Specifications Part 1 - Water Supply, Sewerage and Tube Well Works

17.7 Development of tube-well with object of(Refer annexure A also):-17.7.1 Producing effect of natural gravel pack (in case of naturally packed design.)17.7.2 Producing maximum sand free yield of water for the specified standard drawdown in alluvium and rocky areas.17.8 Conducting yield test by over pumping of the tube well(Refer annexure A also).17.9 Installation of suitable submersible pump assembly as specified andcomprising of i) submersible pump/ ii) Motor iii) Riser/Colum Pipeline iv) Airlinev) Sluice and Reflux valve. Alternatively installation of hand pump India mark IIincluding construction of platform and necessary drainage arrangement if yieldof the tube well is not enough for installation of submersible pump.17.10 Strata:-17.10.1 Rocky area shall mean, area where the strata essentially comprises of the rockformation. Rock may be with or without fissures and faults, joints and beddingplanes, may have fractured and weathered zones. Rocks may be soft, mediumor hard, and comprise of shale sand stones, lime stones, dolomites, quart-sites,basalts, granites, schist, fillets, slates, gneisses and their intercalation, intrusiveand conglomerates of these, but shall exclude clays, sands, pebbles, cobblesand boulders moorum and silt stones.17.10.2 All alluvium areas shall mean areas where the strata comprises of loose,unconsolidated materials like clays, sits and gravels, pebbles, cobbles andboulders.17.11 Verticality and alignment :-17.11.1 Verticality of a tube well means verticality of casing pipe or housing pipe up to200 mm dia and up to 30 m depth in one direction and in one plane and up to50 m depth for casing pipes of more than 200 mm dia.17.11.2 The bore hole should be in a vertical alignment so that installation of verticalturbine pump or submersible pump can be done in the tube well without anydifficulty. Alignment means plumbness and straightness of the tube well.Plumbness refers to the variation with the depth of the actual centre line of thetube well from the true vertical line drawn through the centre of the tube wellfrom top, down to its depth. Straightness merely considers whether actualcentre line of the tube well is straight or otherwise. Thus a tube well may bestraight but not in plumb, since its alignment may be displaced in one directionor other from the vertical.17.11.3 The limits of verticality of shallow and deep tube wells are specified in the tablegiven below:-Urban Administration & Development Department Page 202