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261
147. Proposed Filter Beds.-The proposed filter beds in connection with this project are shewn on Drawing No. 2; they are three in number having a combined area of 1,666 square yards and are arranged to discharge into a small service reservoir of a capacity of 250,000 gallons which with the one now being constructed at Kennedytown will prevent the irregular action that would result from the variation in draw-off from the mains without such provision.
The top water level of the service reservoir is 251.5 feet above Ordnance Datum admitting of a direct communication being made with the distribution mains below the exhaust from the hydraulic motors without interfering with their action.
148. Estimate.-The estimated cost of this project is as follows:-
Construction of reservoir including compensation and purchase of land $160,000 Cast iron main,
Filter beds and reservoir,
55,000
35,000
Total,......... $250,000
149. The cost of the erection of pumping machinery with the necessary buildings for pumping the water from the reservoir into the existing conduit has, together with the annual charges connected with such a project, been considered, and I am of opinion that the laying of the cast iron main is preferable.
150. Increasing the Capacity of the Existing Reservoir. The practicability of increasing the capa- city of the present reservoir has also been considered, and I am of opinion that after the construction of the reservoir on the lower site this work might be undertaken by raising and strengthening the embankment.
The present outlet arrangements are unsatisfactory, the whole of the water being drawn off from near the bottom of the reservoir.
151. The project, as shewn on Drawings Nos. 5 and 6, includes raising the embankment 11 feet and the overflow weir 10 feet thus increasing the storage capacity from 68,000,000gallons to 91,000,000 gallons and the improvement of the outlet works so as to admit of the water being drawn off at different levels. As this involves the fixing of a stopping plate in the existing culvert, the present plate situated in the valve tower being of insufficient strength to bear the increased pressure of water safely, the carrying out of this work will necessitate emptying the reservoir, which cannot be done without seriously interfering with the water supply to the City of Victoria and Hill Districts until after the lower reservoir and the project previously described has been completed.
The estimated cost of this work is $35,000.
152. The completion of the two foregoing projects providing for the storage of 169,000,000 gallons in two reservoirs having a combined catchment area of 500 acres, will practically exhaust the means available within the Pokfoolum Valley for increasing the water supply.
153. Supply to be derived from Works in Pokfoolum Valley.-These works will secure on the basis already adopted, (see paragraphs Nos. 104 and 105), a daily supply of 880,000 gallons, as com- pared with a daily supply of 540,000 gallons from the existing works, throughout the year.
154. The construction of a catchwater 6,000 feet in length contouring the bill on the western side of the Pokfulam Valley at a level of 550 feet would intercept an additional catchment area of some 170 acres and would admit of a daily supply of 1,000,000 gallons being obtained throughout the
year.
The estimated cost of this catchwater is $18,000.
TAITAM VALLEY.
155. Proposed Reservoirs.-In the Taitam Valley detail surveys have been made of five sites shewn on Drawing No. 7, all of which are more or less suitable for the construction of reservoirs.
Two of these sites Nos. 1 and 2 are situated above the existing reservoir and within its catchment area, the other three are situated lower down the valley. One of which, No. 3, is at a sufficient eleva- tion to admit of water collected in a reservoir on it being discharged into the existing Taitam Tunnel. 156. Proposed Reservoir Site No. 1.—The proposed reservoir on site No. 1 would be formed by the construction of a masonry and concrete dam as shewn on Drawing No. 8.
This reservoir would have a capacity of 70,000,000 gallons with a top level of 780 feet above Ordnance Datum, a catchment area of 220 acres and a maximum depth of 50 feet.
The waste weir is situated at the north end of the dam and has a length of 80 feet. It is antici- pated that the depth of water over this weir will not exceed 3 feet.
The bye-wash channel will be constructed on solid ground and discharge into the valley below the dam.
The outlet commencing in a suitable valve well will be carried through the main dam and dis- charge into the stream below it.
The construction of this reservoir will involve a diversion of the road as shewn on the drawing. Estimated cost $140,000.
157. Proposed Reservoir Site No. 2.-The proposed reservoir on site No. 2 would be formed by the construction of a masonry and concrete dam as shewn on Drawing No. 9.