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

Since the network is pressurized, small elevation differences along the
length of the lateral do not affect the uniform distribution signifi-
cantly. However, these variations should be held within 2 to 3 in. (5
to 8 cm). The rock is placed in the absorption area first, to the ele-
vation of the distribution laterals. The rock should be leveled by
hand, maintaining the same elevation throughout the system, before lay-
ing the pipe. After the pipe is laid, additional rock is placed over
the pipe.
c. Distribution Boxes
If used, distribution boxes should be installed level and placed in an
area where the soil is stable and remains reasonably dry. To protect
the box from frost heaving, a 6-in. (15-cm) layer of l/2- to 2-l/2-in.
(1.2- to 6.4-cm) rock should be placed below and around the sides of the
box. Solid wall pipe should be used to connect the box with the distri-
bution laterals. Separate connections should be made for each lateral.
To insure a more equal division of flow, the slope of each connecting
pipe should be identical for at least 5 to 10 ft (1.3 to 3.0 m) beyond
the box.
7.3 Evaporation Systems
7.3.1 Introduction
Two basic types of onsite evaporation systems are in use today:
1. Evapotranspiration beds (with and without infiltration)
2. Lagoons (with and without infiltration)
The advantages of these systems are that they utilize the natural energy
of the sun and, optionally, the natural purification capabilities of
soil to dispose of the wastewater. They must, however, be located in
favorable climates. In some water-short areas where consumptive water
use is forbidden (e.g., Colorado), they may not be allowed.
Mechanical evaporators are in the experimental stage, and are not com-
mercially available. For this reason, they are not included in this
discussion.
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