Important Points During Excavation Procedure

During Excavation Procedures:

1) The excavation shall be done to correct lines, dimensions and levels as per drawing. Adequate side slopes shall be maintained during excavation of loose soil to prevent soil from sides of excavated pits from falling back into the pits.

2) Wherever required, proper shoring and strutting shall be provided to maintain and prevent sides of excavations from collapsing.

3) No heavy equipment shall be allowed within 6m from edge of excavation or within a distance equal to depth of excavation, whichever is less.


4) Excavated materials shall not be deposited within 1.5 m from edge of the excavation.

5) Any material obtained from the excavation which in the opinion of the Site Engineer is useful, shall be stacked separately in regular stacks as directed by Site Engineer. Any excavated material, which is not suitable for backfilling shall be carted away from the work place as per directions of Site Engineer.

6) Planks placed over trenches for crossing shall not be slippery and of width not less than 75 mm wide.

7) Necessary barricades shall be erected and maintained around excavated areas. Also warning lamps at night shall be provided to ensure safety.

8) Pits shall not be excavated to final founding level, if concreting work is not to be carried out immediately. Last 15 cm shall be excavated prior to providing blinding layer with lean concrete (PCC). PCC shall be of proportion 1:2:4 or as specified by Consultant. 9) If by mistake, excavation is carried out below the level mentioned on the drawing, the same shall be made up to correct level by filling with concrete.

10) If any bottom of excavation is left exposed and is deleteriously affected by atmosphere or water, it shall be dewatered and excavated to sound base. Base of excavation shall then be filled up to the required level with lean concrete. (Grade M-15 or as specified by Consultant)

10) Removal of buried piping, cables or any other underground services shall not be done without prior permission of Site Engineer and all measures shall be taken to protect such lines till their removal. 11) Adequate precautions as per Consultant’s advice shall be taken to ensure that the excavation operations do not damage the adjoining structures or dislocate underground services. 12) Any trees coming in the alignment of the excavation shall be cut after obtaining prior approval of concerned authorities and any specific requirement laid out by them shall be complied with. Cut trees shall then be removed from site as per instruction of Site Engineer. 13) Roots of trees not coming in the portion of excavation pits but whose removal is essential shall be removed and hollows shall be filled up during backfilling. 14) Suitable drainage arrangements shall be provided to prevent surface water entering excavated pits. Water within the pits shall be bailed out or dewatering shall be carried out using pumps of adequate capacity to keep excavations free of water. Water removed shall be disposed off, away from the excavated area. 15) Where water table is high, lowering of water table shall be carried out by well point system so that general water table is below excavation level. 16) Excavation in rock shall be carried out either by chiseling with pneumatic drills or by blasting. Chiseling shall be carried out to obtain correct slopes, shape and pattern of excavation pits as per drawings. 17) Blasting shall be resorted to when excavation is to be done in hard rock, when chiseling becomes uneconomical. Blasting shall be carried out by the licensed blaster. License from statutory bodies shall be obtained prior to undertaking of blasting work. 18) Blasting shall be controlled blasting unless specified otherwise. Controlling shall be done by covering portion of rock to blasted with steel plates or woven mesh of wire ropes, meshed at 200 x 200 mm spacing and then loaded it with sand bags. Loading shall be adequate to prevent rock pieces from blowing away.  19) Such blasting shall be preferably carried out during lunch time if the work is carried out within the premises of existing office, factory or working place. Blasting operation shall not be carried out during night time. 21) Depth, dimension and levels of excavated pits shall be approved and recorded by the Site Engineer in the field book with signature of concern persons. Nature of the soil at the excavated pit bottom shall be examined by Site Engineer. If there is doubt regarding safe bearing capacity (SBC) of soil, Consultant’s opinion shall be taken and appropriate test shall be carried out to determine safe bearing capacity of soil. Further excavation shall be carried out in such cases, if the consultant advice to do so. 22) After approval from Site Engineer, bed of the excavated pits shall be firmly consolidated and leveled by watering and mechanized compacting. Compaction shall be carried out using surface vibrators in case of small pits and by roller if the area is large. Defective spot shall be dug and filled with concrete. 23) Concrete foundation work shall start only after Site Engineer gives the permission to do so in writing. Laying plain cement concrete shall be carried out after the compaction of sub base has been carried out to the satisfaction of Site Engineer. However, it shall be ensured that base is in moist condition before laying PCC. If necessary, base shall be saturated with water for not less than 6 hrs but not exceeding 20Hrs.