Upper Mai HP

Task: Feasibiliy study & Detailed Design of Headworks

Capacity: 10 MW

Status: Completed

Salient features (Mai Headworks arrangements- (as per Design Basis Report, 2009)):

Location:	Maimajhwa and Mabu VDC, Ilam District, Eastern Development Region of Nepal
Hydrology:
Average Flow	3.63 m3/s
Design Flow	3.45 m3/s
Design Flood	255 m3/s. (100 Years Flood)
Diversion Weir :
Type	Concrete gravity dam
Slope	Rectangle with vertical drop
Crest Elevation	1628 msl.
Crest Length	12m
Maximum Flood Level	1632.50 msl.
Under Sluice with Radial Gate :
Invert level	1624.00 msl.
Size	2 m X 1.5 m
Length	11.50 m
Max. Discharge	100 years of Flood.
Intake :
Type	Rectangle orifice, Semi-Frontal
No of Orifice	3 nos.
Size	1.5 m wide X 2 m high with 2 center piers.
Sill Elevation	1626.00 msl.
Design Discharge	3.45 m3/s. (During normal Flow condition)
Gravel Trap and Spillway :
Type	Single chamber Hopper type.
Bed Slope	Drop in 1: 1 Slop after 3.4m flat length.
Size	6.15 m long X 4 m wide X 5.50 m average height.
Normal Water Level	1627.82 msl
Maximum Water Level	1631.92 msl
Top wall Level	1630.50 msl
Gravel Flushing :
Size of opening	1.5 m wide X 0.5 m hight.
Size of Flushing Gate	600 mm X 600 mm
No. of opening	Single
Max. Size of Particles to be Flush out	500 mm as per hydro lab report.
Trash Canal :
Length of Trash canal	5.5 m
Size of Flap Gate opening	2.0 m wide X 2.0 m high.
Headrace Canal :
Type	Rectangle, closed canal.
Slope	1 : 500
Trace Rack	Fine Trash rack
Size of canal gate	2.1 m wide X 2.0 m high.
Normal water Level	1627.80 msl.
Maximum opening of gate	2.0 m
Maximum Discharge	5 m3/s.
Settling Basin :
No. of chambers	4 Nos.
Size (Parallel Section)	30 m long X 4.0 m wide X 4.12 m Avg. height.
Length of transition zone	22.50 m
Length of settling zone	30.00 m
Normal Water level	1627.60 msl.
Slope at settling zone	1 : 50 (V : H)
Nos. of flushing gate	4 nos.
Size of Flushing Gate Max. length of flushing canal	1.0 m wide X 1.0 m high. 26.75 m
Slope of Flushing Canal	1 : 70
Forebay and spillway : Spillway crest level	1627.65 msl.
Length of crest level Spillway canal size	12.80 m 1.5 m wide X 15.75 m length X 1.2m Avg. high.
Design Discharge	3.14 m3/s.

Project Title: Upper Mai HP