Hydrogeological and Geophysical Investigation for Borehole Sitting

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Tender Organisation:

GARGAAR RELIEF AND DEVELOPMENT ORGANIZATION (GREDO)

Tender Sector:

Management Consultancy Tenders

Tender Service:

Worldwide

Tender Region:

African

Tender Country:

Somalia

Tender CPV:

79720000 : Investigation services

Tender Document Type:

Tender Notice

Tender Description:

Tenders are invited for Hydrogeological and Geophysical Investigation for Borehole Sitting in Walaweyn. HYDROGEOLOGICAL AND GEOPHYSICAL INVESTIGATION FOR BOREHOLE SITTING IN WALAWEYN GREDO GREDO is an indigenous local NGO. Non-profit non-partial, non- political and voluntary organization based in Baidoa. To reach the most affected grass-root communities in Bay and Bakool regions and lower Shebelle effectiv Tender Description Request for consultancy services (REF:GREDO/RQ/8032 LOWER SHABELLE/BHA III - WASH/2023 Terms of Reference HYDROGEOLOGICAL AND GEOPHYSICAL INVESTIGATION FOR BOREHOLE SITTING IN WALAWEYN Reference: GREDO– Ground Water Consultancy Area of Interest: Hydrogeological and geophysical investigation for borehole sitting Location: Lower Shabelle, Somalia-Walaweyn District. Position Type: Consultant/Firm Duration: 14 days Start date: 01th June-2023 INTRODUCTION GREDO is an indigenous local NGO. Non-profit non-partial, a non-political and voluntary organization based in Baidoa. To reach the most affected grass-root communities in the Bay, Bakool, and Lower Shebelle regions effectively and efficiently, the necessity of local partnership in relief programs appeared. Responding to the partnership need, a group of Somali intellectuals and well-wishers initiated in December 1992 a local non-governmental organization called Gargaar Relief and Development Organization GREDO). BACKGROUND As severe drought grips most parts of Somalia, the Lack of safe drinking water access has contributed to staggering levels of diarrhoeal diseases, particularly among the young, the immune-compromised, and the poor. Unsafe water sources complemented by poor sanitary environments are a major cause of malnutrition throughout Somalia. The existing water sources in Lower Shabelle are already overstretched due to the effects of drought on the groundwater levels. While water points do exist, many have fallen into disrepair where communities simply do not have the resources (funds, skills) to repair them. In addition, the continued influx of more IDPs due to floods and persistent floods as well as the closure of WASH programs by some of the humanitarian agencies is putting pressure on the existing water supply system. The current volume of water supplied cannot meet the existing demand. Many of the households cannot meet the recommended 15 liters per person per day as per the Sphere standards. In addition, the recurrent seasonal floods in Beletweyn have also worsened the situation whereby almost all the communities along the riverine areas depend on the river as their source of water. It’s in this grim reality that GREDO is planning to drill some new boreholes in Walaweyn which will serve more than 10,000 people and up to 12,000 people in 20 years (taking into account an average urban growth rate of 4% per annum). By targeting a minimum of 30 litres/p/day, the sustainable discharge rate per day should be above 150 m3 per day, equivalent to 13 m3/h over 12 hours of pumping per day without undesired effect –depletion of the aquifer or changes in water quality. GREDO will engage a consultant firm to carry out a borehole sitting study in the selected location where the new borehole is to be constructed. The objective of this survey is to ascertain the drilled borehole will meet or exceed the water demand for the next 20 years. OVERALL OBJECTIVES OF THE HYDRO-GEOLOGICAL SURVEY To conduct water resource mapping while also conducting the hydrogeological and geophysical investigation for the optimal sitting of a drinking water borehole in Lower Shabelle (Walaweyn district) by assessing Five Villages or sites in Walaweyn. These target locations are aimed at determining suitability for mechanical drilling of borehole SCOPE OF THE WORK The Consultant is expected to use both secondary and primary data in the exercise. Secondary data will involve desk study of available information/data on existing boreholes, drill logs, reports, and maps while primary data will be obtained by carrying out field reconnaissance and measurements of existing boreholes and geophysical prospecting within the studied area using a combination of geophysical methods as below described..: The outcome of the consultancy will be a detailed hydrogeological survey report giving details of the findings and recommendations SURVEY APPROACHES REQUIRED: The hydrogeological/geophysical investigations will be carried out in a multistep approach: a) Desk study: Review of existing data, topographical maps, satellite images, existing studies and borehole site investigations in the area, geological reports and maps (if available), borehole and surface water records, etc. b) Hydrogeological fieldwork: Detailed reconnaissance survey of the project area. (GPS coordinates/P codes, water level measurements, condition of these boreholes, usage, and performance, estimation of the hydraulic characteristics from existing well test and aquifer test, ), vertical geophysical prospecting at known boreholes for calibration purposes: measurement of the real resisitivities of geological formations based on the existing borehole logs. c) Geophysical measurements of vertical and horizontal electric sounding, vertical electric 2D tomography, EM method, and possibly seismic refraction method are recommended for this assignment. d) Analysis and interpretation of field data for the selection of potential sites for drilling e) Presentation of the results to hydrogeologist/geologist experts from GREDO and the Ministry of Energy and Water Resource for validation of the best possible site f) Field validation of the site to ensure there is no obstacle to drilling (explanation and agreement with the community, no land tenure or future urban planning issues, access to the drilling machine, risk of contamination, …) g) reporting REPORTING The final report will contain items a) to f) and will be submitted to GREDO. The report shall include all raw field data in the appendix, interpretations, and justifications, hydrogeological evaluations, conclusions, and recommendations related to the investigated areas. In addition, appropriate maps, diagrams, and data plots shall be presented. Of considerable importance will be an objective assessment of the applicability and success of the methods to be applied. - The outline table of contents of the final report will be as follows: o Executive summary (1 page) o Introduction, review of previous studies and hydrogeological information of the studied area, including the history of groundwater depletion or known changes in quality: mineral content including unharmful –iron- and harmful -fluorides, nitrates…-; and toxic elements such as arsenic; bacteriological pathogens. o Geology and hydrogeology (incl. Inventory of positive and negative boreholes, aquifer characteristics –storage and hydraulic- and well characteristics –sustainable discharge rate- based on available data., and water quality)) o Calibration of the geophysical instrument at known boreholes (yield, log) for the geophysical characterization of the geological formations, including the aquifer(s). o Methods of investigations, including the combination of geophysical methods. o Geophysical prospecting on different sites. o Interpretation and comparison of studied sites: aquifer and borehole potentials, Most suitable drilling site and justification, target aquifer(s) for drinking water production, mentioning assumptions, risks, and risk management. o proposed drilling method, with equipment characteristics (incl. estimation of the casing and screen positions) o Simplified Environmental and societal impact of the drilling and required risks reduction measures o Conclusion EXPECTED DELIVERABLES The consultant/firm is expected to deliver: 1. An inception report presenting 1/ the steps and methodology for the assignment against the present Terms of Reference, and justifying any difference or discard with the TOR ; 2. the implementation plan and requirements for the site investigation. A brief note with the recommended sites selected for borehole reconnaissance and geophysical survey, for GREDO’s validation before the field deployment, 3. The presentation of the fieldwork, interpretations, and conclusions to the GREDO and the water authorities. 4. The final report WORK PLAN ACTIVITY DESCRIPTION Time Line W1 W2 Secondary data collection, review of field documents on existing boreholes and studies, and analysis Key informant interviews (face-to-face or remote) Fieldwork: Reconnaissance of existing boreholes, geophysical prospecting, and final validation of the selected site Presentation to GREDO and authorities, Reporting REQUIREMENTS GREDO seeks to invite qualified consultants/firms who meet the following requirements to submit their detailed narrative and financial proposal on how to undertake the assignment. 1. Technical proposal on how the assignment will be conducted including methodologies, data analyses and interpretation, reports, and schedules. ( List software to be used for analysis) 2. Proven field technical and field experience as a Consultant with a Master’s degree in geology, hydrology, engineering geology, physical, or earth science, or in any related field and having good experience working in this sector. 3. Consultancies performed in the last 10 years, especially with reference letters for each hydrogeological surveys consultancy 4. Proof of availability of all the equipment, personnel, and ability to mobilize them on short notice (Include a list of equipment, Brand/Manufacturer, and CVs of the personnel) to perform the survey. 5. Submit a detailed financial proposal including all professional fees, report costs, and subsistence costs. Please note all costs must be broken down into details (no lump sums, no contingencies, etc.) The consultant/firm will be responsible for their own security; insurance while in the field and GREDO will not

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