Current through Register Vol. 48, No. 38, September 20, 2024
a)
Emergency Power or Pumping Facilities
1) All
plants shall be provided with an alternate source of electric power or pumping
capability to allow continuity of operation during power failures. Methods of
providing power or pumping capability include:
A) The connection to at least 2 independent
public utility sources such as substations. A power line from each substation
into the treatment plant with capability for switchover to the second power
source by plant operating personnel will be required.
B) Portable or in place internal combustion
engine equipment which will generate electrical or mechanical energy. Refer to
Section 370.136(d).
C) Portable
pumping equipment when only emergency pumping is required. Refer to Section
370.136(d).
2) Standby
Generating Capacity Requirements
Standby generating capacity normally is not required for
aeration equipment used in the activated sludge process. In cases where a
history of long term (4 hours or more) power outages have occurred, auxiliary
power for minimum aeration of the activated sludge will be required.
3) Degree of Treatment Required
No reduction in degree of treatment due to power outages will
be allowed when the wastewater is to be treated by installations using
trickling filters, waste stabilization ponds and/or other low energy usage
treatment devices.
4)
Continuity of Disinfection
The design shall provide for continuous disinfection during
all power outages, if required due to critical outfall locations and receiving
waters.
5) Continuity of
Dechlorination
For facilities using dechlorination equipment, the design
shall provide for continuous dechlorination during all power outages, if
required due to critical outfall locations and receiving waters.
b) Water Supply
1) General
An adequate supply of potable water under pressure should be
provided for use in the laboratory and general cleanliness around the plant. No
piping or other connections shall exist in any part of the treatment works
which, under any conditions, might cause the contamination of a potable water
supply.
2) Direct
Connections
A) Potable water from a municipal
or separate supply may be used directly at points above grade for the following
hot and cold supplies:
i) Lavatory
sink
ii) Water closet
iii) Laboratory sink (with vacuum
breaker)
iv) Shower
v) Drinking fountain
vi) Eye wash fountain
vii) Safety shower
viii) Fire protection sprinklers
B) Hot water for any of the above
units shall not be taken directly from a boiler used for supplying hot water to
a sludge heat exchanger or digester heating unit.
3) Indirect Connections
A) Where a potable water supply is to be used
for any purpose in a plant other than those listed in subsection (b)(2)(A), a
break tank, pressure pump and pressure tank shall be provided. Water shall be
discharged to the break tank through an air-gap at least 6 inches above the
maximum flood line or the spill line of the tank, whichever is higher. A sketch
of an acceptable break tank is contained in Appendix G, Figure No. 4. In-line
backflow preventers are not acceptable.
B) A sign shall be permanently posted at
every hose bib, faucet, or sill cock located on the water system beyond the
break tank to indicate that the water is not safe for drinking.
4) Separate Potable Water Supply
Where it is not possible to provide potable water from a
public water supply, a separate well may be provided. Location and construction
of the well should comply with requirements of the governing State and local
regulations. Requirements governing the use of the supply are those contained
in subsections (b)(2) and (b)(3).
5) Separate Non-Potable Water Supply
Where a separate non-potable water supply is to be provided,
a break tank will not be necessary, but all sill cocks and hose bibs shall be
posted with a permanent sign indicating the water is not safe for
drinking.
c)
Sanitary Facilities
Toilet, shower, and lavatory should be provided in sufficient
numbers and at convenient locations to serve the expected plant
personnel.
d) Floor Slope
Floor surfaces shall be sloped adequately to a point of
drainage.
e) Stairways
Stairways shall be installed in lieu of ladders for access to
those units requiring inspection and maintenance, including but not limited to
trickling filters, digesters, aeration tanks, clarifiers and tertiary filters.
Spiral or winding stairs are permitted only for secondary access where dual
means of egress are provided. Stairways shall have slopes between 30 and 40
degrees from the horizontal to facilitate carrying samples, tools, etc. Each
tread and riser shall be of uniform dimension in each flight. Minimum tread run
shall not be less than 9 inches. The sum of the tread run and riser shall not
be less than 17 nor more than 18 inches. A flight of stairs shall consist of
not more than a 12 foot continuous rise without a platform.
f) Flow Measurement
1) Flow measurement facilities shall be
provided so as to measure the following flows:
A) Plant effluent flow.
B) Plant influent flow, if significantly
different from plant effluent flow, such as for lagoons and plants with excess
flow storage or flow equalization.
C) Excess flow treatment facility
discharges.
D) Other flows required
to be monitored under the provisions of an NPDES discharge permit.
E) Flows required for plant operational
control, including but not limited to return activated sludge flow, waste
activated sludge flow, recirculation flow and recycle flows.
2) Indicating, totalizing and
recording flow measurement devices shall be provided for all mechanical plants
for all flows except those specified in subsection (f)(1)(E) above. Flow
measurement equipment for lagoon systems shall consist of, at a minimum,
elapsed time meters used in conjunction with pumping rate test or calibrated
weirs. All flow measurement equipment must be sized to function effectively in
the full range of flows expected and shall be protected against
freezing.
3) Flow measurement
equipment including entrance and discharge conduit configuration and critical
control elevations shall be designed to ensure that the required hydraulic
conditions necessary for accurate measurement are provided. Conditions that
must be avoided include turbulence, eddy currents, air entrainment, etc., that
upset the normal hydraulic conditions that are necessary.
g) Sampling Equipment
Effluent composite sampling equipment shall be provided at
all mechanical plants and at other facilities where necessary to meet discharge
permit monitoring requirements.
