TM 5-814-3/AFM 88-11, Volume III
FLOW MEASUREMENT, SAMPLING, AND PROCESS CONTROL
18-1. General considerations.
a. In designing and constructing any wastewater treatment facility, a number of miscellaneous design
details must be considered. They include water supply systems, lighting requirements, service buildings and
equipment, landscaping, and proprietary processes and equipment. Requirements are given in other TM and
AFM publications. Specific information may be obtained from HQDA (CEEC-EB) WASH DC 20314-1000
for Army projects and HQ USAF/LEEE WASH DC 20332 for Air Force projects.
b. Equipment for indicating, totalizing and recording the effluent wastewater flow will be provided for
all secondary treatment plants with flows greater than 0.10 million gallons per day and smaller plants in
special cases. For plants less than 0.10 million gallons per day, recording and totalizing equipment will be
provided as required to assure effluent limitations within regulations imposed by the regulating authority. In
plants requiring recirculation of wastewater, meters with means for indicating the rates of recirculation are
required. Venturi meters, weirs, Parshall flumes, and magnetic flow meters are satisfactory for measuring
wastewater flow; Parshall flumes being generally preferable for military projects when measuring influent or
effluent. Measuring devices will be designed, or specified, with a view toward obtaining the maximum
accuracy of measurement throughout the expected range of flow. Principles of design of such devices are
covered in standard handbooks.
18-2. Flow measurement.
Monitoring is required by EPA when NPDES permits are issued to assure compliance with the permit.
Additionally, certain operational monitoring is required to ensure that proper treatment plant performance
is maintained. Refer to the EPA Handbook for Monitoring Industrial Wastewater for further information.
a. Continuous recording of flow. Wastewater flow rates will be monitored and recorded for purposes
of evaluating treatment plant performance and will also be used when treatment changes are involved.
Continuous flow measurement is necessary in order to monitor diurnal variations in flow which may affect
treatment plant efficiency. Flow rates must also be taken into account when sampling wastewater quality
b. Types of flow measuring devices. The following paragraphs describe the types that are suitable for
use in wastewater treatment plants. For additional comments refer to table 18-1.