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Located at the foot-hills of Arya Tea Estate at an altitude of 3,600 ft and 12 km from Darjeeling Town via Bloomfield Tea Estate; Sidrapong Hydel Power Station is the oldest Hydel Power Station or hydroelectric power plant in India.
There are two approaches to the station and one can choose either as per their liking. The first approach is via Arya Tea Estate. The road up to the Tea Factory is well laid and jeepable, covering a distance of 6 km from Darjeeling. Beyond Arya Tea Factory thence, there exists a steep pony track up to Sidrapong Forebay covering a length of about 3 km. This approach though not much developed offers an added incentive. Visitors are required to travel through the lush tea gardens of the Arya Tea Estate. Further, the sight of young maidens plucking tea humming to a traditional song is worth a trek.
The second approach to Sidrapong Power Station is via Bloomfield Factory, the same covering a stretch of 11 km. The existing foot track beyond Bloomfield Factory has recently been developed by Darjeeling Gorkha Hill Council to a 14 ft wide metalled road and a visitor needs no longer trek any distance to reach the Sidrapong Forebay. He or she simply needs to cross the Kotwali Jhora through a new bridge near the existing intake to do so. This new all-weather road is today, the most popular among visitors.
The fateful meeting of the Municipal Commissioners of Darjeeling held on the 11th February, 1896 presided over by Mr. R. T. Greer, I.C.S.the then Deputy Commissioner of Darjeeling and the Chairman of Darjeeling Municipality, resolved to set up a Hydro Power Station to light up Darjeeling town by seeking a loan of Rs. 1 lakh (Rs. 100,000) from the Government. A site for the power station was selected at the foot of the Arya Tea Estate at Sidrapong, what was then a fine orchard of the Maharajah of Burdwan and considering the importance of the scheme in the public interest, Maharajahdiraja Sir Bijoy Chand Mahatab Bahadur, G.C.I.E.K.C.S.I., I.O.M. was pleased to make it over the municipality. The work for the installation of power station started immediately. The machines and equipment came from Britain. There being no proper road communication all the equipment, machinery and construction materials had to be transported manually—a Herculean task, quite inconceivable in the present day.
The first plant consisted of two 65 kW Crompton-Brunton single-phase, 2300 volts and 83.3 hertz alternators coupled with two Gunther’s Turbines. India’s first Hydro-Electric Power Station with 2× x 65 kW capacity was commissioned on the 10th November 1897 by C. C. Stevens, the then Acting Lieutenant Governor of Bengal. It is a noteworthy fact that the first power utility run on commercial basis for use of general public in India was developed in public sector under state patronage. The total initial cost of installation of this power station had been only Rs. 1.2 lakhs (120,000 rupees).
For the first few years Darjeeling Municipality had to run Sidrapong Hydel Power Station at a loss, there being not many taker of electrical energy then. But as the demand started growing one 135 kW set was added in 1905 and a third 135 kW set was installed in 1909 in the same power house. The place being too small a new power house was built in 1916 at a higher location, now known as Jubilee Power House. In this way the total capacity of the station grew from 130 kW to 1000 kW. But owing to the limited supply of water the generation could not be increased to match the growing demand of the town and of the neighbouring tea gardens to run their factories with electricity. Various schemes were prepared to install larger power station elsewhere. In 1914 the late George P. Robertson, the then Municipal Engineer, while out on survey in this connection was drowned in the Great Rangeet River.
In the meantime the demand for power grew rapidly. The old single phase system of supply being out-dated, unsuitable for a modern supply system and wasteful, the Municipal Commissioners resolved in a meeting held on 9 June 1931 to replace all the old machines and recondition the system of supply from single-phase 83 Hz to three-phase 50 Hz.
In 1931, in place of old 7 machines in single-phase system with a total capacity of 1000 kW, five 200 kW units in the new 3 phase system were installed, of which one at the Lower Power House. Since water was found insufficient to run 4 sets of 200 kW each in the present power house, one 200 kW set was later in 1942 shifted to a still lower location at Singtam (Darjeeling Singtam) Power Station, which may be called third stage of Sindrapong since it runs in tandem with Sidrapong Power House utilising the discharge water from its tailrace. The present installation, therefore, consists of 3 sets of 200 kW at Sidrapong Power House besides one DC Hydel Generation set of 20 kW for auxiliary power.
TAKE OVER BY WBSEB
WBSEB West Bengal State Electricity Board inherited Sidrapong Hydel Power Station while taking over the Darjeeling Electric Supply Undertaking from Darjeeling Municipality on January 30, 1978  and had since been smoothly running the power station till early 1990s when it was considered that the aging power station need to be converted into a heritage site.
WATER SOURCE: FLUME
The Power Station is fed with water from the three Jhoras, viz. Kotwali, Hospital & Barbatia.
Kotwali Flume: 1700 ft
The minimum quantity of water available in the driest month of April is 1.5 cusecs. The conduits are of black plain sheets of 16 gauge thickness combined with C. C. duct. The size of conduit is 2′ x 2′ in section. There is a silt tank just near the intake which is freeing the water from sand and loose stones.
Hospital Jhora Flume
It has been taken along the side of precipitous rocks which have been cut in places to make room for it. It gives about 3 ft³/s of water in the driest season in April. The water being waste-carrying and dirty it has two silt tanks one at each end to screen out detritus. The size of the conduit is 2 ft x 2 ft with black plain sheet combined with masonry duct of the same size with concrete lining inside.
Barbatia Flume: 2500 ft
This provides the largest quantity of clean water: about 4 ft³/s of water in the driest season. The flume terminates in a Suspension Bridge 284 ft long and 6 ft wide. The counduit over the bridge is of black plain sheet and 2 ft 6 in in breadth and 1 ft 0 in deep and a foot-way runs alongside. A few feet from the point of diverting the Jhora, there is a silt tank (22′x 7′8″x5′) rectangular in shape. There are two scour gates at the bottom level of the tank to wash out the silt. In the rains when there is a voluminous supply of water but full of grit, this bottom gates are left partly open so that the grit is automatically scoured out.
Water from Hospital Jhora and Kotwali Jhora are collected in a reservoir 112′ x 49′ x 12′ which is connected with anotehr larger reservoir 223′ x 60′ 15′ adjacent to it.
Water from the smaller reservoir is passed through an underground cast-iron pipe 24″ in diameter to a pentrough 20′ x 4′ x 10′, the bottom of which is on the same level as the reservoir. From the pentrough the water runs down to the gates of the turbines through dobule rivetted steel pipes 720 ft. long 15″ inside diameter and 3/16″ plate in 20 ft sections and with flanged joints. There are two bends in the length, one of 28 degrees at about two-thirds the way down and the other of 90 degrees just bend the Power House. The bends are of cast-iron tested to 250 lbf/in². There are no expansion joints. They are kept full of water and are buried underground so that the temperature variation is small. The pipe line is connected to a 36″ diameter steel receiver pipe 27 ft long and plate 3/8″ thick. It is amde in two parts, one being tapered to 20″ diameter and the other part fitted with a blank end bolted on. The receiver is provided with two branches each 15″ inside diameter for the two turbines andone 9″ branch for the 20 kW set.
Another penstock that takes off from the larger reservoir for a length of 725 ft consists of 24″ steel pipe each section 24 ft long with 3/16 in thick walls. The ends fit into loose collars, which are filled in with lead and rings of ferro-concrete connected by iron bolts and are cast round the collar-ends to prevent the lead being blown out. The lower length is 20″ inside diameter and of 5/16″ steel in 20 ft sections. The two different sections are connected with a 24″ x 20″ steel reducing piece 20 in long.
Before entering the machines there are Sluice Valves with provision for 3″ bypass valve to reduce the pressure at the time of opening the main valve. There are provisions for running all the machines from both the reservoirs separately in case of necessity by providing interconnection in the pipes along with necessary valves/gates.
It is located immediately below the machine floor level on the northern part of the building. It has housed four 0.4/6.6 kV transformers.
For many decades, the project was ignored by the state and the private sector. Larger and modern power supply networks were developed to supply the growing populations of Darjeeling and Kalimpong. The number of workers at the power plant dwindled and the machinery fell into disrepair. During the Gorkhaland political agitation, the local residents struggled to preserve the station from rival groups seeking to demolish it. The station was damaged around this time due to a landslide and remained shut for a decade. The central government and the West Bengal State Electricity Board revived the power station again in 1997 to mark centenary of the station. In a special ceremony, the station was accorded heritage status by the central government, with a pledge to revive the power plant. However, efforts at repairing the plant and re-starting operations languished for 6 years owing to persistent technical problems and lack of attention from state authorities. The residents of the towns of Sidrapong, Risheehat, Arya and Bloomfield formed a committee on December 1, 2003 to revive and resuscitate the historic hydel project, in defiance of the government, which they blame for perpetually ignoring the monumental establishment.
1. Encyclopedia Darjeeling by Barun Roy, Published by New Media Foundation, Kolkata
2. Fallen Cicada by Barun Roy, Published by Beacon Publications, Darjeeling.
3. Sidrapong, Heritage Power Station, Published by Corporate Public Relations Department, WBSEB, Vidyut Bhavan, Calcutta 700 091. November 10, 1997 Centenary Booklet
4. Jhora in Nepali refers to a stream or a rivulet
* Roy Barun (2003), Fallen Cicada (1st ed.), Beacon Publications
* Roy Barun (Ed) (1998), Beacon, Electricity - The ever lasting nightmare / Sidrapong - A Glorious Chapter in our History (15th January ed.), Beacon Publications