224 



T. W. KEELE. 



As the time for completing the tunnels depends princi- 

 pally on the number of faces at which the men can work, 

 I have made provision in the estimate for 39 shafts along 

 the main tunnel line, the average distance apart would be 

 3696 feet and the average depth 300 feet. 



In the branch tunnel to Crown Street, I have allowed for 

 32 shafts at varying distances apart from 1452 feet in the 

 thickly populated portions of the line to 3388 feet where 

 the settlement is not so dense. Along the tunnel to Ryde 

 the greatest distance between shafts would probably be 

 about 7392 feet where crossing the Harbour, which would 

 leave 31,680 feet on the south side, and 4752 feet on the 

 north side, and the shafts would be spaced at distances apart 

 of 3168 feet and 2376 feet, respectively. 



The total length of the six tunnels connecting the several 

 reservoirs from Wingecarribee to the Cataract Reservoir, 

 would amount to 20J miles. Provision has been made for 

 their being lined with concrete throughout, and for their 

 capacity to deliver 150 million gallons per day. They would 

 thus be capable of passing a large quantity of water quickly 

 from one reservoir to another, so that during storms, which 

 occur sometimes on one portion of the Catchment Area and 

 do not extend to the other, the surplus water, which other- 

 wise would run to waste when a reservoir is full, would be 

 passed on to those lower down. In this way it will be pos- 

 sible to obtain a greater benefit from the rainstorms over 

 the whole area than would result from a series of discon- 

 nected reservoirs. 



I estimate that the main "Pressure tunnel" from the 

 Cataract Reservoir to Bankstown, together with the two 

 branch tunnels, could be completed in five years, if the works 

 were all being carried on at the same time, at a total cost of 

 £3,761,468. 



