Senegal - Third Water Supply Project : interim phase drinking water component - environmental impact study (Vol. 1 of 2) : Partial volume

v. PmILE COpy Republic of Senegal THD WATER PROJECr 'TINERIM PHASE" DRINAING WATER COMPONENT Environmental Impact Study Patrick LAURAS/Jean-Luc PIGEON Consulting Engineers SETUDE 11, boulevard Pershing 75017 PARIS E9440 (M) March 1995  TABLE OF CONTENTS 1. SCOPE OF SURVEY 1 2. SUMMARY AND RECOMMENDATIONS 2 3. REGULATION AND ADMINISTRATION FRAMEWORK 5 3.1. For the management of water resources and the supply of drinking water 5 3.2. For the protection of the environment 6 4. DESCRIPTION OF THE PROJECTED INVESTMENTS 7 4.1. Resource immobilization investments 7 4.2. Investments for water transport 8 4.3. Investments concerning the functional structure of the networks 8 4.4. Investments into distribution 9 4.5. Tailoring of needs and resources 9 4.6. Technical summary of installation production conditions 11 5. STATE OF THE ENVIRONMENT AND PROJECT IMPACTS 14 5.1. General data concerning survey area 14 5.2. Underground water resources: current situation and project impacts 14 5.3. Impacts due to layout of piping and construction 19 5.4. Sanitary imnpacts connected to water and drainage 21 6. ALTERNATIVE ANALYSIS OF PROJECT 23 6.1. Absence of overall alternatives 23 6.2. Individual or technical alternatives 23 7. MEASURES OF COMPENSATION TO THE BENEFIT OF THE ENVIRONMENT 27 7.1. Compensatory measures and recommendations concerning the use of water resources mobilized by the project ........................... 27 7.2. Compensatory measures and recommendations concerning the sanitary impacts of the project 32 7.3. Compensatory measures and recommendations concerning impacts due to the piping layout 35 APPENDICES APPENDIX 1 Memos drafted at DAKAR subsequent to the 1st mission (June 1994) 39 APPENDIX 2 Memos drafted at DAKAR subsequent to the 2nd mission (February 1995) 53 APPENDIX 3 Synthetic evaluation of ground water table 70 APPENDIX 4 Maps of neighboring effects 83 APPENDIX 5 Reproduced documents 97 REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 - Fax. 16 (1) 45 72 97 63  2 2.SUMMARY AND RECOMMENDATIONS The survey of the impacts of the 3rd water project upon the environment was carried in the frame of the 2 missions to DAKAR from June 13 to 24 1994 and from February 8 to 24 1995 inclusive during which the main departments concerned by the CAP VERT water supply project were encountered, with the Ministry of Hydraulics, with SONEES, with the Cayor Canal survey mission. In the field, all the installations of the installations and the layout of the new pipes have been reconnoitred entirely. 2.1. Potential impacts of the project on the underground-water resources are acceptable as long as a careful follow-up policy is applied r Impact of the new drawing off considered in the North Coastal ground-water is moderate. Potential drawing-off from the ground-water table and its piezometric evolution have been evaluated by BRGM in 1992 thanks to modelling of the ground-water table behavior and demonstrating that: water exports by evaporation are in the great majority: 300,000 m3/day in 1992 with only 70,000 m3/day drawn off; * the loss induced by the new bore holes (35,000 m3/day) will not be felt on the north-south piezometric dome which protects the North Coastal ground-water table against the invasion of salt water; the effect of the bore holes will only be felt on the GUEOUL-THIES line i.e. near the layout zone: the induced drop should be around 2.5 to 5 meters over 15 years, acceptable considering the depth of the aquifer. However, it should be pointed out that under the current climatic conditions, the resource of the North coast is not perennial and the implementation of a long-term supply project, like the Cayor canal, should make it possible to reduce the water drawn off. r On the other hand, the resources in the CAP VERT region are a justified subject of concern. A considerable drop in the level of some of the aquifers have been observed. However, these drops are not a consequence of the project but result from the current drawing off of the ground- water table on the peninsula and the limestone ground-water table of POUT and SEBIKOTANE. It will be possible to maintain this amount of drawing off in the interim phase as long as piezometric evolutions are followed up regularly and critically together with the chlorine contents, sign of a possible intrusion by salt water. The amounts of water taken for WS at CAP VERT are from ground-water which, in some cases, is barely being refilled at the present time. Therefore, we have to insist upon the fact that the supply scheme for water to CAP VERT, in the interim phase is necessarily provisional. It would be very inadvisable to count on maintaining this amount of drawing off beyond a period of 10 or 20 years. r The report recommends a number of accompanying measures for the project. To some extent, this concerns arrangements for following up the evolution of the ground water used for WS in CAP VERT: creation of 21 supplementary piezometers (already provided for in the GERSAR/BETURE draft project); REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 1 1, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  3 requirement to confrmn the organization already set up by the Hydraulics Management (Direction de l'Hydraulique)and SONEES so as to follow up on a monthly basis 88 piezometers (to which the 21 piezometers to be created must be added); need to establish a forecast frame of reference for the piezometry of the North Coastal ground-water table so as to react in the event of the real piezometry drifting with respect to the forecasts of the BRGM model under the responsibility of the water resources management and planning department; need to stipulate a regulation for checking the water drawn off by a decree applying to the water code law. and, to some extent, the recommendations and compensatory measures: * regular cleaning of the PANTHIOR dam to improve the refilling of the SEBIKOTANE ground-water table; * preliminary survey to create other water refilling retainments; establishing of a budget provision in order to be able to compensate for the drying up (or more probably the drop in the flow-rate) of several village wells near the new bore holes on the North Coast (deepening of the wells or connection to SONEES pipes) at the expense of the owner. 2.2. Impacts upon the environment and neighborhood of the installations are generally very limited r There are three potential impacts that are worth mentioning at this stage: the crossing of the PIKINE - DAGOUDANE - THIAROYE built-up area will require particular attention conceming the work on the site in order to minimize the effects of nuisance upon the populations; the construction of the MAMELLES reservoir is in a sensitive area; crossing a number of the gardens will have a temporary effect upon the "market gardening" process. REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  4 r The main recommendations made in this study concern: the need to establish particular technical arrangements on the site for contractor consulting when crossing dense urban zones is involved (sheet piled excavations, rapid covering of trenches, maintained access to homes, etc.) and for the safety of the people concerned; * the need to pay attention to how the Marnelles reservoir is inserted while complying with the natural topology of the site; * the need to provide for financial compensation in the event of temporary market garden produce loss; * the need to ensure repair of the sites for crossing the listed forest of Pout and the rewooding perimeter of Mbaw. 2.3. The sanitary impacts of the project are rather positive r The project will serve districts where inhabitants do not have running water in their homes at the present time (43,000 social connections are scheduled). This impact will be positive on the populations concerned. r However, it is certain that the water shortage will continue and that there will still be cuts, less numerous than at the present time, during the first years of the interim phase. It is important to underscore the fact that to attenuate this shortage, SONEES is committed to a water savings policy by searching for leaks and locating outdated networks, by anti-waste communication, etc. In 1994, using its own capital, it will refurbish a 40 km line (out of a total line length of 1600 km). This considerable effort have to be maintained for several years and it would be worth reinforcing it with a tertiary network renewal program forming part of the distribution section of the 3rd water project. r From another standpoint, fears about the risks of reinforced pollution caused by dumping into the sea are unjustified. r However, pollution by nitrates from the THIAROYE sand layer could lead to a problem of drainage connected to high urbanization and is liable to become increased. The current contents are already very high (150 to 300 mg/A) and therefore, it is advisable to: maintain the current device to dilute this water more before putting it into distribution (connection to ALG 1); carefully monitor the nitrate contents and their bacteriological levels; REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  5 3.REGULATION AND ADMINISTRATION FRAMEWORK Before going on to analyze the project and its impact, we have to briefly outline the regulation and administrative framework of the water and environmental sectors in Senegal. 3.1. For the management of water resources and the drinking water supply r The government is the authority as concerns water in Senegal, on the basis of the following principles: water production, transport and distribution are public and governmental services (law of July 19, 1965); hydraulic resources are part of the public domain. Their use comes under government control (law of March 4, 1981 concerning the Water Code), as is water dumping. At the present time, the Hydraulics Department at the Ministry of Hydraulics is responsible for these skills, with three different departments: one department in charge of following up the rural WS (DEM); one water resources management and planning department; one drainage division. r The production and dilution of drinking water in the urban environment has been delegated to SONEES, a national company under government authority. This "delegation" is comparable to a concession i.e. the government assets required by WS have been transferred to SONEES (law of July 5, 1983 and decree of August 1, 1983). Accordingly, investments in the drinking water supply field are made by SONEES, the owner. As far as drainage is concerned, "delegation" is more like licensing because the government is owner of the networks and equipment managed by SONEES. REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  6 r An institutional reform should be taking place in the framework of the "3rd water project". The general outline of the reform has been sketched out by consultant HSD ERNST and YOUNG: they will be the subject of negotiations in the near future. In the following, we only point out the highlights concerning the "environmental management" section of our survey, considering them as working hypotheses: * the ownership of the equipment and prime contracting of the work will be covered by a national company; * the management of the equipment, water distribution and relations with clientele will be handled by an operating company via a licensing contract; * govermmental facilities for exercising its authority and control may be improved by establishing a go-between organization between government and users (Higher Water Council) and a technical organization having the necessary personnel and a budget (Higher Water Commission). Refer to appendix 5.1 for more details. 3.2. For the protection of the environment Three documents can be mentioned with respect to this impact study: * the decree of January 1, 1950 for the protection of green areas and forestry reserves: the MBAW forestry reserve is concerned by the project; * the decree of June 27, 1978 for the protection of traditional villages (the project avoids them); * a decree regarding the protection of monuments, historical and archaeological locations. The MAMELLES location is protected in this way. REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  7 4.DESCRIPTION OF THE PROJECTED INVESTMENTS The investments projected for the interim phase to reinforce the WS of CAP VERT can be described by four main sub- systems: investments to mobilize additional resources; water transport investments; investments concerning the functional structure of the networks; investments into the distribution networks. The total cost of the investments comes to 116 billion francs to which must be added approximately 5 billion for prime contracting. Figure 1 identifies the main investments in a schematic diagram. 4.1. Resource mobilization investments During the interim phase, it should be possible to increase the resources available to CAP VERT from 191,000 to 262,000 m3/day. To do this, it is intended to raise the capacity of the NGNITH water treatment station from 39,000 to 64,000 m3/day and to sink 11 bore holes into the ground-water table of the North Coast for a capacity of 35,000 m3/day. r Bringing the NGN1TH station up to level The NGNITH works was commissioned in 1971. It was designed to handle 64,000 m3/day (some civil engineering sections were even designed for 132,000 m3/day: exhaust station). Installing several electromechanical equipment items was, however, deferred to the point that the effective capacity never exceeded 39,000 m3/day. Bringing the works up to level so that the capacity reaches 64,000 m3/day means carrying out a series of local operations: * reinforcing the pumping and discharge capacities; bringing some equipment up to level; making some major civil engineering repairs (filter bases, decanting devices); * partial automation (dosing, washing of filters, extraction of sludge from the decanter); * creation of a 3000 m3 reservoir. The cost of these investments is estimated at 2.313 billion F.CFA (SONEES estimation after devaluation). REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  8 r Creation of 11 bore holes operating at 125 to 150 m3/hour in the North Coastal ground-water table Subsequent to the BRGM study and to the water resources of the North Coastal ground-water table (results given in section "impact analysis"), it was decided to reinforce the drawing-off capacities from 27,000 to 62,000 m3/day. The holes will be located near the centerline of national highway 2, spread out over forty or so kilometers between GUEOUL and KELLE. They will be connected to the new conduit by discharge pipes having a diameter of 300 mm. They will be identical in design to the existing SONEES holes. The cost of the bore holes is estimated at 3.515 billion F.CFA (SONEES estimation after devaluation). r To accompany these investments, the piezometer network will be densified: 21 new piezometers will be installed, added to the 140 existing piezometers. The estimation amounts to 706 million F.CFA. r In the THIES region, it is also intended to install 2 supplementary bore holes to supply the city, estimated at 838 million F.CFA. 4.2. Investments for water transport The transport of the new resources from NGNITH and the North Coast area to CAP VERT will be by the partial doubling of the existing "ALG" conduit: 103 km 1000 a piping between GUEOUL and THIES and 54 km 1500 0 piping between THIES and DAKAR. In general, the new supply pipes will follow the ALG pipe. They will depart from it over a distance of several kilometers to cross inhabited or built-up areas. The cost of the 1000 0 pipe is estimated at 38.88 billion F.CFA and that of the 1500 o pipe at 39.74 billion F.CFA. 4.3. Investments concerning thefunctional structure of the networks r The project provides for the implementation of a remote management system installed at point B (arrival and dispatching point for the water resources). This will be a complete monitoring, alarm, control and measurement system working on the networks with 6 secondary plants and 49 satellites. The installation cost is evaluated at 2.9 billion F.CFA. r A large 25,000 m3 reservoir has to be installed alongside the existing reserves of MAMELLES. It will practically double the capacity of the total current reserves at DAKAR-PIKINE (35,000 m3). Costs are estimated at 2.4 billion francs CFA. REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  9 4.4. Investments of the distrihution section This concerns all the investments related to the CAP VERT distribution networks: * restructuring of the primary networks and interconnections (approximately 105 kIn); * renewal of any old leaky pipes (approximately 45 km); * extension of the distribution networks to new districts (approximately 400 km); * continuance of the "social connections" policy (approximately 43,000 new connections); * equipping of the distribution networks with meters, analyzers and pressure gauges to be incorporated into the remote management system outlined above. The distribution investments are estimated at 27 billion francs CFA of which 2.5 billion went to prime contracting. 4.5. Tailoring of needs and water resources The CAP VERT population represents approximately 2,000,000 inhabitants today. It should continue to increase at a rate of approximately 5% per annum. This extremely fast development among the DAKAR population explains the outstanding water requirement upsurge (although forecasts are based on constant requirements per subscriber): * the average theoretical requirements work out to 280,000 m3/d in 1992 i.e. the deficit regarding average requirements was around 30%; for the 1999 horizon, the average theoretical requirements will be around 380,000 m3/day; the deficit will still be around 35% in spite of recourse to new resources during the interim phase. Accordingly, the goal of the interim phase may not be to re-establish balance between needs and resources but simply to preserve the water supply situation awaiting a large-scale structuring project such as the CAYOR CANAL which should resolve the problems at DAKAR to the year 2020 at the least. This provisional nature of the drawing-off from underground resources in the interim phase is essential in analyzing impacts as proposed in the following paragraph. REPUBLIC OF SENEGAL Environmental Impact Study Patrick LAURAS / Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE Tel. 16 (1) 45 72 97 60 -  4.6. Technical summary of the work production conditions The layouts of the large pipelines have been defined generally by GERSAR/BETURE (modified "mission 0" reports), far more accurately than before with engineering studies concerning the detailed pre-production project: only minor changes are liable to be made to these layouts that we have checked through from end to end as part of assignments in DAKAR for the impact survey. More generally, impacts on the neighborhood are small compared to the amount of investment. This is due to the fact that the pipes are laid underground and that ground equipment is almost all located on sites that have already devoted to WS. The engineering studies in terms of the detailed re-production proLect lead to the following indications: An expected work duration of 2 years from 1996 to 1998. The implementing of the Cayor Canal is to take place between the years 2000 and 2005 and the operation of the interim phase will take between 3 and 8 years, better establishing the provisional drawing-off device regarding the underground resources (as a reference, in 2002 and according to mission 0, the deficit of the needs with respect to the resources was 4 1%). A soil survey campaign was started in July 1994 to distinguish between five types of soils: laterites, limestone marnes, plastic and sandy clays, clayey or silty sands and sands whose physical, mechanical and chemical characteristics have been determined. A detailed topographic survey was engaged on the Thies-Dakar section beginning in July 1994 with the survey of study bands of 30, 50 or 100 m and the marking out of the control axis. This topographic surveys led to the underpinnings of maps to 1 :1000th and to lengthwise detailed profiles down to 1 :100th in elevation in urban areas so as to define the constraints of the layout accurately. From Thies to Dakar, the layout will run parallel to the existing pipe (ALGI) except in two places: - the descent from the Thies plateau to allow for the right of way of the Cayor canal, - the crossing of the Thiaroye-Pikine urban area, characterized by fast and uncontrolled development of urbanization and by a group of constructions that it would be difficult to penetrate. The layout in the Thiaroye-Pikine urban area was retained, after land surveys and acknowledgement of restructuring projects provided for on the site. Accordingly, the layout follows that of the Bonna pipe in the crossing of the Mbaw wooded perimeter, runs along that perimeter via the North, follows the future layout of the motorway to the South in the unconstructed area (North of the police station), crosses a dense dwelling area, following the streets so that the machinery can pass without the homes being demolished, runs along the North motorway layout in the unbuilt parts of the Faidherbe camp, follows the main tracks of the Guinaw Rails to avoid any damage to the existing constructions and meets back on the layout of the existing ALG to the North at the intersection with the SNCS track at Pikine. At this level, two homes will have to be destroyed as they fall within the right of way of the existing pipeline.  Between Thies and Dakar, the technical characteristics of the works will take into consideration passages of infrastructures (SNCS track) to enable one of the two ALG pipes to be used in the event of maintenance or repairs while maintaining most of the flow, and integrate the future reinforcing constraints in the Cayor Canal phase. Finally, the part of the development chosen gives privilege to the visual and landscaped impact while using a totally buried layout between Thies and Dakar. The production construction conditions are as follows: - minimum right of way of 20 m during work on site outside ofthe urban areas (10 to 12 m after construction), - excavation material placed on the existing pipe but limited to a height of 3 m, or evacuated for sites in the urban areas, - the possibility of setting slight deviation angles on the pipes to avoid the main baobab trees in the line of the layout, - maintained water services during the work, - sheet piled excavations for the crossing of urban areas, - work carried out in the dry season in areas sensitive to erosion (e.g.: the Thies plateau). Acknowledgement of pipe laying constraints will require the following of the contractor: - servicing and maintenance of all the tracks to be used, - setting up signposting and providing the necessary information, - maintaining all the passages providing access to the land lots and the circulation of livestock, - minimizing impact upon the surrounding crops by avoiding destruction of hedges and tall standing trees, - the setting-up of all necessary arrangements to prevent the run-off of site water, - reduction to 15 m of the right of way in crossing the Mbaw perimeter.  5.STATE OF THE ENVIRONMENT AND PROJECT IMPACTS Analyses of the initial state of the environment and the impacts of the project have been grouped together here to make for easier reading regarding problems resulting from the project. 5.1. General data concerning the survey area The population of the DAKAR built-up area is estimated at 1.58 million inhabitants in 1993 and it is expected to reach 3 million inhabitants in 2010 (i.e. 25% of the country's total population) with an annual growth rate of 5 to 6%/annum (directorate of forecasts and statistics). The climate is sub-desert tropical with a dry season and a wet season from July to September when 90% of rainfall occurs. The rainfall in the project area is 400 mm/annum with heavy showers sometimes exceeding 150 mm in 24 hours and above all, 50 mm in one hour. The mean annual temperature between 1955 and 1989 was approximately 24