Section 25 in General Specification and Conditions of Contract
25. Bund - (a) Main Dam.
(i)Jungle clearance: - Before construction of the bund is started the total area of land to be occupied by the base of the dam should be demarcated by fixing boundary stones or dagbelling.The area to be occupied should be cleared of all obstructions, small and big bushes grass stumps, loose stones and rubbish of all descriptions.Small and big trees should be cut down and their roots should be entirely removed. In case removal of all roots be found impossible, the roots may be burnt to a depth of not less than 3" from the surface of the ground and the hollows thus formed should be cleared and filled up with good quality of earth well rammed and watered. This should be done after the benching in completed all holes or hollows lying within this area whether existing or produced while uprooting the stumps of trees should also be made free from the rubbish of the nature stated above are similarly treated.The rate of clearing jungle should include the cost of removing and stacking at a suitable place proposed by the Engineer-in- Charge of his representative of all the bushes, grass and shurbs etc., removed from the base of the bund and dagbelling of the central lines and both inner and outer toes of the bund. The rate for cutting trees should include the cost of taking out or bushing roots and stacking the wood at a suitable place ordered for purpose of disposal by public auction as a State property. As the earth work of the bund is to be measured by bank sections the contractor should get finally measured all earthwork done in filling pits and hollows etc. before starting the earthwork of the dam. If he fails to do so the Engineer-in-Charge will be at liberty to make payment for this earthwork according to his own knowledge and measurements and this will be considered as final.(ii)Dagbelling. - A small trench of a triangular section 9" in with on top and 6" deep will be dug to demarcate the inner and outer toes of the bund and also the excavation or bank lines of the canal after the jungle has been cleared from the base of the dam.(iii)Digging and benching base and putting the same earth on the outer slope including ramming, watering, dressing lead and lift. - After the jungle is cleared and the base of the dam levelled, block levels will be taken and a plan prepared. The contractor should see this plan and sign it to avoid disputes so that earth work quantities of bank may be correctly taken out. The surface to be occupied by the base of the bund will then be benched according to the drawing supplied or the written instructions of the Engineer-in-Charge of the work. The purpose of benching being to give a proper frictional grip to the fresh earth used in the construction of the bund. The work should be carried out under proper instructions. The soil taken out of benching will be used in the construction of the bund on its outer slopes, if so ordered by the Engineer-in-Charge.If this soil is not suitable i.e. if it contains roots of weeds etc. it should be stacked along the outer of the bund so as to form germ.Under all circumstances the contractor shall obtain written orders of the Engineer-in-Charge of the work regarding the disposal of the benching earth.The rate provided for the work includes all lead, lift, ramming, rolling, watering, dressing etc. of this item of earth work.(iv)Sand shall be removed from the bed of the nullahas directed by the Engineer-in-Charge and shall be deposited by him up to a distance of 500ft. from the excavation. The contractor shall have the benching work measured before it is covered up otherwise, the measurements taken by the Engineer-in-Charger shall be considered as final.(v)Earthwork of bund complete with lead, lift consolidation with a steam road roller with sufficient water and dressing. - (a) For the construction of embankment good hard earth should be used. Earthwork should be done in layers of not more than 6" in thickness and the slopes should be made according to the drawings or written orders of the Engineer-in-Charge. Profiles must be erected at suitable intervals, say at every 50ft. so that the bank may be property constructed according, to the designed sections. Before the excavation of the borrow pits is commenced the surface of the ground to be dug should be cleared of all vegetable roots, rubbish growth by the contractor at his own expense. The borrow pits should not be with in 100ft. from the inner toe of the bund and should be dug more than 1ft. in depth upto 1 chain in the next chain they can be dug 2ft. deep, care being taken that no porous state are uncovered on the tank side of the bund. Then the pits should be dug with the written instructions of the Officer-in-Charge of the work. All borrow pits should be arranged with certain amount of regularity having regard for the convenience of the work during executions and for the safety and appearance of the work, after its completion. Suitable size paths should be left between rows of pits for carriage of earth by donkeys and bullocks or by tramway line. In no case earth should be taken from the outside of the tank without written orders of the Engineer-in-Charge or his authorised representative. The earth to be used in the bank should be of soil mixed with fair proportion of clay Sand or saline oil or soil containing Bajri or small size kankar will not be allowed to be used for construction of the earthen dam. The contractor should see the site for selection of soil and tender rates to cover all lead and lift etc.(b)Consolidation, ramming and dressing. - All clods should be broken in the borrow pits and should in no case be taken to the bank and broken up there. No grass roots of trees or bushes and rubbish of any kind should be carried to the bank. The earth should be laid in layers as stated above. The benched surface should be thoroughly watered before laying the first layer of earth. After good watering a layer of 6" in thickness should be put and evently spread on the watered surface and should be properly rolled with a steam road-roller of not less than 8 tons. The rolled surface will then be roughened and watered before putting the next layer of 6" of earth and rolling is to be continued till the bank is finished to the top. Earth adjacent to the masonry corewall should be well rammed with iron rammers and sufficient watered Special care will be taken of this work, Sufficient number of steam road-rollers and iron rammers as ordered by the Engineer in-Charge should be provided by the contractor at his own cost. All profiles, dagbells and other necessary items for demarcating the work should also made by the contractor at his own expense.(c)Watering. - Sufficient number of power, pumps pipe line and house pipes should be arranged by the contractors for supplying water to each and every portion of the bund where earth work is in progress. The earthwork shall be done in six inch layers. After a layer of earth has been rolled and consolidated it shall be thoroughly watered. The next layer shall be evenly laid on it and rolled and consolidated dry. This process shall go on alternately throughout the days. The thorough watering on each consolidated layer will soak down into the soil below and make it stiff like the natural ground. The watering shall also help in making a compact junction between the two layers. Some water will rise from the lower layer into the upper layer by capillary action and the water from the top layer shall soak down into the dry earth below.After the completion of a day's the area on which the earthwork has been in progress shall be divided into shell, compartments or kiaries by means of dowlies and flooded with water so that during the night the water or moisture soaks every portion of the dry earth that may be there owing to faulty watering and consolidation.(d)Ramming. - In parts of the embankment where roller cannot be worked on or cannot reach, the consolidation should be done by heavy rammers worked by the lines of men moving in uniform manner backward and forward on the surface till the layer is thoroughly consolidated. When manual labour is used for carrying the materials the work people should as much as be made to work over the rolled portion of the dam but not in single file (row).(e)Testing the construction of the dam. - At the close of each week the work constructed during it shall be tested by means of small trial pits two feet which shall be excavated throughout its depth and any change in construction or alteration of the completed work thus found to be necessary shall be carried out in accordance with the written instructions of the Engineer-in- Charge without any extra charge.(f)Junctions of earthwork. - Junctions shall be avoided as much as possible, but where unavoidable, they shall be constructed as under:-(i)Cross Section Junctions - The loose surface earth of the end slop of the old embankment shall be entirely removed and that slope be thereafter cut into series, of joggles and tongues sloping vertically up it. The excavated surface shall be well wetted and the new earthwork consolidated in intimate union with it.(ii)Longitudinal Junction - All loose surface earth shall be removed and the solid surface of the old embankment shall be cut into a series of benching of irregular width and depth which shall be wetted. The new earthwork shall be then constructed in layers sloping steeply, on the old embankment and shall be consolidated in intimate union with it.Such junctions shall not be raised more than 10ft. in height in one season and in case of (i) they shall be broken up into vertical sections not exceeding 5ft. in height and separated by horizontal breaks of not less than 50ft. over which the subsequent work shall lay by distance of not less than 50ft.(g)The measurement of earth work will be made by the bank but under no circumstances will the contractor be allowed measurements in excess of quantities computed by sections of the completed bund irrespective of any settlement due to rains or other factors.(a)Materials - Stones to be used shall be free from cracks hard durable and not affected by weather. These shall be from the quarry or quarries approved by the Engineer-in-Charge.(b)Bajri - Bajri shall be clean, sharp and gritty to the touch. It shall be free from organic and vegetable matter. It shall not contain any mixture of clay and shall be washed free of all clay and foreign matter.Screening - The bajri shall be used in mortar for masonry plastering and pointing and it shall be screened so as to exclude all particles retained on screen of sixty four meshes to the Square Inch. For use in lime concrete the bajri may contain particles up to one quarter inch size and screens to exclude larger particles shall only be used.Glass and Water test - Bajri shall be tested for cleanliness by shaking up five cubic inches in a number of clean water and if any perceptible thickness of mud forms after ten minutes quiescence the bajri shall be rejected.(c)Kankar lime or Stone lime.(i)Description and Source. - The kankar for burning shall be of the class known as 'Bichwa' kankar having a blue-grey fracture. It shall, be broken to two inches guage and shall be free from earth and other impurities. The kankar or stone quarry shall be subject to the approval of the Engineer-in-charge of the work.(ii)Manufacture - For firing the kiln, coal, charcoal, wood or screened cinders may be used as the Engineer-in-Charge may direct in on circumstances 'uplas' (cow-dug) shall be used. In drawing the kiln care should be taken to remove as much wood as has possible. The kankar or stone after burning shall be carefully picked so as to exclude all over and under burnt pieces and shall then be ground fine and screened through a sieve having one hundred forty four meshes to the square inch, all particles which fail to pass through the sieve being rejected.(iii)Storage and delivery - When the contractor supplies the lime as part of his contract entered into for the construction of a building bridge or other structures, he shall deliver the material at the site of the work and shall store it in a weather proofs had provided by him for the purpose.(iv)Royalty and other rules. - The contractor shall be entirely responsible for the due observance of departmental, Forest, Municipal or other rules regarding trees falling, blasting, burning and other operations carried out by him and for the payment of bills for royalty and other charges. The Engineer-in-charge shall have the right to deduct from any sum due to the contractor any claims from the forest or other departments for Royalty or other charges.(v)Bad lime. - Lime which has been condemned by the Engineer-in-Charge shall be removed from the site of the work by the contractor within twenty-four hours, failing which the Engineer-in-Charge or his representative shall have the right of removing it at the contractor's cost.(vi)Tests - At the direction of the Engineer-in-charge the lime shall be tested in following manner:The lime to be tested shall be passed through a screen having one hundred fourty-four meshes to the square inch and if an appreciable quantity is retained on the screen, lime is liable to be rejected.Briquettes shall be made by adding about 20% of water to portion of the lime selected from the bulk supplied by the contractor and approved by the Engineer until a stiff paste is formed. This paste shall then be well pressed down into mould such that area of the briquette at the smallest section shall be one square inch. The moulds required shall be supplied by the Engineer. In making the briquette the mould shall rest on a sheet of glass and the upper surface of the lime in the mould shall be struck off level with trowel and the mould shall then be laid until the lime attains its initial set in nine hours.After this period the briquettes still in the mould shall be placed in water for two days to allow it to set gradually and shall then be taken out of its mould and placed in water for 20 days. At the end of the later period it shall be taken out of water and allowed to dry in shade for twenty-four-hours after which it shall be tested. If the briquettes break with a tenstile stress of less than one hundred pounds, the lime shall be rejected. The test load shall be supplied at the rate of five hundred pounds per minute.(d)Surkhi - The surkhi shall be made from perfectly clean and fully burnt, but not over and under burnt bricks or Dhamni Miti (Loom) well burnt and shall be screened through screens having sixty four meshes to the square inch, all particles which are retained on the screen shall be rejected.Stacking - Surkhi shall be stacked at the place directed by the Engineer and shall be protected from dust and foreign matter by adequate coverings.(e)Mortar - Mortar must of such proportion of slacked lime and sand or surkhi as may be specified for each particular class of work. Usually 2 of sand to 1 of lime. The mortar shall be ground in a bullock mill.The slacked lime is to be first placed in the mill trench in an even layer and ground for 180 revolutions with sufficiency of water.Thoroughly wetted and is then to be added evenly sand the mixture ground for another 180 revolutions.The mortar must be stirred continuously during the process particularly in the angle of Ghani-Water may be added during grinding as required, care being taken not add more water then will bring the mixed materials to the consistency of stiff paste.All mortar shall be used as soon as possible after grinding. As a rule it should be used on the day on which it is ground but in no case should mortar, 48 hours previously ground is permitted to be used or remain at the site of the work.In all cases the mortar must be kept damp and not allowed to dry.The ground quick lime and surkhi after being screened shall be in specified proportion and kept together heap till required. Then before being used they the mixed well into a adding water to ensure perfect slacking. After which the sand is added in the specified proportion and the whole well mixed. The proportion generally be to 1:1. The mortar to be ground for lime mortar.Masonry Works
