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

against freezing and to stabilize .the pipe before backfill-
ing. Procedures for constructing the distribution network are
discussed in Section 7.2.8.
3. The gravel or rock is covered with untreated building paper,
synthetic drainage fabric, marsh hay or straw to prevent the
unconsolidated soil cover from entering the media. The media
should be covered completely. If untreated building paper is
used, the seams should overlap at least 2 in. (5 cm) and any
tears covered. If marsh hay or straw is used, it should be
spread uniformly to a depth of 4 to 6 in. (10 to 15 cm). In
bed construction, spreading a layer of hay or straw covered
with untreated building paper is good practice.
4. The backfill material should be similar to the natural soil and
no more permeable. It should be mounded above natural grade to
allow for settling and to channel runoff away from the system.
7.2.2.5 Operation and Maintenance
a. Routine Maintenance
Once installed, a subsurface soil absorption system requires little or
no attention as long as the wastewater discharged into it is nearly free
of settleable solids, greases, fats, and oils. This requires that the
pretreatment unit be maintained (see Chapter 6). To provide added in-
surance that the system will have a long, useful life, the following
actions are suggested:
1. Resting of the system by taking it out of service for a period
of time is an effective method of restoring the infiltration
rate. Resting allows the absorption field to gradually drain,
exposing the infiltrative surfaces to air. After several
months, the clogging mat is degraded through biochemical and
physical processes (1)(4)(6)(13)(15). This requires that a
second absorption system exist to allow continued disposal,
while the first is in the resting phase. The systems can be
alternated on a yearly basis by means of a diversion valve (see
Figure 7-3).
2. The plumbing fixtures in the home should be checked regularly
to repair any leaks which can add substantial amounts of water
to the system.
3. The use of special additives such as yeast, bacteria, chemi-
cals, and enzyme preparations is not necessary and is of
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