sanjen (upper) hydroelectric project:
The Sanjen (Upper) Hydroelectric Project (SUHEP) is located on the Sanjen Khola, a tributary of the Trishuli River, at Chilime VDC in Rasuwa district of the Central Development Region of Nepal. Sanjen (Upper) Hydroelectric Project (SUHEP) is located at 150 km road head distance towards north-west of Kathmandu. Geographically the project area lies between longitudes from 85016'30" E to 85018'15" and latitudes from 28013'00"N to 28014'25"N.The headworks site of Sanjen (Upper) Hydroelectric Project is located at Tiloche about 2 km upstream from the confluence of the Sanjen Khola and Chhupchung Khola whereas the Powerhouse is located near Simbhu Village just upstream of confluence of Sanjen Khola and Chhupchung Khola. Sanjen Hydroelectric Project receives tailwaters from SUHEP power house and additional 0.5 m3/s discharge from Chhupchung Khola at Simbu and its powerhouse is located at Chilime Village adjacent to Headworks of existing Chilime Power Plant.
Detail topographic survey of the project area has been completed at different stages from SUHEP headworks to SHEP tailrace with 1 m contour interval, control points has been established at site and referenced co-ordinate are obtained with respect to National Geodetic Station and verified. The surveyed maps and data have been used for project layout, planning, design and estimates as maps and referenced coordinates are the important basis for project design and construction. Refer (SJCL, Detail Project Report, 2011)
Hydrological and sediment study of the river basin remained important for any hydroelectric project. Reliable hydrology and best prediction of long term hydrology for the computation of project capacity and project benefits is critical aspect of any project. Moreover, the flow patterns, maximum flow, minimum flow, flood frequency analyses are important to carry out for the design aspect of project. Hydrology and Sediment Study of the Sanjen River and its catchment have been carried out based on the catchment characteristics, climate of the project area, field measurements and investigations, previous studies and recorded data from Department of Hydrology and Meteorology and maps compiled from aerial photography by Department of Survey. All the information has been processed using different approaches, mathematical tools and formulas so as to estimate stream flow characteristic i.e. Long Term Mean Monthly Flow Data, Flow Duration Curve, Flood Flow Analysis and Rating Curve, Low Flow Analysis and Extreme Hydrology for different return periods. The findings were used in the project planning, capacity optimization and design. For Details of the Study Refer (SJCL, Feasibility Study Report, 2011) Refer (SJCL, Detail Project Report, 2011)
Geological and Engineering Geological Study:
Study is concerned with geological, engineering geological and geotechnical investigations of the project area. Most of the study is confined to the area where major engineering structures such as headworks, headrace tunnel, surge tank, penstock, powerhouse and tailrace has been planned to construct. Hence thorough geological, engineering geological studies of the area were done as possible for site conditions. ERT of the selected areas has been carried out, however drilling and other geotechnical investigations are required to carry-out during final designs after improvements in access roads. Detailed geological studies of the project area was carried in October 2010-March, 2011 that cover almost all works as defined by scope of work. Investigations were carried to achieve stated objectives. All data and information collected at the study is based on surface exploration. Details are given in detail geological, engineering geological and geotechnical study report (Vol.1: Main Report, Vol. 2: Drawings and Vol. 3: Annexes). ERT of selected location i.e. SUHEP PH site, HRT alignment at Tentachet Valley and SHEP PH site all completed. The investigated findings and results have been used in planning and design of structures. The Sanjen (Upper) Hydroelectric Project is basically a run-off-river scheme with the provision of daily peaking pondage for 1.2 hours. The headworks site of Sanjen (Upper) Hydroelectric Project is located at Tiloche about 2 km upstream from the confluence of the Sanjen Khola and Chhupchung Khola. This project utilizes water from Sanjen Khola. The main attractive feature of this project is the peaking pondage. The design discharge is 11.07 m3/s which is equivalent to 40% exceedence flow and gross head is 161.3m. The project is optimized as a 14.8 MW scheme comprising a 3.3 m high diversion weir with a 14 m long ungated spillway, a 3.0 m wide gated undersluice, an intake, an intake channel, a side channel spillway, a 75 m long two-bay-desanding basin and flushing facilities.The waterway consists of.1.4 km long headrace tunnel, a forebay, coupled with a peaking pondage, a 468 m long penstock. Three set of generating units with 5 MW capacity each will be installed in a surface powerhouse at Simbu in Chilime Village. The tail water feeds water to the lower 42.5 MW scheme of the cascade system. An arrangement is also made to dispose water back into the source river. Power evacuation will be made through a 5 km long 132 kV transmission line connected to the Chilime Hub of NEA near Chilime Village. The total annual energy generation from the plant is 85.996 GWh out of which 11.067 GWh will be produced during the four months of dry season from Poush to Chaitra. However, the annual energy available for sale excluding outage, station consumption and transmission losses, totaling 4% comes out to be 82.557 GWh. Out of which 10.633 GWh is the dry months total and 71.924 GWh is wet months total.