The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
How To Design And Install Plumbing
A distributing tile line of the same diameter as the collecting line is laid on the gravel fill directly over the collecting line. The distributing tile line is also aerated by fresh air vents to help in the oxidation process. It must be covered with tarred paper or some other material to prevent earth or sand from entering it, thus causing stoppage of the line. The septic tank outlet invert is discharged into a cemented water-tight drain which connects with the distributing line, Fig. 14.
The number of feet of tile necessary to produce satisfactory results is determined by the number of people contributing to the septic tank. If a dosing device or siphon compartment is used in connection with the septic tank the cubical content of the tile should be equal to that of the siphon unit. About 10 feet of tile per person contributing to the tank is adequate under normal conditions.
In extremely cold weather it becomes necessary to protect the filter trench against frost. This can be done by covering it with straw, tarred paper, or some material which will resist cold.
Distribution Field. In localities where the subsoil consists of sand, gravel, or sandy loam, the distribution field can be used as a means of disposing of the effluent of a septic tank. This type of purification unit is less costly to construct. It uses the earth as a means of purifying the discharged effluent.
The open jointed tile lines are constructed of field tile no less than 4 inches in diameter. The distribution field may be of any design the installer feels is best suited to the soil. The rows of tile may be laid parallel to one another with spaces of 10 feet between them, Fig. 15. They may be branched into a main run on a 45° angle to the main. The tile may be installed in the form of a large wagon wheel having a 36-inch tile set vertically at the distributing unit, Figure 16.
The drain tile must be placed as close to the surface of the soil as possible to take advantage of the oxygen and aerobic bacteria found there. The type of soil determines the amount of tile necessary to serve the installation. For sandy soil it is safe to allow 30 feet of tile per person contributing to the tank. For soil which does not leach water as readily as does sand, at least 50 feet of tile per person must be used.
