Environmental Impact Assessment Project Number: 41924 July 2014 Document Stage: Final Nam Ngiep 1 Hydropower Project (Lao People’s Democratic Republic) Appendix D: Environmental Flow Assessment Report Prepared by Nam Ngiep Power Company Ltd. with assistance from ERM-Siam Co., Ltd. and Environmental Research Institute, Chulalongkorn University for the Asian Development Bank. This is an updated version of the draft originally posted in January 2012 available on http://www.adb.org/projects/documents/nam-ngiep-1-hydropower-project-results-eia The final report is a document of the borrower. The views expressed herein do not necessarily represent those of ADB's Board of Directors, Management, or staff, and may be preliminary in nature. Your attention is directed to the “Terms of Use” section of this website. In preparing any country program or strategy, financing any project, or by making any designation of or reference to a particular territory or geographic area in this document, the Asian Development Bank does not intend to make any judgments as to the legal or other status of any territory or area. Appendix D Environmental Flow Assessment Report (Originally Prepared by Kansai and Amended by ERM) Nam Ngiep 1 Hydropower Project Environmental Flow Assessment Report NAM NGIEP 1 POWER COMPANY LIMITED July 2014 0185065 www.erm.com The world’s leading sustainability consultancy FINAL REPORT NAM NGIEP 1 POWER COMPANY LIMITED Environmental Flow Assessment Report Prepared by The Kansai Electric Power Company, Inc., (Kansai, January 2012) Updated by ERM-Siam Co., Ltd. (July 2014) Reference 0185065 For and on behalf of ERM-Hong Kong Co., Ltd. Approved by: Terence Fong Signed: Position: Partner Date: 10 July 2014 This report has been prepared by Environmental Resources Management the trading name of Environmental Resources Management Ltd with all reasonable skill, care and diligence within the terms of the Contract with the client, incorporating our General Terms and Conditions of Business and taking account of the resources devoted to it by agreement with the client. We disclaim any responsibility to the client and others in respect of any matters outside the scope of the above. This report is confidential to the client and we accept no responsibility of whatsoever nature to third parties to whom this report, or any part thereof, is made known. Any such party relies upon the report at their own risk. CONTENTS ABBREVIATIONS III 1 INTRODUCTION 1 1.1 BACKGROUND 1 1.2 PROJECT DESCRIPTION 2 1.3 PURPOSE OF THE ENVIRONMENTAL FLOW ASSESSMENT 4 2 PHYSICAL AND HYDROLOGICAL ENVIRONMENT OF NNP RIVER 6 2.1 TOPOGRAPHY 6 2.2 NNP RIVER BASIN 7 2.3 METEOROLOGY AND HYDROLOGY 9 2.4 SEDIMENT 21 2.5 WATER QUALITY 23 2.6 DOWNSTREAM GEOMORPHOLOGY 28 3 EXISTING BIODIVERSITY AND ECOSYSTEM SERVICES OF THE DOWNSTREAM NAM NGEIP RIVER 33 3.1 DOWNSTREAM BIODIVERSITY 34 3.2 DOWNSTREAM ECOSYSTEM SERVICES 43 4 CHANGE OF DOWNSTREAM FLOW REGIME DUE TO THE PROJECT 51 4.1 CHANGE OF FLOW REGIME 51 4.2 CHANGE OF WATER QUALITY 55 5 ENVIRONMENTAL FLOW FOR NNP1 PROJECT 59 5.1 ENVIRONMENTAL FLOW OF OTHER HYDROPOWER PROJECTS IN LAOS 59 5.2 PROPOSED ENVIRONMENTAL FLOW 60 6 ENVIRONMENTAL FLOW ASSESSMENT 68 6.1 EVALUATION OF CHANGE IN ENVIRONMENTAL FLOW ON DOWNSTREAM BIODIVERSITY AND ECOSYSTEM SERVICES 68 6.2 WATERSHED MANAGEMENT ACTIVITIES IN THE NAM NGIEP WATERSHED 72 7 MONITORING PLAN 74 7.1 HYDROLOGIC AND WATER QUALITY MONITORING PLAN 74 7.2 WATER QUALITY STANDARD 77 7.3 FISH MONITORING PLAN 77 REFERENCES 79 ENVIRONMENTAL RESOURCES MANAGEMENT NAM NGIEP 1 POWER CO., LTD 0185065 ERM EFA revision_FINAL.docx 10 July 2014 i ANNEXES Annex A Water Quality Test Results Annex B Fish and Fisheries Survey Locations along the Nam Ngiep River in January 2008 Annex C Non uniform Flow Analysis Annex D Release of Environment Flow ENVIRONMENTAL RESOURCES MANAGEMENT NAM NGIEP 1 POWER CO., LTD 0185065 ERM EFA revision_FINAL.docx 10 July 2014 ii ABBREVIATIONS ADB Asian Development Bank BOD Biochemical Oxygen Demand COD Chemical Oxygen Demand DO Dissolved Oxygen EFA Environmental Flow Assessment EGAT Electric Generating Authorities of Thailand International KANSAI Kansai Electric Power Co., Inc IAP Independent Advisory Panel IUCN International Union for Conservation of Nature and Natural Resources LHSE Lao Holding State Enterprise MSL Height above Mean Sea Level NNP Nam Ngiep NNP1PC Nam Ngiep 1 Power Company Limited TDS Total Dissolved Solids CHEMICAL ABBREVIATIONS As Arsenic Cd Cadmium Cu Copper Fe Iron Hg Mercury Mn Manganese Ni Nickle P Phosphorus Pb Lead 3- PO4 Phosphates N Nitrogen NH3 Ammonia - NO3 Nitrate Zn Zinc ENVIRONMENTAL RESOURCES MANAGEMENT NAM NGIEP 1 POWER CO., LTD 0185065 ERM EFA revision_FINAL.docx 10 July 2014 iii 1 INTRODUCTION 1.1 BACKGROUND The Nam Ngiep 1 Hydropower Project (NNP1 Project) involves construction and operation of a 290 megawatt (MW) hydroelectric power generation facility on a build-operate-transfer basis on the Nam Ngiep (NNP) River, Lao PDR. The NNP1 Project site is located on the NNP River (Figure 1.1), in the provinces of Vientiane, Xieng Khouang and Bolikhamxay, approximately 145 km northeast from the city of Vientiane or 50 km north from Pakxan District. The NNP1 Project will generate 272 MW of its capacity for export to Thailand and 18 MW for domestic supply. Figure 1.1 Project Location The Project will be funded predominantly by private sector funds and the Project proponent is Nam Ngiep 1 Power Company Limited (NNP1PC) whose owners include Kansai Electric Power Co., Inc. (KANSAI) of Japan, Electric Generating Authorities of Thailand International (EGAT) of Thailand and Lao Holding State Enterprise (LHSE) of Lao PDR. Therefore three (3) countries will each benefit from the NNP1 Project which also aims to contribute to poverty reduction amongst the local Lao population through provision of infrastructure, employment and compensation, education and electricity (Figure 1.2). ENVIRONMENTAL RESOURCES MANAGEMENT NAM NGIEP 1 POWER CO., LTD 0185065 ERM EFA revision_FINAL.docx 10 July 2014 1 Figure 1.2 Benefit of the Project Nam Ngiep 1 Hydropower Infrastructure Project Compensation Construction & Operation Employment Education Electricity Electricity An initial Environmental Flow Assessment (EFA) was prepared for the NNP1 Project by KANSAI in August 2012. The Asian Development Bank (ADB) and the Project’s Independent Advisory Panel (IAP) made comments on the initial EFA report and requested that NNP1PC revise it. NNP1PC has therefore contracted Environmental Resources Management ERM- Siam Co. Ltd (ERM) to undertake this task to fill gaps in the initial EFA study to the satisfaction of ADB’s requirements. 1.2 PROJECT DESCRIPTION The NNP1 project consists of a main power station and a re-regulation power station. The main power station is designed to have a capacity of 272.0 MW and annual power generation of 1,515.0 GWh. The re-regulation dam is planned to re-regulate and stabilize the maximum plant discharge of 230.0 m3/s released from the main power station for the safety to the downstream area of the re-regulation dam. The re-regulation power station is designed to have 18 MW and annual power generation of 105 GWh. The main dam creates a reservoir with the normal water level (NWL) at Elevation Level (EL) 320 m and minimum operating level (MOL) at EL 296 m. The effective storage capacity is 1,192 Mm3 at NWL 320 m. The dam inundation area is approximately 72 km length and includes a total surface area of just under 70 km2. The basic specifications of the main features are shown Table 1.1. Table 1.1 Main Features of the Project Facility Items Unit Specifications Main Power Station Main Reservoir Flood water level EL. m 320.0 Normal water level EL. m 320.0 Rated water level EL. m 312.0 Minimum operating level EL. m 296.0 Available depth m 24.0 ENVIRONMENTAL RESOURCES MANAGEMENT NAM NGIEP 1 POWER CO., LTD 0185065 ERM EFA revision_FINAL.docx 10 July 2014 2 Facility Items Unit Specifications Reservoir surface area km2 66.9 Effective storage capacity 106 m3 1,192 Catchment area km2 3,700 m3/s 148.4 Average annual inflow mill.m3 4,680 Main dam Concrete gravity dam Type - (Roller-Compacted Concrete) Dam height m 148.0 Crest length m 530.0 Dam volume 103 m3 2,034 Crest level EL. m 322.0 Spillway Gate type - Radial gate Number of gates - 4 Design flood m3/s 5,210 (1,000-year) Intake Type - Bell-mouth Number - 2 Discharge capacity m3/s 230.0 Penstock Type - Embedded and concrete-lined Number - 2 Length m 185.81 Diameter m 5.2 Powerhouse Type - Semi-underground Length m 25.0 Width m 62.5 Height m 47.2 Maximum plant Turbine and m3/s 230.0 discharge generator Gross head m 132.7 Effective head m 130.9 Type of turbine - Francis Rated output MW 272 (at Substation) Annual power GWh 1,546 (at Substation) generation Voltage kV 230 Transmission line Distance km 125 Connecting point - Nabong S/S Width of right of way m 80 (40 m each side of CL) Number of towers - 262 Re-regulation Power Station Re-regulation Flood water level EL. m 185.9 reservoir Normal water level EL. m 179.0 Rated water level EL. m 179.0 Minimum operating level EL. m 174.0 Available depth m 5.0 Reservoir surface area km2 1.27 at NWL Effective storage capacity 106m3 4.6 Catchment area km2 3,725 Re- regulation Type - Concrete Gravity dam Dam Dam height m 20.6 Crest length m 290.0 Dam volume 103 m3 23.9 Crest level EL. m 187.0 (non-overflow section) Re-regulation Type - Fixed wheel gate Gate Number - 1 Discharge capacity m3/s 5,210 (1,000-year) Saddle dam Type - RCC associate with rock fill dam Crest length m 507.1