Project Upper Irkhuwa Hydropower

Upper Irkhuwa Hydropower Project is situated in Bhojpur District, in Province no 1. Project area lies between 27°22’58” N and 27°24’17” N latitude and 87°01'33" E and 87°03'51" E longitudes. The Project area is approximately 12 kilometres south east from Dingla, one of the major historical town of Bhojpur. Upper Irkhuwa Khola, within the Project area, lies entirely within Dobhane, Khatama and Kuda kaule Village Development Committees (VDCs)Major structure of project such as Headworks, surge tank and powerhouse lie on left bank of the Irkhuwa Khola. Waterway of the project passes through both bank. Due to topography of waterway, it crosses the Irkhuwa Khola twice. Initial and final stretch of water lie on left bank whereas middle stretch through right bank. The headworks site has been proposed at Irkhuwa Khola at about 400m upstream from the confluence of Irkhuwa Khola and Phedi Khola whereas the proposed powerhouse site is located about 800 m upstream from the confluence of Irkhuwa Khola and Benkhuwa Khola which lies in Kuda Kaule VDC.Powerhouse is proposed about 4.0 km downstream from the headworks on left bank of Irkhuwa Khola.

The two headworks have been proposed for diversion of required water, one at the Irkhuwa khola which is designed for full discharge as main headworks. Other at Phedi Khola which will be operated during dry season.

The proposed main diversion weir axis area is located about 400m upstream from the confluence of Irkhuwa khola and Phedi Khola at Irkhuwa khola to divert the water into waterway. Also, additional headworks is proposed at the Phedi khola to add the additional discharge to Irkhuwa Khola headworks. The catchment area at the intake site at Irkhuwa khola is 74.17 km2 and at Phedi intake is 63.18 km2. The powerhouse site of Upper Irkhuwa Hydropower Project is proposed at an elevation of 692 masl. Design discharge of the project at 45.0% exceedance flow is 7.80 m3/s including both Irkhuwa khola and Phedi Khola. Design of headworks has been carried out considering for 100 years return period flood discharge of 373.19 m3/s. Similarly, Power house design has been carried out considering 100 years return period of 383.80 m3/s.

Installed capacity of the Upper Irkhuwa Hydropower Project is 14500 kW. This ROR scheme comprises of 25 m long diversion weir with full reservoir level at 920.90masl will divert the design flow discharge to the intake at left bank. One number of under sluice 2.5 m wide and 2.5m high has been provided. Similarly, three no of intake 2.5m width & 1.5m high have been provided. Immediately after intakes, 7.5m length and 9.30m width gravel trap has been proposed to settle the gravel size of more than 5mm with gravel flushing arrangement. Settling basin is a surface type with two bays having length 55.5.0 m, width 6.50 m and 3.14 to 7.74m height. Settling basin has been designed for 0.20mm sediment particle with 90% trap efficiency of the basin. Also 24 m boulder weir has been proposed to divert water from Phedi khola to Irkhuwa khola with weir height of 3.33 m from river bed level. Crest elevation of Phedi weir is proposed at 924.60 masl. Intake arrangement is done by placing two gate of each 3.0m width and 0.8m height which will draw the diverted flow from Phedi diversion weir.