a result of an incomplete poldering system begun in the 1970’s under the military dictatorship with the intention to reclaim land from the Rio de la Plata and create a new government administrative center.  The perimeter embankments were constructed using a poldering system- an embankment was created and infilled while excess water was pumped out.  The embankment material was demolition debris from projects underway in the city at that time as new highways were being cut through the existing fabric.  Sediment from the river was deposited by natural currents, combining with the landfilling process through the mid-80’s, with the intent that the excess water would then be pumped out, a process which was never finished. Upriver seeds from the ecosystems of the Parana and Uruguay Rivers were deposited here by currents, floodwaters and birds.  In 1984 the project to reclaim the land was abandoned and two years later it was declared a “Natural Park and Ecological Reserve” (municipal law 41,247/86).  The rich sediment, tidal fluctuations and floodwaters, and introduced plants from gardens and parks in the city make for a diverse ecosystem of hyacinth lagoons, mudflats, and hillocks which is now recognized by Bird Life International as important avian habitat.

The depositional currents of the Rio de la Plata have the effect of growing the Argentina side of the Rio de la Plata; Since 1888 the city has added nearly 20% of it's landmass; this zone holds a high concentration of the industrial and ecological infrastructure of the city, including the Reserva Ecologica

However, before the city edge was defined by the Reserva Ecologica, it contained a popular and prosperous bathing promenade, as were popular in many cosmopolitan cities in the early 20th century.  In 1918 Jean Claude Nicolas Forestier, pupil of Alphand, was contracted to come to Buenos Aires and produce an urban plan for modernizing the industrial capital city.  Like many places throughout the Americas this was a time of great growth and optimism and also over European fetishism and capital investment.

The sunbathing promenade was the only project that was realized from this plan, but it was wildly popular.  Given its location near downtown in close proximity to working class and bourgeois neighborhoods, it succeeded for a time in giving space for rich and poor to stroll and be seen but also to bath in the river, have a meal, or fish.  The quality of the water slowly deteriorated and by 1950 the river was closed off to recreational use, though the “balneario” promenade remained.

It was under this context that the project to reclaim land from the river for a seclude governmental center for the military dictatorship was undertaken 28 years later.  Considering this, it seems as if the water channel in front of the promenade was purposefully maintained in order to create separation between the people and the government, acting almost as a moat and providing a high degree of access control at the southern edge.  This area has since become filled in with water hyacinth, a florescent chimera ecosystem and an aching historical reminder.

The sunbathing promenade- balneario municipal- in 1925 looking from the city out towards the Rio de la Plata where the Reserva Ecological will eventually be formed; the formal gardens and park along its edge mediated the comingling of recreations and work; the depositional tendency of the Rio de la Plata on the shoreline can be seen to the right side of the image

the balneario is seen at the city's edge with the bustling new port "Puerto Madero" between it and downtown Buenos Aires; to the far right in the center of the image you can just make out the Plaza de Mayo, the ceremonial heart of the city; the biplane wing is conveniently in the frame

The sunbathing promenade is seen swarming with people; the number of people wading makes clear the shallow depths of the water here, and the popularity and social vitality of a social place to bath, be seen, and eat; at this moment in time most of the population was fundamentally connected to the Rio de la Plata in a quotidian way

For our purposes this study is particularly interesting for three reasons:

1) the fecundity of the Rio de la Plata biome and the appropriateness of the water hyacinth as a catalyst in these chimera ecosystems is a major force that must be respected and utilized.  The question of how is not one of intentionality however, as the biome will assert itself regardless of the presence or form of human intentions.

2) the sediment load of the Rio de la Plata makes a strong case for land reclamation strategies along the coast.  History has shown that these can be wildly effective with relatively small efforts. However, they make dredging a constant, arduous, and monumental task.  The Rio de la Plata is a geologic force.

3) the presence of the river in the quotidian life of the inhabitants of the city was fundamental to the making of modern Buenos Aires and the mixing of social types and classes (as well as the mixing of other types of ecosystems).  The loss of this characteristic in the second half of the 20th century paralleled many of the economic and social problems experienced by the city during that time.  This suggests that any environment remediation in this hydrological system- in our case the Riachuelo portion- is fundamentally a political economic question concerned with issues of environmental and social justice.

With the close proximity of the Reserva Ecologica to my site, the historical and thematic issues of the place will play an important role in the concept and execution of the thesis project.  The instrumental landscape of the Reserva Ecologica consists of the dump trucks, conveyor belts, and wrecking balls used in the demolition projects, but also the historical bathing promenade and resultant hyacinth lagoon, the estuarine currents and floodwaters, the sediment load of the Rio de la Plata, the gardens dispersed throughout the city whose seeds make their way here, the autonomous and individual birds flying through this zone bringing seeds and eating insects, and the construction debris itself.

the Reserva Ecologica is a ruderal landscape- refuse and overflow from the Rio de la Plata and the city coalesce here into one spectacular landscape; its situation- large polluted port complexes on either side, perched between downtown Buenos Aires and the Rio de la Plata, make the Reserva Ecological a chimera of all the fecundity and failed intentions of cities and continents

A gold dredge in Nome, Alaska where a decade long gold rush occured between 1899-1909

The question is this:  which instruments and what dredging regime is most appropriate for environmental remediation of the Riachuelo, and what will the resultant canal landscape be?  Admittedly, identifying the specific actual dredger and regime to be used is outside the scope of this project.  However, be considering the different types of machines and the landscapes they create through the mobilization of sights, sounds, materials, and a whole host of equipments and their concomitant expertise, we can identify desired results and causal relationships with specific instruments.  This will allow us to speculate on the type of dredge instruments to be used, and how, and therefore test our thesis of landscape instrumentalism with a specific design proposition.

In their most basic incarnation, dredgers are simply machines used for underwater excavation.  Applications include the improvement and deepening of shipping channels and ports, land reclamation, excavation of minerals, and environmental remediation.  There are three basic types:  hydraulic dredges, mechanical dredges, and hydrodynamic dredges. All three types engage in acts of dislodging, lifting, transporting, and disposing; mostly of a slurry composed of sediments and water from the bottom of the targeted waterway.  Each dredger is an assemblage of equipments and instruments including barges, hoses, cutters, hydraulic arms, pumps, and engines to name a few.  In this way, discreet acts of dredging can be thought of as instances of accelerated geological processes.

Considered from a materialist perspective dredging can be a generative act; the machines, equipments and specialized knowledge of the operator enter into a sort of duel or partnership with the water- its currents, chemicals, and biologies- and the sediments with its silica, organic matter, and toxic compounds.  Dredgers are typically imagined as landscape-building machines, used for beach nourishment and building new islands, cutting deeper channels and widening shipping ports.  Landscape instrumentalism is interested in the ways that the act of dredging itself generates landscapes- the movement of the dredger, sediments, the knowledge of operators and fleeing of local schools of fish all swirl together to create a violent and dynamic processual landscape.

Landscapes of Dredge

mechanical dredge operation landscape- each object is labeled and the four main relations between objects are represented as actions that are numbered; the primary characters or instruments work to create a dynamic landscape-in-process

hydraulic dredge operation landscape

Dredging operations are paradoxical by their nature.  Conceived as a specific linear process outlined in the above four steps– dislodging- raising- horizontal transport- final placement– these operations are nonetheless part of a larger network of relations that feed back in to the newly created situation, often working to undo the original intentions of the dredging program; the channel begins to resilt due to the construction of steeper banks and exposing of destabilized sediments to still-active erosive currents.  Every act is a spicy mix of human intentions and hard-headed ecologies and geologies pushing against one another.  Because of this, discreet dredging acts are necessarily part of a larger regime of dredging that works over time to counteract or harness the larger forces at work- ocean currents, river flow, meteorological events, specific geology, and local structures.

A dredging regime must attempt to comprehend these relations that are external to the discreet dredging operation and counteract or exacerbate them through an extended account of time and space which transgresses the limitations of scope and scale established through accepted engineering science [limitations which are necessary to ensure that measured goals are met within acceptable means and methods].

Dredging the Riachuelo

Some Considerations:  Developing a dredging regime for the Riachuelo in Buenos Aires with the intended goal of environmental remediation presents its own specific demands that must be approached:

+ high levels of toxicity in the sediments from industrial activities including fecal coliform, chromium, copper, lead, zinc, and PCB’s

+ the bulkheads which protect the urban structures along the edge of the canal must be protected and reinforced

+ local meteorological events, especially the winter sudestada storms can raise water levels in the canal upwards of 12 feet

+ daily tidal fluctuations vary the water levels in the canal by 3 feet

+ ongoing port operations of the Puerto Dock Sud, including dredging of the boat basins and darsena sud shipping channel, at the mouth of the canal, and relocation of the sand mining operations

+ human settlements along the banks of the canal- neighborhoods will be visually and aurally impacted by dredge work, and dredge work will be impacted by the stormwater runoff and detritus that filter from and through these settlements into or along the canal

+ biological communities, such as local fish populations or hyacinth blooms will impact the ability of dredgers to work with the sediments and slurry targeted by their instruments (the cutterheads, buckets, barges, and pipelines and also the strategies and technical knowledge of the designers and operators)

+ existing objects sunken into the bottom of the canal, especially cars and boats.  These are the detritus of 200 years of industrial and urban use, often quite careless or intending to externalize negative outputs of industrial processes.  In the area between Puente Avellenada and the Darsena Sud it is estimated that there are 57 boats sunken in to the bottom of the canal recently extracted by the Argentine Naval Prefect with the collaboration of ACUMAR, the river basin authority

+ the clearing of the camino de sirga by ACUMAR.  The camino de sirga, spanish for “canal tow path”, is to be cleared of private constructions and opened for pubic access to the Riachuelo.  The camino de sirga is defined as a 35 meter setback on either side of the canal.

Sediments:  The Riachuelo currently transports approximately 320,000 m3 of sediment per year.  All of this is considered contaminated and much of it is dredged by the Port Authority of Argentina and confined at the Yarara disposal side on the river side of the petrochemical dock in the port.  Historical deposited sediments in the Riachuelo, all heavily contaminated, vary from 1′- 14′ feet thick.  When still maintained for port operations, the depth of the Riachuelo was 24′.

Because of the shallow depth of the Rio de la Plata, a trunk line is dredged from the sea up to the Parana River, with branches leading to Montevideo and Colonia in Uruguay, and the Argentine cities of La Plata and Buenos Aires; nearing Buenos Aires the dredge channel branches again; "Canal Norte" heads to Puerto Nuevo, "Canal Sud" goes to the Puerto Dock Sud at the mouth of the Riachuelo

the geology underlying Buenos Aires and the Riachuelo is a loess called "pampeano", with the margins of the city and the bed of the Riachuelo contaning much more fine-grained clay and mud; this type of soil in ideal coastal situations can be dredged effectively with a cutter suction dredge or a trailing hopper dredge because it does not consolidate to a high degree

Instruments:  The geology of the river basin suggests that dredging operations can be carried out most effeciently- the most amount of sediment can be moved with the least amount of effort- with a hydraulic dredge such as a cutter suction dredge.  However, a dredging regime also needs to consider:  safety of users and neighbors, noise, horizontal transport of sediments, mixing of soil layers, creation of loose spill layers, and dewatering or treatment method. 

Given the proximity to dense populations to the canal, the likelihood of encountering large voluminous objects in the sediments (such as cars and mopeds), the continual and extended need for dredging, the distance from a disposal site, limited disposal space on the banks for dewatering and treatment, the need for precise maneuvering, and the desirability of opening the canal to municipal navigation for reasons of tourism and transportation, the needed instrument would likely have an articulated arm with grab capabilities and be capable of maneuvering without a tug boat.

Conclusions:  A mechanical dredge will be fitted out and deployed in the canal- constantly making the canal landscape- size to be determined.  It will work on a yearly cycle that must be developed in consideration with strategies for stormwater and upstream siltation, flood events, adjacent urban populations, existing contaminants, noise pollution, river ecosystems, new contaminant sources, and containment and disposal of sediment.

This canal landscape will be a place of acceleration and deceleration.  The dredging regime will have the stated goals of:

+ removing, treating, and confining the contaminated sediments of the canal

+ making the canal and its banks open for municipal transportation at all times

+ maintain low levels of noise pollution in the canal and the immediate areas

+ reduce costs of maintenance dredging for the Puerto Dock Sud at the mouth of the Riachuelo

+ contribute to the re-development of health ecological communities within the canal landscape

+ contribute to the creation and maintenance of the camino de sirga  as a public, accessible part of the city

This dredging regime will be implemented in accordance with a larger project and program (which is currently being hatched).

the Prefectura Naval (Argentine Navy), alongside the river basin authority ACUMAR and the Environmental Ministry, pulls sunken boats from the Riachuelo and stacks them on the future camino de sirga; the question, of course, is "what kind of massive hulking floating-bridge-barge-type-thing is that?"

Can environmental remediation operations generate the conditions for industry and recreation along the canal?

The water hyacinth, native to the estuary, has bloomed in the Riachuelo before to such an extent that industrial shipping operations were shut down in 1905 and 1967; the hyacinth grows at an incredible rate, provides habitat, and is a hyperaccumulator of heavy metals that frequently result from industrial operations, such as cadmium

To start the project; a speculation on the potentiality of the canalized portion of the Riachuelo in Buenos Aires, Argentina.  The project proposes that the environmental remediation operations necessitated by the federal court “Mendoza” decision of 2008.  The operations are to intended to be carried out by the river basin authority, ACUMAR.

This speculation proposes the humble water hyacinth and the rumbling dredge to generate a series of ephemeral landscapes in the canal and at the mouth of the river.  The intent is to use the speculation as a method for bringing up the right questions.

The operations would happen at various scales- picking hyacinth, operating a dredger, conveyor belt systems, sedimentation- over decades.  The plan set would necessarily be secondary to continual maintenance and construction processes.

year 2011

year 2013- the first move is to inhabit the canal, create a processing center for the dredge spoils, and open access to the new public-industrial landscape with a pedestrian bridge (in red);the canal surface has been taken over by water hyacinth and navigation channels for the harvest boats and dredgers are maintained; a sediment processing platform is created at the mouth of the Riachuelo

year 2060- a poldering construction system, using the demolition debris from infrastructural projects in the city, allows for the establishment of new sediment catchment basins near the dredge spoils processing platform; the continued collection and composting of hyacinth, processing dredge spoils, and sedimentation from the Rio de la Plata estuary begin to create new landforms within polder boundaries created from construction rubble

year 2100- the manufactured soils created from the spoiled industrial residue of the canal combines with the rich biome of the estuary to create a new urban nursery for reforesting the city; new public-industrial landscapes are created through continual remediation, recreation, and industrial operation along the canal

View of the Canal from La Boca neighborhood- the water hyacinth overtaking the Riachuelo Canal, generating a new public landscape.

View looking toward the Rio de la Plata- the new poldered lands are organized along a main spine; the spine is a bundle of functions, moving manufactured soil, people, and also separating the public landscape from the petrochemical dock; constructed spurs run between the poldered lands, subject to the flood; the adjacent polders are near eye level and protected from the salin waters of the Rio de la Plata.

looking back toward the city from the Rio de la Plata- newly constructed lands provide space for an urban nursery that reforests the city; sports fields, boating areas, and birding also begin.

This brings up several key questions useful to the current thesis regarding the material practice of instrumentality (a list in the thick of the editing process):

1. How would people (workers and recreational users) access the canal?

2. What instruments are needed to tend, harvest, transport, and compost the hyacinth?

3. What are the instruments used in dredging?  a) How frequently are they operating?  b) how is the loading and unloading best achieved?  c)  what is the best way to stockpile the volume?  d) how is the contaminated sediment treated and what are the necessary instruments in this process?

4) What are the space and machine requirements needed to produce manufactured soil?

(have a pithy, insightful question that I should really be addressing?  Feel free to post it!)