NOTE: Delete paragraph and subparagraphs thereto
for plants below 1.31 L/s 0,000 GPD Capacity. For
plants below 0.66 L/s 5,000 GPD capacity, hopper
bottom only should be specified for settling tanks.
For plants above 4.38 L/s 100,000 GPD capacity,
mechanical sludge collectors only should be used in
settling tanks. For plants between 0.66 L/s and
4.38 L/s 15,000 and 100,000 GPD capacity, either
hopper bottom or mechanical sludge collector should
be allowed as a Contractor's option. However, of
the various types of mechanical sludge collectors,
rotating sludge collectors appear to be available
for plants of 1.31 L/s 30,000 GPD and above;
chain-and-flight, 1.75 L/s 40,000 GPD and above;
traveling reciprocating type, 0.66 L/s 15,000 GPD
and above.
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The sludge collector shall be bridge supported rotary type designed to move
settled sludge to a center sludge hopper. The equipment shall include a
drive assembly, a sludge collector assembly supporting bridge, and overload
alarm system.
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NOTE: Insert required loads. 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).
SECTION 11375N
Page 53
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