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All loose stone pieces on the blasting area are to be removed prior to charging of holes, as these stones will result as fly rock during actual blasting operations in addition to those from the blast itself.
It is essential that the whole positions be marked in the field using measuring tape with white/red paid so that the holes are drilled as per the design. While drilling, accuracy is to be maintained with regard to position of the holes, verticality, burden, spacing depth etc. Drilling should be done under strict supervision of a competent officer/supervisor. Drilling should not be left unattended and to the discretion of the drilling crew.
Plug the drilled holes with wooden plugs such that water, mud, drill cutting do not get into them so that they do not loose their depth.
The contractor only upon completion of drilling shall transport explosives to the drilled site. No simultaneous drilling and charging to be taken up. All the necessary statutory requirements for storing of the explosives at a magazine, site, transportation, handling and usage are to be fulfilled as per government regulation/laws
A licensed shot firer/blaster should be made available at the blasting site for executing the blasting activities and a competent person from the client should over see all the drilling and blasting operations.
Priming of explosives should be done at a safe place and charging is to be carried out as per the approved design. Before charging the holes, if presence of water is found in the drilled hole, it should be flushed out. Stemming is to be carried out with suggested material and to a suggested length. The initiation sequence is to be followed as per the approved initiation system and delay sequencing.
No blasting should be carried out without proper muffling. To restrict the flying fragments from the blast, the blast area shall be muffled comprising of 1” x 1”, 14 SWG link mesh old rubber tyres of trucks and rubber blasting mats of minimum specified size and weight. The blasting block shall be covered fully and in addition. 3m on all four sides of the charged block as shown in Figure4. Sand bags are to be placed over the muffling material if required. It is necessary to have a barricade around the entire station areas and cut and cover areas related to these stations. In addition, depending on the local conditions it may be necessary to erect a canopy of sufficient strength to cover the proposed excavation site or area.
|Total number of holes||Depend upon pattern|
|Total drill depth||48|
|Type of explosive||Cartridge slurry/emulsion|
|Charge per hole,kg||0.125(1 cartridge|
|Stemming length,m||0.5 to 0.6|
|Stemming material||Drill cutting/crusher dust|
|Maximum charge per delay, kg||1.25|
|Initiation system||Shock tube initiation system|
|Blasted volume, m3||46.0|
|Specific charge, kg/m3||0.65|
|Muffing material||Link mesh of 1” x 1” of 14 SWG on the blast area and plus 3m on all the sides, old tyres, sand bags and above that blasting mats (1.5m x 2.7m. 1.1MT) of sufficient numbers, thickness, size and strength to cover the blast completely plus 3m on all the sides (placed skin to skin for tyres and with an overlap of 0.5m in case of rubber mats)|