e.
Average turbidity, NTU:
[_____].
f.
UV transmittance @ 253.7 nanometers (nm), through
a 1 cm cell:
[_____].
g.
Influent [fecal coliform][_____], MPN/100 mL:
[_____].
2.1.2
Performance Requirements
**************************************************************************
NOTE: Typical values for nominal average intensity,
UV density and theoretical retention time are 5100
microwatts per square cm, 3.35 watts per liter, and
7 seconds, respectively. Nominal average intensity
will vary between manufacturers. Density depends
upon the design of the particular UV system and the
number of lamp banks. Retention time depends upon
the channel geometry and number of lamp banks.
Insert values per specified equipment manufacturer's
calculations.
**************************************************************************
2.1.2.1
Inactivation
**************************************************************************
NOTE: Predominate effluent criteria used in
performance requirements for UV systems is for whole
body contact: 200 most probable number (MPN)/100 ml
of fecal coliforms, with a maximum 7-day average of
400 MPN/100 ml. Some states have different microbe
and disinfection standards; therefore, determine the
site specific disinfection requirements from the
state permitting authority.
**************************************************************************
The system shall be capable of reducing the influent [fecal coliform]
[_____] count to [200 MPN/100 mL] [_____] on a 30 day geometric mean of
daily samples.
2.1.2.2
UV Dose
**************************************************************************
NOTE: Conventional units for UV dosage are
microwatt-seconds per square cm. The standard
dosage of UV radiation is determined by the
effluent; unfiltered effluent may require a 30,000
dosage while a dosage of 16,000 to 20,000 is more
typical of filtered effluent to achieve a
disinfection safety factor of 2.0. Insert value per
equipment manufacturer's recommendation.
**************************************************************************
The UV dosage shall be not less than [_____] microwatt-seconds per square
cm based on peak design flow conditions, lamp output at 65 percent of its
initial level after 1 year (8750 hours) of lamp operation without fouling
on the lamp sleeves, and minimum UV transmittance as stated in paragraph
Effluent Characteristics.
SECTION 11376
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