41
THE THREATENED DESTRUCTION OF THE
ESSEX OYSTER CULTURE.
By WILLIAM ROME, F.L.S., F.S.A.
[Great alarm has been raised in Essex in consequence of a pro-
posal of Sir Robert Rawlinson, K.C.B., to get rid of the London
sewage by forming a conduit to convey it to the North Sea at Fowl-
ness and Southminster. Sir R. Rawlinson's paper was read before
the Society of Arts, and the following extracts will render the nature
of his scheme intelligible :—
" The London sewage is the richest known in manurial ingredients, and
amounts in daily volume, at its lowest estimate, to 670,000 tons. . . I do not,
however, plead for the purification of the Thames on the score of any probable
income to be derived from sewage farming, as this would be begging the main
question, which is to free the River Thames from pollution at all costs, by a
sewage conduit and additional steam pumping, and, by a tunnel under the
river, bring the south sewage to Barking, sending the whole eastward, once
and for all, to the great North Sea, and then to let reclamation of land and
sewage irrigation follow. The length of the conduit from Abbey Mills, east-
ward to Fowlness Island, Southminster, and Burnham Marshes, will be about
46 miles, through an agricultural district ; and sea outlets must, in the first in-
stance, be provided along this shore over the Maplin Sands to low water of
spring-tides. This f consider is a work necessary to be done, if it should even
be proved to be as fruitless of pecuniary results as the sewage precipitation and
mud-barge process. The conduit will be a canal, or 'new river,' for the convey-
ance of sewage in its fresh state, along which it will flow unceasingly, at not less
than two miles in the hour, to be as unceasingly disposed of at the eastern ter-
minus. The question may be put, But will it not be a nuisance to the neigh-
bourhood in its course ? My reply is, that the works must be designed and
executed so as not to be a nuisance. Portions will be covered, portions will be
in tunnel, and some portions may be open ; but at no point need there be one-
tenth the nuisance there is now at the existing outlet works, nor more than at a
well-managed sewage farm, nor so much as from a heavily manured field. . . .
The flow along the London sewage conduit is to be two miles per hour, so that
the sewage from each day will pass from the junction with the metropolitan
sewers at or near Abbey Mills to the outfalls to the sea in 23 hours. . . .
Along the entire line of the proposed conduit sewage may be supplied to
farmers, and dairy farms may produce milk for London. Italian rye grass may
be grown and sold, as also turnips, mangolds, and other crops. In warm and
dry summers hay may be made, and in wet seasons silage. Land is not corrup-
ted by sewage irrigation, but is improved, as the solids out of 100 tons spread
over one acre of land would not give a surface deposit of one 100th part of an
inch in thickness. In warm summer time 1,000,000 gallons of sewage may be
utilised on one acre in one day, and where something like this volume is used and
the land is light and porous, a very small volume drains from the sub-soil. In
exceptionally hot weather no water flows from the land. ... It will be possible
to send sludge, having 90 per cent, of water, to any distance in open troughs or
pipes to be used in warping low land ; and this mode of disposing of it will be
far cheaper than barging it to sea. . . . Diluted clay in brickfields is sent along
open troughs considerable distances, and this form of conveyance for the sewage
sludge may enable the County Council to dispense with sludge-barges. I say
that this or some similar work must be carried out to free the River Thames from
pollution, and that for this purpose the Barking and Crossness out-falls must
subsequently be so altered, modified, and dealt with as not to pass any sewage to