The Surveyor and municipal engineer . February, 1^98).(Showing Cyclopean Rubble.) voirs into the river would be correspondingly increasedFurther observations since the Bill was in Parliament havestitislied me that we may calculate on from theworks 75,000,000 gallons a day for supply in addition to the27,0:10,000 gallons for compensation. THE DAMS AND RESERVOIRS. Considered geologically, the whole of the watershed areaconsists of rocks of Lower Silurian age, principally inferiorplates, but in parts of very hard grits and conglomerates. Itis tho presence of thick bands of the latter s
The Surveyor and municipal engineer . February, 1^98).(Showing Cyclopean Rubble.) voirs into the river would be correspondingly increasedFurther observations since the Bill was in Parliament havestitislied me that we may calculate on from theworks 75,000,000 gallons a day for supply in addition to the27,0:10,000 gallons for compensation. THE DAMS AND RESERVOIRS. Considered geologically, the whole of the watershed areaconsists of rocks of Lower Silurian age, principally inferiorplates, but in parts of very hard grits and conglomerates. Itis tho presence of thick bands of the latter stretching acrossthe Ehin at a place called Caban Goch and resisting disintegra-tion which has determined the position of the contraction inthe sides of the valley and rendered it so eminently suitablefor the location of a barrier dam. At this spot the bed of theriver is 700 ft. above ordnance datum, tho bottom of thevalley being about 200 ft. wide, and at 120 ft. higher onlyGOO ft. Immediately above this contraction the valley widens. Cahkg-Ddd Culvert Iv\c w ai io\, >i\(. Ii-Sikkam (July, 1,S9GJ. ont into a broad flat, and 1,540 yards higher up the riverClaorwen joins the Elan on its right bank. These conditionspointed nimiistakably to tho Caban gorge as the site of thelowest dam, and consequently determined the area of gather-ing ground to be utilised. Tho height of tho wall to bo built was, after much considera-tion, at 122 ft. above the bed of tho rivor, and the con-tents of the reservoir behind it will be nearly 8,000,000,000 Drceuber 2, 1898.] AND COUNTY ENGINEER. gallons. As compared with tho height of the wall above theriver, the Vyruwy (Liverpool works) is So ft. and tho Thirl-mere (Manchester works) i5()ft. The river Eltin has in thepoint affected by this dam a rise of 30 ft. in a mile, so thatthe 122-ft. barrier backs the water up that valley 4 miles,and up tho Claorwen, which is somewhat steeper, about 2\miles. Tho length of drought which it was deemed adv
Size: 1768px × 1413px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectgreatbritain, bookyea
