MIL-HDBK-1005/16
Section 6: PACKAGE PLANTS AND SMALL FLOW TREATMENT SYSTEMS
6.
6.1
General. Treatment systems handling less than 1.0 mgd
(3.8 ML/d) are generally considered small flow treatment systems.
Military bases often have remote facilities or groups of
facilities serviced by small flow treatment systems. This
section provides general information on designing for small flow
treatment systems as well as information on specific systems that
are not covered in the Primary Design Guidance Documents. Also
included at the end of this section is a discussion on the proper
use of garbage grinders and grinder pumps in collection systems
feeding small flow systems and package plants.
6.1.1
Types of Small Flow Treatment Systems. The primary
treatment systems used for small flow applications are package
treatment plants, Imhoff tanks, septic tanks, mound systems, and
waterless toilets. Filtration/reuse systems are sometimes added
to Imhoff tanks or septic tanks when additional treatment of the
effluent is necessary. WEF MOP 8 addresses Imhoff tanks. The
remaining small flow treatment systems are described in this
section.
6.1.2
Unique Characteristics of Small Flow Treatment Systems.
Package plant units are generally modularly constructed steel
units assembled onsite from factory-supplied, pre-assembled
components. These treatment systems can provide treatment within
a range of about 10,000 gpd up to approximately 1 mgd per
treatment unit. For package plant systems, the principles of
design do not differ from larger treatment plants, although the
choice of equipment usually will. This difference usually stems
from economies of scale: certain operations are economically
feasible only on a large scale. Types and characteristics of
package plant systems and a typical package plant layout are
provided in this section.
In contrast, Imhoff tanks, septic tanks, mound systems,
and waterless toilets are only applicable to very small flows.
Small flow systems must make larger safety factor allowances for
flow variation and temperature effects relative to total
wastewater flows than larger treatment systems. While small flow
systems inherently have less operational flexibility, they are
capable of performing effectively and efficiently. Design
criteria for septic tanks, mound systems, waterless toilets, and
filtration/reuse systems are given below following the sections
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