^^O AN IRRIGATION SETTLKMKNT. 



large part they play in passiiiji the ^i(lc drainayc waters can he seen when 

 it is stated that, apart from oversow walls, there are only >ix ;i(|ue(luels 

 under which the waters of the higger dongas are carried. 



Except for tlie head regulator, there is not a single gate across the 

 furrow, which I consider to be a defect which should lie remedied. 



The lirst couple of miles of the furrow are through river silt, and Mr. 

 Lut/. employed the " spocling " or sluicing method <>i excavation con- 

 siderably in this length. 



The first aqueduct is at i j miles, and there is a slight deviation here 

 from the original official alignment to keep the excavation otit of rock. 



Rock excavation begins at 2-] miles and the second and widest 

 aqueduct on the furrow is at the bend at 2'f miles. The typical drystone 

 section (with pitching on both sides) continues right up to the slight 

 masonry al)utment. Zinc plates carry the gravel and slight masonry 

 side walls, and the plates are supported by a framework of bent trolley 

 rails. This is the only aqueduct of this type. 



The river channel becomes very narrow at 2'1 miles, so that, in spite 

 of the big fall in the river above, the furrow is not completely out of 

 the reach of Hoods till the third mile. At 3| miles the canal meets a 

 high level branch of the river which is parallel to and high above the 

 narrow and deep Xeus Gorge, but cut otif from it by a ridge of granite. 

 rocks. The original idea was to make the furrow along the rock face of 

 this channel on the side farthest away from the river, but when 

 examining the alignment I approved of Mr. Lutz's suggestion to build an 

 earth dam faced with drystone work at the lower end of this high level 

 channel, and turn the furrow into the tank thus formed, which is fifty 

 yards long. This tank forms a good silting reach, and has already 

 almost conipletely silted up, with the furrow running down the centre. 

 When the silting operations are complete the furrow will be straightened 

 and trimmed up. By this means, about half a mile of difficult furrow- 

 making was saved. Small gaps in the river side of the sluit have been 

 filled up by masonry overflow walls, and these leak ratlier liadly. Tlie 

 third aqueduct is at t;^ miles, which is of drystone construction on corru- 

 gated iron centerings. 



Lower down the heaviest walling and mck-work in the wimle furniw 

 is met with. The walling is 23 feet high in one place, and twu very 

 (Hfficult lengths have been blasted out of rock. 



.At five miles the first tunnel is reached It is too yards long, has a 

 fall of 1 foot, and is 6 feet high liy 5 feet wire. Uelow the tunnel is a 

 long masonry overflow wall, with two tilting escapes, and the last 

 aqueduct of the usual type is at 5I miles. Heavy walling follows u|) to 

 the cutting for the second tunnel, which is 208 yards long, has i8in. fall, 

 and is of the same section as the first, 5 feet by 6 feet. This brings us to 

 the sixth mile, which completes the most difficult length of the furrow. 

 Krom there to the Paarden Island syphon there is nothing exceptional 

 in the work, wliich consists of cutting, dry walling, and tilting escapes, 

 though there are very few places where the work can he called easy, 

 the cutting sometimes reaching 10 feet in depth through rock. 



.\ 22-fcet fall is given over rock a little beyond the thirteenth mile, 

 and the furrow enters Krantzkop (not belonging to the Commission) 

 about a quarter mile lower. A slight deviation had to be made just 

 within Krantzkop to avoid the shop there. .\ length of walling serves 

 instead of ;i cutting through a leegte, anti a 27-inch jiijie through the 

 wall under the furrow passes the side drainage instead of ilie usual tilting 

 escape. 



The mainland furrow ends at T/ miles, and the water is carried over 

 to Paarden Island in a 27-inch pijie 1,360 feet long, having 5 feet fall from 

 end to end. The pipe is made of very thin (about ,^r6in.) galvanised steel, and 

 was sent out in 4ft. sheets, bent to shape and punched, but not rivetted, so 

 that several sheets could be nested, thereby saving space and ocean freight. 

 The pipes cost £460 in Port Elizabeth, and transport to site cost about 

 the same. The riveting was done cold on the spot, and the pipe was laid 



