Public Health Engineering Department Tender

Providing and placing of new graded gravel as (i) Size of Gravel vary from 50 mm at the bottom to 2. to 5 mm at the top as detailed: (a) Passing 80 mm screen but held on 10 mm- 150 mm layer (b) Passing 25 mm screen but held on 10 mm- 50 mm layer (c) Passing 10 mm screen but held on 5 mm- 50 mm layer Passing (d) 5 mm screen but held on 2 mm- 50 mm layer (ii) The filter gravel shall be as spherical as possible, hard, clean and uniform in quality and also shall not contain such impurities as dirt and clay as per IS: 8419 (Part-I) for filter gravel specifications. The work also includes washing the gravel with required concentration of HCL acid and finally with water and placing the same in filter beds as per direction of Engineer- In- Charge and technical specification complete in all respect. The gravel shall not contain more than 5% acid soluble matter as determined by solubility test in Appendix B of IS: 8419 (Part-I) amended up to date. (For RGF)

Providing and Placing of new filter media as (i) Sand shall be hard and resistant quartz or quartzite and free of clay, fine particles, soft grains and dirt of any description. (ii) Effective size shall be 0.45 to 0.70 mm. (iii) Uniformity Coefficient not be more than 1.70 nor less than 1.30. (iv) Ignition loss should not exceed 0.70% by weight. (v) Soluble fraction in HCL acid shall not exceed 5.0% by weight, (vi) Silica content should not be less than 95% (vii) Specific Gravity shall be in the range between 2.55 to 2.65 (viii) Wearing loss shall not exceed 3.0%. and as per specifications given in IS: 8419 (Part-I). Filter media (fine sand and coarse sand) should be processed through disintegrator and dust separator in automatic plant including screening of sand to desired specification and washing and cleaning of sand with water by aqua wash technology at quarry site. (For RGF)