Ontario Provincial Board of Health Annual Report, 1909
Report on Guelph Sewage Disposal Works (pg. 90)
by F. L. Mc Arthur, City Engineer
The sewer farm is situated just outside the city limits, in a south-westerly direction, along the Speed River, and contains in all about fifty acres of land. Nearly half of this area is good soil, and covered with scattered trees, while the remaining portion, farthest from the river, is rough and rocky. The river opposite the disposal works is about sixty feet wide, with an average depth of two feet six inches.
The septic tanks, as shown on the plans, have already been constructed, and are now in operation, giving splendid results. They have a joint capacity of 240,00 gallons. The flow of sewage reaching these tanks about mid-day is approximately at the rate of 250,000 gallons per twenty-four hours. There are now about 800 buildings connected with the sewer system. Assuming six people to each building, using 100 gallons per capita, this would represent 450,000 gallons of domestic sewage per day of average strength, or, at the outside, 500,000 gallons. It is evident, therefore, that more than half the flow of main sewer represents sub-soil water which finds its way into the system. I am satisfied that by gauging the flow accurately at various points, the leakage can be located and most of the sub-soil water diverted from the sewer.
The proposed filter beds, eight in number, will have a joint area of 4.63 acres. Each bed is to be a rectangle 210 feet long and 120 feet wide, and the filter material will be three feet deep, composed of three layers. The bottom course will be of screened gravel six inches deep. The idea of the gravel being screened is to make the drainage as nearly perfect as possible. The second course is to be of coarse sand and gravel two feet in depth, and the top course six inches of coarse sand. The main effluent drain will be of twelve-inch sewer tile. The branch lines to be of four-in-a field tile and placed twenty feet apart.
The sewage will flow from the septic tanks by means of gravity through a main which passes along the embankment, separating the two rows of filter beds. Valve chambers will be situated along this main, one opposite each pair of beds, by means of which the sewage can be turned upon the different beds. A trough leading from the valve chamber out on to each bed distributes the flow evenly over its surface.
The filtrate will be collected by the under-drains, and discharged into a small creek which leads directly to the river.
The three embankments running nearly parallel to the river will be each twelve feet wide on top, with side slopes of one and a half to one. The one next the river will be constructed so as to act as a dam to keep back the river water in case of an extreme spring freshet. The embankments running nearly at right angles to the river and separating the filter beds will be six feet wide on the top, with side slopes of one and a half to one.
The small stream into which the filtrate is discharged may be easily diverted, and the land used for the construction of more filter beds should they be required.