1.2.1.4
Chlorination Zone
The chlorination zone shall be designed for quiescent plug flow through the
tank and to provide at least 30 minutes contact time at peak flow rate. A
turbulent zone shall be provided at the tank inlet for proper chlorine
solution mixing. The tank shall be baffled to promote plug flow and reduce
short circuiting. Chlorination equipment shall be provided in accordance
with paragraph [GAS CHLORINATION SYSTEM] [CALCIUM HYPOCHLORITE CHLORINATION
SYSTEM]. Effluent from the chlorination zone shall flow over a weir and
exit the plant through a [_____] mm -inch diameter flanged pipe.
1.2.2
Contact Stabilization Plant Design
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NOTE: If effluent standards require a 5-day B.O.D.
of less than 10 mg/L, then effluent filters are
recommended. The filtration unit shall be [one]
[two] [single] [dual] media filter cell(s), with
backwash and backwash holding tanks, and related
pumps, blowers, valves, piping, and control devices.
Insert design and peak flow rates. Comply with TM
5-814-3 for design flow rates. If the ratio of peak
flow to design flow is expected to exceed 2:1, the
peak flow may not be able to meet the 20 to 40
minute detention time requirement for all flows. If
the detention time is not met, provide flow
equalization prior to the treatment plant. Verify
percent suspended solids and BOD removal.
Equalization tank should be sized to handle flow in
excess of plant design flow rate for period of time
that the peak flow is calculated to last. A
dedicated blower system or motor operated valve as
well as an aerating mixer are alternatives which
will be used to aerate the equalization tank. The
air should be shut off before the contents of the
equalization tank are drained back to lift station
or pumped by airlift or grinder pump during low flow
periods. Air overflow weir in the equalization tank
should allow flow to go back to aeration tank or
back to lift station.
Provide seismic details, if a Government designer
(either Corps office or A/E) is the Engineer of
Record, and show on the drawings. Delete the
bracketed phrase, in the last sentence, if no
seismic details are provided. Sections 13080 and
15070A, properly edited, must be included in the
contract documents.
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Treatment of wastewater shall be accomplished through absorption of the
suspended solids and biochemical oxygen demand (5-Day BOD) by contact with
stabilized activated sludge for a short time duration followed by gravity
clarification and chemical disinfection. The treatment plant shall be
sized for a design flow of [_____] L per day gpd and a peak flow of [_____]
L per day gpd. The treatment plant shall remove [80] [_____] percent of
the suspended solids and 5-day BOD for domestic wastewater with 5-Day BOD
SECTION 11390
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