disposed of through dockside sewer connections
or pumped overboard in unrestricted waters.
MSDs on Navy ships increase the potential for
contamination of berthing and working spaces
with raw sewage. Therefore, the Medical Depart-
ment representative must be familiar with the
wastewater disposal system and the procedures
necessary to ensure the health and safety of the
There are basically three different types of
MSDs, including zero discharge systems with full
volume flush (FVF), zero discharge systems with
reduced volume flush (RVF), and flow-through
The zero discharge system with FVF uses a
standard 3- to 5-gallon flush and stores this
wastewater in holding tanks until it is discharged.
The zero discharge system with RVF also
collects and stores the wastewaters until they
are discharged. This system differs from the FVF
system in that it minimizes the volume of
wastewater. The flow-through treatment system
treats the water to acceptable limits before it
discharges the effluent into the receiving water.
Effluent is defined as wastewater or other liquid,
treated or untreated, flowing out of a reservoir,
basin, sewage treatment plant, industrial treat-
ment plant, or MSD.
The collection, holding, and transfer (CHT)
system is the MSD system installed on most naval
vessels. It operates in restricted waters where the
wastes are collected and stored in holding tanks;
at sea the wastes are disposed of over the side;
in port all waste is collected in holding tanks and
subsequently discharged into a sanitary sewer or
ship waste offload barge (SWOB) or held until
the ship reaches unrestricted waters and then
pumped over the side.
Other, less frequently encountered systems
include the Evaporative Toilet System (ETS), the
JERED Vacu-Burn Sewage Treatment System,
the KOEHLER-DAYTON (KD) Recirculating
Flush, and the Pall-Trinity Biological Treatment
System. The operation and maintenance of these
sewage handling and disposal systems are peculiar
to the type of system installed. Such information
may be found in the Ships Information Book
(SIB) and the Manual of Naval Preventive
Medicine, chapter 7.
Inspection of MSDs
MSD components (soil and waste drains,
discharge lines, plugs, plates, valves, comminu-
tors, motors, pumps, and tank penetrations and
manholes) should be regularly inspected for leaks
by engineering personnel. The paper towel
test can be used to detect leaks from pumps,
comminutors, and piping. This test entails
opening a paper towel and holding it 2 to
3 inches from the unit for several minutes. Even
the finest spray can be detected on the paper
All leaks, spills, or other sources of con-
tamination must be reported to the executive
officer, the engineering officer/damage control
officer, and the Medical Department representa-
tive. The leak must be repaired and the system
properly cleaned and, if necessary, disinfected.
Sewage receiving facilities are being con-
structed at all shore activities with fleet support
capabilities. These facilities include sewer risers
for the transfer of wastewater from the ship
discharge risers to the shore sewer system.
Facilities to store, maintain, and repair sewage
transfer hoses are also included. Specific
information and guidelines concerning all aspects
of ship-to-shore wastewater transfer facilities and
operations procedures are provided in the
Ship-to-Shore Hose Handling Operations
Manual, NAVFAC MO-340.
Most Navy ship MSDs are designed to
discharge their wastewater to a shore receiving
facility when in port. This is normally done
by connecting the ship sewage discharge risers
directly to the pier sewage discharge risers.
Wastewater may be discharged indirectly
through connections to a SWOB or another ship
system, which in turn discharges the wastewater
into pier sewer risers.
Most sewage connections, including ship-to-
shore and ship-to-ship, are made by means of
flexible transfer hoses 50 feet in length and
4 inches in diameter. On submarines these hoses
measure 2 1/2 inches in diameter. It is the
responsibility of the shore based handling crew
to deliver sufficient quantities of sewage transfer
hoses and to make connections to pier sewage
risers. The ships crew is responsible for all ship
sewage riser connections.
Sewage transfer hoses must be kept clean and
in good repair. After each use they must be