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71
Flood
works.
The council, on 22nd July, 1919, had before it a comprehensive scheme of works to mitigate'
floodings in various parts of London on both sides of the Thames during times of heavy rainfall.* Part
of this, a storm-relief sewer from Kelvin-road, Highbury, to the Thames at Shad well, was agreed to before
the war. but had to be postponed. The work is the subject of two contracts. Contract No. 1 for the
section from Kelvin-road to Bethnal-green-road has been let to the Metropolitan Tunnel and Public
Works Company, Limited ; Contract No. 2, in respect of the remainder, has been let to Scott and
Middleton, Ltd. Work was begun under contract No. 1 in May, 1921, and the construction of this section
of the sewer, about 2 J miles long, is well in hand. It consists of a brick tunnel, circular in section and 8
to 9 feet in diameter, which is being driven from three working shafts. Work under contract No. 2
was begun in June, 1921. This section is designed as a cast-iron tunnel lined with concrete. It is about
1£ miles long, 11 feet 4 inches in diameter, and is being constructed from the Shadwell end, its outlet
i nto the Thames being through the river wall fronting the new King Edward Memorial Park at Shadwell.
During 1921 unemployment was rife, and the Council on 25th October, 1921, decided to accelerate
the work on other portions of the 1919 scheme, particularly those which would provide work suitable for
unskilled or partly-skilled labour. The works selected were (i) the improvement of the river Graveney,
(ii) the Wandle Valley sewer, (iii) the Charlton storm relief-sewer, and (iv) flood relief works at Hammersmith.
Details are given below.
River
Graveney.
The improvement ot the river Graveney consisted ot forming a concrete aqueduct, partly open
and partly covered, on the line of, or near to, the stream, and the provision of a new aqueduct about
half a mile long to form another connection with the river Wandle. These measures should greatly
facilitate the discharge of storm water. The estimated cost of the work, including provision for land,
compensations and supervision, is £230,000. The Council, on 8th March, 1921, decided to expedite
the preliminaries in order that the work might be begun without delay. H.M. Government,
through the Unemployment Grants Committee, agreed to make a grant towards the cost. Tenders
were invited upon the basis—(i.) the tenderer to submit an estimate of the net cost in the
form of a priced bill of quantities, (ii.) an allowance of 2\ per cent, upon the estimate to be
made for all plant, stores and material, other than timber, not forming part of the permanent
work, (iii.) the actual cost of the works, as certified, to be paid, (iv.) 6 per cent, to be paid on the
estimate, after adjustment for quantity and for variation in the rates of wages and cost of materials,
in respect of head office expenditure and remuneration, (v.) any saving in actual cost below the adjusted
estimate to be shared equally between the contractor and the Council, and (vi.) the contractor to lose one
quarter of any excess in cost over the adjusted estimate. Ten tenders were received, and after negotiation
a contract for the work was let to Messrs. John Price and Son. Work was begun in June, 1921, and
during the year substantial progress was made.
Wandle
Valley
sewer.
The Wandle Valley sewer is designed both as a soil sewer and storm-water sewer, bewage will
be carried into the intercepting sewers and so to the southern outfall, while the storm water will be
discharged by gravitation into the Wandle. The sewer will be about 2 .'? miles in length and, if necessary
can be extended to the Thames. The cost will be about £259,000. It was estimated that approximately
80 per cent, of the labour employed (not less than 300 men when the work has assumed its maximum)
would be unskilled. Tenders were invited upon alternative bases of (i.) a fixed price, and (ii.) a
fixed initial price with a provision that any variation in rates of pay or in the cost of materials should
be adjusted in the final settlement, subject to the division between the Council and the contractors of any
excess or saving on the prices for materials stated in the tender in the proportion of three-fourths to the
Council and one-fourth to the contractor. The tender of W. G. Tarrant, Ltd., amounting to £172,794
upon the alternative basis (ii.) was accepted on 10th December, 1921, and work upon the sewer was
begun in December, 1921. The work will occupv about two years.
Charlton
storm relief
sewer.
The Charlton storm relief sewer is designed to afford relief to the southern high-level sewer.
It will connect with the high-level sewer at Charlton and will be constructed across Greenwich marshes
to discharge storm water direct into the Thames. Owing to the recent development of land for building
in Woolwich and Lewisham the construction of this sewer had become urgent. It is, generally speaking,
a straightforward piece of work which would employ a fair number of men, estimated at not less than
200 at a time, of whom 80 per cent, would be unskilled. The actual time occupied in the work would
be about one year. Tenders were invited for the work and they were under consideration at the end
of the year.
Flood relief
works at
Hammersmith.
The low-level area in west London comprises about 2,500 acres in Fulham, Kensington and
Hammersmith. The difficulty of draining this area is very great, even when comparatively moderate
rainfall is experienced. The difficulty is accentuated when such rainfall coincides with the period of
high water in the river. No discharge by gravitation is then possible and the storm water flows into
the two low-level sewers. The sewage in the low-level sewer No. 2 flows direct to Abbey Mills pumping
station, while that in the low level sewer No. 1 is pumped at the Lots-road and the Western pumping
stations. In recent years the rapidity with which the rain water reaches these sewers has increased
greatly. Any scheme for relief works must provide for the discharge of storm water by pumping. The
relief scheme provides for the construction of a sewer about a mile in length having an outlet to the
Thames near Hammersmith Bridge, and the erection of a new pumping station near the outlet. The
sewer itself should be constructed in one year, but the building of the pumping station may take
two years, and the construction of the machinery anything from two to three years. This last period
may be reduced. It was anticipated that the construction of the sewer would take not less than 150
upon each shift, of whom 60 per cent, would be unskilled, and the erection of the pumping station about
100, 60 per cent, being unskilled. On 16th December, 1921, the Council accepted the tender for the
* For details see Annual Report of the Council, 1920, vol. III., p. 121.