Chapter 1: introduction

Project Access

The access to the project area is through an all season 228 km long Mechi Highway connecting Charali at the East West national highway and Taplejung (Figure 2.3). The Mechi Highway starts from Charali, located 4 km east from Birtamod Bazaar in Jhapa District and reaches Kabeli Bazaar (202 km) north on the left bank of the Kabeli River after crossing Phikkal, Ilam, Ranke, Phidim and Gopetar. Apart from this road, seasonal air services are available from Biratnagar to Taplejung which is 26 km further north from the Kabeli Bazaar along the Mechi Highway.

The Headworks and powerhouse are the two major sites of KAHEP, which are to be connected by motorways for the transportation of construction materials. The existing community developed earthen track roads will be upgraded for access to headworks and powerhouse sites. The access road to the headworks starts at Chainage 50 km (Mechi Highway) whereas the road to the powerhouse starts at the Chainage 48+000 at Bhanuchowk bazar of Amarpur VDC at Mechi Highway.

Figure 2.2: Location of the Key Project Structures in relation to the Project Districts and VDCs


Figure 2.3: Road network linking the project area

3. Salient Features of the Project

The project is peaking run-of-river (PROR) type with a proposed installed capacity of 37.6 MW with a design discharge 37.73m³/s. The diversion dam with provisions for ponding will be constructed at 2.5 km upstream of Kabeli Bazaar at Dhuseni village of Amarpur VDC on the left bank and Khudurke Ban of Thechambu VDC on the right bank. The intake on the left bank will feed the underground settling basin and is diverted to the Powerhouse located at Tamor River bank close to Pinase village through a 4.327 km long headrace tunnel. A semi-underground powerhouse will be constructed on the left bank of the Tamor River. The salient features of the project are presented in Table 2.1.

Table 2.1: Salient Features of KAHEP

SN	Items	Description
1.	Project Name	Kabeli-A Hydroelectric Project
2.	Location	Amarpur and Panchami VDCs of Panchthar District and Thechambu and Nangkholyang of Taplejung District
2.1	Project Boundaries	East 87° 45' 50" E West 87° 40' 55" E North 27° 17' 32" N South 27° 13' 41" N
3	Type of Development	Peaking Run-of-the-river (PROR)
4	Hydrology at intake
	Catchment area	862.3 km^2
	100 year flood (Q100)	1860 m^3/s
	Probable maximum flood (Q1000)	2650m^3/s
	Mean monthly flow	61.4 m^3/s
	40 percentile flow	37.73 m^3/s
	Monsoon Design Discharge	40 m^3/s
5.	Headworks
	Type/Length of weir/height	Barrage with 4 radial gates; 3 weir bays and one sluice bay
	Full supply level	575.3 m
	Peaking reservoir net live storage capacity	0.335 million m^3
	Crest elevation	561.5masl for barrage bays and 561.0 for sluice bay
	Gate Size	10 m Width * 9.0 m Height each
	Intake type	Tunnel intake on left bank
	Intake size at trash rack	2 nos. 5.4m Width * 5.8m Height
	Riparian/downstream Release	0.86 m^3/s (10% of average monthly minimum)
6.	Diversion during construction
	Diversion flood (5 year dry season flow)	154 m^3/s
	Diversion tunnel	240m long; 4.8m diameter D-shaped tunnel
	Coffer Dams	80m at upstream side 90m long at downstream side
7.	Approach Tunnel from Intake to Settling Basin
	Number	2 (1 each starting from either intake)
	Length	80.9 m
	Type	Inverted D shaped; Concrete lined
	Cross section	Internal Finished Diameter 3.2 m
8.	Settling basin
	Type	Underground settling basin
	Number	2 basins with 2 hoppers in each
	Length of uniform section	76 m
	Total length including transition	113 m
	Width	15.8 m each
	Height	17 m
	Flushing system	S4 system
	Flushing tunnel length and size	150 m long; 2.25 m D-shaped tunnel with 1.75 m dia. MS pipe
9.	Access tunnel
	Length	437 m
	Type	Inverted D shaped; shotcrete and rock bolt lined
	Cross section	Internal diameter 4 m
10.	Waterways
10.1	Covering Pair Tunnels from outlet of settling basin to start Headrace Tunnel
	Length	60.2 m
	Type	Inverted D shaped; Concrete lined
	Cross section	Internal Finished Diameter 3.2 m
10.2	Headrace Tunnel
	Length after pair tunnels	4327 m
	Type	Inverted D shaped; Shotcrete lined and Concrete lined
	Cross section	Internal Finished Diameter 5.65 m
10.3	Surge Shaft
	Type	Underground and exposed to surface
	Internal diameter	10 m
	Height	51.7 m
10.4	Penstock
	Material	Mild steel
	Length before bifurcation	223.3 m
	Length after bifurcation	27.2 m each
	Internal Diameter	3.55 m
	Shell Thickness	10-20 mm; partly ribbed
11	Powerhouse
	Powerhouse type	Semi-underground
	Powerhouse size (L*B*H)	34.8 x 18.6 x 31.8 m
12	Tailrace
	Design tailwater level	458.5 masl
	Length	93.1 m
	Cross-section	4.9 m wide * 4.65 m high Rectangular box culverts
	Longitudinal slope	1 in 1500
	100 year flood (Q100) in Tamor River	5800 m^3/s
	Probable maximum flood (Q1000) in Tamor River	8260 m^3/s
13.	Turbine
	Turbine type	Vertical Axis Francis
	Number of units	2
	Rated speed	375 rpm
	Turbine Axis Level	457.64 masl
14.	Power and energy output
	Gross head	116.8 m
	Rated net head	111.64 m
	Design discharge	37.73 m^3/s
	Installed capacity	37.6 MW
	Annual estimated energy per excluding 6% outage	201.0 GWh
	Firm energy excluding outage	149.4 GWh
	Secondary energy excluding outage	51.6 GWh
15.	Transmission line (Not part of the project)-to be built by NEA
	Voltage	132 kV
	Length	83.74 km
16.	Access road
	To headworks	7.4 km from Dhubichaur at Mechi highway
	To powerhouse	15 km from Bhanuchowk at Mechi Highway
17.	Project Cost
	Total cost	70.84 Million US$
	Per kW cost	1884 US$
18.	Financial analysis
	Net present value (NPV)	13.09 Million US$
	Simple payback period	6.9 years
	Return of interest (RoE)	15.38 %
	Internal rate of return (IRR)	12.71 %

Source: UFSR 2011 and Additional Report to UFSR 2011

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