Current through August 31, 2023
01.
General. Section
441 regulates individual residence
pump stations, individual residence grinder pump stations, and individual
residence septic tank effluent pump stations. However, this rule does not
regulate grinder pumps or their vaults that are inside of individual residences
or other structures. Certain individual residence wastewater pumping stations
may be under the jurisdiction of the Idaho Division of Building Safety,
Plumbing Bureau. For further defining and delineating of the Plumbing Bureau's
and the Department's statutory and regulatory duties and responsibilities with
respect to individual residence wastewater pumping stations, see the Memorandum
of Understanding referred to in Section
008. (3-31-22)
a. Flooding. Wastewater pumping station
structures and electrical and mechanical equipment shall be protected from
physical damage by the one hundred (100) year flood. Wastewater pumping
stations shall remain fully operational and accessible during the twenty-five
(25) year flood. Local, state and federal flood plain regulations shall be
considered. (3-31-22)
b.
Accessibility and Security. The pumping station shall be accessible by
maintenance vehicles during all weather conditions.
(3-31-22)
02.
Design. Design of wastewater pumping stations shall meet the
applicable requirements of Subsections
441.02.a. through 441.02.c.
(3-31-22)
a. Pumps. (3-31-22)
i. Multiple Units. Duplex pumps for
individual residence wastewater pump stations are not required. However, for
developments having five (5) or more similar facilities, one (1) working spare
pump for each size shall be provided and be readily available at all times.
(3-31-22)
ii. Pump Openings. Pumps
handling raw wastewater shall be capable of passing spheres of at least three
(3) inches in diameter or be a grinder pump. (3-31-22)
iii. Priming. The pump shall be placed so
that, under normal operating conditions, it will operate under a positive
suction head. (3-31-22)
b. Controls. Water level control sensing
devices shall be designed to allow for automatic control of pumps.
(3-31-22)
c. Valves. Suitable means
to facilitate pump removal and to prevent backflow shall be provided. All
shutoff and check valves shall be accessible for maintenance.
(3-31-22)
03.
Submersible Pump Stations - Special Considerations. (3-31-22)
a. Construction. Submersible pumps and motors
shall be designed specifically for raw wastewater use, including totally
submerged operation during a portion of each pumping cycle. An effective method
to detect shaft seal failure or potential seal failure shall be provided.
(3-31-22)
b. Pump Removal.
Submersible pumps shall be readily removable and replaceable without personnel
entering or dewatering the wet well, or disconnecting any piping in the wet
well. (3-31-22)
c. Electrical
Equipment. Section 009 provides
a reference to the requirements of the National Electrical Code, compliance
with which may be required by other law. (3-31-22)
i. Power Supply and Control Circuitry.
Electrical supply, control, and alarm circuits shall be designed to provide
strain relief and to allow disconnection from outside the wet well. Terminals
and connectors shall be protected from corrosion by location outside the wet
well or through use of watertight seals. (3-31-22)
ii. Controls. The motor control center shall
be located outside the wet well, be readily accessible, and be protected by a
conduit seal or other appropriate measures to prevent the atmosphere of the wet
well from gaining access to the control center. The seal shall be located so
that the motor may be removed and electrically disconnected without disturbing
the seal. When such equipment is exposed to weather, it is recommended that it
meet the requirements of weatherproof equipment NEMA 3R or 4.
(3-31-22)
iii. Power Cord. Pump
motor power cords shall be designed for flexibility and serviceability under
conditions of extra hard usage. Ground fault interruption protection shall be
used to de-energize the circuit in the event of any failure in the electrical
integrity of the cable. Power cord terminal fittings shall be
corrosion-resistant and constructed in a manner to prevent the entry of
moisture into the cable, shall be provided with strain relief appurtenances,
and shall be designed to facilitate field connecting.
(3-31-22)
04.
Alarm Systems. Audio-visual alarm systems with a backup power
source shall be provided for pumping stations. The alarm shall be activated in
cases of wet well high water levels and shall be visible from the outside of
the structure. (3-31-22)
05.
Emergency Operation. The pumping station must be sized to allow
for one (1) day's flow between the high water alarm and the building service
invert or the pressure discharge pipe, whichever is closer to the high water
alarm. (3-31-22)
06.
Instructions and Equipment. Wastewater pumping stations shall be
supplied with a complete set of operational instructions, including emergency
procedures, maintenance schedules, tools, and such spare parts as may be
necessary. (3-31-22)
07.
Operation and Maintenance. An operation and maintenance manual
shall be submitted to and approved by the Department as required by Section
425. Adherence to the terms of this
approved manual shall be required. The owner shall be responsible for
maintaining the wastewater facility in a manner that assures its designed
operation. (3-31-22)
08.
Force Mains. (3-31-22)
a.
Velocity and Diameter. At design pumping rates, a cleansing velocity of at
least two (2) feet per second shall be maintained. (3-31-22)
b. Special Construction. Force main
construction near streams or water works structures and at water main crossings
shall meet applicable provisions of Section
430. (3-31-22)
c. Design Friction Losses. (3-31-22)
i. Friction Coefficient. Friction losses
through force mains shall be based on the Hazen and Williams formula or other
acceptable methods. When the Hazen and Williams formula is used, the friction
losses for varying values of "C" shall be evaluated for different types and
ages of pipe. (3-31-22)
ii. Maximum
Power Requirements. When initially installed, force mains will have a
significantly higher "C" factor. The effect of the higher "C" factor shall be
considered in calculating maximum power requirements and duty cycle time to
prevent damage to the motor. The effects of higher discharge rates on selected
pumps and downstream facilities shall also be considered.
(3-31-22)
d.
Identification. Where force mains are constructed of material which might cause
the force main to be confused with potable water mains, the force main shall be
appropriately identified using trench tape saying "raw sewage," "biohazard," or
other appropriate wording. (3-31-22)
e. Leakage Testing. Leakage tests shall be
specified including testing methods and leakage limits. Testing shall conform
with Sections 401.3.6
and 505.3.3 of the "Idaho Standards
for Public Works Construction," incorporated by reference into these rules at
Section 004.
(3-31-22)
f. Thrust Blocking.
Thrust blocking shall conform with Sections
401.3.4 of the "Idaho Standards
for Public Works Construction," incorporated by reference into these rules at
Section 004.
(3-31-22)
g. Maintenance
Considerations. Isolation valves shall be used if force mains connect into a
common force main. (3-31-22)
h.
Cover. Force mains shall be covered with sufficient earth or other insulation
to prevent freezing or other physical damage. (3-31-22)
