Middle Modi Hydroelectric Project (15 MW)

Middle Modi Hydroelectric Project (MMHP) is located about 40 km north-west of Pokhara in Kaski and Parbat Districts, Gandaki Zone of Western Development. The project lies in the Bhuktangle, Deupur and Tilhar VDCs of Parbat District and Salyan and Lumle VDCs of Kaski District. The headworks is located at Birethanti village. At present there is about 1.5km long earthen road access to the headworks area from Nayapul bazaar which is the nearest point with all year road access along the Pokhara – Baglung highway. The powerhouse lies opposite to the Pokhara – Baglung highway at the right bank of the Modi with waterway alignment located at the right bank of Modi Khola.

This project is a simple Run-of-River scheme that utilizes the flow in Modi Khola. Modi Khola is one of the major tributaries of the Kaligandaki River of the Gandaki basin. The proposed project has installed capacity of 15MW, design discharge of 25m³/sec and net head of 70m. The diversion weir across the Modi Khola diverts the water into the side intake. A gravel trap of length 15m settles gravels coming through the six orifices of the intake and settling basin with four parallel settling chambers of length 166m settles sediment particles larger than 0.2mm and passes water into the headrace tunnel. The headrace tunnel of length 2840m of finished diameter of 3.6~4.4m and steel penstock pipe of diameter 3.2m and length 147m feed water to the two units of Vertical Axis Francis Turbines installed in the semi-surface powerhouse to generate 15MW power. The water will then be discharged back into the Modi Khola through 77m long concrete tailrace box culvert. A semi-underground surge tank is provisioned at the end of the headrace tunnel.

The electricity generated from this plant will be connected to the National Grid at the Modi Khola Power Plant Sub Station at Patichaur through 4km long 132kV single circuit transmission line. The total net energy production will be 79.12GWh annually.

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Salient Features

Project	Middle Modi Hydroelectric Project
LOCATION
Type of Project	Run-of-River
Village Development Committee	Bhuktangle, Lumle, Deupur, Salyanand Tilhar VDCs
Districts	Kaski and Parbat
Zone	Gandaki and Dhaulagiri
Development Region	Western Development Region
Headworks Area	Bhuktangle/Birethanti village
Powerhouse Area	Dhaba, Just U/S of Modi HEP (NEA)
River	Modi Khola
HYDROLOGY
Catchment Area at Intake	488 km2
Design Discharge	25 m3/s
90% Annual Dependable Flow	7.31m3/s
Compensation Flow	0.72m3/s
FLOOD
1 in 100 years Design Flood at Weir	972.9 m3/s
1 in 200 years Design Flood at Weir	1084.5 m3/s
ACCESS ROAD
Access Road to HW	Existing Nayapul – Birethanti Road
Access Road to PH	700m from Pokhara-Baglung Highway
DIVERSION WEIR
Type of Weir	Concrete Gravity with Uncontrolled Spillway
Crest Length of Spillway	32m
Weir Crest Level	EL. 1014.5 masl
Height of Weir	5 m from river bed
Flood Level at 1 in 200 years Flood	EL. 1021.85 masl
Under-sluice gate	2 x 3m wide x 4m high
Invert Level of Undersluice	EL. 1010.20 masl
INTAKE
Type of Intake	Side Intake, Orifice Type
No. of Intake Openings	Six (1.2m x 3m each)
Invert Level of Sill	EL. 1012.80 masl
Design Flow	28.75 m3/s
No. of Gates	Six
Gate Size	1.5m x 3m each
GRAVEL TRAP
Size	15m x 23~7m x 10m (L x B x H)
Flushing Conduit	1m x 1.5m Box, 30m Length
Top Level	EL. 1019.7~1021.93 masl
APPROACH BOX CULVERT
Canal Type	Double Box Culvert
Length of Canal	83m
Size of Canal	3.2m x 3.4m (H x W)
SIDE SPILLWAY
Length	27m
Discharge Capacity	117.3 m3/sec
Location	At Side Wall of Combined Box Culvert
SETTLING BASIN
No. of Basins	Two
No. of Chambers	Four
Nominal Size of Trapped Particle	0.20mm
Trap Efficiency	90%
Transition Section	52m length
Parallel Section Size	114m(L)x7m(W)x8.94~11.22m (H) each including bottom hopper
Flushing Gates	Four (1m x 1m)
Outlet Orifice	Submerged, 8 Nos, 1.25m x 2.5m
HEADPOND
Capacity	1200m3
Size	28m (L) x 12m (W) x 2.5m (H)
Side Spillway	22m Length
Discharge Capacity	25 m3/sec
Normal Water Level	EL. 1013.41 masl
HEADRACE TUNNEL
Section Type	Inverted-D
Finish Diameter	3.6 ~4.4m
Finish Area	12.02~15.21m2
Length	2840m
Support	Fully Concrete Lined (160m) and Shotcrete Lining in Wall and Crown, Concrete Lining in Invert (2680m)
SURGE TANK
Type	Surface and near HRT outlet portal
Finish Diameter	9m
Height	33.49m
USWL	EL. 1024.57 masl
DSWL	EL. 1000.18 masl
PENSTOCK
Material	Steel
Diameter	3.2m
Length	147m
Thickness	10, 12 and 16 mm
POWERHOUSE
Type	Semi – Surface
Dimension	30m (L) x 13.5m (W) x 24m (H)
Turbine Axis Level	EL. 938.30 masl
Floor Level	EL. 944.60 masl
Tail Pond Level	EL. 940.50 masl
TAILRACE
Type	Concrete Box Culvert
Length	77m
Size	4m x 3.6m
Outlet Tail water Level	EL. 940.42 masl
TURBINES
Type of Turbine	Francis (Vertical Axis)
No. of Units	Two
Rated Net Head	69.78m
Unit Discharge	12.50m3/s
TRANSMISSION LINE
Voltage	132kV
Length	4km
Connection	NEA Sub-station at Patichaur, Parbat
POWER AND ENERGY GENERATION
Gross Head	72.91m
Net Head	69.78m
Installed Capacity	15MW
Annual Net Energy	79.124GWh
Dry Season Energy	12.198GWh
Wet Season Energy	66.925GWh
TARGET COMPLETION DATE: July 2014