SPECIAL REPAIR TO CHEMICAL EARTHING PIT OF KITE AND COBRA HANGERS AT INS KALINGA UNDER GE(P) NAVY KALINGA

Amount

M & L for 16 Nos of Chemical earth pits with targeted/ achieving result from 3.5 ohms upto maximum of 7.0 ohms for each pit and by maintaining of expected Grid value of 0.22 ohms but less than 0.5 ohm for grid of 16 earth pits as in around individual technical building with the following items, specifications and testing complete for each pit and as directed by Eng-in-charge

i) Boring 300 mm dia of earth pit in soft and loose soil upto the depth of not less than 2.5 m deep below ground level by means of any method i.e boring/ digging including removal of excavated material to a distance of 50 m as directed by Engr-in-charge in each pit.

ii) Filling the each bore hole with 50 CM thick compacted layer of earth enhancing compound to reduce the soil resistivity as per Clause 14.5d of IEEE 80:2000 (latest Edition) of make Terec+ as per manufacturers specifications

iii) Placing of 2m length of 80mm dia of copper pipe-in-pipe earth electrode with welded copper plate 70mmx200mm of 20mm thick on top with two nos of contact through bracings by welding. The earth rod should be placed at centre of each bore hole/earth pit with minimum of 30 CM inserted in to Terec+ layer

iv) Back filling with earth enhancing compound to reduce the soil resistivity as per clause 14.5b of IEEE 80:2000 (latest Edition) of make Earthcon upto the ground.

v) Connecting/Jointing/brace welding each electrode of earth pit serially with copper earthing strip 25X3 mm with minimum 8 m distance between two earth pits buried 600 mm below GL in trench of 600 mm wide and 800 mm depth filled with earth enhancing compound to reduce the soil resistivity as per Clause 14.5b of IEEE 80:2000 (latest edition) by enhancing its ionic properties, dispersion properties, hygroscopic properties, expansion properties, diffusion properties etc, incl earth excavation complete all as directed by Eng-in-charge.

vi) Placing 500X500X250 mm HDPE earth pit cover (IEC 62561-5) flushed with ground placed over 100mm thick PCC (1:3:6 Type I) of size 550 x 550 mm including required earth excavation, refilling and packing. The earth pit cover should be UV stabilized, lockable jam free lid, stackable design, resistant to substances including petrol oil, diesel, bitumen and concrete etc. vii) The quoted rate is deemed to be inclusive of necessary removal of excavated soil to a distance of 50 mtr as directed by the Engr-in-Charge. viii) Any other requirement if desired by the Engr-in-Charge as per site conditions shall be provided by the contractor without any extra cost.

Note: a) The earth pits should have a minimum distance of 8m from each other and a minimum distance of 2m from building walls b) If grid value is found less than 0.5 ohms then the contractor will re-execute earth pits or put addl pit with no extra cost to the Govt.

M&L copper strip 25 x 3mm with saddle and fixing screws, including insulating block for connection of pit to bldg test point complete all as specified and directed by Eng-in-charge.

M&L for test point terminal block made of copper earth bus bar (EBB) of size 300x50x6 mm, drilled, screwed and fixed to wall with insulation studs incl connection to copper strip from earth pit to hanger earth point with fixing and jointing accessories complete, all as specified and directed.

Ruchira Associates