[R.O. 2006 §515.010; Ord. No. 796A §1, 3-15-1996]
A. This
Chapter covers guidelines for construction of submersible non-clog
or grinder pump stations. In addition to the following guidelines,
the design and installation shall also conform to Missouri Department
of Natural Resources regulations (10 CSR 21.8). Lift stations include
precast concrete or reinforced fiberglass wet well and valve chamber
complete with base, piping, access doors, and electronic controls.
The pump and controls shall have name plates.
B. Figures
1 to 3 included as attachments to this Chapter show details of the
wet well and valve chamber. The wet well, valve chamber and associated
piping shall be constructed as shown in the figures.
[R.O. 2006 §515.020; Ord. No. 796A §1, 3-15-1996]
The pumping station shall be readily accessible by maintenance
vehicles during all weather conditions. The road shall be minimum
two (2) inch Type I aggregate shaped and rolled on top of six (6)
inch two and one-half (2½) to three (3) inch base rock. The
lift station shall be located off the trafficway of streets and alleys.
[R.O. 2006 §515.030; Ord. No. 796A §1, 3-15-1996]
A. At least
two (2) pumps shall be provided. A minimum of three (3) pumps shall
be provided for stations handling flows greater than one (1) MGD.
If only two (2) pumps are provided, they should have the same capacity.
Each shall be capable of handling flows twice the expected maximum
flow.
B. For pumping
wastewater from single residences or when a minimum velocity of two
(2) fps cannot be achieved in a four (4) inch diameter discharge pipe,
a grinder pump shall be used. In other cases, non-clog submersible
pumps can be used.
C. Except
where grinder pumps are used, pumps shall be capable of passing spheres
of at least three (3) inches in diameter, and pump suction and discharge
piping shall be at least four (4) inches in diameter.
D. Submersible
pumps shall be readily removable and replaceable without dewatering
the wet well or disconnecting any piping in the wet well. A hoist
shall be furnished to lift the pump.
E. Bar racks
shall be provided to protect pumps from clogging or damage. Where
a bar rack is provided, a mechanical hoist shall also be provided.
F. Electrical
systems and components in the wet well shall be suitable for hazardous
locations (National Electrical Code, Class I, Group D, Division I
location). In addition, equipment located in the wet well shall be
suitable for use under corrosive conditions. Each flexible cable shall
be provided with watertight seal and separate strain relief. A fused
disconnect switch located above ground shall be provided for all pumping
stations. When the equipment is exposed to weather, it shall meet
the requirements of weatherproof equipment.
G. Electrical
supply and control circuits shall be designed to allow disconnection
at a junction box located at, or accessible from, the outside of the
wet well. Terminals and connectors shall be protected from corrosion
by location outside of the wet well or by watertight seals.
H. The motor
control center shall be located outside the wet well and be protected
by a conduit seal to prevent the atmosphere in the wet well from gaining
access to the control center. The seal shall be NEC Class 1, Division
2, Group D.
I. Pump
motor power cords shall be designed for flexibility and serviceability
under conditions of extra hard usage and shall meet the requirements
of the Mine Safety and Health Administration for trailing cables.
[R.O. 2006 §515.040; Ord. No. 796A §1, 3-15-1996]
A. The control
system shall be of the encapsulated float type. The electrical equipment
shall be suitable for hazardous locations (National Electrical Code,
Class I, Group D, Division I location). The control shall be located
in a NEMA type 3R enclosure.
B. In small
stations, the pump shall automatically alternate.
C. There
will be an alarm for the following conditions:
5. Pump
motor overheating.
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A local audio/visual alarm or telemetered alarm shall be provided.
Use of a local or telemetered alarm will be decided by the City Engineer.
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[R.O. 2006 §515.050; Ord. No. 796A §1, 3-15-1996]
A. Suitable
shutoff and check valves shall be placed on the discharge line of
each pump. The check valve shall be located between the shutoff valve
and the pump. Check valves shall not be placed on the vertical portion
of the discharge piping.
B. The shutoff
valve shall be quarter-turn, permanently lubricated eccentric type
with resilient faced plug. End connections shall be flanged. Valves
shall be lever operated and equipped with position indicator. The
valve shall be as manufactured by DeZurik or equal.
Check valve shall be swing disc type with outside lever and
spring. End connections shall be flanged. The valve shall be as manufactured
by Clow Valve or equal.
C. Valves
shall not be located in the wet well. There will be a separate valve
chamber where the check and shutoff valves are installed.
D. Accumulated
water in valve chamber shall be drained to the wet well.
E. Lift
station piping shall be Ductile Iron ANSI A21.50, Class 52. Joints
shall be flanged, ANSI A21.10. The piping, valves and supports shall
be coated with one (1) coat epoxy primer and two (2) coats of polyemide
cured epoxy glass enamel.
F. The system
control floats shall be mercury float switches suspended in the wet
well. The operational sequence will be as follows:
[R.O. 2006 §515.060; Ord. No. 796A §1, 3-15-1996]
A. The wet
well size and control setting shall be appropriate to avoid heat build
up in the pump motor due to frequent starting and to avoid septic
conditions due to excessive detention time.
The time between starts for the pump shall not be less than
fifteen (15) minutes. The volume of the wet well between start and
stop elevations shall be sized to provide the above mentioned duration
between starts. A maximum detention time of twenty (20) minutes shall
be allowed at average design flowrate to prevent septic conditions
in the wet well.
B. Ventilation
shall be provided in the wet well. A four (4) inch vent with return
bend shall be used as shown in Figure 2.
C. The wet
well shall be constructed of precast reinforced concrete (ASTM C76).
Water proofing shall be as per manhole water proofing.
[R.O. 2006 §515.070; Ord. No. 796A §1, 3-15-1996]
Access doors shall be heavy duty, single leaf, steel hatches
with galvanized steel channel frame and one-quarter (¼) inch
thick diamond plate cover. The door shall be designed for three hundred
(300) pound/square foot live load and watertightness. A holding arm
shall be provided when door is fully open. Door shall open to ninety
degrees (90°) and lock automatically in that position. A flush,
spring loaded locking device capable of unlocking from the interior
without a key shall be provided. The door shall be as manufactured
by Bilco Company or equal.
[R.O. 2006 §515.080; Ord. No. 796A §2, 3-15-1996]
Prior to the construction or installation of any such lift station,
the specifications for said lift station shall be submitted to the
City Engineer and be approved in writing by him/her.
[R.O. 2006 §515.090; Ord. No. 796A §3, 3-15-1996]
Any lift station thereafter built or installed in the City of
Troy shall carry a warranty by the person building or installing said
system for a period of one (1) year after the date of completion of
the installation and acceptance by the City.