(a) General.
(1) The requirements for individual pump stations shall be reviewed by the city on a case by case basis. In general, pump stations shall be of the duplex, submersible non-clog centrifugal pump type. Other types of pumps may be approved by the city. Developer/engineer must provide supporting documentation as to why the alternate pumps should be used.
(2) Electrical requirements including the control panel will also be reviewed on a case by case basis. Adjustments to the requirements listed below will be made as deemed appropriate by the city.
(b) Pump.
(1) Pumps shall be submersible, non-clog, centrifugal pumps specifically designed for the specified use. Openings and passages of pump shall permit passage of the specified three- inch sphere diameter and typical trash and stringy material associated with sanitary sewage. Pump with appurtenances shall be capable of continuous operation at required submergence depth. Pump shall be designed for remote connection to a base elbow using one or two guide bars.
(2) Casing. Pump casing shall be constructed of cast iron ASTM A-48, Class 30. The casing shall be of uniform quality, surface, and free from defects. The casing shall be capable of withstanding operating pressures 50% greater than the maximum operating pressure. Volute shall have smooth passages, which provide unobstructed flow through the pump.
a. Mating surfaces. Mating surfaces where watertight seal is required shall be machined and fitted with nitrile rubber O-rings. Fitting shall be such that sealing is accomplished by metal-to-metal contact between mating surfaces, resulting in proper compression of the O-rings without the requirement of specific torque limits.
b. Exterior surfaces shall have a factory applied sewage resistant coating shall protect exterior surfaces of the casing in contact with sewage. Exposed nuts and bolts shall be stainless steel.
(3) Impeller. Impeller shall be of cast iron and shall be of the single or double shrouded non-clogging design. Impeller shall be statically, dynamically, and hydraulically balanced. Impeller shall be securely keyed to the shaft with a locking arrangement whereby the impeller cannot be loosened by torque from either forward or reverse direction.
(4) Renewable wearing rings shall be provided on the impeller and casing and shall have wearing surfaces normal to the axis of rotation. Wear rings shall be constructed of bronze or stainless steel. Wearing rings shall be designed for ease of maintenance and shall be adequately secured to prevent rotation.
(5) Shaft shall be a one piece 416 Stainless steel shaft of adequate strength to transmit full motor horsepower to the impeller.
(6) A tandem mechanical shaft seal system running in an oil bath shall be provided. Seals shall be of tungsten carbide alloy with each interface held in contact by its own spring washer.
(7) Pump shall rotate on a minimum of two permanently lubricated bearings with a L-10 bearing life of 40,000 hours.
(c) Motor.
(1) Provide sealed squirrel cage induction motor for submersible operation in conformance with NEMA standards for type motor specified and shall meet the following requirements:
a. UL listed for Class I, Division 1, Group C and D explosion proof hazardous locations.
b. Service factor of 1.15.
c. Horsepower, RPM, voltage and phase shall be as required for the specific application. Nameplate horsepower rating shall not be exceeded by the brake horsepower requirements of the specified head and capacity conditions.
d. Continuous duty submerged and 15 minutes in air at nameplate horsepower and a minimum of 15 evenly spaced starts per hour.
e. Exterior hardware shall be stainless steel.
f. Class F insulation.
g. Lifting lugs of adequate strength to lift the pump and motor assembly shall be cast into the motor housing.
h. Two moisture detector probes to detect seal failure shall be wired internally to control cable.
i. Two normally closed automatic reset thermostats shall be imbedded in the motor windings to open on excessive heat stopping the motor.
j. Provide waterproof power and control cable sized to conform to NEC and ICEA standards and adequate length to connect to the control panel. Seal cables at motor entry point to prevent moisture from entering motor housing and cable wicking.
k. Motor shall not overload throughout the pump-operating curve.
(d) Painting.
(1) Exterior surface of pump and motor shall receive as a minimum the following paint system at the factory:
a. SSPC-SP6, commercial blast cleaning.
b. One coat of modified alkyd enamel to a minimum two mils dry film thickness.
(e) Installation system.
(1) Provide a rail mounted installation system consisting of stainless steel guide rails, upper rail guide bracket, sliding bracket, intermediate rail guide bracket(s) (for rails over 20 ft), and a discharge connection elbow. System shall be of the size and type standard with the pump manufacturer for pump type to be supplied and shall not be used to support the weight of the pump. Stainless steel sliding guide bracket shall be an integral part of the pump unit. Discharge connection elbow and piping shall be permanently installed in the wet well. Pump shall be automatically connected to the discharge connection elbow when lowered into place and shall be easily removed for inspection and service without entering the wet well.
(2) Provide a stainless steel lifting cable capable of supporting the pump and to raise and lower the pump through one continuous motion with the hoist.
(3) All bolts to be stainless steel.
(f) Control system.
(1) A duplex pump control panel shall be provided with, as a minimum, the required contacts and relays for the following pump operation and controls.
a. “Lead” pump shall start when liquid level rises to “lead pump” elevation.
b. If during “lead” pump operation liquid level continues to rise, “lag” pump shall start at “lag pump” elevation and operate with “lead” pump until liquid level drops to “pump off elevation.
c. If liquid level continues to rise to “high water” elevation, the high water alarm shall be activated.
d. Pumps shall alternate between starting cycles. In the event either pump fails to function, the other shall automatically start.
e. Adjustable float switches shall control liquid level elevations.
f. Motors shall automatically shut down upon loss of phase, under voltage, or phase reversal.
g. Provide time delay start (15 sec) for lag pump motor to prevent both motors from attempting to start simultaneously while on standby generator power.
(2) Control panel shall be a NEMA 4X stainless steel enclosure with a dead front with a hinged inner door. Panel shall be UL labeled, as a complete unit, following assembly. Panel shall include, but not be limited to, the following items:
a. Enclosure door shall be provided with stainless steel clamps and provisions for padlocking or shall be equipped with a three-point latching mechanism operated by an oil-tight key-locking handle.
b. Main circuit breaker with external operator.
c. Surge arrester.
d. Surge capacitor.
e. Phase monitor relay (three-phase installation).
f. Entry alarm to detect unauthorized attempt to gain entry into control panel. Provide override for use of authorized personnel.
g. A thermal I magnetic circuit breaker and magnetic starter with three-leg overload protection for each pump. Provide one normally open and one normally closed set of auxiliary contacts on each starter. Contacts shall be in addition to those required for specified control functions.
h. Reduced voltage solid state soft starters.
1. The solid state reduced voltage starter shall be coordinated with the starting and running characteristics of the motor driven load to ensure a complete and operable system. Coordination between the motor control manufacturer and the mechanical equipment supplier is essential and required to ensure that speed-torque requirements are met. Specifically, the motor controller shall provide enough voltage at the time of start and produce enough torque to start the load while maintaining the desired results of a reduced voltage start.
2. Starter shall be installed in control panel.
3. The motor shall be protected from solid state component failure by an isolation contactor that opens when the motor is stopped or when the controller detects a fault condition including a shorted SCR.
4. The soft start shall provide torque control for linear acceleration independent of motor load in a manner to ensure a stable and linear acceleration ramp.
5. A shorting contactor shall be provided. The shorting contactor shall close, shorting the SCRs after the acceleration ramp is complete and open on a stop command to allow a deceleration ramp.
6. The soft start shall be capable of supplying 400% of rated full load current for 23 seconds at maximum ambient temperature.
7. A digital keypad shall be provided to enter operating parameters.
8. A full voltage bypass starter with overload protection shall be included to provide motor operation in the case of soft starter failure. A NORMAL/BYPASS selector switch shall be provided.
9. Should pump/motor require a 460 V installation, provide a transformer sized for control circuit loads and additional 120 V circuits as required. Transformer size shall be adequate to provide 150 percent of the control circuit requirements, a minimum of 3.5 amperes for the receptacle and 100% of other auxiliary 120-volt loads. Provide fused primary and secondary and bond unfused leg of secondary to enclosure.
i. Obtain control circuit voltage between one of the phase conductors and neutral. On high leg systems, the selected phase must be one of the non- high leg phases.
j. Separate circuit breaker with handle to project through inner door for the following:
1. Each pump motor.
2. Control circuit.
3. Cabinet heater.
4. Door mounted duplex receptacle.
5. Battery charger receptacle.
k. Cabinet condensate heater with thermostat.
l. Alternator relay to alternate pumps between successive starts.
m. Mount the following devices on inner door:
1. Hand-off-automatic (H-O-A) control switch for each pump.
2. Non-resettable elapsed time meter for each pump. Meter shall read in tenth of hours through 99,999 hours total time.
3. GFCI type duplex receptacle.
n. Mount operating and warning lights on inner door for the following. Color indicates required lens color.
1. Power on (white).
2. High water level (red).
3. For each pump.
i. Running (green).
ii. Seal failure (red).
iii. Thermal overload (red).
iv. Soft start failure (red).
4. Phase monitor (red).
5. Generator failure (red).
o. Alarm horn and light (red) mounted on top of protective shield. Horn sound level shall be a minimum of 100 decibels at ten feet. Provide horn silence switch on inside panel.
1. In the event of a power loss at the pump station or a failure of the automatically activated stand-by generator, the alarm system shall be operated from a battery back-up power source. Battery back-up power source shall be provided with continuous charge. No alarm relays or indicator lights (except the alarm silence relay and alarm light) shall be part of the battery charging circuit.
2. At a minimum, the following conditions shall be monitored by the system, and each shall cause activation of the audible and visual alarms:
i. Loss of power supply.
ii. Pump failure for each pump for seal failure or thermal overload.
iii. High water level.
iv. Loss of telemetry transmission line. Provide contacts for signal from telemetry system.
v. Standby generator failure.
p. Auxiliary contacts for remote signal for the following:
1. Pump run status for each pump.
2. High water alarm.
3. Pump failure alarm for both pumps on thermal overload or seal failure.
4. Loss of power.
5. Loss of phase to indicate over I under voltage, phase loss, or phase reversal.
6. Standby generator failure.
7. Generator low fuel.
8. Generator run status.
q. Provide laminated plastic labels to identify all control components.
r. Provide a plastic laminated electric diagram with wire I terminal numbers and color codes permanently fastened to inside of enclosure door.
(3) Switches, push buttons, and indicator lights shall be 30.5 mm oil tight / watertight units. Lights shall be LED push-to-test type.
(4) Wire shall be sized as required for load and application according to NEC. Wiring shall be neatly bundled and continuous from point to point. Wiring shall be totally accessible with permanent marking on each end to match the schematic drawing. Control and signal wire shall be a minimum of #14 AWG, stranded, 90 degree insulated and color-coded. Color coding shall be as follows:
a. Red AC control.
b. Blue DC control
c. Yellow External source control
d. White AC neutral
e. Green Ground
(5) Provide UL listed mercury float switches encapsulated in buoyant waterproof housing with sufficient cable to extend to control panel. Float and cable shall be designed and manufactured for use in a sewage wet well environment. Sensor levels shall be field adjustable.
(6) Conduits running into wet well shall have a positive seal in accordance with NFPA 70.
(g) SCADA.
(1) SCADA will be provided for all new pump stations.
(2) Type of system and monitored conditions shall be consistent with the existing system in use by the city at the time the new pump station is constructed.
(3) Design of the system shall be closely coordinated with the city.
(h) Portable hoist.
(1) Provide one galvanized or stainless steel portable host at each pump station with reach as required for the safe removal of each pump.
(2) Hoist shall have a capacity of 150% of equipment weight and capable of 360 degree rotation.
(3) Hoist shall have winch with quick disconnect cable anchor for receiving stainless cable with swagged ball end.
(4) Electric winch shall be provided on hoist.
(5) Provide lifting cable for each pump. Lifting cable shall be stainless steel with snap hook on pump end and swagged ball on winch end. Cable shall have sufficient length to reach from installed equipment to lifting winch.
(6) Provide number of floor mounted stainless steel sockets at each pump station as required for the removal of the equipment.
(7) Portable hoist shall be as manufactured by Halliday Products, Them Inc., or Wallace B E Products.
(i) Pressure gauges.
(1) Pressure gauges shall meet the following requirements:
a. Use. Pressure reading for sanitary sewer force main.
b. Liquid fill. Glycern.
c. Dial. White aluminum with black markings.
d. Dial size. Four-inch minimum
e. Case & ring. Aluminum.
f. Accuracy. One-half percent (.5%%) of full scale (Grade 2A).
g. Stem connection. Back.
h. Gauge reading. Combination reading in psi and feet of water (ft) with range as appropriate for system pressure.
i. Equipped with a stopcock and a diaphragm isolator for use with sewage.
j. Mounted on piping in the valve box. Provide accessories as necessary so gauge shall face up with numbers reading towards access hatch.
(2) Provide a 1/4-inch tap on each effluent pipe for pressure gauge.
(j) Pre-cast concrete wet well and valve vault.
(1) Pre-cast concrete wet wells and valve vaults shall be in conformance with the requirement for pre-cast concrete manholes with the following exceptions:
a. Tops shall be flat.
b. Tops of wet wells and valve vaults shall be a minimum of two feet above the 100-year flood elevation.
c. Steps are not required.
d. Ring and covers shall be replaced with access hatches as described herein.
(k) Access hatch.
(1) Hatches shall be sized and located to facilitate the easy removal of pumps, motors, valves and other items from the wet wells and valve vaults. They shall meet the following requirements:
a. Frame shall be aluminum extrusion and aluminum checkered tread plate for the door(s). Frame shall be equipped with necessary anchors for setting in concrete. Hinges, nuts, bolts, and washers shall be stainless steel and tamper proof from outside.
b. Design and construct hatches for a minimum 310 lb. live load unless an H20 load is anticipated.
c. Provide the following:
1. Bituminous coating at locations which will have contact with concrete.
2. Waterproof hatch where required by the city.
3. Positive open door latch.
4. Retractable lifting handle.
5. Double doors shall be interlocked.
6. Padlocking provision. Provide lock for each hatch and keyed alike for multiple hatches.
7. Provide doors requiring greater than a 50 lb. lift with a stainless steel spring assist.
(2) Hatches shall be of one manufacturer.
(l) Safety net.
(1) Pump access hatches shall be provided with a rail mounted safety net system for fall through protection. The safety net shall be designed to slide on guide rails to facilitate entry and repositioning. Slide rails and hooks shall be constructed of aluminum with stainless steel corner hooks and eye bolts. Netting material shall be polyester. The safety net system shall be hatch net as manufactured by Safe Approach, Inc., or approved equal.
(m) Yard hydrant.
(1) Provide a non-freeze, self draining, post type yard hydrant with wheel handle operator. Interior parts and casing shall be bronze with cast aluminum casing guard. Seat washer shall be replaceable. Drain port shall be a minimum of 1/8-inch diameter. Hydrants shall have a 3/4-inch hose bib and a 3/4-inch inlet.
(n) Sign.
(1) Pump stations shall have a metal sign mounted on the fence at the gate to the pump station. Sign shall be a minimum of 18 inches square and white with blue lettering. Sign shall read “City of Claremont Wastewater Pump Station”, “Name” of Pump Station, Emergency Contact Phone Number.
(Ord. of 11-7-16, No. 10-16)