G.O. (Ms.) No. 194, Mullai Periyar Dam New Trash Rack Arrangement, 2009

What the government approved

G.O. (Ms.) No. 194 of the Public Works (P1) Department, dated 9 September 2009, accepts a proposal from the Chief Engineer, Water Resources Department, Madurai Region. It sanctions Rs.59,48,000 for a new trash rack arrangement in the leading channel of Periyar Lake.

The approved location is about 130 m upstream of the tunnel entry at Thekkady Head Sluice. The purpose is to increase and stabilise the quantity of water drawn from Mullai Periyar Dam through the irrigation tunnel to Vaigai Dam.

Why the new arrangement was proposed

The Public Works (P1) Department recorded the following operational problems with the existing trash rack at the tunnel entrance:

• The existing rack has an area of 152 square feet and uses steel members with openings spaced at 8 cm centre to centre.
• The arrangement reduces the available flow area to 132 square feet, resulting in a stated flow reduction of 13.15 per cent.
• The maximum drawal was stated to be only 2,050 cusecs even when the water level exceeded 136 feet.
• Trash sticks to the rack because of suction at the tunnel entrance.
• Cleaning requires the gates to be closed for about three hours per day, three times a week, to protect divers.
• These closures were stated to reduce average drawal by about 100 cusecs per day, amounting to 1,000 mcft per year.

Main features and intended result

The new trash rack sanctioned under G.O. (Ms.) No. 194 is to be placed where the flow velocity is described as normal. Its openings are proposed at 8 cm centre to centre, extending to a level of 145 feet and covering a water height of 44 feet.

The stated expected results are:

• Maximum water drawal through the irrigation tunnel.
• More consistent transfer of water from Periyar Dam to Vaigai Dam.
• Reduced surplus supplies to Kerala.

Funding and relevance to readers

The sanctioned expenditure is assigned to the capital outlay account for the Periyar Project. Funds were to be provided through the Revised Estimate or Final Modified Appropriation for 2009 to 2010, with inclusion in the Supplementary Estimates.

G.O. (Ms.) No. 194 concerns irrigation infrastructure and government expenditure. It does not describe a sale, transfer, classification or acquisition of private land.