a.
Design: The sludge collector assembly shall operate at a linear
speed of 5 to 20 mm per second 1 to 4 fpm. The mechanism and its
component parts shall be designed, with a minimum factor of safety
of 4, to withstand all structural and mechanical stresses brought
about by the drive assembly and the following loadings: dead load
and maximum anticipated sludge load. The mechanism shall be
designed for continuous 24-hour service under design load without
excessive wear, damage, or failure. The mechanism shall be
capable of operating in a dry chamber without overloading the
equipment. Stresses developed under the aforementioned operating
conditions and loads shall not exceed the allowable stresses
conforming to AISC 335.
b.
Motor Drive Assembly: Motor drive assembly shall include a motor
speed reducer, drive sprocket on output shaft of speed reducer,
drive chain from drive sprocket to driven sprocket, shear pin, and
chain guard. Unit shall be fully enclosed and designed for
mounting outside and exposed to the weather.
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NOTE: Insert electrical power characteristics. On
the project drawings, show:
1. Type of plant: (Extended aeration, Step
Aeration, or Complete Mixing).
2.
Design flow.
3.
5-day BOD loading.
4.
Suspended solids loading.
5. Whether a comminutor is needed for plants 1.09
L/s 25,000 GPD or less in size.
6.
Whether mechanical aerator should be allowed.
7. Whether plant should be concrete only, steel
only, or either concrete or steel at Contractor's
option.
8.
Whether piling is required for foundations.
9. Whether hypochlorinator or whether chlorinator
should be used for plants in 4.38 to 6.57 L/s
100,000 to 150,000 GPD range.
10. Whether raw sewage recirculation box
(recirculation to pumping station) is needed.
11. Whether plant is to be of aboveground or
belowground construction.
12.
Seismic loading (if necessary).
13.
Electric power characteristics for motors.
14.
Whether automatic operation of air lift pumps
SECTION 11375N
Page 49
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