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Tender Details
- Country: Somalia
- Summary: Borehole Drilling in Ceel Xume Village
- SOT Ref No: 73642502
- Deadline: 10 Nov 2022
- Competition: ICB
- Financier: Other Funding Agencies
- Purchaser Ownership: Public
- Tender Value: Refer Document
- Notice Type: Tender
- Document Ref. No.:
- Purchaser's Detail :
- Description :
- Tenders are invited for Borehole Drilling in Ceel Xume Village in Odweine District This assignment aims to drill, construct and develop a new borehole in Ceel-xume, ensuring a minimum required safe yield and water quality parameters. The main objective is to develop reliable production boreholes digging 350 m -400m. MOBILIZATION Mobilization shall consist of all, necessary manpower, drilling rig and tools, and construction materials to different sites. Demobilization shall consist of clean-up work and operations including, but not limited to those necessary to the removal of personnel, equipment, and incidentals from the project site. The contractor shall also mobilize all the necessary materials such as water for drilling, drilling chemicals fuels etc, which are required during the progress of the works. DRILLING The contractor shall clear the site during rigging up and excavation of mud pit and measurements shall be the net-in-site volume obtained from the difference between the lines and levels of the ground surface agreed with the Employer before excavation is commenced. Where drawings do not indicate profiles, then these shall be held to be equal to the net plan area with the sides taken as vertical. The contractor shall only adopt mud system since collapse and circulation loss is expected in the area. The contractor shall use different drilling fluid Bentonite, drilling foam etc., with appropriate drilling technique. Units of measurements for drilling shall be in meters and measurements are taken based on geological samples taken after drilling. The rates of drilling shall be based on geological formations. Geological logging shall be performed after the end of each drilling and drawings should be submitted accordingly. Drilling up to the estimated depth shall not necessarily proceed and drilling can be ceased based on the hydrogeological and geological condition when approved by Employer Hydrogeologist (Engineer). The upper unconsolidated shall be drilled 17-inch drill bit. The remaining diameter of the wells shall not be less than 12 ΒΌ inch. The drilling equipment and methods used should be capable of drilling through both overburden and bedrock. If the boreholes are drilled with rotary equipment and the following drilling fluid may be used, Drilling mud containing Bentonite or other clay minerals. Drilling mud composed of water and a thickening agent containing no solid particles. Examples are the starch-based mud, revert, and polymer-based mud such as quick thick. INSTALL CASINGS Surface steel casing of minimum 14 inch might be needed for the upper unconsolidated sediments. Deep boreholes beyond 300 m depth steel preproduction casing and screens of 8" in diameter shall be used The rates of casing (blind or screen) shall include installing up to desired depth. Installations of casings and screens shall be up to required depth as per standards and the geological logs to meet the function of the aquifer and the type of pumps to be used. Minimum wall thickness for all well casing shall be 6 mm. Well screen shall be continuous slot wire wound screens as manufactured by Johnson screens or equivalent. For different sizes, the slot size should be specified by the Engineer after sieve analysis of the aquifer samples. GRAVEL Gravel for drilled wells shall be river gravel, round and having sufficient strength and proper sizes to meet the designed screen for proper filtration (the gravel should be siliceous in composition). Gravel should also be washed with water to remove weathered particles before packing. Gravel shall be supplied and packed up to the required depth and shall be measured in meter cube. Gravel size is selected based on the geological strata of the drilled well. WELL CLEANING AND D EVELO PMENT The well shall be cleaned and developed so as to arrange the positions of gavels for a good filter media so that clean water can be drawn while developing. The time interval for cleaning and developing shall be of minimum twelve (12hrs) and the unit of measurement is in hours (hrs). The well shall be grouted with mass concrete up to a maximum depth of 2m and a well head shall be constructed facilitating a good drainage that protect vertical seepage around the well
- Documents :
Purchaser : AGRICULTURAL DEVELOPMENT ORGANIZATION (ADO)
Hargeisa office, Somaliland
Email :abdirahman@adosom.org
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