Melamchi Diversion Scheme

mdsi. Construction of Tunnel and Headwork
The major work under this scheme is the construction of Diversion tunnel approximately 26.3 km long excavated by drill and blast method in order to divert 170 MLD of raw water from Melamchi River to Sundarijal outlet where the raw water is treated before sending it to Bulk Distribution System (BDS).

The contract for construction of headworks and tunnel was awarded on 19 February 2009 with intended completion date of 2 September 2013. Actual physical works started in April 2010. But due to the unsatisfactory performance of the Contractor it was terminated on 25 September 2012.

Other additional works comprises the construction of:

  • Headwork diversion tunnel and temporary cofferdams on the Melamchi and Ribarma Rivers
  • Headworks intake structures, including earthworks, cuts, civil works and hydraulic steelworks
  • Adits from portals at ground level to the Diversion tunnel at Ambathan, Gyalthum and Sindhu Excavated at 18.4 m2 cross sectional area
  • Gate valve arrangements at portals and spillway/bypass flushing system to Bagmati River other control works at downstream and portals and Sundarijal
  • Tunnel Flushing system at Ambathan adit
  • River training and intake at Ribarma with de-sanding basin
  • Pipeline (of 1.6 m dia.) from tunnel portal to WTP, length approximately 235m

ii. Construction Maintenance and Management of Access Roads
Access Roads refer to the roads used to visit different Adit points (project sites) including main intake. This includes the construction of about 43 km of access roads and upgrading of about 29 km of existing roads making easier / accessible to visit project sites (Adit points) round the year.

More specifically these access roads are categorized as:

Adit Access Road (AAR) – AAR refers the roads to reach to different Adit points of the project sites which include – Sindhu Adit (Bahunepati – Sindhu Adit ,15.4 km), Gyalthum Adit (xxxxx to Gyalthum Adit, 4.2 km) and Ambathan Adit (Timbu – Main Intake at Ambathan Adit, xx km)

Main Access Road (MAR)– MAR refers the road from Melamchi Pul Bazar to Timbu which length18 km long including 10 bridges.

Upgrading Access Road (UAR)- Upgrading of Jorpati-Sundarijal road (6.0 km), Jorpati Gokarna-Narayantar and Lamidanda – Melamchi Pul Bazar – Timbu (feeder road), 22.2 km.

In addition to the above roads, this package also includes:

  • Maintenance of Lamidanda-Timbu feeder road the Headworks access road and the four Adit Access Roads-Sundarijal, Sindhu, Gyalthum and Ambathan;
  • Construction of approximately 235 m length of road as an extension of the Sundarijal AAR up to Sundarijal Portal; and
  • Construction of approximately 45 m length of road to access the Sindhu Adit portal.

iii. Construction, Operation and Management of Camp site Offices
This is also an crucial part of the works to be completed by the Contractor under the Melamchi Diversion Scheme (MDS). This refers the construction, operation and management of Camp site office at Malamchi Pool Bazar (main Camp) and Other Camps at Ambathan Adit, Gyalthum Adit, Sindhu Adit and Sundarijal Adit.

This also includes the operation and maintenance of camp site facilities to (Employer/Engineer) such as power supply, telecommunication/internet, water supplies, sanitation/sewerage disposal, garbage; camp roads; buildings; structures; security; accident & emergency; safety; fire equipment; welfare; laundry and recreation facilities as agreed in the Contract.

This package also covers procurement of various equipments, vehicles etc. needed for project implementation and bear its operational cost including fuel, periodic maintenance to both Employer and Project Engineer (DSC). The responsibility of operation and management of storage of explosives, construction materials, testing system etc. also goes to the Contractor.

Not only at the Adit camps, the contractor should takeover and operate all existing services of Main Camp Site office located at Melamchi Pool Bazar.