NIT 5 Item 3

Removal/extracting of filter media and gravel of various sizes with the help of manual process viz labour, tool & tackles available on filter bed on upper platform of the filter bed and dumping near the house building or as per direction of Engineer-in-charge to filling after completion of under drainage work.

Dismantling of old/existing under drainage system of filter bed viz concrete structure over filtration system & RCC Tee, MS header, pipes etc and to remove the broken debris from the filter bed at a suitable place or as per direction of Engineer-in-charge tackles within the premises of the plant with the help of labour, tool & tackles.

Renovation of damaged concrete slab of back wash channel with cement concrete & chemicals of required grade to make structure strong & leak proof including provision of 80 mm dia. hole for fixing of RCC Tees & other necessary parts in all respect.

Supply of 75mm dia. 6kg. / cm2 HDPE pipe (PE-80) with provision of holes with standard size & spacing to release air & water in length of 1.3 mtr. Each or as per existing arrangements/sample. Make: - ISI, Any DJB approved

Supply & fixing of 75 mm dia. HDPE end cap (Heavy Duty) at one side of 1.3 mtr. HDPE pipe with required T&P items.

Fabrication & Supply of Rubber “O” Ring for fixing of HDPE pipe into RCC Tee or as required.

Fabrication & Supply of 80x80x80 MM size RCC tee as per sample or direction of Engineer-in-charge.

Fabrication & Supply of one side threaded MS J- Hook tee as per sample or direction of Engineer-in-charge.

Fabrication & Supply of “U” type MS clamps for covering 3” dia. MS pipe of air header

Fabrication & Supply of one side threaded other side “U” type MS coupler with washer & rubber.

Supply of 12nos. MS flanges for MS air header pipe or as per requirement & welding the same with MS air header pipe.

Supply of 3” diameter MS pipe of class B with provision of holes with required size and spacing as per upper hole size (as per existing arrangement/ sample) of RCC Tee for proper fitting over RCC Tee during laying. Make: - TATA/Jindal.

Supply of hardware items like nut bolt washer, packing sheet, hardener, fasteners and other necessary parts required for work etc.

Election of complete drainage system as laying and fixation of RCC Tee with proper alignment and levelling, Insertion of HDPE pipe in RDD Tee using O ring, Fitting of MS air Header pipe over RCC Tee with J-Hooks and clamps Tightening, joining MS Air header pipe and all other necessary allied process required to complete the job as per Filter Bed Design.

Reinforcement by way of providing and placing cement concrete of required grade as per filter design to cover RCC tee and HDPE pipe with associated system.

Supply of filter media sand which shall consist of hard durable grains, the filter media sand should be free from clay dust, root and other foreign impurities but it should not contain impurities. More than 5% volume, it should contain less than 5% acid suitable matter in hydro-chloric acid in 24 hours. The specific gravity of the grains of sand should be greater than 2.50. The effective size of sand should not be less than 0.45mm. It should be uniformity co-efficient & not exceed 1.60. The filter media sand confirms to BIS8419 (part A) 1977 as amended up to date.

Supply of gravels of filter beds of 4 sizes as per filter bed specification as per requirement of size. 1. 50mm-37mm, 2. 37mm-12mm, 3.12mm-6mm, 4. 6mm-2.5mm

Filling of existing /old and new gravel as per standard or as directed by Engineer-in-charge after separating different 4 sizes including cleaning /washing of gravel to remove soil, dust etc. From dumped location with the help labour, T&P items.

Filling of existing /old and new filter media as per standard or as directed by Engineer-in-charge after cleaning/ washing of media to remove soil, dust etc. from dumped location.

Testing and commission the under-drainage system in the filter bed.

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