Reservoir has buttress walls and rubber floor
A BOUNDARY wall formed by a but- tress structure of reinforced concrete backfilled with excavated material, and an 18-acre floor made waterproof by a continuous sheet of butyl rubber, are two unusual features of a settling reservoir being constructed at Chertsey in England.
When completed later this year, the structure will contain 90 million gal lons of raw water awaiting treatment at a nearby purification works.
The perimeter wall of the reservoir, which follows the boundary of the
site, is 2,940 ft. long and consists es- sentially of 48 reinforced concrete modular units, each 57 ft. long and six special units of a shorter length. All the units stand 30 ft. high.
Concreting
The face wall of each unit slopes backwards, away from the inside of the reservoir, at an angle of 60 degrees to the horizontal and is supported on buttress walls at 15ft, centres. These rest on L-beams, concreted into the
naturally occurring gravel strata which covers the site.
Concreting of the wall units, which is now almost complete, is carried out using a single set of four shutters fabricated from 4in. mild steel plate. The pour sequence is to concrete the lower parts of the L-beams first (see 1. in Fig. 1) and follow with a large pour to form the remainder of the beams together with kickers for the buttress and main face walls(2). The buttresses are then poured in a single lift through 'letter box' openings in the sides of the
Pouring concrete for part of the buttress wall. The hopper is at mid-height where concrete is discharged through letterbox openings.
Far East BUILDER, May 1970
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