| (a) The requirements of this section apply to both
completely mixed aerated lagoons and partially mixed aerated lagoons,
unless otherwise specified.
(b) A minimum of 1.6 pounds of oxygen per pound of
influent five-day biochemical oxygen demand (BOD5 )
must be maintained in an aerated lagoon system, even with the largest
single aeration unit in a lagoon system out of service.
(c) The aeration equipment must have an audio-visual
alarm system. If a wastewater treatment facility is not staffed 24
hours per day, the alarm system must be connected to a telemetry
system, such as an auto dialer or Supervisory Control and Data Acquisition
system, with battery backup.
(d) The BOD5 removal in
each aerated lagoon must be calculated using the following equation:
Attached Graphic
(1) The value of K for domestic wastewater in a completely
mixed lagoon is 0.50 day-1 at 20 degrees
Celsius. The value of K for domestic wastewater in a partially mixed
lagoon is 0.28 day-1 at 20 degrees Celsius.
(2) The value of K must be adjusted for the minimum
monthly water temperature using the following equation:
Attached Graphic
(3) The value of K must be determined for high-strength
or industrial wastewater by either a laboratory study or an evaluation
of an existing wastewater treatment facility treating wastewater
with similar organic strength and industrial contributions.
(e) Aeration Equipment.
(1) The size of the aeration equipment in an aerated
lagoon must be able to supply the oxygen demand determined in subsection
(b) of this section.
(2) For the purpose of sizing aeration equipment,
an aerated lagoon must comply with the mechanical and diffused air
requirements in §217.155(c) of this title (relating to Aeration
Equipment Sizing).
(3) If multiple partially mixed aerated lagoons are
used in series, the power input may be reduced as the influent BOD5 to each lagoon decreases.
(f) Aerated Lagoon Design Requirements. An aerated
lagoon system must be designed according to the requirements for
a wastewater treatment lagoon in §217.203(f) of this title (relating
to Design Criteria for Natural Treatment Facilities) and §217.207(d)
of this title (relating to Stabilization Lagoons).
(g) Scour Prevention. An earthen-lined aerated lagoon
system must include a concrete scour pad in each area of the earthen
liner that is subject to a velocity equal to or greater than 1.0
foot per second.
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