IMPROVEMENTS. IN THE CONSTRUCTION OF SEWERS
Year: 1884

page_text: I JAMES HOLROYD of Burmantofts near Leeds in the County of York Sanitary
Engineer do hereby declare the nature of my said Invention for "IMPROVEMENTS.
IN THE CONSTRUCTION OF SEWERS " and in what manner the same is to be
performed to be particularly described and ascertained, in and by the following
statement:-
The object of my Improvements is to provide in one and the same sewer for
the ordinary or normal dry weather sewage, and also for the increased amount
resulting from rainfall, storm or surface water, preventing at the same time
sewage matter from depositing and accumulating in the sewer during the dry
weather.
The methods of meeting these two requirements hitherto, have been either a dual
system of sewers, the one for the normal dry weather flow of sewage, and the
other for storm or surface water; or by the construction of circular or oval
sewers of sufficient capacity to be equal to both requirements. There is however
a practical objection to both of the methods In the former (i.e. the dual system)
the objection arises from the increased cost and unavoidable complications of the
system, and in the latter from the absence of flushing or cleansing power, obtainable
in a sewer constructed of a capacity very much larger than is required by the
normal dry weather flow of sewage.
To meet the above difficulties we construct the sewer, so that on the one hand
it shall be equal to the maximum requirements of storm water and rainfall, and on
the other secure a constant flow of the normal weather sewage at a sufficient
velocity to prevent any deposit accumulating in the sewer.
The method on which it is proposed to construct the sewer to meet the herein
before mentioned points is as follows;
Instead of the ordinary circular or oval pipe or brick sewer I accomplish the
object intended by the use of a special form of invert block as the foundation
of the sewer, constructed in such a manner that the dry weather flow is contracted
within a comparatively small area by hollowing out in the invert block a sunken
channel sufficient to carry off or conduct away the dry weather flow.
This invert block may be constructed either of stoneware. or earthenware of
suitable section for the diameter and thickness of the wall of the sewer of which
it forms the base foundation or invert.
And in order that my Invention may be more clearly understood reference is
given to the accompanying drawings and to the letters and marks thereon.

page_text: DESCRIPTION OF DRAWINGS.
The figure shewn in the drawing is a transverse section of a sewer with my
improvements applied. The invert block is shewn at a, and may be constructed
of stoneware or earthenware of a section suitable to the diameter and thickness
of the walls b of the sewer of which it forms the base foundation or invert.
Instead of the invert as is usually the case being of the same or nearly the same
radius as the sewer itself, a sunk channel is formed in the invert block as shewn
at c.
The capacity of this sunken channel is adapted to take the normal dry
weather flow of sewage. It will readily be seen that the dry weather flow being
thus confined within the narrow limits of the sunken channel c, will acquire a
higher velocity than would be the case if distributed over a wider surface or area
of sewer constructed in the ordinary way.
The invert blocks a may be constructed so as to join up to each other either with
butt joints, flanges, or with holes for dowelling them together as may be most
desirable to meet special circumstances, and the section of block may be varied and
made to suit the diameter of sewer and the thickness of its walls.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The arrangement and application of invert block a having a sunken channel c
formed therein for containing and conducting away the normal or dry weather flow
of sewage, whilst the capacity of the sewer may be adapted to the exceptional
conditions of rainfall and storm water.
f
Dated this Twentyfirst day of November 1884