Excavation for building foundation or for other purpose shall be done in a safe manner so that no danger to life and property prevails at any stage of the work or after completion.
Permanent excavation shall have retaining walls of sufficient strength made of steel, masonry, or reinforced concrete to retain the embankment, together with any surcharge load.
Excavation for any purpose shall not extend within 300 mm under any footing or foundation, unless such footing or foundation is first properly underpinned or protected against settlement.
Support to adjoining buildings and structures
Notice to adjoining property
Prior to any excavation close to an adjoining building in another property, a written notice shall be given to the owner of the adjoining property at least 10 days ahead of the date of excavation. The person undertaking the excavation shall, where necessary, incorporate adequate provisions and precautionary measures to ensure safety to the adjoining property and shall supply the details of such measures in the notice to the owner of the adjoining property. He shall obtain approval of the authority regarding the protective provisions, and permission of the owner of the adjoining property regarding the proposed excavation in writing.
The protective measures shall incorporate the following:
1) Where the level of the foundations of the adjoining structure is at or above the level of the bottom of the proposed excavation, the vertical load of the adjoining structure shall be supported by proper foundations, underpinning or other equivalent means.
2) Where the level of the foundations of the adjoining structure is below the level of the bottom of the proposed excavation, provision shall be made to support any increased vertical or lateral load on the existing adjoining structure caused by the new construction.
If on giving the required notice, incorporating or proposing to incorporate the protective provisions which have duly been approved by the authority, the owner of the adjoining property refuses to permit the proposed excavation or to allow necessary access and other facilities to the person undertaking the excavation for providing the necessary and approved protection to the adjoining property, the responsibility for any damage to the adjoining property due to the excavation shall be that of the owner of the adjoining property.
Every excavation shall be provided with safe means of ingress and exit kept available at al times. When an excavation has been completed, or partly completed and discontinued, abandoned or interrupted, or the permits have expired, the lot hall be filled graded to eliminated all steep slopes, holes, obstruction or similar sources of hazard. Fill materials shall consist of clean, noncombustible substances. The final surface shall be graded in such a manner as to drain the lot, eliminate pockets, prevent accumulation of water, and preclude any threat of the damage to the foundations on the premises or on the adjoining property.
Methods of protection
a) Shoring, bracing, and sheeting : with the exception of rock cuts, the sides of all excavations, including related or resulting embankments, 1.5 m or greater in depth or height measured the level of the adjacent ground surface to the deepest point of the excavation, shall be protected and maintained by shoring, bracing and sheeting, sheet piling or other retaining structures. Alternatively, excavated slopes may be inclined not steeper than 1:1, or stepped so the average slope is not steeper than 45 0 with no step more than 1.5 m high, provided such slope does not endanger any structure, including subsurface structures. All sides or slopes of excavations of embankments shall be inspected after rainstorms, or any other hazard increasing event, and safe conditions shall be restored. Sheet piling and bracing needed in trench excavation shall have adequate strength to resist the possible forces resulting from earth and surcharge pressure.