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

687 Republic of Senegal THIRD WATER PROJECT "INTERIM PHASE" DRINKING 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 conceming 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 impacts connected to water and drainage ...................................... 21 6. ALTERNATIVE ANALYSIS OF PROJECT ................................. 23 6.1. Absence of overall altematives ................................. 23 6.2. Individual or technical altematives ................................. 23 7. MEASURES OF COMPENSATION TO THE BENEFIT OF THE ENVIRONMENT .27 7.1. Compensatory measures and recommendations conceming 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 conceming 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 SWdy Patrick LAURAS J Jean Luc PIGEON THIRD WATER PROJECT SETUDE - 11, bd Pershing 75017 PARIS INTERIM PHASE T61. 16 (1) 45 72 97 60 - Fax. 16 (1) 45 72 97 63  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 0 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;