AXTOFAGASTA RAILWAY WATERWORKS. 127 



A full pressure test of 610 lbs. per square inch was made 

 on this main, and both pipes and joints have stood admirably. 



Service Reservoirs. 



With the exception of a new covered concrete reservoir at 

 Antofa^asta the storage of water is effected by means of steel 

 plate tanks. 



Each water station has a square steel tank erected on a 

 steel o-irder trestle for the locomotive and station supply. The 

 tanks are built up from 4 feet square pressed steel plates with 

 the edg;es turned up to form a liange. The tanks are 24 feet 

 square and 8 feet high and have a capacity of 28,600 gallons 

 The plates are bolted together on the outside, and a strip of 

 sheet lead is inserted between the flanges projecting i inch outside 

 the interior face of the tank. This is afterwards caulked down 

 and fills the joint, making it watertight. 



At Kilometre 170, before reaching the nitrate district, two 

 large riveted steel tanks, circular in plan and with a capacity of 

 660,000 gallons each, have been erected. Nos. 1 and 2 mains 

 deliver into these, and they act as storage and balancing tanks. 



At Antofagasta until 1915, storage was carried in seven 

 circular riveted steel plate tanks of the following capacities. — 



2 of 96,800 gallons 



2 of 517,000 gallons 



3 of 398,200 gallons 



or a total storage of 2.422,200 gallons, equal to four-and-a-half 

 days' supply. Steel tanks were doubtless originally decided upon 

 on account of earthquake shocks which frequently occur, and 

 also because of the difiticulty of obtaining good workmen in 

 masonry and concrete in the earlier days. 



The steel tanks after cleaning are coated with a cement wash 

 and this has preserved the plate from corrosion. 



Since 1909 there has been a rapid increase in the average 

 daily consumption, and increased storage capacity for the town 

 supply became a necessity. A circular concrete. covered reservoir 

 of 2,200,000 gallons capacity was designed and appproved, and 

 the work of construction was commenced in April, 1913. It was 

 successfully completed and filled in August, 1914. A steam- 

 driven concrete mixer was used, which resulted in a far better 

 quality of concrete than could have been counted upon had 

 Chilian hand labour been employed. The cement was imported 

 from England in barrels and cost £3 15s. 7d. per ton placed on 

 the site. The stone taken out of the excavation was very poor 

 in quality and partially decomposed and was not good enough 

 for the concrete, but fortunately good stone was found at a dis- 

 tance of a kilometre. The concrete in the floor and walls was 

 composed of: — 



4 parts of stone, crushed to 2i inch ring. 



2 parts sand. 



IJ parts cement. 



