1 March 1997
compartments to facilitate cleaning and repairs. Wet wells for all stations will have no length,
width or diameter smaller than 1.2 meters (4 feet). Eye bolts or trolley beams will be provided in
smaller stations, and overhead bridge cranes in large stations, for hoisting and removing
equipment from mountings. Stairs will be provided in medium to large sized stations so that
personnel may inspect and maintain equipment. Smaller stations, except those utilizing
submersible pumps, will require the use of vertical safety ladders. A suitable means will be
provided to service and maintain all equipment. A floor drainage system will be provided in the
dry well, and throughout the superstructure, for collection of wash down, seepage, and stuffing
box leakage. These wastes will be piped or conveyed to the wet well, either by gravity or by
sump pump. Openings to the wet well and dry well through the main floor of the station will be
above the maximum flood level, or will otherwise be protected from flooding.
c. Materials of construction. Large to medium sized,conventional type stations will ordinarily
be constructed ofreinforced concrete. The above ground portion of the building maybe of
masonry, wood, or metal panel construction. Therequirements of Department of Defense (DOD)
Construction CriteriaManual 4270.1-M will be followed in designing for fire resistivestructures.
Small package type stations will generally bemanufactured of steel or fiberglass with separate
wet wellsconstructed of precast concrete or fiberglass manhole sections. Where steel structures
are used, cathodic protection, in conformance with TM 5-811-7, or appropriate corrosion control
measures will be provided for the underground steel shell. Alternatively, steel structures may be
protected by a concrete or gunite coating where proof can be furnished by the manufacturer of
satisfactory design life. All structures will be designed to withstand flotation.
d. Personnel safety. Guards will be placed on and around all equipment where operators may
come in contact with moving parts. Railings will be required around all floor openings, and along
platforms or walkways, where there is a danger that personnel may fall. Floors, grating, and
plates will be nonslip. Warning signs will be placed at all hazardous locations. Rubber mats will
be provided in front of all electrical equipment where the potential exists for electrical shock.
Adequate lighting and ventilation will be provided as required in following paragraphs. In
attended stations where the possibility exists for toxic, explosive, or otherwise hazardous
atmospheres, proper design for personnel safety will be in conformance with TM 5-814-3/AFM
88-11, Vol. 3. Design for fire protection will be in accordance with DOD Manual 4270.1-M.
Wastewater pumping stations will be classified as light hazard, industrial type occupancies.
Always provide a quick, unobstructed exit for people working around pumps.
9-3. STRUCTURAL SYSTEMS. The foundation design will be based upon a soils analysis and
recommendations of a geotechnical engineer experienced in the field of soils mechanics and
foundation design. Information on ground water conditions and the classification of soil types will
be obtained through borings at the pump station location. For below grade structures the soils
survey will be performed during the time of year when ground water is at its highest. Conditions
to be considered in the design will be not only soil bearing qualities, but also soil swell potential
and ground water infiltration into the structure through the lowest point of entry which bill be
either pipe penetration of a joint in the concrete. Usually ground water should be at least one
foot below the lowest point of entry. The structural design layout will show design of pipe
anchors and pipe supports under pump operating conditions, and foundations under heavy
equipment. Structural steel will be provided to support piping and conduit. Reinforced concrete
bases raised above the floor will be provided for pumps, engine drives, large valves and control
devices, and floor mounted electric equipment. Centrifugal pumps and driver will have common
foundation and base plate. Refer to TM 5-805-4 for noise and vibration control for equipment
installations. Floors will slope to floor drains located around all pumps. Floor loading will
consider moving large equipment in and out for repair, maintenance, and replacement. Crane