E1042, VOL. 1
EXECUTIVE PROJECT FOR THE ARROYO MALDONADO CATCHMENT
DEVELOPMENT OF THE PROJECT
FINAL REPORT
ENVIRONMENTAL IMPACT ASSESSMENT
Summary
Contents
1.
INTRODUCTION ........................................................................................................................................ 1
2.
STUDY OF ALTERNATIVES .................................................................................................................... 4
3.
CONCLUSIONS AND RECOMMENDATIONS ...................................................................................... 4
4.
PRELIMINARY ENVIRONMENTAL STUDIES AND ANALYSIS ..................................................... 5
5.
ENVIRONMENTAL CLASSIFICATION OF THE PROJECT ............................................................. 6
6.
AREA OF INFLUENCE OF THE PROJECT........................................................................................... 7
7.
DESCRIPTION OF THE WORKS ............................................................................................................ 7
8.
SCHEDULED PROJECT IMPLEMENTATION PHASES .................................................................... 9
9.
CHARACTERIZATION OF SENSITIVE AREAS AND POINTS ......................................................... 9
10.
IMPACTING ACTIONS IDENTIFICATION AND SELECTION .................................................. 10
11.
IDENTIFICATION AND ENVIRONMENTAL IMPACT ASSESSMENT ..................................... 10
12.
ENVIRONMENTAL IMPACT ASSESSMENT MATRIX ................................................................ 13
13.
MITIGATION MEASURES ................................................................................................................. 13
14.
MITIGATION MEASURES FOR THE CONSTRUCTION STAGE .............................................. 13
15.
MITIGATION MEASURES FOR THE OPERATION AND MAINTENANCE STAGES ............ 16
16.
ENVIRONMENTAL MANAGEMENT PLAN (EMP) ...................................................................... 16
17.
PARTICIPATORY APPROACH ......................................................................................................... 17
18.
PUBLIC CONSULTATION ................................................................................................................. 17
1. INTRODUCTION
1.The City of Buenos Aires frequently suffers from serious flooding that damages property,
the economy, and affects the bulk of its population. Over 25 deaths have been recorded
since 1985. Of the two possible causes of flooding of the City of Buenos Aires, rain is the
most significant. The second cause is the so called “Sudestada”, a phenomenon of
exceptionally high tide in the Rio de la Plata, due to strong winds coming from South East. A
complete set of defenses has been constructed in the past to counter the phenomenon.
However, for natural and meteorological reasons, the two events are not compatible and
cannot concur to create a more severe danger.
2. Funded by the World Bank under the current Flood Protection project (4117-AR), a four
year study of the Buenos Aires drainage system identified structural weaknesses in the
surface and underground network, designed an Hydraulic Master Plan, and carried out the
project feasibility study. Indications suggested that major infrastructure investment was
required to address the issue of structural weaknesses satisfactorily. An international joint
venture group was selected to undertake the Hydraulic Master Plan for the city’s urban
drainage system and the feasibility study of the works for the most important basin, the
Maldonado stream. The team comprised two international consulting firms along with two of
the most important local consultancies in the country. The study had two key objectives: (i)
identify improvements to the city’s drainage system in order to alleviate the problems caused
by flooding and (ii) review the current infrastructure and make proposals to improve public
safety and reduce the impact of flooding on people, buildings, traffic and life generally in the
City. The study focused on the development of a master plan for the whole city covering an
area of 29,300 ha including the implementation of an integrated drainage basin study of the
streams that cross the city, and the formulation of proposals for structural and non-structural
solutions, leading to an optimization of the drainage network of the City. In the context of the
hydraulic master plan, this work delivered the three following products:

A program of structural and non-structural measures, with at least initial design,
for all the drainage basins of the City.

The executive design of the structural measures of the Arroyo Maldonado
(Maldonado Stream) drainage basin.

The sector management system.
3. Floods have a direct impact on the Maldonado water basin situated in a very central area
of the City, and populated by more that one million people. Floods also have an almost as
important indirect impact on the economic development of the City, by blocking the vital
1
transport network (streets, railway and underground) that links the more affluent districts of
the North of the City, to the industrial, more popular areas of the South. (See Map 1)
4. The worsening hydrologic situation and ensuing damages to the life of the City, are
motivating the City to substantially increase infrastructure investment in this sector. The
levels of investment in drainage infrastructure have been inconsistent with economic and
population growth of the City for the past 70 years. There is a need to rapidly scale up the
infrastructure asset base to help put the City on a more balanced protection level, while
ensuring for the future a platform for sustainable growth.
5. Among several drainage basins in the City, the Maldonado is the one with largest surface
and population affected by floods, where flood recurrence is higher, where population density
is highest, and where the highest ratio of elderly people can be found. The Maldonado
stream is the major rain drainage collector of the City; it runs from South to North cutting
across areas of different economic condition: from the poor conurbations of the North West
to the up-market blocks of Recoleta. Its basin has been urbanizing continuously since 1936,
the year in which the river was buried.
6. Today the Maldonado basin overflows with almost an annual frequency, causing clogging
of the drainage system of the City and consequent flooding of the basin. It is almost
impossible to separate the technical problems of the buried stream from the hydrological
consequences of the Urbanization and densification of the City, or from the effects of the
modified patterns of precipitation: all this causes have concurred to worsen the issue of
flooding to the point that, in the last 20 years, the flooding events dramatically increased in
frequency: 37 episodes of flooding happened between 1984 and 2004.
7. Along with above physical issues, the need to link institutional strengthening with
infrastructure investment is of the utmost significance. Increasing infrastructure spending
without ensuring appropriate management of the hydraulic risk in the near term as well as
risk management and transfer in the medium term could slow the benefit of the investment in
physical assets and affect economic development. Equally important, lack of institutional
capacity would prevent an effective execution of strategic infrastructure programs, whose
bulky
and
multiyear
commitments
would
be
subject
to
disruptive
“stop-and-go”
implementation. On the other hand, rational management of infrastructure services can yield
substantial fiscal and efficiency benefits and help improve the City’s productivity and
competitiveness (e.g. via cutting direct and indirect damage costs) along with access to basic
public services by poor segments of the population.
8. The assessed project includes the construction of two alleviation tunnels from the main
storm drainpipe of the Maldonado basin, with important associated works, as well as
2
reinforcement works of the stormwater secondary system of collectors, to avoid significant
inconveniences generated by floods that are produced by storms for a recurrence period (Tr)
of 10 years and to mitigate those due to minor frequencies. The catchment area already has
an important and extensive stormwater drainage system. Nevertheless, it is not enough to
meet the new requirements of urbanization and intensification of the territorial occupancy
generated after its design and construction, dated in 1919 and 1929-1939, respectively.
9. The hydrologic study conducted for the Maldonado watershed included the analysis of
precipitation data collected at the Observatory in Villa Ortúzar (1937 to 1998) and
Aeroparque (1961 to 1998). The intensity, duration and frequency (IDF) of rainfall events
were assessed by means of standard hydrologic analyses techniques.
The spatial and
temporal distribution of intense storms historically observed in the hydrometeorological
records, were studied in detail as well (Figure 1). A risk analysis of storm intensities having
durations of less than 30 minutes was conducted and a “design storm” time-distribution
profile having an exceedance probability of 25% was selected as the input to be used for the
hydrologic and hydraulic modeling of the different alternatives. The spatial distribution of a
given design storm (e. g. how the rainfall intensity decays with area) was estimated with a
standard technique developed in the USA with data from Chicago, Illinois.
10. Once the hydrologic analysis was completed, the hydraulic modeling of the different
alternative solutions was accomplished with the help of the software package InfoWorks CS
developed by Wallingford Software, United Kingdom. This software allows planners and
engineers to predict environmental impact following a rainfall event by modeling of the key
elements of storm-sewer and drainage systems. The software transforms rainfall into runoff
and incorporates the solution of the full St. Venant equations for modeling of free-surface and
pressurized flows commonly observed in urban areas during storms. InfoWorks CS
incorporates full interactive views of data using geographical plan views, long sections,
spreadsheet and time varying graphical data.
11. The main purpose for developing the model was to use it in the evaluation of the
alternative solutions for the Maldonado flood control project. The goal was to seek a solution
that would afford the City of Buenos Aires protection against floods associated with rainfall
events having return periods of up to 10 years, while mitigating the impact of storm events
with return periods larger than a decade.
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2. STUDY OF ALTERNATIVES
12.During the planning and design stages of the project 27 technical alternatives were
studied to improve the current drainage system within the Maldonado basin; they were
analyzed from technical, economical and environmental points of view and selected by
applying a multicriteria evaluation analysis.
13. The studied alternatives were based on: (a) different levels of protection 5, 10, 20 and 50
years of storms recurrence, (b) different control systems (conduction, volumetric reservoirs,
mix), (c) different conduction methods (open trench, tunnels), (d) different final discharge
sites of the waters (Rio de la Plata, Riachuelo), and (e) different constructive technology
(tunnel boring machine, manual method).
14.The alternative of drainpipes relative to those of impoundments in constructed volumetric
reservoirs shows less negative environmental impacts during construction as well as during
the functioning (especially in case of functioning without gates or pumps). The final
disposition in the Riachuelo, is limited for its return period of five years due to structural
existing interferences. Moreover, this site discharge would eventually stimulate jurisdictional
conflicts between the City of Buenos Aires and the homonymous Province.
15.The use of relatively deep tunnels (selected to alleviate the main conduct) will produce
during the construction fewer problems to the population, to the productive activities and to
the transit, than the works at open trench, which also interfere the public services. The main
conduct runs under Juan B. Justo Avenue which has a remarkable heavy traffic. It is
expected that its interruption would generate important impacts on population welfare.
16.Other issue which is worth remarking is that the tunnel boring machine method is less
risky than the conventional construction method.
3. CONCLUSIONS AND RECOMMENDATIONS
17. The alternative of two tunnels without storage incorporated in the tunnels is the
recommended one for the development of the Executive Project since it meets the technical
requirements of the project in terms of flood control while minimizing the environmental
impact of the works.
18. The geotechnical exploration program, which includes borings spaced about 100 meters
along the alignment is adequate and corresponds well with smart engineering practice in
similar projects. The results from the soil testing program and the evaluation of existing
4
precedent of underground excavations in the city of Buenos Aires allows for an adequate
characterization of anticipated behavior of subsurface materials during excavation.
19. The vertical and horizontal tunnel alignment chosen are adequate and take into account
pertinent parameters including presence of existing structures, access, and right of way. The
vertical alignment is susceptible to improvement by raising the present tunnel elevation, but
requires ground treatment at critical locations at the intersection with existing underground
structures.
20. The use of Tunnel Boring Machine is indispensable for the excavation of the saturated
sand deposits encountered along the entire length of the short tunnel and along about 5.5
kilometers (downstream half) of the long tunnel.
21. Monitoring of excavation behavior is required during construction. The field
instrumentation program included in the present design appears to be adequate. Data
collected from the instrumentation needs to be digested and evaluated in a timely fashion.
The need for implementation of preventative measures at critical locations (i.e. intersection
with existing structures) would be evaluated on the basis of the analysis of the
instrumentation data and field observations.
4. PRELIMINARY ENVIRONMENTAL STUDIES AND ANALYSIS
22. It must be pointed out that the environmental variables were considered at each phase of
the design, from the preliminary ideas to the executive project. Different constructive
methodologies were analysed in order to reduce negative impacts either for the resident or
for the crossing population within the project’s area of influence.
Table I. Actions performed during the Planning and Design Phases
Project and environmental background data gathering and analysis.

Field works concerning soils, water quality, climate, transit, urban surveys, queries and
interviews with key stakeholders, etc.

Diagnosis of the Environmental Base Line during the Planning Phase.

Environmental Evaluation of Alternatives.

Blueprint Environmental Preliminary Evaluation.

Publication of the preliminary project. Seminars were conducted with the participation of
specialized professionals of the area, NGOs, local and international experts.

Geotechnical fieldworks.

Executive Project Environmental Impact Assessment.

Consultation meeting between the City Government and environmental NGO for project
presentation and discussion. Agreement to continue with the meetings during the
implementation phase.

5
Table I. Actions performed during the Planning and Design Phases
Regulation and procedures established by the environmental legislation in force, as well as
by the bid and the Environmental Management Plan, obeyed by the Executive Project.

Contractor Bids including an Environmental Management Plan that minimizes undesired
environmental effects. Special emphasis was focused on the location of site works and work
actions that imply transit disturbance.

Permissions requested to cut avenues and streets with adequate anticipation, as well as to
cross railway lines, interferences with other public services networks and occupation of
parcels, to the authorities and corresponding companies.

Adequate information and training of the future staff on expected environmental issues,
implementation and control of environmental protection measures, contingency plans and
environmental regulations and procedures applicable to activities and construction sites.

Assignment of specific responsibilities to future staff in relation with the implementation,
operation, monitoring and control of mitigation measures.

Requirement to the contractor of contingency plans elaboration for emergency situations
(e.g. machine and equipment oil spills, collapses, erosion, flooding during works) with
significant environmental consequences.

Coordination and agreement concerning mitigation measures with application authorities
(Coordinated Action Agreement for works in the Public Street Nr 24/ 97).

Communication and Environmental Education Program (PROCEAH) for an efficient and
adequate implementation of social communication mechanisms allowing to establish
effective contact with all the stakeholders affected by the works.

Announcement of temporary diversions of public transport with not less than a week before
its occurrence by massive graphic communication media, radio and television.

Neither expropriations nor involuntary movement of residents are demanded.

5. ENVIRONMENTAL CLASSIFICATION OF THE PROJECT
23. The objective of the works is aimed to improve the environmental quality of the city. They
consist in collecting, conducting and discharging the storm water that cannot been absorbed
by the urbanized and densely populated land. Nevertheless, considering the magnitude and
dimension of these works, especially in an area of the complexity of the city of Buenos Aires,
the construction could cause undesirable impacts that must be mitigated. Considering the
type of project and its location area, it was recommended to classify it environmentally as
Category “A” following the World Bank Safeguard Operational Policies.
24. Local legislation regards this type of project as of high potential impact. Furthermore,
article 13° of law 123-GCBA (modified by law 452-GCBA) stated that the Executive Project
for Arroyo Maldonado Catchment area is “susceptible to produce an environmental impact of
relevant effect”. Thus, an Environmental Impact Assessment was demanded by local
authorities. This procedure is supervised by the Government of the city of Buenos Aires,
through its “Dirección de Política y Evaluación Ambiental”, that depends on the “Secretaría
de Producción Turismo y Desarrollo Sustentable”.
6
6. AREA OF INFLUENCE OF THE PROJECT
25. Due to the magnitude and importance of the project, as well as the complexity of its
location area, three scales of influence have been considered: regional, local and punctual.
The regional area of influence comprises the city of Buenos Aires, and a small portion of the
Province of Buenos Aires, where the upper basin of the Arroyo Maldonado is placed
26. The Local Area of Influence was defined as the portion of the Arroyo Maldonado
catchment area that extends in the territory of the city of Buenos Aires. A more detailed
description of the environmental issues were considered in this area, by using the gathered
data and the field studies. Based upon the abundant urban information sources (e.g.
housing, population density, industries, urban equipment, infrastructure, public services,
noise, transportation, transit, etc.), available by GIS and related through the modelling to the
flood risk maps, it was possible to achieve an exhaustive identification of sensitive areas.
The punctual area of influence is established by those works that impact defined points
within the city (See Table II “Characterisation of Sensitive Areas and Points”, Paragraph 37).
7. DESCRIPTION OF THE WORKS
27. The project comprises the construction of two alleviation tunnels of the main drainpipe,
with its related works, to reinforce the secondary storm water drainage system that discharge
into the main conduct. The location, components and construction technologies related to
these works are described as follows (see Figure 1, Location of the Works).
28. Tunnels: Two tunnels of 6,90 m diameter each were designed. One of them around
4,600 m (“short tunnel”) and the remaining 9,840 m (“long tunnel”), totalling then a
conduction of about 14 kilometres length. The tunnels will be built by tunnel boring machines
(TBM) of EPB type (Earth Pressure Balance or mix), with pressure compensation during
excavation, to counteract the groundwater and soil pressures of the surrounding area. By
using this method, significant urban impacts on the surface are avoided. This constructive
system requires initial working shafts and exit shafts for the TBMs, in the surface, punctually
disturbing the surroundings.
29. The short tunnel starts in Juan B. Justo Av. and the Niceto Vega Street. It runs under the
main drainpipe of A° Maldonado up to Santa Fe Av., continuing under Int. Bullrich Av. up to
Libertador Av., and then crossing under Parque 3 de Febrero up to Sarmiento Av and
Costanera Av, to end in the Discharge Work, located in the peninsula Punta Carrasco, Río
de la Plata. (See Fig. 1. Location of the works).
7
30. The long tunnel, starts in the intersection of J. B. Justo Av and Cuenca Street, running
under the main drainpipe (under J. B Justo Av.) up to Castillo Street, continuing under Godoy
Cruz Street up to del Libertador Av., following an approximate parallel path to the previous
tunnel up to the common discharge structure. The important existing infrastructure works
intercepted by the tunnels (Lines B and D of the Subway and underground potable water
pipe) determine the deepness of the works. The project design requires keeping a minimum
separation between the current infrastructure and the works to be carried out, equal to the
diameter of the excavation (around 8.00m) in the cross of such interferences.
31. The tunnels will receive the flow from the main drainpipe from three derivation structures,
two in the long tunnel and one in the short one. The former are located in the J. B. Justo Av.
and Cuenca Street intersection, and in the tunnel and H. Pueyrredón Av. intersection. The
derivation of the short tunnel is located at of J. B. Justo Av. and Niceto Vega Street
intersection. These works include the derivation structure and a connection chamber with the
tunnel. To discharge in the Río de la Plata, both tunnels end in the Discharge Work, which
includes the chambers and the discharge channels and a pumping station (to empty the
tunnels for periodical maintenance).
32. From an urban environmental viewpoint, these works are considered as “Sensitive
Points” given the estimated potential punctual impacts, during the construction stage.
Therefore, further environmental variables affected by the works were analyzed. Figures 2 to
5 show the general location of the works that constitute “sensitive points”, which were
identified according either to the name of the street intercepting the main drainpipe or to its
location(Fig 2: Sensitive Point 1-N. Vega, on short tunnel; Fig-3: Sensitive Point 2- Cuenca
(on long tunnel); Fig-4: Sensitive Point 3- Honorio Pueyrredón ,on long tunnel; Fig-5:
Sensitive Point 4- Punta Carrasco).
33. Storm water drainage system reinforcement: The existing storm water secondary
drainage system will be reinforced, including the replacement and construction of 46 km of
conducts that will extend through all the catchment area of Aº Maldonado and will be built by
open trench method (See Figure 1). The connection between the new and the existing storm
water system will be made with flow distribution chambers designed to optimise the
distribution of water between the existing and the new conducts. The discharge of the drains
will connect to the main existing drainpipe, without direct link with the tunnels. The new
drains, of circular or rectangular section, will, replace totally or partially some stretches of the
existing ones, placed parallel to those, linking them by the chambers already mentioned.
8
8. SCHEDULED PROJECT IMPLEMENTATION PHASES
34. The proposed schedule for the total implementation of the works with the use of two TBM
will demand a period of 48 months. Estimating the beginning of the works by September of
2005, their finalization could be reached by the end of 2009. The finalization and functioning
of the short tunnel will demand thirty seven months.
35. The provision of the TBM machine will require around 12 months before it is in operative
conditions to start the tunnel construction. Nevertheless, the works will start immediately after
the signature of the contract, given that initial waiting period of the TBM will be used to
perform all the previous works required. So, the machine can operate in the shortest
available time after its setting .
36. The works will include: (a) Work quarrier settlement, elaboration of reinforcement
concrete segments (b) Setting, assembly, functioning start of long tunnel TBM, (c) Long
tunnel construction, (d) Setting assembly, functioning start of short tunnel TBM, (e)
Derivation chambers construction, (f) Short tunnel secondary drainage network construction,
(g) Long tunnel secondary drainage network construction, (h) Dividing wall construction, (i)
Discharge and pumping works at Punta Carrasco, (j) Tasks completion, site conditioning,
and facilities removal.
9. CHARACTERIZATION OF SENSITIVE AREAS AND POINTS
37. The sensitive areas were identified taking into account the basin main characteristics and
the project involved activities. During construction, the area surroundings the works will be
considered as of immediate influence of the project. The tunnels do not define a linear area
of influence because its alignment and construction are deeply underground, with low
expected impact on surface and on human activities and welfare. The activities of potential
impact are those that will affect the surroundings of the works in the surface (e.g. the
Connection and Derivation Chambers). The urban characteristics of each “sensitive point”,
include the following variables: (See also Figs. 6, 7 and 8).
Table II. Characterisation of sensitive areas
Point 1-
Point 2-
Point 3-
Juan B. Justo Av. and N.
Vega Street
Juan B. Justo Av. and
Cuenca Street
Juan B. Justo Av. and H.
Pueyrredón Av.
Components
Derivation chamber and
connection short tunnel
and shaft exit of TBM
Derivation chamber and
connection long tunnel and
shaft exit of TBM
Derivation chamber and
connection long túnel
Population density.
155.3 inhab/ha
200.8 inhab/ha
224.8 inhab/ha
Location
9
Table II. Characterisation of sensitive areas
Point 1-
Point 2-
Point 3-
Location
Juan B. Justo Av. and N.
Vega Street
Juan B. Justo Av. and
Cuenca Street
Juan B. Justo Av. and H.
Pueyrredón Av.
inhab/house
3.4 inhab/house
2.9 inhab/house
2.96 inhab/house
Industrial activity
1.37 unit/ha
1.31 unit/ha
2.24 unit/ha
Commercial activ.
5.1 unit./ha
3.93 unit/ha
17.58 unit/ha
Services activity
2.13 unit/ha
2.4 unit/ha
4.32 unit/ha
Total Economic
activity
8.58 unit/ha
7.64 unit/ha
24.14 unit/ha
TMDA
53.486 veh/day
66.837 veh/day
57.253 veh/day
Buses
1080 veh/day
3121 veh/day
2181 veh/day
Trucks
1159 veh/day
1577 veh/day
2587 veh/day
Predominant use of
land
Mix, with commercial
activity, services and big
deposits
Mix, with workshops and
deposits of car parts, with
certain degree of
deactivation.
Mix, with great commercial
activity of sales and
collocation of car spare
parts
Affects the transit
Slight
Moderate
Intense
Point 4- Work
quarrier settlement,
elaboration of
reinforcement
concrete segment
Discharge work and
starting shaft
Area of about.
20,000 m2
Punta Carrasco is a recreational area which forms a peninsula in the Rio de la Plata
coast including a large open space with a great vegetal coverage. This area is
connected with the Costanera R. Obligado Av., which has a heavy transit. An
important transit of trucks enters and leaves the City Port. The TMDA is of 40,000
vehicle/day.
10. IMPACTING ACTIONS IDENTIFICATION AND SELECTION
38. The actions generated during the construction stage will be mostly temporary .The most
significant ones are included in Table III.
11. IDENTIFICATION AND ENVIRONMENTAL IMPACT ASSESSMENT
39. The project will not generate negative impacts on groundwater as well as on the waters
of Rio de la Plata. The tunnels will receive the flows from the existing Maldonado channel by
three derivation structures being drained water totally isolated from the groundwater. The
waters dumped in Rio de la Plata will have the same quality of those currently discharged by
the Maldonado channel. Therefore, significant impacts are not expected on the river.
10
40. International Waterways. The Guarantor and the Borrower agreed that the works to be
carried out under the Water and Sewerage and Drainage components will have no impact on
the navigability and/or the course (regime) of the Río de la Plata.. Consequently, both, the
Guarantor and the Borrower concurred that it is not necessary to request the Comisión
Administradora del Río de la Plata its no objection to proceed with said works.
(See Table III).
11
TABLE III. ENVIRONMENTAL IMPACTS
ACTION
EFFECTS
Works site and ancillary
installations
Increase of the transit of equipment in the accesses to the work sites, atmospheric emissions, noise and gas, road and streets
deterioration, affectation of resident population activities, affectation of work sites for alternative uses, overloading and services
alteration, wastes generation, washing water spill.
Preparation of the work area.
Transit interruption and/or disturbance, occupation of the public areas, alteration of surface runoff , dust and particles emissions,
increase of noise, affectation of resident population activities and welfare, sediment concentration in drained water, alteration of urban
aesthetic attributes, effects on economic activities.
Supply and movement of
materials
Emission of dust and gas, increase of noise, occupation of public areas, road and street deterioration, alteration of transit and transport,
affectation of resident population activities and welfare.
Excavation and movement of
soils
Emission of dust and gas, increase of noise, occupation of public areas, road and street deterioration, alteration of transit and transport,
affectation of resident population activities and welfare, alteration of surface runoff, effluents generated by ground water pumping,
sediment concentration in drained water, generation of soils and rubble.
Movement of trucks,
machines and equipment
Emission of dust and gas, increase of noise, occupation of public areas, road and street deterioration, alteration of transit and transport,
oil spill, wastes generation for trucks and machines maintenance.
Generation of residues and
emissions
Deterioration of urban aesthetic attributes, presence of rodent and insect disease vectors, soil, surface and groundwater contamination,
alteration of surface runoff, atmospheric contamination, affectation of resident population activities and welfare.
Interference with public
services infrastructure
Disturbance of public services, alteration of transit and transport, affectation of resident population activities and welfare.
Energy and water services
demand
Limitation in current use capacity, affectation of resident population, commercial and industrial activities.
Demand of work force
Social welfare improvement, demand of food and other services increase, unemployment decrease, quality of life improvement.
Health and safety at work
Improvement of work conditions quality, welfare of operative staff, greater working efficiency.
Archaeological and
paleontological findings
Improvement of the cultural and historic properties, delay of works, possibility of determining other layout alternatives.
Closure and abandonment of
work
Generation of rubble, emissions of particles and fumes, spill of washing water, alteration of transit and transport.
12
12. ENVIRONMENTAL IMPACT ASSESSMENT MATRIX
41.From the EIA, it can be concluded that:

Relevant negative impacts will take place during construction.

Mitigation measures must be adopted to minimize the above referred impacts.

Significant positive impacts during functioning phase, will fulfil the objectives of the
project

“Matrix of the Final EIA” shows the comparison between the temporary negative
impacts that can be mitigated during construction and the permanent positive
impacts during the operation phase.
13. MITIGATION MEASURES
42. Impact mitigation was based, on prevention actions and to a lesser extent on corrective
measures. This criterion is more cost-effective, (corrective measures costs frequently
surpass those related to prevention). It is worth remarking that benefits of the urban
sanitation works can be properly observed at the operation phase.
43. During construction the urban aesthetics will be worsened by the intense soil
excavations. Furthermore, they will generate dust and noise emissions, pavement breaking,
transit alteration by avenues and streets detours, altering significantly the comfort of the
resident population, as well as the main urban activities. Regulations and technical
specifications were aimed to mitigate these negative effects.
44. Fulfilment of the recommended specifications is closely linked to the Environmental
Supervision of the most complex works carried out by an external international firm
contracted by UECBA-SUPCE. Moreover, the observance of the Mitigation Measures Plan
will depend on adequate information dissemination to all the involved staff. This objective is
expected to be achieved mainly by the preparation of training workshops, and lectures, as
well as by using graphic information on environmental issues.
14. MITIGATION MEASURES FOR THE CONSTRUCTION STAGE
45. This stage of the work implies the supervision and control of the strict fulfilment of the
mitigation measures. The general environmental requirements to be obeyed during the
construction are:

To avoid contamination of soil, water and air.

To avoid the destruction of natural vegetation.

To avoid soil erosion and sedimentation either in the Rio de la Plata or within the
conducts.

To avoid the use of fire to eliminate wastes and other remaining materials.

To dispose solid wastes in environmentally adequate sites.

To select technologies which meet adequate environmental quality criteria.

To adequately manipulate archaeological and paleontological materials.

To obey specific regulations in force.
In order to fulfil the general referred objectives, the following mitigation measures must be
adopted. (See Table IV)
TABLE IV. MITIGATION MEASURES
FACTOR
MITIGATION MEASURE
Water
Installation of chemical bathrooms in temporary worksites. Wastewaters will be rightly
conducted to avoid their dumping to the storm water or to the Rio de la Plata.
Disposal sites for construction material and for extracted soil storage must have an
adequate drainage system as well as sediment traps, in order to conditioning them
prior to their discharge in sewers or river.
All necessary safety measures will be implemented in order to avoid spills, especially
fuels or other hazardous wastes.
Air
Equipment, machines and trucks will be periodically maintained, according to specific
regulations related to gas and noise emissions.
Time dedication to the different involved tasks will obey specifications related those
activities implying sound levels greater than 80 db. It will be restricted to the normal
sleeping time (10 pm to 06 am).
All measures needed to avoid or minimize the dispersion of dust and particles will be
implemented within the material storage area.
Fire will not be used to waste or remaining material reduction or elimination. The use
of contaminant, toxic substances, which can alter the air quality, will be minimized.
All applicable regulations related to gas and noise emissions will be obeyed.
Vegetation
Adequate measures to avoid destruction of the existing natural vegetation and urban
trees will be adopted. Whether necessary, authorization will be requested to the
Supervision. All the extracted species will be reintroduced in situ or in other adequate
sites.
Natural vegetation and urban trees eventually affected by the works will be protected
adequately by fences, covers, etc.
Soil
The disposal sites will be reduced as much as possible according to construction
requirements and the criteria established in the bid specifications. The identified sites
to carry out the discharge have been selected based upon their adequacy. The soil
will be disposed in those places approved by competent authorities, according to
regulations. Samples of extracted soil will allow to determine its quality. Whether
hazardous materials are detected, the soils will be stored and treated. Otherwise, the
soils will be transported to their final disposal areas. The disposal sites will be
managed under restoration practices. Transit and transport disturbance due to soil
transportation will be of low significant magnitude, given that the “Average Annual
Daily Rate” is of 4,000 trucks/day in direction to the disposal sites, while the increase
FACTOR
MITIGATION MEASURE
due to the works will be 240 truck/day (6 %). Moreover, in the opposite direction the
“Average Annual Daily Rate” is of 32,000 truck/days being the 240 trucks returning to
the working area wholly empty.
Urban area
The facilities must be built and maintained in such a way to ensure safety conditions
for both the staff and the surrounding population.
The work areas will be reduced as much as possible, keeping them with appropriate
health and safety conditions.
The working timetable will be minimized, complying the estimated schedules.
Population/
Safety
The affected population will be recorded with adequate anticipation in order to
prevent the inconveniences they would eventually undergo.
The facilities, work accesses, derivations, hazards and risks will be communicated by
visible signals.
Safety measures will be adopted to avoid accidents (fences, footbridges, etc).
In all the areas affected by the works, the accesses to the houses, workplaces and
parking will be facilitated as much as possible.
The work schedule time will be minimized as much as possible, avoiding whether
possible the development of activities during the night.
Use of land
and urban
equipment
Written authorization will be required for land occupation needed for the works.
All the needed authorizations for public services supply and street occupation will be
managed in due time and manner.
Those areas or sites temporarily occupied by the facilities and works will be
recovered as much as possible to their original condition, excepting those new
components aimed to improve the community quality of life. In such a case a written
authorization should be requested, either from official organisms or private owners.
Economic
activity
Economic directly affected facilities will be reported, as well as the objectives and
estimated duration and expected impacts of the works.
The facilities, work accesses, hazards and risks will be clearly marked.
In all the affected areas by the works, provision should be made to facilitate the
access of staff and suppliers to the workplaces.
The work duration will be shortened as much as possible.
Transit
The areas affected by the works, such as streets and avenues will be reduced as
much as possible.
Facilities, work accesses, derivations, hazards and risks will be clearly indicated, in
order to allow the circulation of heavy transport.
All needed detours to be made during the works will be visibly and adequately
signalled, indicating alternative ways.
Changes of passenger transportation itinerary will be immediately reported.
All applicable legislation related to transport and transit must be strictly obeyed.
Cultural
heritage
The finding of archaeological or historic areas of interest will be treated according to
the current legislation. In case of findings, works will be transitory interrupted with the
intervention of the competent authority. The contractor must cooperate through
protection of the site, assessment and transport to a proper deposit.
Interference
transport with
roads
accesses
New circuit for bus transport lines affected by the works will be established as soon
as possible.
Transport firms will be informed in due time and manner when they are affected
circuit changes.
Derivations and alternative routes will be reported in time and manner by massive
communication means.
FACTOR
Interference
service
infrastructure
Labour
MITIGATION MEASURE
The Supervision will consider and approve the location of the places where energy
and water necessary for the construction and provision of work places will be
extracted
Water extraction for construction should not diminish the availability of sources for
water supply for people housed by the area of influence of the work.
All the necessary procedures for the provision of essential services will be
implemented with adequate anticipation to the involved companies (e.g., EDENOR
and EDESUR for electrical supply, Aguas Argentinas for the water, etc.).
Regulations related to health and safety at work will be strictly obeyed .
All the staff will be trained in relation to health and safety measures, education,
keeping good manners, and environmental awareness.
15. MITIGATION MEASURES FOR THE OPERATION AND MAINTENANCE STAGES
46. According to the Environmental Impact Study, the negative effects estimated for the
operation phase will not be significant, and will be largely compensated by the benefits of the
project. It is expected it will improve the population quality of life, and the assets protection.
Mitigation measures must be focused to ensure the accomplishment of environmental, health
and safety regulations. They are referred as follows:

Periodical tunnels maintenance (estimated annually) in order to avoid sediment
accumulation, exotic bivalves fouling of conducts (“bio fouling”).

Population access restriction to discharge pumping chamber areas.

Conservation and maintenance of discharge chamber area, to avoid landscape
alteration.

Drainpipe maintenance, inlets, manholes, function boxes, urban debris or other
materials elimination, to ensure their proper performance.
16. ENVIRONMENTAL MANAGEMENT PLAN (EMP)
47. The EMP will include subprograms, projects and activities aimed to implement the
different mitigation measures. (See Table V)
TABLE V. ENVIRONMENTAL MANAGEMENT PLAN
PROGRAMS AND OBJECTIVES
PROGRAM
Institutional
Coordination
Community information
Staff training
Health and safety at
work
Environmental
monitoring and
supervision
OBJECTIVE
To coordinate with authorities and related institutions dealing with roads,
infrastructure use and service networks issues; for the construction and
coordination with related authorities in current environmental policies,
including the EMP for archaeological resources.
To inform and contain themselves the affected community and other
stakeholders.
Training to different company levels staff about environmental conservation,
protection and conservation during project construction and operation.
To implement and control health and safety regulations regarding the
protection of all the staff.
To control and supervise quality indicators selected according to legal
requirements, in surface, groundwater, air and land during construction and
operation.
Environmental related To implement tasks to prevent impacts in the event of natural or man-made
accidents
contingencies, like fires, explosions, leakages, and accidents.
To stimulate population awareness about the need of water care and wise
Environmental Training use; to prevent its contamination and depletion, and to maintain clean the
storm water inlets and to promote solid waste adequate treatment.
EMP quality and
management control
EMP Audits
Identification of responsible institutions to ensure EMP and mitigation
measures fulfilment.
To ensure transparency of EMP and mitigation measures accomplishment.
17. PARTICIPATORY APPROACH
48. Aside of the project, the City of Buenos Aires has created a formal organization (Mesa de
Dialogo ambiental) where public institutions and environmental NGOs meet on a regular
basis. On September 7, 2004, the City Government presented a comprehensive version of
the project. Twenty one local NGOs assisted and had the opportunity to react and give their
comments. They all agreed on the long term positive impacts of the project and expressed
their agreement with the EMP for the construction period. The participants also agreed on
pursuing the dialogue with the City during the next phases of preparation and
implementation.
18. PUBLIC CONSULTATION
In order to fulfil requirements of OP. 4.01 concerning Public Consultation, the SUPCE
considered necessary to carried out two main activities:
a) Environmental Dialogue with Representative Non Governmental Organizations.
The meeting took place at the Government House of the City of Buenos Aires on September
6, 2004. Relevant authorities of the City House as well as sixteen NGOs attended the
meeting.
The first activity was aimed to discuss the following issues related to the Environmental
Agenda: Environmental Urban Plan, Metropolitan Policies, Waste Management, MatanzaRiachuelo Basins and Rio de la Plata Coastal Plain, and Local Government Management.
Among the NGO interventions it was remarkable a criticism referred to the lack of information
attributed to the Government Environmental Control Area. Other observation was related to
the management of the Ecological Reserve “Costanera Sur”.
Afterwards the Maldonado Basin Executive Project was firstly presented by the Head of the
Executive Unit (UECBA-SUPCE), followed by an exhaustive presentation by staff members
of the Unit. Different aspects were discussed by NGO and GO representatives, being the
presentations positively regarded. The main issues included aspects related to the
construction techniques, and environmental impacts identification and mitigation.
b) Project presentation to the Center of Participation and Management
The presentation took place at the “Club Atlanta” on September 24, 2004. This meeting main
objective was to inform the project status to the direct beneficiaries by the project.
Firstly, SUPCE staff members presented the Hydraulic Master Plan and the Maldonado
Basin Executive Project. Neighbours have made questions and observations, most of them
related to the work costs and duration, and non structural measures.
Even though, some criticism was made, principally related to the historical lack of efficiency
of former infrastructure project, it was considered as a positive fact the clear proposal of
mitigation measures.
The public was somewhat sceptical. Nevertheless, the technical rigor showed by the project
design stimulated a hopeful feeling of the assistants.
The project was welcomed by the public affected by the floods. They expressed that they
prefered the inconveniences brought about by the works than those derived from the floods.
There was agreement in that the work is aimed to improve the quality of life of the population
housed by the areas threatened by flood events.
Finally, it was recommended to promote a more active participation of the neighbours.