Guyana project Task 1 - East Demerrara Water Conservancy Drainage and Dam Security Study The East Demerara Water Conservancy (EDWC) is a freshwater impoundment located in region 4 above the most densely populated section of the Guyana coast. It is bounded to the north by a 20 mile earthen dam structure build some 150 years ago and to the south by the natural topographic rise composed largely of ancient coastal dune formations. The area consists of an impoundment of some 550 hectares and ranges in depth to approximately 15 feet along the dam. The conservancy provides a source of drinking water for the Guyana's capital, Georgetown but primarily serves to provide irrigation water during Guyana's two dry seasons for the intensively cultivated lands to the north. Irrigation demand is high as the principal crops for the region are sugar cane and rice, the country's principal export crops. The dam is variously constructed of earth and organic material (pegass) depending on the section involved. It has been intervened by numerous water control structures and cuts, many of which have been abandoned over the years. Deterioration of the structure over the years coupled with severe stress events have served to weaken the structure. During the floods of 2004-2005, the dam was overtopped due to high rainfall levels and it is clear from aerial surveys that the structure is creeping, particularly along the east end of the structure. This is the portion where pegass was the principal material of construction. The objective of this task is to produce a comprehensive engineering analysis and assessment of the dam and its associated water control structures. On the completetion of this task, all relevant studies and bidding documents will be prepared for international tend Under this task, the contractor will: 1.Provide a comprehensive evaluation of the structural integrity of the EDWC dam. 2.Locate, map and evaluate all water control structures associated with the dam including structures in service, abandoned water control structures and clandestine cuts. 3.Develop engineering designs, plans and implementation program for the repair and reconstruction of the dam and water control structures consistent with maximum possible flood based on a 1,000 year return period. 4.Assess and identify additional constructions, equipment necessary for dam maintenance and monitoring. 5.Develop a comprehensive maintenance and monitoring plan for water management and dam safety. 6.Identify and catalogue regional sources for suitable construction materials and logistics options. 7.Produce required environmental assessments relating to the dam rehabilitation project including physical works, material extractions transportation and other relevant aspects of the project. 8.Prepare bid specifications, tender packages and notifications required under World Bank and InterAmerican Bank procurement regulations. Task 2 - Topographic Mapping and drainage analysis, and drainage improvement for region 4 coastal lowlands In region 4, the East Demerara Water conservancy lies to the south collecting much of the natural water flow to the coastal north and for agricultural storage. Lowlands to the north are reclaimed lands from tidal areas of the coast and have been impouldered in many areas to provide land for agriculture and development. Much of this land lies below mean sea level and is protected by the EDWC dam to the south and a seawall to the north. Over years of changing landuse, drainage ditches and drainage structures have been constructed modified or abandoned to accommodate changes in land use. No comprehensive plan has been developed to manage these changes and the effects have been a general deterioration of the drainage infrastructure. At the present time, various elements of the coastal drainage network have been analyzed primarily for agricultural exploitation. Other studies exist relating to the function and status of the sea defense system. At the present time, there is no comprehensive analyses of the regions drainage network nor is there a functional topographic base for drainage analysis. Landform model Using airborne Lidar coupled with Color Aerial photography, develop a high resolution high precision topographic model of the East Demerera Water Conservancy and associated coastal lowland area of region 4. During the production of this model, the contractor shall process and refine the raw data and produce a digital model representing: The bare land form Foot prints of structures, roads and other man made structures and trees. Ditch and bank alignments Property ownerships These data will be augmented, where necessary, with ground surveys. The model will be developed using the national geodetic grid and first order ground control points. Model outputs will include raw and finished datasets. Finished datasets will be produced in a DEM digital format suitable for use in programs such as ARCGIS (ESRI), ERDAS (Leica), each pixel shall represent 1 sq. foot ground surface. Vertical precision shall be within 5 cm. As the predominate agriculture in the region is sugar cane and rice, missions will be flown after harvest when dense grass cover is minimized. Drainage analysis and works identification Using the landform model is created, the contractor shall conduct a micro drainage analysis to determine actual water flows in the region, drainage sinks, drainage inputs and outputs, effects of damaged or abandoned drainage structures and local impoundments and develop a rationalized drainage network to mitigate the potential for flooding experienced under the present system. This will then be developed into a microdrainage plan specifically designed to integrate with the existing irrigation system and optimize the ability to manage floodwaters on agricultural lands and in inhabited areas. This analysis shall be presented in mapped paper and digital form suitable for use in ESARI ArcGIS mapping software. Once completed, the contractor shall develop a series of recommendations for drainage works to mitigate potential future flooding, prioritize these works, cost and develop contractor terms of reference for the execution of these works. Works and designs shall be developed to maximize the use of existing structures and systems, gravity based drainage methods and minimize the use of pumps as drainage control where possible. Works will be considered for the coastal lowlands from Shanks Canal west to the Demerara river. Task 3 - Emergency Drainage works, East Demerara Water Conservancy The contractor shall undertake the design and execution of various small works defined under this effort to assist with improving the management of water behind the East Demerara Conservancy Dam. These works will include: Selected ditch improvements Rehabilitation of associated water control structures Improved channeling within the conservancy Opening of additional drainage canals Works to be determined. Works undertaken will not involve construction of new, previously non-existent structures and shall be confined to the rehabilitation and repair of existing structures and drainage complexes. Under this task, works will limited to those activities which do not require the relocation of persons or businesses. Task 4 - Installation of Hydrologic Monitoring Equipment And Data capture Under this task select hydrologic monitoring equipment such as recording weather stations, stream gauges, water level sensing equipment etc. shall be purchased and installed. (need to identify what they already have) Additionally, historical records such as rainfall, stream flow, temperature and tide shall be converted to a digital format compatible with existing systems. Task 5 - Selected equipment purchase and installation Equipment purchased under this task shall be provided to support the management of the EDWC. Equipment may include: Communications support equipment 1 Airboat Safety equipment Generators Dredge and vegetation control equipment Monitoring systems Program Execution and contract management General contractor model to include the dynamic ability to process bids and subcontracts. Contractor shall serve as the project manager and shall assume the responsibility for financial management and project execution. Subcontractors and subcontracts shall require the no objection of the Bank. Bidding shall comply with Bank procurement Rules. Contract shall be between the ???????? Timeline GEF agreement - October 2006 Bid and contract - Prime contractor - December 2006 Mobilization and start work - January 2007 Dam safety and Micro drainage study - January 2007 - November 2007 Initial emergency works and equipment purchase and installation - March 2007 (rainy season December-february) Additional Infrastructure works - October 2007 - 2008