A
.9
785
arrange-
23. Before concluding this report, I may be permitted to record an arrange- Serpentine ment of sewers which has been found advantageous in many places, and which may ment of be applicable to drains, especially when they have to be covered. It is best des- cribed by considering a portion of a town laid out in regular squares.
sewers.
...
w
COMMON
SYSTEM
Assume that the general inclination of the land is in the direction of the arrow. Then a common arrangement would be to lay main sewers in the direc tions shown in full lines, following the streets having the greatest slope, and to provide branches as shewn in dotted lines, to provide for the effluent of the houses in the lateral streets. These branches run right and left, from heads marked thus Now these lateral branches receive, individually, but little sewage. Consequently they must be small in diameter and laid at a steep slope in order to be self-cleans- ing. This necessitates an augmented depth in the main sewers. At the best, these branch sewers are but indifferently flushed, for they are indeed only pro- longations of the house-sewers of houses on the cross streets. The following ar- rangement wherever applicable is an improvement :-
F
H
G
SYSTEM RECOMMENDED.
L
K
B
D