LAKE COLERIDGE.

Press, Volume LXI, Issue 18479, 5 September 1925, Page 8

LAKE COLERIDGE.

EXTENSION OF POWER STATION. - PROGRESS IX AUGUST. The report on the progress made during August with the different -works in the extension of the Lake Coleridge power station states that the "weather during the month was extremely toad, rain or snow falling upon 13 . working days. This was against good progress, being felt *vcry much. up/)u all outside work, and to a lesser degree upon tbc tunnel. The week's races early in the month resulted in a large number of men being off for the best part of a week. Several slips occurred upon various portions of-the work, one of which wrecked the winch house at the gate shaft. The total rainfall for the month was 6.82 inches, which is the heaviest monthly rainfall for the last eight year 9. Intake Works—lntake Caisson. 'Considerable difficulty was experienced in making airtight the steel plate bulkhead whirh was placed upon top of the intake caisson during July. This was eventually completed and compressed air was let into the caisson, the water being forced out. An inspection of the ground at the bottom of the caisson was made. The construction of a reinforced concrete slab above the bulkhead was decided upon so as to give additional strength.,

Tunnel: No further work ■was done upon this tunnel during the month. Intake Cross Drive: The excavation and lining of the cross drive have been proceeded with during the month, upon cooperative contract. During, the month 80 lin. ft. were excavated and 33 lin ft. were concrete lined. It is anticipated that this will be completed to a point ten feet from tho existing tunnel early in the current month, when the concrete lining of tho gate shaft will be commenced.

TVfain_ TimneL The following progress has been made for the month at the various faces:— EXCAVATION. X Lin. feet Lin. ft. for to month. Dito. Intake-end to centre shift .. , 148.5 1560.5 <C»ntre'«hift .to intake end '.. ■ 165 528 Ceplta dh»ft' to outlet end .. 148.5 <98.5 Outlet end-to centre »hait .. 165 2067.5 .Total * ' . _ '.. . 627 4654.5. The length of tunnel still to be excavated'ai end of month was. 2640 lin- ft. ' > LINING. Intake end. to oeatre shift .*■" 148.5 1437.5 Centre shaft to intake end. „ 115.3 . 394.5 Centre sh*ft to outlet'end' .. 30 401.0 Outlet end to centre shift 145.5 1853.5 V,. Total •: .-' M 511.5 4066.5 "Tho length of tunnel still to be lined at end of month-was 3228 lin. ft. Considering that work was much retarded by the absence of many men for a week at. .the GhiSatehurch races,' and also by very /bad weather, the progress made by the contractors is considered satisfactory. At the intake; end the amount -of water has shown u.slight increase, 80 g.p.m. being pumped at the end of the month compared with '6O g.p.m. ;it the commencement of the month. At the centre shaft the water being pumped reached 1000 g.p.m. at the middle of the njonth, but bv the end of the month it had again receded to 900 g.p.'m. This must be considered very gratifying. At the. outlet end of the tunnel a definite flow of water has again developed; it amounted to .approximately 20 g.p.m. at the end of the month. All pumping plant is working very satisfactorily. 1 Surge. Chamber. Hie placing,of -concrete in the wails of the surge.'chamber waa continued, 160 c.yds:' being placed during the mianth. The walls have now been built to within 3ft. of "the finished level. The excavation of , the oentre core, which was left in. to assist in placing of con-, crete, has been commenced. The excavation of No. 6 pipe tunnel; has been completed, and placing of pipes will be' proceeded 'with next njonth. Upon completion of: surge chamber walls the concrete lining of spillway will be undertaken; '"Pipeline. Anchor Block No. 7 was completed to finished level during the month, and forms have been placed t<> complete Anchor Block No. 6. Power House Extension. No, 8 draft tube chamber was excavated and concrete placed up to 1174.5 level. No. 7 draft tube chamber was excavated, and the concrete floor of this chamber was placed. The excavations necessitated continuous pumping. One hundred and'twenty cubic yards of concrete were placed during the month. Timber was ■ stripped from the roof, which has comq out very well. • Weir Basins. The placing of concrete in weir basins was retarded very much on account of the weather, and also by the excavation from the draft tube chambers which bad to -traverse -the -weir basins. In No. 8 weir basin the major portion of floor and obo wall has been placed, and in No. 7 weir basin, a portion of the floor has been placed. Approximately 90 cubic yards of concrete were placed during the month. This work will be completed in October. ( Tail Race. I The widening of the existing tail race below the junction of new tail raee down to the Rakaia River was completed during the month. Eighteen hundred and eightv cubic yards were excavated during the month. The work comprised a total" excavation of 4880 cubic yards. The widening of the existing tail race from the junction of new and old races towards the power house, was carried ont by manuaj labour, as it was nob possible to cross the tail race with the drag line. Upon completion of widening of old tail race the drag line was engaged npon excavatron of new tail race, and 1770 cubic yards, were excavated. Total excavated during the month by drag-line was 3650 cubic yards. I Staff: At the end of the month the j working-force totalled 227, as follows: Officers, 6; artisans, 21; labourers, 86; shingle --contractors. 12; tunnel, 130; power house, 14; and cartage, 8.