74



Osier beds for
clarifying
storm waters.
Cost of the
paration
he land.
preparation
oi the " "



Cost of wind
engine and
tower.
EfHuent



therefore, to which attention may be well given in all cases where a
part of the land to be utilised may be reached by gravitation, whilst
the remainder must be served, if reached at all, by pumping.
The Osier beds, intended to clarify storm waters, when they dilute
the sewage beyond the quantity which the land is intended to cleanse,
occupy a narrow strip of land running alongside the river from the lowest
filtration areas to the main outlet. These Beds are severally laid out
(see Map), as at Great Malvern, in levels, and so arranged that the
storm water, having passed through them consecutively and deposited
such solid matter as will be arrested in the furrows, will reach the outlet
into the river in a clarified state — the intention being to check, as far
as possible, by the successive levels, the onward rush of the water and
so encourage deposition in the furrows whenever the beds come into
use.
The delivery of the sewage to the filtration areas is $o designed that
when the full quantity they are intended to purify is exceeded by sudden
storms the excess will pass onward to the river through the Osier Beds
instead of into the Colne direct.
