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DISTRIBUTION WORKS.
49. Distribution Project.-On the completion of the foregoing works it was evident that the system of mains existing in the City would be quite inadequate to distribute the water supply now available, and as there existed many streets in the City unprovided with water pipes it was decided after careful consideration that practically an entirely new system was necessary.
50. Accordingly, when considering the project for the construction of the Pokfoolum filter beds and service reservoir, I was instructed also to prepare a project for setting the distribution works on a satisfactory basis.
51. Particulars of these projects will be found in my report dated February 4th, 1889.
52. The report and plans were referred to Mr. CHADWICK, C.M.G., Consulting Engineer to the Crown Agents, who during a stay in the Colony went into the question and reported on the 28th December, 1889, recommending generally the adoption of the project which consisted of dividing the City into three zones according to the elevation of the ground.
53. The lower zone extends from the sea to approximately the 150-feet contour, the next zone from the 150-feet contour to the 250 one, and the uppermost zone from the 250-feet contour to the Pokfoolum conduit.
54. The three principal mains were 14", 12" and 10" in diameter, and the project included completing the system of mains in every street and providing fire hydrants at an average distance apart of 300 feet.
55. Mr. CHADWICK, however, proposed an important addition to this project, viz., the substitution of hydraulic motors for the ordinary reducing valves to reduce the pressure of the water before entering the mains in the lower zones.
56. Sites were selected in the Garden, Arbuthnot and Bonham Roads for the erection of hydrau- lic motors to utilize the surplus pressure by actuating pumps raising water to reservoirs to be con- structed above the level of the built area of the city which now extended in places up to and even above the level of the Pokfoolum conduit.
57. The works finally decided upon and carried out during the years 1890-1892 consisted of :—
(a) The laying of 20 miles of cast iron mains varying from 14" to 3" in diameter.
(b) The erection of Pumping Stations and Motors at Garden, Arbuthnot and Bonham Roads. (c) The construction of service reservoirs on the Peak Road, the hillside South of Belilios
Terrace, and at West Point above the Pokfoolum Filter Beds.
58. The flow of water in the several districts is commanded by 250 valves. Four hundred and twenty-three fire hydrants and 108 fountains have been provided.
59. In the Garden Road pumping station is installed a duplex direct acting horizontal Worth- ington motor. The power cylinders and pumps, the latter being double acting, are placed tandem.
60. This motor is actuated by the flow of water from the Albany service reservoir down Garden Road and is available for pumping water to the reservoir on the Peak Road and the one south of Belilios Terrace.
61. In the Arbuthnot Road pumping station is installed a direct acting horizontal duplex hydraulic motor from the designs of Messrs. HAWTHORN DAVEY & Co. The power cylinders and pumps, the latter being differential ram pumps, are placed tandem.
62. This motor is actuated by the flow of water from the Albany service reservoir down Arbuthnot Road and is also available for pumping water to the reservoir on the Peak Road and the one south of Belilios Terrace,
63. In the Bonham Road pumping station is installed a motor, of similar design to the one in Arbuthnot Road, actuated by the flow of water from the Pokfoolum service reservoir down the hillside and along Bonham Road.
64. This motor is available for pumping water to the reservoir on the hillside above the Pokfoolum filter beds and to the one south of Belilios Terrace. It has, however, been designed mainly for the pumping of the water to the Hill District, the water supply of which will be referred to later on.
65. The general arrangement of the motors may be briefly described as follows.
The water at the full pressure available from the reservoir is conducted to the power cylinders and by suitable valve arrangement actuates the pistons, the exhaust water being conducted into the distributing mains at reduced pressure for the supply of the City. The motion thus given to the pistons is communicated to the pumps, the rods of which are connected direct to those of the pistons.
66. A "bye-pass connection" is made between the mains on the upper side and those on the lower side of the motor. This bye-pass, in addition to being furnished with ordinary valves, is provided with an automatic reducing valve which regulates the pressure in the distributing mains with which the exhaust from the motor is connected.