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It was deposited on a swampy area adjacent to the Lower Dain. necessary to carry out a certain amount of nullah diversion and training at this site and this work was executed under the Main- tenance Contract. A new contract to continue the removal of silt in 1934 was prepared and tenders were called for in the Gazette at the end of December.
245. Access Roads. This item was referred to in paragraph 215 of last year's Report. The access road to the Lower Dam and a length of the Wanchai Gap-Aberdeen Road were surfaced by the Roads Department during the year.
246. Reconstruction of Main Outfall Nullah at Aberdeen.- This work which was referred to in paragraph 216 of last year's Report was completed on the 30th April, an extension of 28 days on contract time being necessary. The maintenance period ex- pired on the 30th August and the retention money was paid to the Contractors, The Eastern Mercantile & Construction Co. The work under this contract consisted of the enlargement, due to increased catchment area, of the existing nullah at the old Aberdeen Paper Mills, and necessitated the demolition and re- construction of the existing west side wall of the nullah, the main road bridge, the foot bridge and a short length of the Peak outfall sewer. The crossectional area of the old nullah was increased from 150 to 250 square feet by the construction of a new channel 15'-6" wide at the base and 6'-6" deep on the west side of, and adjoining, the old nullah. The invert was constructed of 1,2,4, cement concrete 9" thick throughout, a length of 220′ on the outfall side of the bridge being reinforced. The side wall for a length of 162 feet on the upstream side of the bridge was con- structed of 1,2,4, cement concrete 9′′ thick, the remainder of the wall being of gravity section composed of 1,2,4, cement con- crete with displacers. The length of the new channel is 425 feet. The old main road bridge over the nullah, which was originally of three spans, two of which had subsequently been filled in, consisted of a concrete slab about 9" thick supported between piers and abutments on old steel rails. The new bridge of two spans, 24′-9′′ and 13'-9" clear, was constructed of 1,2,4 reinforced cement concrete, of the beam and slab type surmounted by a concrete parapet of the pilaster and balustrade type. The two old piers were demolished and replaced by 1,2,4 cement concrete with displacers. The foundations of the new pier, abutments and side wall of the new channel were piled with 8′′ x 8′′ rein- forced cement concrete piles. Rapid hardening cement was used throughout for the bridge. The width of the bridge was increased from 19′ to 30′ and the level raised from 14.74 to 17.36 A.O.D. The old footbridge, which was of single span, consisted of a concrete slab supported between abutments on rolled steel joists. The new footbridge of two spans and 6'-0" wide was constructed of 1,2,4, reinforced cement concrete of the beam and slab type, the old rolled steel joists being utilized for the Eastern span. A wrought iron handrail parapet supported by reinforced cement concrete posts was erected on both sides of the deck slab.
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The existing concrete sewer was of double box section and was replaced by a 21" diameter mild steel pipe. The two existing manholes were demolished and rebuilt.
1933 Expenditure.........
$225,155.38
Expenditure to 31st Dec., 1933...$2,499,625.70
TYTAM TUK CATCHWATERS.
247. (a) Tytam Tuk East Catchwater.-A Contract for this work was let on the 16th January to Messrs. Yee Lee & Co. for $148,303.00. A high percentage of rock was encountered in the excavations, and progress was slow until the middle of the year, after which the Contractor made very good progress with the excavations. By the end of the year approximately 2,300 linear feet of Catchwater were completed leaving 780 linear feet to be constructed. Owing to the poor nature of rock encountered and the lack of skilled tunnel masons it was decided to execute the outfall tunnel under the Island Road by cut and cover. This work was commenced in October and excavation was practically completed when a serious slip occurred on the 29th December. Remedial measures were immediately put in hand. The outfall cut beyond the Island Road, 300 feet in length, was completed during the year.
248. (b) Mount Parker Catchwater:-First Section.-A con- tract for the outfall section of this catchwater was prepared towards the end of the year and tenders invited. The contract comprises the construction of a reinforced concrete aqueduct, about 650 linear feet of catchwater and a tunnel 540 feet long under Tytam Gap.
249. (c) Pottinger Peak Catchwater:-First Section.-A contract for this work was let on the 30th June to Messrs. Sang Tai & Co. for $41,952.00, and was completed by the end of the year. The work consists of a catchwater 4162 feet in length draining 106 acres of the northern slopes of Mount Collinson and discharging through a low gap approximately 600 feet East of Tytam Gap into a stream collected by the Tytam Tuk East Catchwater. This catchwater was constructed in two sizes hav- ing a crossectional area of 34.0 square feet for the larger and of 28.0 square feet for the smaller. The invert and lower part of the sidewalls were constructed of 1,2,4 cement concrete 44" thick. The side walls and cope were constructed of 1,2,4, 8 lime and cement concrete 44" thick and had a batter of 24 to 1 in soft and 8 to 1 in rock section. Overflows have been constructed at stream crossings. A path of a minimum width of 4 feet was formed along the outside of the catchwater, and this was carried over the overflows on a reinforced concrete decking. Sand traps have been constructed in the invert at all overflows. The outfall section consists of a culvert under the Shek O Road and a section of stepped catchwater.
Second Section.-Survey work for this was completed and plotted during the year.
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