TM 5-814-3/AFM 88-11, Volume III
9-5. Plant hydraulics.
a. Hydraulic loadings. The overall head allowances required for various types of wastewater treatment
plants are shown in table 9-1.
b. Limiting velocities. A minimum velocity of 2.0 feet per second at design average flow is required
for channel flow. At minimum flows, a minimum velocity of 1.5 feet per second is required to prevent
suspended solids from settling in flow channels.
c. Head loss. The total head loss through a treatment plant is the sum of head losses in the conveyance
of wastewater between elements of the treatment process and the losses of head through treatment units.
Head losses from wastewater conveyance are due to frictional losses in conduits, bends and fittings, and
allowances for free-fall surface and for future expansions. TM 5-814-1/AFM 88-11, Volume 1, gives detailed
guidance and charts for computing head losses in pipes and conduits. Head losses through process equipment
are dependent on the specific units and are specified by their manufacturers or by the design engineer. The
design engineer must consider hydraulic constraints in the layout and selection of process equipment and
configurations. Special cases where dual and multiple pumping is required must receive prior approval by
HQDA (CEEC-EB) WASH DC 20314-1000 for Army projects and HQ USAF/LEEE WASH DC 20332 for
Air Force projects.
9-6. Plant auxiliary facilities.
a. General. A potable water supply will be provided. Sanitary facilities: toilet, shower and lavatory with
hot and cold water supply, will be provided except for intallations with less than 0.1 million gallons per day
capacity. The potable water line will incorporate an AWWA approved backflow prevention device to prevent
the contamination of the water supply as required by TM 5-813-5/AFM 88-10, Volume 5. Emergency power
for essential equipment will be provided. Adequate working and storage space is required for all plants. The
general plant layout will facilitate operation and maintenance of the treatment units and their appurtenances.
b. Controls and monitoring. The plant arrangement will take into consideration the related control and
monitoring requirements. Laboratory facilities will be provided for conducting the necessary analytical testing
for the purpose of process control and compliance with regulatory or NPDES requirements. Appendix F lists
required laboratory furniture, equipment, and chemicals for military installations. Standard Methods for the
Examination of Water and Wastewater (current edition), as approved by the EPA, will serve as guidance
in projecting these and additional laboratory needs.
9-3
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