On-Site Wastewater division permits and
supervises the installation of septic systems
where sewer lines are not available so
that sewage may be safely disposed of with
the least impact on individuals and the
septic tank is a two piece concrete box,
sealed at the joints to prevent water seepage.
It is placed just below ground level on an
undisturbed bed of soil and leveled carefully.
The home's waste line is connected to it.
There are doors in the top which allow access
for inspection and pumping of effluent.
doors on the top of the tank allow access
for inspection and periodic pumping.
Inside the doors on the outlet end is
a "tee", which keeps grease from entering
the drain lines and clogging them. The
tank is separated into two chambers by
a "baffle wall", which prevents solids
from entering the second chamber of the
leaving the tank, the effluent is piped to
a distribution device, in this case a "dropbox",
which is carefully leveled. There are two
pipes leaving this box, one to the first
trench, the second, which is higher, to the
second trench. This allows the first trench
to fill before the second. Another box allows
the second trench to feed before the last.
this installation, three trenches are used,
for a total of 300 linear feet. The total
length is determined by the number of bedrooms
in a residence and the soil characteristics.
The number of trenches used is determined
by the lot layout, size, and topography.
Environmental Health Specialist carefully
examines each part of the installation of
the system to ensure that it will operate
according to the design specifications. Here,
he measures the depth of the gravel in the
trench, which allows effluent to move freely
and absorb into the ground. There must be
at least 12 inches of gravel in the trench.
the system is approved, the contractor
may cover the system. The area is seeded
with grass to aid in removing surface
water (evapotranspiration) and the plumbing
is connected to the tank.