EXECUTIVE PROJECT FOR THE ARROYO MALDONADO …



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

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 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 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.

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.

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 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.

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. | |

|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. |( |

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”.

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).

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).

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.

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.

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 |

|Location |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 |Derivation chamber and connection |Derivation chamber and connection |

| |short tunnel and shaft exit of TBM |long tunnel and shaft exit of TBM |long túnel |

|Population density. |155.3 inhab/ha |200.8 inhab/ha |224.8 inhab/ha |

|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, |Mix, with workshops and deposits of |Mix, with great commercial activity |

| |services and big deposits |car parts, with certain degree of |of sales and collocation of car spare|

| | |deactivation. |parts |

|Affects the transit |Slight |Moderate |Intense |

|Point 4- Work quarrier |Punta Carrasco is a recreational area which forms a peninsula in the Rio de la Plata coast including a large open|

|settlement, elaboration of |space with a great vegetal coverage. This area is connected with the Costanera R. Obligado Av., which has a heavy|

|reinforcement concrete |transit. An important transit of trucks enters and leaves the City Port. The TMDA is of 40,000 vehicle/day. |

|segment Discharge work and | |

|starting shaft | |

|Area of about. 20,000 m2 | |

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.

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.

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).

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 |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 |

|equipment |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 |Disturbance of public services, alteration of transit and transport, affectation of resident population activities and welfare. |

|infrastructure | |

|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 |Improvement of the cultural and historic properties, delay of works, possibility of determining other layout alternatives. |

|findings | |

|Closure and abandonment of work |Generation of rubble, emissions of particles and fumes, spill of washing water, alteration of transit and transport. |

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.

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.

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 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/ |The affected population will be recorded with adequate anticipation in order to prevent the inconveniences they |

|Safety |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 |Written authorization will be required for land occupation needed for the works. |

|equipment |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 |New circuit for bus transport lines affected by the works will be established as soon as possible. |

|with roads accesses |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. |

| | |

|Interference service |The Supervision will consider and approve the location of the places where energy and water necessary for the |

|infrastructure |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.). |

|Labour |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. |

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.

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 |OBJECTIVE |

|Institutional |To coordinate with authorities and related institutions dealing with roads, infrastructure use and |

|Coordination |service networks issues; for the construction and coordination with related authorities in current |

| |environmental policies, including the EMP for archaeological resources. |

|Community information |To inform and contain themselves the affected community and other stakeholders. |

|Staff training |Training to different company levels staff about environmental conservation, protection and conservation|

| |during project construction and operation. |

|Health and safety at work |To implement and control health and safety regulations regarding the protection of all the staff. |

|Environmental monitoring and |To control and supervise quality indicators selected according to legal requirements, in surface, |

|supervision |groundwater, air and land during construction and operation. |

|Environmental related accidents |To implement tasks to prevent impacts in the event of natural or man-made contingencies, like fires, |

| |explosions, leakages, and accidents. |

|Environmental Training |To stimulate population awareness about the need of water care and wise 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 |Identification of responsible institutions to ensure EMP and mitigation measures fulfilment. |

|control | |

|EMP Audits |To ensure transparency of EMP and mitigation measures accomplishment. |

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.

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, Matanza-Riachuelo 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.

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