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71
It is therefore necessary to alter or repeal the provisions contained in the Southend-on-Sea
Corporation Act, 1909, so as to enable the Corporation to build additional works and discharge
from them into the sea.
No such discharge into the estuary of the River Thames will be undertaken until screens
for the removal from the sewage of gross solid matter have been constructed and sewage tanks
provided for the sedimentation of all sewage entering the sewers of the Corporation.
Sewage and storm water entering the sewers of the Corporation at a rate exceeding three
times the average daily dry weather flow shall not of necessity undergo screening and
sedimentation.
The recommendations of the Royal Commission on Sewage Disposal will be followed.
The present degree of purification will be lessened.
The Scheme provides for the outflow of sewage at the Eastern boundary of the Borough below
low-water mark, at a distance of two miles E.S.E. of the present outfall and just to the West
of a peculiar and constant low-tide neck of land from which its attendant water-inlet takes the
name of ' Knock Swin.'
The state of purification of sewage thrown from a seaside resort, such as is Southend-on-Sea,
need not, I feel, be for the consideration of the Port of London Sanitary Authority provided
solids are screened and a degree of purification beyond this attained. This Authority's interest,
though extending to foreshore pollution, is nob of the vital moment in the same matter as is that
proper to Southend-on-Sea.
As the Authority dealing with shell-fish layings, however, the Port of London Sanitary
Authority is interested.
Mr. Deane, the Consulting Engineer detailed on behalf of the Corporation of Southend
to conduct float experiments with regard to the flow of water at and about the Knock Swin,
i.e., the outfall, has supplied for the perusal of the Port of London Sanitary Authority a series
of maps of his experiments, which trace clearly the direction of flow from the proposed sewage
outfall at various states of the varying tides.
These distinctly show, amongst other matters of interest: —
(1) That the set of the tide in flood trends Eastward and Northward over the flats
which lie in front of Southend, especially Thorpe Bay.
(2) That the set of the tides on the ebb is parallel to the shore at first, then trending
Southward over the flats.
(3) That the flow in calm weather from the proposed sewage outfall would reach the
Mouse Light, a total distance of nine miles on one ebb tide.
(4) An extremely interesting record of the flood tide in and about the Swin.
The presence and shape of the Swin and projecting knock are suggestive of a peculiar
condition of flow, but one is hardly prepared for the findings that floats laid at low water at the
Swin mouth are actually carried Northward and Eastward past Shoeburyness and over the
Maplin Sands as the tide flows, so that, as Mr. Deane reports, ' at neap tides most of the water
required to cover the Maplin Sands in front of Shoeburyness finds its way through the
Knock Swin, passing to the North-East. Had it been possible to follow the floats further,
I should have expected them to have continued on, in a North-Easterly direction, under the
influence of the ebb tides.'
The significance of this is that a portion of the last emptyings of the proposed sewer would
be carried, on the rising tide, away over the Maplin Sands in a well-diluted state by a back-eddy
current due to Shoeburyness. This current helps to account for the persistent shape and position
of the Knock Swin, a curve, roughly, North and East.
The two areas of foreshore affected by the flood flow of the ebb tailings from the sewer
would be the areas C and D, which have been placed under orders by your Worshipful Committee
as shell-fish layings.
I am of opinion that the question of pollution of shell-fish beds is but little affected by the
proposed change of outfall position, any slight disadvantage in areas C and D being compensated
by slight improvement in areas A and B owing to the moving of the outfall to the E.S.E.
This consideration only applies to dry weather sewage flows, and even so, the lessened
degree of purification proposed and increase of population since the foreshore shell-fish beds of
this district were under review have to be borne in mind. It is advantageous that the area D
under the Shell-Fish Orders of the Port Sanitary Authority was so arranged as to include the.
lower portion of the Maplin Sands.
The interests of the Port of London Sanitary Authority are foreshore pollution and pollution
of shell-fish layings. The shell-fish layings of this district are already under Orders.
I would, therefore, suggest that there is no cause for opposition to the present Southend
Sewage Scheme by this Authority."
Before the 1926 Scheme comes into operation it will be necessary to interfere with the standard
of purification laid down in the 1909 Act, but this standard will not be lowered below the eventual
standard (say, 50 percent. purification against the present 60-70 per cent.) during the carrying out
of certain works which require that the Southend filter beds shall be no longer in operation.
The eventual change over of the system and the time of change over, i.e., 1927-1930, should
naturally, it would appear, be considered a continuous period.
Although by criticism and formal enquiry the Scheme could be held up, it could not be eventuallv
altered.