MIL-HDBK-1138
Section 6:
SEPTAGE MANAGEMENT
6.
6.1
Septage Management Alternatives. This section
provides information on the characteristics of septage, the
monitoring and management of septage collected from various
locations and delivered to the site, and various methods
typically used to treat septage.
Approval must be obtained from your environmental
office before a treatment system receives septage because the
treatment system is likely to be disrupted from the high strength
of septage and because there is a potential for toxic components.
6.2
Septage Characterization. Septage is generally
defined as the liquid and solid material pumped from septic
tanks, grease traps, pit privies, vault toilets, recreational
vehicle disposal stations, cesspools, and similar holding tank
locations while they are being cleaned. Septage is not
industrial waste. The majority of the wastewater that is
discharged to a septic tank is absorbed into the surrounding
drain field. The material remaining in the tank is characterized
by a high content of organics, grease and other floatables, and
grit. The quantity and constituents of septage vary
significantly depending on the source and seasonal effects such
as groundwater levels.
The quality of septage can also be negatively affected
by industrial contributions if significant concentrations of
industrial process wastewater or by-products have been mixed with
a load of septage. Therefore, to minimize the potential for a
treatment plant upset or for discharge of toxic materials to the
environment, septage entering a treatment facility should be
monitored in accordance with par. 6.3.
6.2.1
Septage Quantity. The most accurate method for
estimating future septage quantities is to review historical data
from local haulers. They should have records of the quantity of
septage pumped over specific periods. Septage quantities can
also be estimated by multiplying the number of residential septic
tanks in a service area by the average pumpout volume per unit,
as follows:
No. of Septic Tanks x Typical Volume of Septic Tank
Pumpout Interval
An average volume of a septic tank is approximately
750 gallons (2.8 cubic meters). A typical pumpout interval for a
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