MIL-HDBK-1005/16
3.3.2.5
Domestic Flows, Minimum Flow. To determine the minimum
flow for resident population, multiply the annual average flow by
the ratio of minimum flow to annual average flow based on
wastewater flow data for the facilities being studied. If no data
are available, see WEF MOP FD-5. For nonresident populations,
assume the minimum flow is zero.
3.3.2.6
Infiltration. A typical allowance for infiltration is
included in the per capita flows of domestic wastewater. This
allowance is 500 gallons per day per inch diameter mile
(gpd/in.-mi) (46 liters per day per millimeter diameter kilometer
[Lpd/mm-km]) of sewer. For existing systems, estimate
infiltration by comparing the measured wastewater flow with water
use. Also, check variations of flow with weather conditions.
Refer to WEF MOPs FD-5 and FD-6.
3.3.2.7
Inflow. Surface drainage or runoff is normally very
large in relation to sanitary flow. Surface drainage or inflow
should be kept out of sanitary sewers by rational design
procedures, adequate construction specifications and inspection,
and enforced regulation. Manhole covers can be a large source of
inflow. In areas subject to overflow by surface drainage, the
problem can be reduced significantly by using solid covers with
half-depth pickholes. Using bolted and gasketed manhole covers
in areas subject to flooding can also reduce the problem.
Existing sewer systems should be evaluated for inflow
by the designer of new intercepting sewers, trunk sewers,
collector sewers, or treatment facilities fed by the existing
sewers. If inflow is significant, sources should be determined
by inspecting manhole covers, roof and other drainage
connections, smoke testing, and internal televised inspection of
sewers. All inflow that is cost-effective to remove should be
eliminated by rehabilitating the sewer system to prevent
oversizing of new sewers and wastewater treatment facilities.
Refer to WEF MOP FD-6.
3.3.2.8
Industrial Flows. Industrial flows will vary based on
the nature of the activity and should be estimated on a site-
specific basis. If flow data for the wastewater to be treated
are unavailable, base the estimate on similar existing
activities. For additional information on industrial wastewater
flows, refer to WEF MOP FD-5, MIL-HDBK-1005/9, and
MIL-HDBK-1005/17.
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