Q 58
ABERDEEN VALLEY WATER SCHEME.
240. Preliminary and Survey Works.-This work was referred to in paragraph 203 of last year's Report. The survey for the Second Section of the West Catchwater was completed early in the year.
A contour survey of the Lower Reservoir was made for capacity purposes. Other surveys included one of the site adjacent to the Lower Dam on which silt from the Lower Reservoir has been deposited and one for the proposed Aberdeen Village new Filters and Service Reservoir.
241. Upper Dam.-This work was referred to in paragraph 204 of last year's Report. A few minor works were carried out under the Maintenance Contract during the year. These included fencing around the rain gauge, a turning ground for cars, concrete steps at the south end of the Dam and improvements to the beeching in the stream bed at the foot of the Dam.
242. East Catchwater. This work was referred to in paragraph 205 of last year's Report.
1st Section. Minor improvements were made at the outfall, including trimming back the slopes of the large cutting and realigning and regrading a small length of "Lady Clementi's Ride" in order to re-open this path.
2nd Section.—A contract was signed by Messrs. Blackmore & Blackburn on the 13th January for $50,008.10 for this work. Work commenced early and was completed, except for a few minor works and trimming and clearing the site, by the 26th October. In two places, owing to the difficult nature of the ground, it was necessary to carry the Catchwater on piers by means of a reinforced concrete aqueduct of box section, the lengths of the two sections being 67 and 175 feet, whilst at a third place it was necessary to resort to tunnelling to carry the catchwater past three large boulders, the length of tunnel being 34 feet. This section of the Catchwater collects water from an area of 169 acres on the Southern Slopes of Mt. Nicholson and also from the overflow of Wongneicheong Reservoir. It discharges the water into the first section of the Catchwater, a description of which was given in the 1931 Report. This section collects 2/3 of an inch of rain per hour and overflows have been designed to discharge any excess rainfall up to a rate of 3⅓ per hour. The Catchwater is 5,802 feet in length and was constructed of four different sizes varying from an effective cross-sectional area of 4 square feet at its commencement to 17.20 square feet at its junction with the first section. The invert and lower part of the sidewalls were constructed of 1:2:4 cement concrete 3″ thick in the smaller sections and 4½″ thick in the larger sections, whilst the remainder of the side walls were constructed of 1:4:8 cement concrete of thicknesses similar to ...