6o 
THOMPSON YATES LABORATORIES REPORT 
which are generally constructed of concrete, but where the transverse depressions in 
the land are, of galvanized iron, supported on tressels. Syphons are provided under 
any cartways which are encountered in the course of the carriers. Special provision 
is made for storm water, which mostly enters the sewers (as few surface water drains 
exist), and in storm time reaches the Farm more rapidly than it can be filtered through 
the land. 
The provision for storm water consists of a plot of land some 20 acres in 
extent, which is banked round to the height of 3 feet. The storm water accumulates 
on this plot, and is gradually run off through a Coke Screening Chamber with double 
screens, filled with coke of small size, which suffices to arrest most of the suspended 
matter in the diluted sewage ; and also filter beds composed of burned clay ballast 
of about 2 feet in depth. The area of these beds is about 1.75 acres, and they 
give a satisfactory effluent compared with the brook when filled with storm water. 
The Farm is underdrained with agricultural drain pipes, which are laid at depths 
varying between 4 and 6 feet. 
In the case of the Walton Farm, this takes at the present time the sewage of 
about 35,000 inhabitants spread over an area of 1,650 acres. It has an acreage of 183 
acres. There is only one outfall sewer to this Farm, the internal dimensions of which 
are 3 ft. 6 in. by 2 ft. 4 in. It has a gradient of 1 in 1,300. This sewer discharges 
through a 38-inch and also an 18-inch pipe into a tank elevated some 6 or 8 feet 
above the highest point of the Farm. From this tank underground pipe carriers 
are laid to the different parts of the Farm, where they terminate in chambers provided 
with penstocks, and the sewage is distributed from these chambers into the various 
parts of the Farm which require the irrigation. 
No special provision is made on this Farm for dealing with storm water, 
which must all be accommodated upon the surface of the land. This Farm, like the 
West Derby Farm, is extensively underdrained, and these drains also are collected 
in the main effluent drains, which discharge into a natural watercourse. 
Both the West Derby and the Walton Farms are used for the purpose of 
raising crops, principally ryegrass, cabbages, potatoes, mangel-wurzels, and turnips. 
WEST DERBY FARM 
Dry weather flow per 24 hours : — 
Gallons 
Total 
High-level sewer... 
Low-level sewer ... 
725,000 
2 5 1 ,000 
j-976,000 
Walton Farm 
66o,000 
