Underwater Inspection of the Water conductor system of 4X30 MW Khodri Hydroelectric Project by Remote Operated Vehicle ROV

Head Race Tunnel (HRT): The underwater inspection shall cover the entire accessible length of the Head Race Tunnel (HRT), comprising a concrete-lined circular tunnel of 7.0/7.5 m diameter and approximately 4.6 km in length, together with the downstream trifurcation into three tunnels of 4.4/4.8 m diameter, each approximately 1.0 km long. The inspection shall include the concrete lining, construction and expansion joints, bends, transitions, invert, Adit junctions, surge shaft interface, trifurcation section, any unlined or shotcrete-lined sections, and the transition zones leading to the penstocks or pressure shafts.

Surge Shaft: The underwater inspection shall cover the entire accessible submerged portion of the surge shaft of 21 m diameter and 46 m height, including its walls, base slab, gate slots, embedded steel components, gate guides, bottom sill, anchor bolts, steel liners, expansion and construction joints, penstock interface joint, and all other submerged civil and hydro-mechanical components forming an integral part of the water passage system.

Penstocks Internal 3D Scanning: The dry/wet inspection shall cover two penstocks, each of 5.5 m diameter and approximately 85 m in length, which further bifurcate into four penstocks, each of 4.2 m diameter and approximately 24 m in length, along their entire accessible length. The inspection shall include the internal surfaces, steel liners, weld joints, bends, bifurcation sections, supports, anchor blocks (where accessible), expansion joints, and all other associated submerged components. In addition, the Contractor shall carry out dry-condition 3D laser scanning of the penstock inlet to spiral casing joint (from the inside), the internal surface of the spiral casing, stay vanes, adapter cone, and draft tube of one generating unit to accurately capture the as-built geometry and identify any deformation, misalignment, erosion, corrosion, cavitation, or other defects.

3D scanning of the exposed external surfaces of the penstock & Main Inlet Valve (MIV) within the powerhouse building for one generating unit to accurately capture the as-built geometry and identify any deformation, misalignment, erosion, corrosion, cavitation, or other defects.

Draft Tube Gate Cavity: The underwater inspection shall cover the draft tube gate cavity, including all embedded parts and surrounding civil structures, such as the concrete lining, pier walls, invert, floor slab, and the transition to the tailrace. The inspection shall also include all submerged hydro-mechanical components, including guide tracks, bottom sill beam, top and side sealing interfaces, embedded steel components, surrounding concrete, steel-to-concrete interfaces, anchorage arrangements, grout condition, and any other associated structural or hydro-mechanical components. The inspection shall identify and document any signs of cracking, spalling, erosion, corrosion, cavitation, misalignment, seepage, grout deterioration, deformation, or other defects affecting the integrity and serviceability of the structure.