REPAIR/RECONSTURCTION /RE-STRENGTHENING OF DAMAGED RETAINING WALL NEAR BLDG NO P-39 AT OFFRS MESS OF CERTAIN UNIT UNDER GE GANGTOK

SOIL / GEOTECHNICAL INVESTIGATION a) The soil investigation should aim to provide data for design of soil strengthening/ control measures, slope stabilization, retaining walls with appropriate foundation depth.Provision of Soil investigation work as per relevant IS code including conducting of standard penetration test up to the explored depth, collection of samples at different depth for field and lab test including :- a) Classification of soil properties b) direct shear test c) Tri-axial-shear test d) Consolidation test e) Field test f) Liquid limit g) Plastic limit Item Continued as 1.02

h) Specific gravity j) Relative density k) Natural moisture content l) Chemical properties of Soil m) Settlement analysis to determination of bearing capacity of soil to foundation level including settlement analysis. For depth upto 10m or refusal and submission of 06 copies report shall be as per latest IS duly vetted by any NIT/IIT. i) Area plan showing the bore hole location duly marked ii) Soil strata profile along with soil classification. iii) Record the depth of water table. iv) Test result of soil parameteres like CN etc. v) Recommendation of type of foundation, depth vi) Liqification Analysis vii) Recommendation for soil filling under floor

CONTOUR & DIGITAL TOPOGRAPHICAL SURVEY / GEOPHYSICAL STUDY CONTOUR SURVEY : The site reconnaissance shall include both site inspection and local enquiries concerning existing and proposed features on and adjacent to the site. With an approximate understanding of the overall topographic feature and knowledge of the distinction(s) of movement and aerial extent of the slide, a detailed field investigation plan can be developed to delineate the aerial extent and a general direction of movement of the landslide zone/scouring due to rain water assess the geology and geologic structure, estimate the cause(s) of the sliding/scouring, and predict future movement. The survey should include both the existing stretch of retaining walls and the stretch without retaining walls in order to evolve viable and sustainable structural solutions to stabilize the proposed stretch. Detailed Field Investigations and Mapping A detailed investigation plan shall be drafted to delineate the: 1. Type of landslide, its size and mechanism and future possibilities. 2. Aerial extent of the slide, identification of the direction of deformation. 3. Location and shape of slide plane(s). 4. Nature of landslide block(s). 5. Possibility of further or future movement on slopes above the existing slide. 6. Distribution of ground water and its seasonal variation. 7. Type of soil in the site area. Item Continued as 1.04

With the above activities, a detailed survey details/geomorphological map should be evolved which should assist in design of ground strengthening and slope stabilizing measures. The topographical survey of the area shall be carried out with DGPS/suitable leveling instruments/appropriate field survey methods, capturing all existing major topographical feature of the area like trees, nalias, water bodies, roads ,railway lines, structure etc. Spot level shall be provided in 5m center or less and contours at 0.30 m interval or as specified by Engineer-in-Charge. The contour map evolved should include the profile of the vulnerable damaged retaining wall from the foundation level to existing infrastructures in proposed area which should assist in design of retaining walls .

GEOPHYSICAL INVESTIGATION (a) Laboratory testing for soils : The geotechnical engineer should conduct sufficient in situ and/or laboratory testing to characterize the physical geotechnical parameters of the earth materials affecting the proposed development as specified in IS 2720 from Part 1-41. (b) Laboratory testing for rocks : The following testing of rocks shall be carried out :- (i) Preparation of rock specimen for laboratory testing as per IS:9179:1979. (ii) Determination of slope mass rating as per IS 13365. (iii) Determination of point load strength index of rocks as per IS:8764: 1998. (iv) Determination of unconfined compressive strength of rock materials as per IS 9143. (v) Determination of modulus of elasticity and Poisson's ratio of rock materials in uniaxial compression as per IS 9221. (vi) Determination of slake durability index of rocks as per IS 10050. (vii) Determination of tensile strength by indirect tests on rock specimens as per IS 10082. (viii) Determination of dynamic modulus of rock core specimens as per IS 10782. (ix) Determination of strength of rock materials in triaxial compression as per IS 13047. (x) Seismic testing of rock mass as per IS 13372.

GROUND WATER FLUCTUATION & SLOPE STABILITY ANALYSIS Investigation of ground water, shall includes determining ground water level, pore water pressure, ground water logging, ground water tracing test, pumping test, water quality analysis, electricity survey, geothermal survey, and geophysical logging (electric logging and radioactive logging). The seasonal variations in ground water and influence of ground water due to flooding by nearby natural source of water should be mapped during the investigation. Based on the results of the above measurements and tests, ground water control works can be planned and designed if affecting the stability of the proposed area as marked on Site Plan.

PLANNING, DESIGNING AND DRAWINGS INCLUDING DETAILED PROJECT REPORT INCLUDING DETAILED DESIGN REPORT DULY VETTED BY IIT / NIT Submit Detailed Project Report (DPR) including detailed design report for planning and designing of protective work alongwith following data duly vetted by IIT/NIT as specified. (06 Ink Signed copies with photographic evidence of soil exploration) (a) Structural Drawing Detailed, design and calculations / analysis for proposed retaining structure and allied works as per ground condition for tentative area of as per proposed plan and Geo investigation data.. (b) Detailed design calculations for all items for proposed structures and structure drawings. (c) Preparation of Construction Drawings including architectural and structural with detailed execution notes & technical specifications of all items as per relevant MORTH specification and relevant IS Code for Slope Stabilisation, Retaining walls. or any other suitable protective methods. (d) Bill of Quantity (BoQ) for execution of proposed work. NOTE : (a) The quantity mentioned is of indicative type. However, design related if any additional other test required as per site condition / technical requirement / latest codal provision / NBC provn / softare (STADD pro latest version) required to complete the work maintaining Structural safety, durability, soundness and economy will also be followed and deemed to be the part of project and included in the quoted rate. (b) Sumission of vetted 06 ink signed hard copies with Recommendation of GE and CWE duly vetted from NIT/IIT along with soft copy (stadd files) to be submitted with compliance to details mentioned.

PHASE-II :- The work is situated in hill / valley / sloping terrain and the Contractor shall be deemed to have visited and examined the site and fully satisfied himself regarding site conditions, nature of soil, strata, gradients, access, restrictions in movement, climatic conditions, water logging, and all other factors affecting execution of the work before submission of tender.

Surface excavation not exceeding 30 cm in depth and averaging 15 cm in depth, getting out in any type of soil on hill / valley / sloping ground, including dressing the excavated surface to required lines, levels and slopes, and disposal of excavated material within 50 metres lead and lift up to 1.5 metres, complete, all as specified and directed. NOTE :- Removal of vegetation, bushes, and shrubs from hill/valley side slopes, including stacking of useful materials and disposal of surplus materials from the slope with all leads and lifts, shall be included in the quoted rate. The rate shall also include the cost of all materials, machinery, labour, and other incidental charges required for completion of the work.