On-Site Wastewater Treatment and Disposal Systems - Forced ...

TABLE 7-4
DOSING FREQUENCIES FOR VARIOUS SOIL TEXTURES
Soil Texture Dosing Frequency
Sand
Sandy Loam
Loam
Silt Loam
Silty Clay Loam
Clay
4 Doses/Day
1 Dose/Day
Frequency Not Criticala
1 Dose/Days
Frequency Not Criticala
a Long-term resting provided by alternating fields may be
desirable.
Selection of Application Method: The selection of an appropriate method
of wastewater appllcatlon depends on whether improved absorption or
improved treatment is the objective. This is determined by the soil
permeability and the geometry of the infiltrative surface. Under some
conditions, the method of application is not critical, so selection is
based on simplicity of design, operation, and cost. Methods of appli-
cation for various soil and site conditions are summarized in Table 7-
5. Where more than one may be appropriate, the methods are listed in
order of preference.
e. Porous Media
The function of the porous media placed below and around the distribu-
tion pipe is four-fold. Its primary purposes are to support the dis-
tribution pipe and to provide a media through which the wastewater can
flow from the distribution pipe to reach the bottom and sidewall infil-
tration areas. A second function is to provide storage of peak waste-
water flows. Third, the media dissipates any energy that the incoming
wastewater may have which could erode the infiltrative surface.
Finally, the media supports the sidewall of the excavation to prevent
its collapse.
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