USE, CONSTRUCTION, AND COST OF SERVICE RESERVOIRS. 147 



NOTES ON THE USE, CONSTRUCTION, AND COST OF 

 SERVICE RESERVOIRS IN NEW SOUTH WALES. 



By C. W. DARLEY, M.Inst. C.E. 



Engineer-in-Chief for Harbours, Rivers and Water Supply. 



[With Plates xiv. - xix.] 



[Bead before the Royal Society of N.8. Wales, October 7, 189 1J] 



The Harbours and Rivers Branch of the Public Works Depart- 

 ment having been intrusted with the design and construction of 

 works connected with the water supply for the City of Sydney 

 and most of the country towns in New South Wales where water 

 has been laid on, a considerable amount of experience and infor- 

 mation has been gained in the construction of Reservoirs of all 

 kinds to suit various requirements ; at present this information is 

 stored away or scattered amongst papers where it is almost inac- 

 cessible, and certainly serves no useful purpose, but when collected 

 together in a concise form it may be of some use to members of 

 the Engineering profession, and as a large number of Engineers 

 are now members of the Royal Society this seems a fitting oppor- 

 tunity to bring the subject before them. 



There are two (2) distinct classes of Reservoirs used in con- 

 nection with Town Water supplies, namely, " Storage " and 

 " Service " Reservoirs. 



The former are necessarily large in extent, usually of sufficient 

 capacity to retain at least twelve months supply of water, and 

 may generally be looked upon as artificial lakes, the water being 

 impounded with an earthen, masonry, or concrete dam, and stored 

 on the natural surface. Rarely can these Reservoirs be con- 

 structed sufficiently near a city to enable them to be used for 

 " Service " purposes. 



The latter or second class of Reservoirs have to be constructed 

 close to or within the city or town to be supplied. The special 



