Wednesday, 17 May 2017

Otago Central Railway [19]: Clyde completed

Well since my last post I have been putting in extra details in the Clyde yard and checking them against the current Linz aerial footage that I have used. This work is now complete. There is just some checking to be done against the 1992 aerial footage and also one change to be done to Cromwell yard with the pre-1961 goods shed location before I start writing.

The east end of Clyde yard. Starting from the right we have the site of the engine depot (E), former cattleyards (Y), coal depot (F) and water tanks (W). In the middle we have the site of the turntable and to the left can be seen a row of houses of which three still remain today. Whitby Street did not cross the railway here as it was built across after the line closed, so there was not a street going between two of the houses as is the case today.

The middle of Clyde yard. As can be seen the three houses remaining on the north side of the line were part of a row of six or more originally. A water vat and some more houses were on the south side opposite. House 212 was at one time the stationmaster's house. Station facilities included a goods shed and loading bank; the shed was relocated nearby after the station closed, as seen in the next map. The Clyde station building was for many years occupied by a vintage farm machinery museum that was evicted for lease arrears; it was believed the group was using the site for storage and had no intention of opening to the public. The building for the last two years is now occupied by a rail trail related business.

West end of Clyde yard. The stockyards were in this position when aerial photos were taken in the 1960s. We can also see the sites of three more houses (one still exists today), a water vat and the current location of the goods shed, which was moved to become part of the Clyde Briar Herb Museum complex. At the time of writing the museum is closed due to some of the buildings being earthquake prone and in poor condition.

The Clyde railyard as seen in February 1979. The operating facilities were limited to the immediate vicinity of the station just 14 months prior to closure.

Entrance to the Cromwell Gorge just above the Clyde Dam as seen in February 1979. The new highway can be seen joining to the old route at Dairy Creek with the extension above it being started. New oxidation ponds are being built and a gully filled just below them, some of the extensive earthworks that changed the shape of the gorge to reduce instability. 

Clyde dam site February 1979. The green rectangle shows where the river diversion channel was already being cut out of the river bank. Foundations and sluices were built in this channel and then the river was diverted through them to give a dry foundation under the rest of the dam. This is where the administration offices and staff parking are located today, just below the powerhouse.

Google Earth view of the dam today with water spilling on the spillway to the right. To the left can be seen the diversion channel with four low level sluice channels in the water at the bottom of it it. Three of these sluices were permanently closed when the dam began filling; the remaining channel is closed by a gate which can be opened if needed to draw down the reservoir and which is regularly tested for correct operation. Directly above the channel are two high level sluices or penstocks that have never been completed. There may have been an intention to extend the powerhouse and add two more turbines and generators at this location when the dam was first designed. However the design was changed midway through construction to add the earthquake slip joint and the associated changes apparently included deleting the last two penstocks and associated generation machinery. 

Early stage of dam construction with the diversion sluices in place above the channel.

Another view of the diversion from the upstream side of the dam. The high level sluices to the "spare penstocks" are visible as well as the four vertical gates in place to close off the sluices when the lake is ready to be filled. One of the sluices is now fitted with a radial gate to allow it to be reopened if necessary.

In 1992 a group of environmentalists took the opportunity to raft the river before the dam was completely closed up. This upstream view of the dam shows the river at its pre-hydro level. The entrances to the four operational penstocks and two "spare penstocks" can be seen with the sluice gates below the latter. The rafters passed through one of the diversion channels before they were permanently closed to fill the lake.