HomeMy WebLinkAboutLift Station Standard Policy
CITY OF PRIOR LAKE
SANITARY SEWER LIFT STATION
STANDARDIZATION POLICY
APRIL 7, 2003
TABLE OF CONTENTS
I. GENERAL........................................................................................................................... 1
IT. LIFT STATION TypES....................................................................................................... 1
ill. ELECTRICAL OPTIONS .......... .......................................................................................... 1
IV . START-UP AND TESTING............................................... ....... .......................................... 2
V. CONSTRUCTION AND CONSTRUCTION DOCUMENTATION.................................. 3
VI. LIFT STATION WARRANTy.......... ........................... ....................................................... 4
VIT. TYPE ONE LIFT STATION................................................. ............................................... 4
Vill. TYPE TWO LIFT STATION........... ...... ........... ........................................................... ...... 14
IX. TYPE THREE LIFT STATION.........................................................................................23
Sheet No.1.................................................................................................................................... .34
Sheet No.2................................................................................................ .................................... .35
Sheet No.3... .............. .............................................. ......... ....... ..... .............................................. ...36
Sheet No.4.................................................................................................................................. ...3 7
Sheet No.5....................................................................................... ............................................ ..3 8
Sheet No.6.................................................................................................................................... .39
F: \ WPWIMl244-08IPrior Lake LS Standard. doc
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PRIOR LAKE SANITARY SEWER LIFT STATION
STANDARDIZATION POLICY
April 7, 2003
1. GENERAL
To provide for the standardization of all sanitary lift stations in the City, the City of Prior
Lake, Minnesota, has adopted the following general standards for the rehabilitation of
existing sanitary lift stations and the design and construction of future sanitary lift stations
within the City of Prior Lake.
The standardization of lift stations within the City will simplify operation and
maintenance of the -stations and will reduce the spare parts inventory that will be
necessary to keep on hand.
In order to provide uniformity and standardization, the City of Prior Lake will obtain the
following items for inclusion in the construction of new, and rehabilitation of existing, lift
stations:
· Pumps
· Pump Discharge Elbows
· Mini CAS (Control and Status) Monitoring Unit
· Pump Controller
· SCADA Equipment
II. LIFT STATION TYPES
The City has defined three different levels of sophistication that may be required for any
one lift station installation. The City of Prior Lake shall determine the level of
sophistication required for existing and proposed lift stations within the City of Prior
Lake, Minnesota.
Lift stations with pumps and discharge piping that cannot pass a 3-inch solid will be
provided with grinder pumps.
III. ELECTRICAL OPTIONS
The pump station electrical requirements, available utility voltages, and standby power
requirements must be identified prior to completing the lift station electrical design.
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The City will contact the serving electric utility to determine which service voltages are
available. Three-phase power is preferred to avoid the use of phase-converters,
capacitors, or variable frequency drives used as phase converters.
If there are utility charges to provide three-phase service, the City will obtain an estimate
of the charges from the serving utility, and prepare a cost comparison between a three-
phase installation and a single-phase installation.
Preferred three-phase service voltages:
· 277 /480V AC, three-phase, four-wire, grounded-wye
· 120/240V AC, three-phase, four-wire, delta with grounded center tap
· 120/208V AC, three-phase, four-wire, grounded-wye
Single-phase voltage:
· 120/240V AC, single-phase, three-wire, grounded center tap
For stations that require a connection for portable standby power, confirm the City's
ability to provide standby power in the required capacity at the desired voltage, using the
City's existing portable engine-generator sets.
Obtain information from the serving electric utility regarding available fault current at
each service voltage. The entire lift station electrical system and control panel shall be
designed to withstand the available fault current.
The final voltage selection shall be determined by City staff, based on a cost-benefit
comparison of available operating voltages.
IV. START-UP AND TESTING
A factory trained service representative shall be present at the time when the station is to
be put into service and turned over to the Owner. The service representative shall instruct
the Owner in the proper operation and maintenance of the equipment. The service
representative shall provide a minimum of eight (8) hours for field testing and training.
At the time of start up, the Contractor shall conduct the necessary pumping test to
determine the proper operation of the system. The Contractor shall furnish all meters,
equipment and water required for these tests and the tests shall be so conducted as to
check the operation of the pumping system. Necessary measurements ofthe electrical
consumption shall be made to determine whether or not the pump is operating within the
conditions recommended by the pump manufacturer. Perform a witnessed operational
test of all equipment. Confirm proper operation of all station features and functions.
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Record phase-to-phase and phase-to-ground voltages during no-load conditions and
during all pump operating conditions. Record pump motor phase currents during all
pump operating conditions. In the event that the tests show the equipment does not
comply with the specifications of the pump manufacturer, this shall be sufficient cause to
reject the pump. All tests therein required shall be supervised by the Engineer.
No "start ups" shall be scheduled for Fridays.
V. CONSTRUCTION AND CONSTRUCTION DOCUMENTATION
A. Submittals
1. Shop Drawings: Shop drawings shall be submitted for approval by the
Engineer. Submit the following as a minimum for review:
· Detailed specifications, dimensions, and weights of pumps,
hatches, valves, piping, manholes, and other appurtenances.
· Size and model number of pump and motor.
· Factory-certified pump curves for the specific pump to be
delivered.
· Detailed electrical data.
· Control drawings and data.
· Typical installation guide.
· Access hatch drawings.
· Technical manuals.
· Parts lists.
· Operation and maintenance manuals and data.
· Printed warranty for pumps and appurtenant equipment.
· Motor performance chart including curves for torque, current,
power factor, input/output kilowatts, and efficiency. Include data
on starting and no load characteristics.
· Certified factory performance test curves for each pump provided
shall be furnished and approved prior to shipment of the unit to the
site. Test curves shall cover the full range of operation from shut
off to maximum capacity including head capacity curve,
horsepower curve, wire to water efficiency, shut offhead, and
recommended operating range. Factory testing of all pump
equipment shall be made in accordance with the test code of the
Hydraulic Institute Standards. Pumping equipment that fails to
meet the specified requirements shall be replaced with pumping
equipment that does meet the specified requirements.
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B. As-Built Documentation
1. As-builts:
· Submit a complete set of drawings, documentation and
manufacturer's operation and maintenance instructions for the
project. Construction record drawings shall be updated to show
"as-built" conditions.
· Submit complete electrical schematics showing control panel "as-
built" conditions.
· Submit complete instrumentation and control "as-built"
information including ladder logic.
· All drawings shall be submitted in reproducible hard copy format
and in electronic format (either AutoCAD .DWG or Adobe .PDF
format).
VI. LIFT ST A nON WARRANTY
The Contractor shall warrant Contractor-supplied lift station components and Contractor's
work for twelve (12) months from final completion and written acceptance by the City of
Prior Lake.
VII. TYPE ONE LIFT STATION
A. General
A Type One Lift Station is a lift station with a lower level of sophistication. This
type lift station will utilize floats for pump control and will be provided with local
alarms. Remote communication will not be provided for this type lift station.
This type of lift station will be provided with one, two, or three pumps at the
City's discretion. Attached, please fmd drawings for two different Type One Lift
Stations. Sheet Nos. 1 and 2 are for larger non-grinder pump lift stations. Sheet
No.3 is for a smaller grinder pump lift station. Sheet No.4 provides details for
both non-grinder and grinder lift stations.
B. Wet Well and Valve Manhole
1. Materials of Construction: Main structure shall be reinforced concrete pipe
and/or reinforced concrete. All wet well hardware and fasteners shall be
stainless steel.
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2. Buovancy: Without justification using site specific soils and ground water
information, the wet well, wet well base slab, and wet well cover shall be
designed to overcome the buoyant forces on the lift station assuming a
ground water elevation at the surface, no soil interaction with the
structures, and a minimum safety factor of 1.10 based on the dead loads of
the concrete structure, excluding all equipment, hatches, piping, etc.
3. Structure Reinforcement: The concrete structure, including base slab and
wet well shall be designed and constructed to overcome the pressure
associated with minimum and maximum ground water elevations and a
structural safety factor which meets current industry standards. The top
slab shall be designed to handle AASHO H20 vehicle loads when structure
is located away from potential vehicle loads. The top slab shall be
designed at a minimum for AASHO H20S loads when the placement of
the lift station may allow vehicle loads (the City of Prior Lake shall make a
case by case determination of minimum needs. It is the City's intent to not
construct lift stations or valve manholes within roadways).
4. Hatch: A heavy duty aluminum access hatch shall be cast into the top slab
of the lift station and valve manhole. The hatch assembly shall include a
recessed padlock locking device, flush steel drop handle which does not
protrude above the cover and an automatic hold open arm with vinyl grip
on release handle and a stainless steel cable holder bracket (a cable holder
bracket will not be necessary on the hatch for the separate valve manhole).
Hatches will be equipped with a compression spring assist so that cover
will require no more than 30 pounds of force to open using lifting handle.
Hatches will have a removable "T" handle operated slam lock system with
a slam lock plug. A thick coat ofbitumastic coal-tar epoxy shall be
applied to the exterior of the hatch frame that will be in contact with the
concrete. The hatches shall be sized to allow removal of the pumps and
valves.
The hatch or hatches shall provide a clear opening for easy removal of
pump or pumps and all equipment, valves and piping to be located in the
wet well or valve manhole. A minimum of 2 inches of clearance will be
provided between the sides of the pumps and the hatch and a minimum of
6 inches clearance will be provided between the front ofthe pump (side of
pump away from guide rails) and the hatch, assuming the pumps are
brought straight up through the hatch following the guide rails which are
set to meet manufacturer's standards. Hatches in non-traffic areas shall
withstand AASHO H20 loads at a minimum. Hatches in traffic areas shall
withstand AASHO H20S loads, at a minimum. (The City of Prior Lake
shall make a case-by-case determination of minimum needs. It is the
City's intent to not construct lift stations or valve manholes within
roadways.) A "master" lock shall be provided for each hasp on the access
hatches keyed to City of Prior Lake specifications.
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Each hatch shall be provided with removable safety grating or retractable
safety netting. The City shall decide which safety system will be used on a
case-by-case basis.
5. Wet Well Size and Dimensions: The wet well dimensions and size shall
follow the recommendations of the most recent standards of the
Hydraulics Institute.
Wet well sizing shall maintain pump cycling at or below 10 starts per
hour.
The lower portion of the wet well shall be sloped to reduce solids
residence times within the station to reduce the potential for odors.
The high water alarm elevation shall be at least 6 inches below the invert
of the deepest influent pipe.
The low water alarm shall be above the pump manufacturer's minimum
operating water level, and above the top of the submersible pump and
motor unit.
Pump and wet well settings, including high water and low water alarms
and pump off and on settings, shall be separated by at least 1 foot in
elevation.
Oversize wet well to accommodate increase in flows should flow increases
be likely. Avoid odor production using sloped fillets and adjustable pump
on/off elevation settings.
Single pump installations should be avoided.
Provide a separate valve manhole for 3-inch diameter and larger discharge
pIpmg.
Wet well dimensions shall promote the use of standard pump sizes
wherever possible. Consult the City for a list of standard pump sizes.
6. Valve Manhole Size and Dimensions:
Provide a minimum of 9 inches of clear space between the valve manhole
structure and flanged or otherwise bolted fittings for ease of construction
and repair.
Provide adequate space for maintenance personnel to enter the valve vault
to repair or replace piping, valves, etc.
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See Drawing No. 1 for additional requirements.
C. Discharge Piping
1. Sizing: Discharge piping velocities shall be above 2.5 feet per second and
below 10 feet per second.
Acceptable discharge piping velocities may be lowered based on life cycle
costs calculated by the City.
2. Piping and Fitting Materials: Unless otherwise stated, ductile iron pipe
and fittings shall conform to the requirements of ANSI! A WW A
C151/A21.51 for 150 pound working pressure with flange or mechanical
joints. Flange joints shall conform to ANSI!A WW A CI15/A21.15, drilled
in accordance with ANSI B 16.1 Class 125. The weight, class, or nominal
thickness shall be shown on each pipe. All buried ductile iron pipe within
20 feet of lift station and valve manhole structure shall be a minimum of
Class 53.
Mechanical joint fittings shall conform to A WW A C 11 0/ ANSI A21.1 0
rated at 250 psi, or A WW A C 153/ ANSI A21.53 rated at 350 psi. Rubber
gaskets shall conform to A WWA C Ill.
All ductile iron pipe and fittings shall be lined with cement mortar in
accordance with ANSI!A WW A C104/A21A unless otherwise noted.
3. Special Fittings: Flanged coupling adapters shall be Dresser Style 227,
Smith Blair 912, or equal.
4. Check Valves: Swing check valves shall be of the outside lever and
weight type and meet the material requirements of A WW A C508. Check
valves shall have a 316 stainless steel hinge pin. The hinge pin shall
operate in bronze or babitte support bearings conforming to ASTM B 16.
The seat ring shall be bronze conforming to ASTM B62. Lever arms and
disc shall be keyed to the shaft.
When there is no flow through the line, the gate shall hang lightly against
the seat. The maximum permissible leakage shall be 1 fl. oz. per hour per
inch of nominal valve size.
Check valves shall be as manufactured by Clow Valve, Golden Anderson,
or approved equal.
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5. Gate Valves: Gate valves four (4) inches and larger shall be resilient
seated gate valves conforming to A WW A C509. Allowances shall be
made for material thickness associated with ductile iron valves.
D. Pumps and Guide Rails
1. Pump Type: Install City-furnished Flygt submersible, non-clog sewage
pumps and discharge elbows capable of passing a three-inch diameter
solid sphere.
If properly sized pumps and piping cannot pass a three-inch diameter solid
sphere, install City-furnished Flygt submersible grinder pumps and
discharge elbows.
2. Non-Grinder Pump Warranty: The pump manufacturer shall warrant the
total non-grinder submersible pumping package for eighteen (18) months
from the date of shipment, or for twelve (12) months from the date of
written acceptance by the City of Prior Lake, based on whichever date is
later. This total pumping package warranty will be a 100% not pro-rated
warranty. The total pumping package includes all pump components,
including bearings, power cables, etc. The major wear parts such as
mechanical seals, impeller, pump housing, wear rings, and ball bearings,
are pro-rated on a linear basis over a full five (5) years following the time
period stipulated previously in this paragraph.
3. Grinder Pump Warrantv: The pump manufacturer shall warrant the total
grinder submersible pumping package for twelve (12) months from the
date of shipment, or for twelve (12) months from the date of written
acceptance by the City of Prior Lake, based on whichever date is later.
This total pumping package warranty will be a 100% not pro-rated
warranty. The total pumping package includes all pump components,
including bearings, power cables, etc.
4. Pumps and Motors: Pumps shall be centrifugal, non-clog, solids handling,
submersible explosion proof wastewater type pumps capable of handling
raw unscreened wastewater. The entire pumping unit shall be explosion
proof. The pump casing shall have a centerline discharge equipped with
an automatic pipe coupling arrangement for ease of installation and piping
alignment. The pumps shall automatically connect to the discharge piping
when lowered into position. Sealing of the pump to the discharge piping
(discharge elbow) shall incorporate a watertight metal-to-metal contact
between machined surfaces. The pumps shall be equipped with stainless
steel chains long enough and strong enough to raise the pump for removal
and inspection. The pumps shall be easily removable by one operator with
a portable hoist for inspection or service, requiring no bolts, nuts, or other
fasteners to be removed for this purpose, and no need for personnel to
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enter the wet well. No portion of the pump shall bear directly on the sump
floor.
The pump volute, motor, and seal housing shall be high quality grey cast
iron, ASTM A-48, Class 35B. All external mating surfaces shall be
machined and Buna N Rubber o-ring sealed. All fasteners exposed to the
water shall be 304 stainless steel.
The pump impellers shall be double shrouded (non-grinder pumps) or
single shrouded (grinder pumps) non-clog type. The impeller shall be
dynamically balanced. The impeller shall be A 48 Class 35 B Cast Iron.
A wear ring system shall be installed to provide efficient sealing between
the volute and impeller. Replaceable metal wear rings shall have a Brinell
Hardness of200 or more.
The pump shafts shall be AISI Type 431 stainless steel. Pump shaft and
motor shaft shall be the same unit. Couplings will not be allowed.
The pump bearings shall have a B 1 0 bearing life of a minimum of 50,000
hours.
The pump shall be provided with an oil chamber for the shaft sealing
system. The drain and inspection plug, with positive anti-leak seal, shall
be easily accessible from the outside.
The pump shall have an electrode probe mounted in the seal chamber. The
probe shall be connected via submersible cable to the motor control center
to alarm a seal failure when liquid is sensed, including a light in the
control panel to notify the operator of a problem.
The pump shall have two mechanical seals mounted in tandem. Each seal
shall be held in contact with its own spring. The upper tandem set of seals
shall operate in an oil chamber located just below the stator housing. This
set shall contain tungsten-carbide rings (for non-grinder pumps) or carbon-
ceramic rings (for grinder pumps). This set of seals shall function as an
independent secondary barrier between the pumped liquid and the stator
housing. The lower of the tandem set of seals shall function as the primary
barrier between the pumped liquid and the stator housing. This set of seals
shall contain one stationary and one positively driven rotating, corrosion
resistant tungsten-carbide ring (for both non-grinder pumps and grinder
pumps).
The motor stator, rotor and bearings shall be mounted in a sealed
submersible housing. The stator windings shall have Class H or better
insulation. Motors shall be equipped with thermal overload protection
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capable of resetting automatically after cool-down. The motors shall also
be equipped with a seal leak detection and warning system that will be
connected to the motor control center to alarm a seal failure when liquid is
sensed, including a light in the control panel to notify the operator of a
problem.
The pump and motor shall be designed so that they may operate partially
or totally submerged in the water. The pump and motor shall be rated for
continuous duty.
Motors shall be sized so they are not loaded above full-load rating at any
point on the impeller operating curve. Operation in the motor "service
factor" range is not acceptable.
Minimum motor efficiency shall be designated by the City.
Motors shall be suitable for City-determined voltages, phases and hertz of
operating power at a City-specified maximum rpm.
Protect all pumping equipment metal surfaces in contact with pumpage,
other than stainless steel or brass, with a factory-applied spray coating of
acrylic dispersion zinc phosphate primer with a polyester resin paint finish.
The power cable shall be sized according to NEC and lCEA standards and
shall be of sufficient length to reach the control panel without any need for
splices. The use of junction boxes will require special consideration and
written authorization from the City of Prior Lake. The outer jacket of the
cable shall be oil resistant chloroprene rubber. The motor and cable shall
be capable of continuous submergence underwater without the loss of
watertight integrity to a depth of 65 feet.
5. Guide Rails: Lift stations shall be equipped with dual stainless steel guide
rails to guide the pump into proper alignment with the discharge elbow.
The guide rails shall extend from the discharge elbow to the upper guide
holder on the access door.
Guide rails shall be of full length single piece construction from the
factory. Field welded guide rails shall not be acceptable.
Guide rail supports shall be stainless steel.
The guide rail diameter and guide rail bracing spacing shall be as
recommended by the pump manufacturer. Intermediate guide rail braces
shall be stainless steel.
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All piping and bracing inside the wet well structure shall be stainless steel
with the exception of the discharge elbows and the ductile iron discharge
pIpmg.
E. Pump Control
1. Level control shall be accomplished using float switches and a pump
controller/alternator. Provide five float switches with the following
functions:
· High Level Alarm
· Start Lag Pump
· Start Lead Pump
· Stop Both Pumps
· Low Level AlarmlRedundant Stop
2. Float switches shall be non-mercury type. Provide intrinsically-safe
barrier relays on each float switch circuit.
3. Install City-furnished U.S. Filter Control Systems Model CB2D pump
controller/alternator. The front face ofthe pump controller/alternator shall
be extended thru the inner doors of the control panel for operator access.
F. Motor Starters / Variable Frequency Drives
1. Starters shall be NEMA-style, NEMA-rated for the application. Starters
shall have replaceable contacts and solid-state type adjustable overloads
that provide NEMA Class 10 protection for submersible pump motors.
2. Approved starter manufacturers:
· Allen-Bradley
· Square D Company
· Cutler- Hammer/Westinghouse
· General Electric
3. Where phase conversion equipment is needed to convert single-phase
utility power to three-phase power for pump motors, provide variable
frequency drives (VFDs) that are rated for single-phase input voltage by
the drive manufacturer. When VFDs are used, the control panel shall be
oversized to dissipate heat from the VFDs, and the panel shall be located
in an area that is not exposed to direct sunlight.
4. Approved VFD manufacturers:
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· Allen-Bradley
· Cutler- Hammer/Westinghouse
· ABB
G. Permanent Standby Power - (When required)
1. Engine-generator set shall be a diesel-powered unit with four-cycle
industrial diesel engine, double-wall base fuel tank, weatherproof housing,
silencer, battery, battery charger, alternator, control panel, silencer, and
related equipment.
2. Size the engine-generator set for continuous duty at peak flow conditions.
Provide fuel storage for 24 hours, minimum operation at continuous peak
station flow. Engine generator shall be sized to allow starting both pumps
at a duplex lift station and all three pumps at a triplex lift station.
3. Locate the unit on the project site, and provide adequate sound abatement
so that the installation complies with Minnesota Pollution Control Agency
(MPCA) noise rules.
4. Provide automatic transfer switch in the pump control panel, so that the
unit will automatically start and transfer upon loss of utility power, or
upon abnormal supply voltage conditions. Acceptable manufacturers:
· Automatic Switch Company (ASCD)
· General Electric / Zenith
5. Provide generator with an "Emergency Stop" push button located inside
the lockable housing. Do not provide generator switch on the outside of
the housing.
6. Acceptable permanent standby power generator manufacturers:
· Caterpillar
· Cummins/Onan
H. Portable Standby Power - (When required)
1. Provide Crouse-Hinds connector to match available connectors on the
City's existing portable generator sets. Select connector ampacity to match
the station service entrance amperage rating.
2. For stations where an existing connector exists, salvage and install the
existing connector on the new pump control panel if the connector is ofthe
required type.
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3. Provide main and standby circuit breakers with circuit breaker
manufacturer's "walking-beam interlock" to allow only one breaker to be
closed at a time.
I. Control Panel
1. Control panel enclosure shall be NEMA Type 3R, constructed of Type 304
or Type 316 stainless steel. The enclosure shall be low-profile, two-door
design, with stainless steel hinges, stainless steel three-point latch, and
stainless steel vault handle with padlock provisions. Control panel
enclosure shall be free-standing type with stainless steel supporting legs
and skirting secured with stainless steel tamperproofhardware.
2. Size the enclosure to accept all electrical equipment without
overcrowding, and in accordance with UL 508 requirements.
3. The completed panel shall bear UL labels in accordance with Minnesota
Board of Electricity requirements.
4. Control panel shall contain a voltage monitoring relay to protect motors
from operating during phase failure, phase reversal or undervoltage
conditions. For single-phase stations, the voltage monitoring relay shall
protect motors from operating during undervoltage conditions.
5. Provide front-panel components as required by equipment, and as
indicated on attached Sheet No.5. See attached Sheet No.5 for general
control panel layout requirements.
J. Outside Communication
1. Provide a 20" wide by 30" high by 10" deep space in the control panel for
the addition of SCADA equipment in the future. Communication
equipment will not be added at this time.
K. Spare Parts
1. A spare parts package shall be provided for each lift station. The spare
parts package shall contain the following items:
· One set of each, of upper and lower seals.
· Spare fuses and lamps, consisting of a minimum of 10% spare each
type used, or quantity six (6) of each type used, whichever is
greater.
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VIll. TYPE TWO LIFT STATION
A. General
A Type Two Lift Station is a lift station with a medium level of sophistication.
This type lift station will utilize floats for pump control and will be provided with
local alarms and simple remote communication. This type of lift station will be
provided with one, two, or three pumps at the City's discretion. Attached, please
find drawings for two different Type Two Lift Stations. Sheet Nos. 1 and 2 are
for a larger non-grinder pump lift station. Sheet No.3 is for a smaller grinder
pump lift station. Sheet No.4 provides details for both non-grinder and grinder
lift stations.
B. Wet Well and Valve Manhole
1. Materials of Construction: Main structure shall be reinforced concrete pipe
and/or reinforced concrete. All wet well hardware and fasteners shall be
stainless steel.
2. Buovancv: Without justification using site specific soils and ground water
information, the wet well, wet well base slab, and wet well cover shall be
designed to overcome the buoyant forces on the lift station assuming a
ground water elevation at the surface, no soil interaction with the
structures, and a minimum safety factor of 1.10 based on the dead loads of
the concrete structure, excluding all equipment, hatches, piping, etc.
3. Structure Reinforcement: The concrete structure, including base slab and
wet well shall be designed and constructed to overcome the pressure
associated with minimum and maximum ground water elevations and a
structural safety factor which meets current industry standards. The top
slab shall be designed to handle AASHO H20 vehicle loads when structure
is located away from potential vehicle loads. The top slab shall be
designed at a minimum for AASHO H20S loads when the placement of
the lift station may allow vehicle loads. (The City of Prior Lake shall
make a case-by-case determination of minimum needs. It is the City's
intent to not construct lift stations or valve manholes within roadways.)
4. Hatch: A heavy duty aluminum access hatch shall be cast into the top slab
of the lift station and valve manhole. The hatch assembly shall include a
recessed padlock locking device, flush steel drop handle which does not
protrude above the cover, and an automatic hold open arm with vinyl grip
on release handle and a stainless steel cable holder bracket (a cable holder
bracket will not be necessary on the hatch for the separate valve manhole).
Hatches will be equipped with a compression spring assist so that cover
will require no more than 30 pounds of force to open using lifting handle.
Hatches will have a removable "T" handle operated slam lock system with
Page 14
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a slam lock plug. A thick coat ofbitumastic coal-tar epoxy shall be
applied to the exterior of the hatch frame that will be in contact with the
concrete. The hatches shall be sized to allow removal of the pumps and
valves.
The hatch or hatches shall provide a clear opening for easy removal of
pump or pumps and all equipment, valves and piping to be located in the
wet well or valve manhole. A minimum of 2 inches of clearance will be
provided between the sides of the pumps and the hatch and a minimum of
6 inches clearance will be provided between the front of the pump (side of
pump away from guide rails) and the hatch, assuming the pumps are
brought straight up through the hatch following the guide rails which are
set to meet manufacturer's standards. Hatches in non-traffic areas shall
withstand AASHO H20 loads at a minimum. Hatches in traffic areas shall
withstand AASHO H20S loads, at a minimum. (The City of Prior Lake
shall make a case-by-case determination of minimum needs. It is the
City's intent to not construct lift stations or valve manholes within
roadways.) A "master" lock shall be provided for each hasp on the access
hatches keyed to City of Prior Lake specifications.
Each hatch shall be provided with removable safety grating or retractable
safety netting. The City shall decide which safety system will be used on a
case-by-case basis.
5. Wet Well Size and Dimensions: The wet well dimensions and size shall
follow the recommendations ofthe most recent standards of the
Hydraulics Institute.
Wet well sizing shall maintain pump cycling at or below 10 starts per
hour.
The lower portion of the wet well shall be sloped to reduce solids
residence times within the station to reduce the potential for odors.
The high water alarm elevation shall be at least 6 inches below the invert
of the deepest influent pipe.
The low water alarm shall be above the pump manufacturer's minimum
operating water level, and above the top of the submersible pump and
motor unit.
Pump and wet well settings, including high water and low water alarms
and pump off and on settings, shall be separated by at least I foot in
elevation.
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F: \ WP WIMI 244-08\Prior Lake LS Standard. doc
Oversize wet well to accommodate increase in flows should flow increases
be likely. Avoid odor production using sloped fillets and adjustable pump
on/off elevation settings.
Single pump installations should be avoided.
Provide a separate valve manhole for 3-inch diameter and larger discharge
plpmg.
Wet well dimensions shall promote the use of standard pump sizes
wherever possible. Consult the City for a list of standard pump sizes.
6. Valve Manhole Size and Dimensions:
Provide a minimum of 9 inches of clear space between the valve manhole
structure and flanged or otherwise bolted fittings for ease of construction
and repair.
Provide adequate space for maintenance personnel to enter the valve vault
to repair or replace piping, valves, etc.
See Drawing No. I for additional requirements.
C. Discharge Piping
1. Sizing: Discharge piping velocities shall be above 2.5 feet per second and
below 10 feet per second.
Acceptable discharge piping velocities may be lowered based on life cycle
costs calculated by the City.
2. Piping and Fitting Materials: Unless otherwise stated, ductile iron pipe
and fittings shall conform to the requirements of ANSI! A WW A
C1511A21.51 for 150 pound working pressure with flange or mechanical
joints. Flange joints shall conform to ANSI! A WW A C 115/ A21.15, drilled
in accordance with ANSI B 16.1 Class 125. The weight, class, or nominal
thickness shall be shown on each pipe. All buried ductile iron pipe within
20 feet of lift station and valve manhole structure shall be a minimum of
Class 53.
Mechanical joint fittings shall conform to A WW A ClIO/ANSI A21.10
rated at 250 psi, or A WW A CI53/ANSI A21.53 rated at 350 psi. Rubber
gaskets shall conform to A WW A C Ill.
All ductile iron pipe and fittings shall be lined with cement mortar in
accordance with ANSI! A WW A C 1 04/ A21A unless otherwise noted.
Page 16
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-~._'--_._---~,~~--"-~~_.~.,-,...._,---_.~_._--~._,-,_...,.,..._"._~-<._,.._-----.._--_...~-
3. Special Fittings: Flanged coupling adapters shall be Dresser Style 227,
Smith Blair 912, or equal.
4. Check Valves: Swing check valves shall be of the outside lever and
weight type and meet the material requirements of A WW A C508. Check
valves shall have a 316 stainless steel hinge pin. The hinge pin shall
operate in bronze or babitte support bearings conforming to ASTM B 16.
The seat ring shall be bronze conforming to ASTM B62. Lever arms and
disc shall be keyed to the shaft.
When there is no flow through the line, the gate shall hang lightly against
the seat. The maximum permissible leakage shall be 1 fl oz per hour per
inch of nominal valve size.
Check valves shall be as manufactured by Clow Valve, Golden Anderson,
or approved equal.
5. Gate Valves: Gate valves four (4) inches and larger shall be resilient
seated gate valves conforming to A WW A C509. Allowances shall be
made for material thickness associated with ductile iron valves.
D. Pumps and Guide Rails
1. Pump Tvpe: Install City-furnished Flygt submersible, non-clog sewage
pumps and discharge elbows capable of passing a three-inch diameter
solid sphere.
If properly sized pumps and piping cannot pass a three-inch diameter solid
sphere, install City-furnished Flygt submersible grinder pumps and
discharge elbows.
2. Non-Grinder Pump Warrantv: The pump manufacturer shall warrant the
total non-grinder submersible pumping package for eighteen (18) months
from the date of shipment, or for twelve (12) months from the date of
written acceptance by the City of Prior Lake, based on which date is later.
This total pumping package warranty will be a 100% not pro-rated
warranty. The total pumping package includes all pump components,
including bearings, power cables, etc. The major wear parts such as
mechanical seals, impeller, pump housing, wear rings, and ball bearings,
are pro-rated on a linear basis over a full five (5) years following the time
period stipulated previously in this paragraph.
3. Grinder Pump Warrantv: The pump manufacturer shall warrant the total
grinder submersible pumping package for twelve (12) months from the
date of shipment, or for twelve (12) months from the date of written
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acceptance by the City of Prior Lake, based on whichever date is later.
This total pumping package warranty will be a 100% not pro-rated
warranty. The total pumping package includes all pump components,
including bearings, power cables, etc.
4. Pumps and Motors: Pumps shall be centrifugal, non-clog, solids handling,
submersible explosion proof wastewater type pumps capable of handling
raw unscreened wastewater. The entire pumping unit shall be explosion
proof. The pump casing shall have a centerline discharge equipped with
an automatic pipe coupling arrangement for ease of installation and piping
alignment. The pumps shall automatically connect to the discharge piping
when lowered into position. Sealing of the pump to the discharge piping
(discharge elbow) shall incorporate a watertight metal-to-metal contact
between machined surfaces. The pumps shall be equipped with stainless
steel chains long enough and strong enough to raise the pump for removal
and inspection. The pumps shall be easily removable by one operator with
a portable hoist for inspection or service, requiring no bolts, nuts, or other
fasteners to be removed for this purpose, and no need for personnel to
enter the wet well. No portion of the pump shall bear directly on the sump
floor.
The pump volute, motor, and seal housing shall be high quality grey cast
iron, ASTM A-48, Class 35B. All external mating surfaces shall be
machined and Buna N Rubber o-ring sealed. All fasteners exposed to the
water shall be 304 stainless steel.
The pump impellers shall be double shrouded (non-grinder pumps) or
single shrouded (grinder pumps) non-clog type. The impeller shall be
dynamically balanced. The impeller shall be A 48 Class 35 B Cast Iron.
A wear ring system shall be installed to provide efficient sealing between
the volute and impeller. Replaceable metal wear rings shall have a Brinell
Hardness of 200 or more.
The pump shafts shall be AISI Type 431 stainless steel. Pump shaft and
motor shaft shall be the same unit. Couplings will not be allowed.
The pump bearings shall have a B 1 0 bearing life of a minimum of 50,000
hours.
The pump shall be provided with an oil chamber for the shaft sealing
system. The drain and inspection plug, with positive anti-leak seal, shall
be easily accessible from the outside.
The pump shall have an electrode probe mounted in the seal chamber. The
probe shall be connected via submersible cable to the motor control center
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to alarm a seal failure when liquid is sensed, including a light in the
control panel to notify the operator of a problem.
The pump shall have two mechanical seals mounted in tandem. Each seal
shall be held in contact with its own spring. The upper tandem set of seals
shall operate in an oil chamber located just below the stator housing. This
set shall contain tungsten-carbide rings (for non-grinder pumps) or carbon-
ceramic rings (for grinder pumps). This set of seals shall function as an
independent secondary barrier between the pumped liquid and the stator
housing. The lower of the tandem set of seals shall function as the primary
barrier between the pumped liquid and the stator housing. This set of seals
shall contain one stationary and one positively driven rotating, corrosion
resistant tungsten-carbide ring (for both non-grinder pumps and grinder
pumps).
The motor stator, rotor and bearings shall be mounted in a sealed
submersible housing. The stator windings shall have Class H or better
insulation. Motors shall be equipped with thermal overload protection
capable of resetting automatically after cool-down. The motors shall also
be equipped with a seal leak detection and warning system that will be
connected to the motor control center to alarm a seal failure when liquid is
sensed, including a light in the control panel to notify the operator of a
problem.
The pump and motor shall be designed so that they may operate partially
or totally submerged in the water. The pump and motor shall be rated for
continuous duty.
Motors shall be sized so they are not loaded above full-load rating at any
point on the impeller operating curve. Operation in the motor "service
factor" range is not acceptable.
Minimum motor efficiency shall be designated by the City.
Motors shall be suitable for City-determined voltages, phases and hertz of
operating power at a City-specified maximum rpm.
Protect all pumping equipment metal surfaces in contact with pumpage,
other than stainless steel or brass, with a factory-applied spray coating of
acrylic dispersion zinc phosphate primer with a polyester resin paint finish.
The power cable shall be sized according to NEC and lCEA standards and
shall beof sufficient length to reach the control panel without any need for
splices. The use of junction boxes will require special consideration and
written authorization from the City of Prior Lake. The outer jacket of the
cable shall be oil resistant chloroprene rubber. The motor and cable shall
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F:\WPWIM1244-08\Prior Lake LS Standard. doc
be capable of continuous submergence underwater without the loss of
watertight integrity to a depth of 65 feet.
5. Guide Rails: Lift stations shall be equipped with dual stainless steel guide
rails to guide the pump into proper alignment with the discharge elbow.
The guide rails shall extend from the discharge elbow to the upper guide
holder on the access door.
Guide rails shall be of full length single piece construction from the
factory. Field welded guide rails shall not be acceptable.
Guide rail supports shall be stainless steel.
The guide rail diameter and guide rail bracing spacing shall be as
recommended by the pump manufacturer. Intermediate guide rail braces
shall be stainless steel.
All piping and bracing inside the wet well structure shall be stainless steel
with the exception of the discharge elbows and the ductile iron discharge
pIpmg.
E. Pump Control
1. Level control shall be accomplished using float switches and a pump
controller/alternator. Provide five float switches with the following
functions:
· High Level Alarm
· Start Lag Pump
· Start Lead Pump
· Stop Both Pumps
· Low Level AlarmlRedundant Stop
2. Float switches shall be non-mercury type. Provide intrinsically-safe
barrier relays on each float switch circuit.
3. Install City-furnished U.S. Filter Control Systems Model CB2D pump
controller/alternator. The front face of the pump controller/alternator shall
be extended through the inner doors of the control panel for operator
access.
F. Motor Starters / Variable Frequency Drives
1. Starters shall be NEMA-style, NEMA-rated for the application. Starters
shall have replaceable contacts and solid-state type adjustable overloads
that provide NEMA Class 10 protection for submersible pump motors.
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F:\WPWIM1244-08\Prior Lake LS Standard. doc
2. Approved starter manufacturers:
· Allen-Bradley
· Square D Company
· Cutler- Hammer/Westinghouse
· General Electric
3. Where phase conversion equipment is needed to convert single-phase
utility power to three-phase power for pump motors, provide variable
frequency drives (VFDs) that are rated for single-phase input voltage by
the drive manufacturer. When VFDs are used, the control panel shall be
oversized to dissipate heat from the VFDs, and the panel shall be located
in an area that is not exposed to direct sunlight.
4. Approved VFD manufacturers:
· Allen-Bradley
· Cutler-Hammer/Westinghouse
· ABB
G. Permanent Standby Power - (When required)
1. Engine-generator set shall be a diesel-powered unit with four-cycle
industrial diesel engine, double-wall base fuel tank, weatherproof housing,
silencer, battery, battery charger, alternator, control panel, silencer, and
related equipment.
2. Size the engine-generator set for continuous duty at peak flow conditions.
Provide fuel storage for 24 hours, minimum operation at continuous peak
station flow. Engine generator shall be sized to allow starting both pumps
at a duplex lift station and all three pumps at a triplex lift station.
3. Locate the unit on the project site, and provide adequate sound abatement
so that the installation complies with Minnesota Pollution Control Agency
(MPCA) noise rules.
4. Provide automatic transfer switch in the pump control panel, so that the
unit will automatically start and transfer upon loss of utility power, or
upon abnormal supply voltage conditions. Acceptable manufacturers:
· Automatic Switch Company (ASCD)
· General Electric / Zenith
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F:\WPWIM1244-08\Prior Lake LS Standard. doc
5. Provide generator with "Emergency Stop" push button located inside the
lockable housing. Do not provide a shutdown switch on the outside of the
housing.
6. Acceptable permanent standby power generator manufacturers:
· Caterpillar
· Cummins/Onan
H. Portable Standby Power - (When required)
1. Provide Crouse-Hinds connector to match available connectors on the
City's existing portable generator sets. Select connector ampacity to match
the station service entrance amperage rating.
2. For stations where an existing connector exists, salvage and install the
existing connector on the new pump control panel if the connector is of the
required type.
3. Provide main and standby circuit breakers with circuit breaker
manufacturer's "walking-beam interlock" to allow only one breaker to be
closed at a time.
I. Control Panel
1. Control panel enclosure shall be NEMA Type 3R, constructed of Type 304
or Type 316 stainless steel. The enclosure shall be low-profile, two-door
design, with stainless steel hinges, stainless steel three-point latch, and
stainless steel vault handle with padlock provisions. Control panel
enclosure shall be free-standing type with stainless steel supporting legs
and skirting secured with stainless steel tamperproofhardware.
2. Size the enclosure to accept all electrical equipment without
overcrowding, and in accordance with UL 508 requirements.
3. The completed panel shall bear UL labels in accordance with Minnesota
Board of Electricity requirements.
4. Control panel shall contain a voltage monitoring relay to protect motors
from operating during phase failure, phase reversal or undervoltage
conditions. For single-phase stations, the voltage monitoring relay shall
protect motors from operating during undervoltage conditions.
5. Provide front-panel components as required by equipment, and as
indicated on attached Sheet No.5. See attached Sheet No.5 for general
control panel layout requirements.
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J. Outside Communication
1. Provide an 8-channel Sensaphone automatic telephone dialer and standard
telephone service to alert operators of station alann conditions. Alann
dialer channels shall be wired as follows:
a. Channell - Wetwell High Level Alarm
b. Channel 2 - Wetwell Low Level Alarm
c. Channel 3 - Power Failure / Phase Failure
d. Channel 4 - Pump No. 1 Alarm
e. Channel 5 - Pump No.2 Alarm
f. Channel 6 - Pump No.3 Alarm (if applicable)
g. Channel 7 - (Spare)
h. Channel 8 - (Spare)
2. Provide a 20" wide by 30" high by 10" deep space in the control panel for
the addition of SCADA equipment in the future. The space taken up by
the communication device in Item #1 directly above can be a part ofthis
space requirement for future SCADA.
K. Spare Parts
1. A spare parts package shall be provided for each lift station. The spare
parts package shall contain the following items:
· One set of each, upper and lower seals.
· Spare fuses and lamps, consisting of a minimum of 10% spare each
type used, or quantity six (6) of each type used, whichever is
greater.
IX. TYPE THREE LIFT STATION
A. General
A Type Three Lift Station is a lift station with a high level of sophistication. This
type lift station will utilize a submersible transducer for pump control, with a float
switch back-up system, and will be provided with full SCADA outside
communication. This type of lift station will be provided with one, two, or three
pumps at the City's discretion. Attached, please find drawings for two different
Type Three Lift Stations. Sheet Nos. 1 and 2 are for a larger non-grinder pump
lift station. Sheet No.3 is for a smaller grinder pump lift station. Sheet No.4
provides details for both non-grinder and grinder lift stations.
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B. Wet Well and Valve Manhole
1. Materials of Construction: Main structure shall be reinforced concrete pipe
arid/or reinforced concrete. All wet well hardware and fasteners shall be
stainless steel.
2. Buoyancy: Without justification using site-specific soils and ground water
information, the wet well, wet well base slab, and wet well cover shall be
designed to overcome the buoyant forces on the lift station assuming a
ground water elevation at the surface, no soil interaction with the
structures, and a minimum safety factor of 1.10 based on the dead loads of
the concrete structure, excluding all equipment, hatches, piping, etc.
3. Structure Reinforcement: The concrete structure, including base slab and
wet well, shall be designed and constructed to overcome the pressure
associated with minimum and maximum ground water elevations and a
structural safety factor which meets current industry standards. The top
slab shall be designed to handle AASHO H20 vehicle loads when structure
is located away from potential vehicle loads. The top slab shall be
designed at a minimum for AASHO H20S loads when the placement of
the lift station may allow vehicle loads. (The City of Prior Lake shall
make a case-by-case determination of minimum needs. It is the City's
intent to not construct lift stations or valve manholes within roadways.)
4. Hatch: A heavy duty aluminum access hatch shall be cast into the top slab
of the lift station and valve manhole. The hatch assembly shall include a
recessed padlock locking device, flush steel drop handle which does not
protrude above the cover and an automatic hold open arm with vinyl grip
on release handle and a stainless steel cable holder bracket (a cable holder
bracket will not be necessary on the hatch for the separate valve manhole).
Hatches will be equipped with a compression spring assist so that cover
will require no more than 30 pounds of force to open using lifting handle.
Hatches will have a removable "T" handle operated slam lock system with
a slam lock plug. A thick coat ofbitumastic coal-tar epoxy shall be
applied to the exterior of the hatch frame that will be in contact with the
concrete. The hatches shall be sized to allow removal of the pumps and
valves.
The hatch or hatches shall provide a clear opening for easy removal of
pump or pumps and all equipment, valves and piping to be located in the
wet well or valve manhole. A minimum of2 inches of clearance will be
provided between the sides of the pumps and the hatch and a minimum of
6 inches clearance will be provided between the front ofthe pump (side of
pump away from guide rails) and the hatch, assuming the pumps are
brought straight up through the hatch following the guide rails which are
Page 24
F: \ WP WIM1 244-08\Prior Lake LS Standard. doc
set to meet manufacturer's standards. Hatches in non-traffic areas shall
withstand AASHO H20 loads at a minimum. Hatches in traffic areas shall
withstand AASHO H20S loads, at a minimum. (The City of Prior Lake
shall make a case-by-case determination of minimum needs. It is the
City's intent to not construct lift stations or valve manholes within
roadways.) A "master" lock shall be provided for each hasp on the access
hatches keyed to City of Prior Lake specifications.
Each hatch shall be provided with removable safety grating or retractable
safety netting. The City shall decide which safety system will be used on a
case-by-case basis.
5. Wet Well Size and Dimensions: The wet well dimensions and size shall
follow the recommendations of the most recent standards of the
Hydraulics Institute.
Wet well sizing shall maintain pump cycling below 10 starts and stops per
hour.
The lower portion of the wet well shall be sloped to reduce solids
residence times within the station to reduce the potential for odors.
The high water alarm elevation shall be at least 6 inches below the invert
of the deepest influent pipe.
The low water alarm shall be above the pump manufacturer's minimum
operating water level, and above the top of the submersible pump and
motor unit.
Pump and wet well settings, including high water and low water alarms
and pump off and on settings, shall be separated by at least 1 foot in
elevation.
Oversize wet well to accommodate increase in flows should flow increases
be likely. Avoid odor production using sloped fillets and adjustable pump
on/off elevation settings.
Single pump installations should be avoided.
Provide a separate valve manhole for 3-inch diameter and larger discharge
pIpmg.
Wet well dimensions shall promote the use of standard pump sizes
whenever possible. Consult the City for a list of standard pump sizes.
Page 25
F:\ WPWINI1 244-08\Prior Lake LS Standard. doc
6. Valve Manhole Size and Dimensions:
Provide a minimum of 9 inches of clear space between the valve manhole
structure and flanged or otherwise bolted fittings for ease of construction
and repair.
Provide adequate space for maintenance personnel to enter the valve vault
to repair or replace piping, valves, etc.
See Drawing No.1 for additional requirements.
C. Discharge Piping
1. Sizing: Discharge piping velocities shall be above 2.5 feet per second and
below 10 feet per second.
Acceptable discharge piping velocities may be lowered based on life cycle
costs calculated by the City.
2. Piping and Fitting Materials: Unless otherwise stated, ductile iron pipe
and fittings shall conform to the requirements of ANSI! A WW A
CI51/A21.51 for 150 pound working pressure with flange or mechanical
joints. Flange joints shall conform to ANSI! A WW A C 115/ All.15, drilled
in accordance with ANSI B 16.1 Class 125. The weight, class, or nominal
thickness shall be shown on each pipe. All buried ductile iron pipe within
20 feet of lift station and valve manhole structure shall be a minimum of
Class 53.
Mechanical joint fittings shall conform to A WW A C 11 0/ ANSI A21.1 0
rated at 250 psi, or A WW A C 153/ ANSI A21.53 rated at 350 psi. Rubber
gaskets shall conform to A WW A C 111.
All ductile iron pipe and fittings shall be lined with cement mortar in
accordance with ANSI! A WW A C 1 04/ AlIA unless otherwise noted.
3. Special Fittings: Flanged coupling adapters shall be Dresser Style 227,
Smith Blair 912, or equal.
4. Check Valves: Swing check valves shall be of the outside lever and
weight type and meet the material requirements of A WW A C508. Check
valves shall have a 316 stainless steel hinge pin. The hinge pin shall
operate in bronze or babitte support bearings conforming to ASTM B16.
The seat ring shall be bronze confonning to ASTM B62. Lever arms and
disc shall be keyed to the shaft.
Page 26
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When there is no flow through the line, the gate shall hang lightly against
the seat. The maximum permissible leakage shall be 1 fl. oz. per hour per
inch of nominal valve size.
Check valves shall be as manufactured by Clow Valve, Golden Anderson,
or approved equal.
5. Gate Valves: Gate valves four (4) inches and larger shall be resilient
seated gate valves conforming to A WW A C509. Allowances shall be
made for material thickness associated with ductile iron valves.
D. Pumps and Guide Rails
1. Pump Type: Install City-furnished Flygt submersible, non-clog sewage
pumps and discharge elbows capable of passing a three-inch diameter
solid sphere.
If properly sized pumps and piping cannot pass a three-inch diameter solid
sphere, install City-furnished Flygt submersible grinder pumps and
discharge elbows.
2. Non-Grinder Pump Warranty: The pump manufacturer shall warrant the
total non-grinder submersible pumping package for eighteen (18) months
from the date of shipment, or for twelve (12) months from the date of
written acceptance by the City of Prior Lake, based on which date is later.
This total pumping package warranty will be a 100% not pro-rated
warranty. The total pumping package includes all pump components,
including bearings, power cables, etc. The major wear parts such as
mechanical seals, impeller, pump housing, wear rings, and ball bearings,
are pro-rated on a linear basis over a full five (5) years following the time
period stipulated previously in this paragraph.
3. Grinder Pump Warrantv: The pump manufacturer shall warrant the total
grinder submersible pumping package for twelve (12) months from the
date of shipment, or for twelve (12) months from the date of written
acceptance by the City of Prior Lake, based on whichever date is later.
This total pumping package warranty will be a 100% not pro-rated
warranty. The total pumping package includes all pump components,
including bearings, power cables, etc.
4. Pumps and Motors: Pumps shall be centrifugal, non-clog, solids handling,
submersible explosion proof wastewater type pumps capable of handling
raw unscreened wastewater. The entire pumping unit shall be explosion
proof. The pump casing shall have a centerline discharge equipped with
an automatic pipe coupling arrangement for ease of installation and piping
alignment. The pumps shall automatically connect to the discharge piping
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F: IWPWlMl244-08IPrior Lake LS Standard. doc
when lowered into position. Sealing of the pumps to the discharge piping
(discharge elbow) shall incorporate a watertight metal-to-metal contact
between machined surfaces. The pumps shall be equipped with stainless
steel chains long enough and strong enough to raise the pump for removal
and inspection. The pumps shall be easily removable by one operator with
a portable hoist for inspection or service, requiring no bolts, nuts, or other
fasteners to be removed for this purpose, and no need for personnel to
enter the wet well. No portion of the pump shall bear directly on the sump
floor.
The pump volute, motor, and seal housing shall be high quality grey cast
iron, ASTM A-48, Class 35B. All external mating surfaces shall be
machined and Buna N Rubber o-ring sealed. All fasteners exposed to the
water shall be 304 stainless steel.
The pump impellers shall be double shrouded (non-grinder pumps) or
single shrouded (grinder pumps) non-clog type. The impeller shall be
dynamically balanced. The impeller shall be A 48 Class 35 B Cast Iron.
A wear ring system shall be installed to provide efficient sealing between
the volute and impeller. Replaceable metal wear rings shall have a Brinell
Hardness of 200 or more.
The pump shafts shall be AISI Type 431 stainless steel. Pump shaft and
motor shaft shall be the same unit. Couplings will not be allowed.
The pump bearings shall have a B 10 bearing life of a minimum of 50,000
hours.
The pump shall be provided with an oil chamber for the shaft sealing
system. The drain and inspection plug, with positive anti-leak seal, shall
be easily accessible from the outside.
The pump shall have an electrode probe mounted in the seal chamber. The
probe shall be connected via submersible cable to the motor control center
to alarm a seal failure when liquid is sensed, including a light in the
control panel to notify the operator of a problem.
The pump shall have two mechanical seals mounted in tandem. Each seal
shall be held in contact with its own spring. The upper tandem set of seals
shall operate in an oil chamber located just below the stator housing. This
set shall contain tungsten-carbide rings (for non-grinder pumps) or carbon-
ceramic rings (for grinder pumps). This set of seals shall function as an
independent secondary barrier between the pumped liquid and the stator
housing. The lower of the tandem set of seals shall function as the primary
barrier between the pumped liquid and the stator housing. This set of seals
Page 28
F:\WPWINlJ 244-08\Prior Lake LS Standard. doc
shall contain one stationary and one positively driven rotating, corrosion
resistant tungsten-carbide ring (for both non-grinder pumps and grinder
pumps).
The motor stator, rotor and bearings shall be mounted in a sealed
submersible housing. The stator windings shall have Class H or better
insulation. Motors shall be equipped with thermal overload protection
capable of resetting automatically after cool-down. The motors shall also
be equipped with a sea11eak detection and warning system that will be
connected to the motor control center to alarm a seal failure when liquid is
sensed, including a light in the control panel to notify the operator of a
problem.
The pump and motor shall be designed so that they may operate partially
or totally submerged in the water. The pump and motor shall be rated for
continuous duty.
Motors shall be sized so they are not loaded above full-load rating at any
point on the impeller operating curve. Operation in the motor "service
factor" range is not acceptable.
Minimum motor efficiency shall be designated by the City.
Motors shall be suitable for City-determined voltages, phases and hertz of
operating power at a City-specified maximum rpm.
Protect all pumping equipment metal surfaces in contact with pumpage,
other than stainless steel or brass, with a factory-applied spray coating of
acrylic dispersion zinc phosphate primer with a polyester resin paint finish.
The power cable shall be sized according to NEC and ICEA standards and
shall be of sufficient length to reach the control panel without any need for
splices. The use of junction boxes will require special consideration and
written authorization from the City of Prior Lake. The outer jacket ofthe
cable shall be oil resistant ch10roprene rubber. The motor and cable shall
be capable of continuous submergence underwater without the loss of
watertight integrity to a depth of 65 feet.
5. Guide Rails: Lift stations shall be equipped with dual stainless steel guide
rails to guide the pump into proper alignment with the discharge elbow.
The guide rails shall extend from the discharge elbow to the upper guide
holder on the access door.
Guide rails shall be of full length single piece construction from the
factory. Field welded guide rails shall not be acceptable.
Page 29
F:\WPWINll244-08\Prior Lake LS Standard. doc
Guide rail supports shall be stainless steel.
The guide rail diameter and guide rail bracing spacing shall be as
recommended by the pump manufacturer. Intermediate guide rail braces
shall be stainless steel.
All piping and bracing inside the wet well structure shall be stainless steel
with the exception of the discharge elbows and the ductile iron discharge
plpmg.
E. Pump Control
1. Level control shall be accomplished using a submersible pressure/level
transducer and solid-state pump controller/alternator. In addition, float
switches shall be provided as a backup system to the submersible
transducer and solid-state controller. The float switch backup circuitry
shall be independent of the primary level control circuitry for redundancy.
Provide two float switches with the following functions:
· High Level Alarm / Start Pumps
· Stop Pumps
2. Float switches shall be non-mercury type. Provide intrinsically-safe
barrier relays on each float switch circuit.
3. Install the following City-furnished equipment:
· U.S. Filter Control Systems Model D153 pump controller.
· U.S. Filter Control Systems Model AIOO submersible
pressure/level transducer.
· U.S. Filter Control Systems intrinsically-safe barriers.
· U.S. Filter Control Systems Model D153 pump
controller/alternator. The front face of the pump controller/
alternator shall be extended thru the inner doors of the control
panel for operator access.
F. Motor Starters / Variable Frequency Drives
1. Starters shall be NEMA-style, NEMA-rated for the application. Starters
shall have replaceable contacts and solid-state type adjustable overloads
that provide NEMA Class 10 protection for submersible pump motors.
2. Approved starter manufacturers:
· Allen- Bradley
· Square D Company
Page 30
F:\WPWlM1244-08\Prior Lake LS Standard. doc
· Cutler-Hammer/Westinghouse
· General Electric
3. Where phase conversion equipment is needed to convert single-phase
utility power to three-phase power for pump motors, provide variable
frequency drives (VFDs) that are rated for single-phase input voltage by
the drive manufacturer. When VFDs are used, the control panel shall be
oversized to dissipate heat from the VFDs, and the panel shall be located
in an area that is not exposed to direct sunlight.
4. Approved VFD manufacturers:
· Allen-Bradley
· Cutler- Hammer/Westinghouse
· ABB
G. Permanent Standby Power - (When required)
1. Engine-generator set shall be a diesel-powered unit with four-cycle
industrial diesel engine, double-wall base fuel tank, weatherproof housing,
silencer, battery, battery charger, alternator, control panel, silencer, and
related equipment.
2. Size the engine-generator set for continuous duty at peak flow conditions.
Provide fuel storage for 24 hours, minimum operation at continuous peak
station flow. Engine generator shall be sized to allow starting both pumps
at a duplex lift station and all three pumps at a triplex lift station.
3. Locate the unit on the project site, and provide adequate sound abatement
so that the installation complies with Minnesota Pollution Control Agency
(MPCA) noise rules.
4. Provide automatic transfer switch in the pump control panel, so that the
unit will automatically start and transfer upon loss of utility power, or
upon abnormal supply voltage conditions. Acceptable manufacturers: .
· Automatic Switch Company (ASCO)
· General Electric / Zenith
5. Provide generator with an "Emergency Stop" push button located inside
the lockable housing. Do not provide a shutdown switch on the outside of
the housing.
Page 31
F:\WPWIMI244-08\Prior Lake LS Slandard.doc
6. Acceptable permanent standby power generator manufacturers:
· Caterpillar
· Cummins/Onan
H. Portable Standby Power - (When required)
1. Provide Crouse-Hinds connector to match available connectors on the
City's existing portable generator sets. Select connector ampacity to match
the station service entrance amperage rating.
2. For stations where an existing connector exists, salvage and install the
existing connector on the new pump control panel if the connector is of the
required type.
3. Provide main and standby circuit breakers with circuit breaker
manufacturer's "walking-beam interlock" to allow only one breaker to be
closed at a time.
1. Control Panel
1. Control panel enclosure shall be NEMA Type 3R, constructed of Type 304
or Type 316 stainless steel. The enclosure shall be low-profile, two-door
design, with stainless steel hinges, stainless steel three-point latch, and
stainless steel vault handle with padlock provisions. Control panel
enclosure shall be free-standing type with stainless steel supporting legs
and skirting secured with stainless steel tamperproofhardware.
2. Size the enclosure to accept all electrical equipment without
overcrowding, and in accordance with UL 508 requirements.
3. The completed panel shall bear UL labels in accordance with Minnesota
Board of Electricity requirements.
4. Provide front-panel components as required by equipment, and as
indicated on attached Sheet No.6. See attached Sheet No.6 for general
control panel layout requirements.
J. Outside Communication
1. Outside communication shall be via an expansion of the City's existing
SCADA system. SCADA system expansion shall be constructed by
System Control Services, Inc., under separate contract directly with the
City.
2. SCADA system contact person:
Page 32
F: \ WPWlN\1244-08\Prior Lake LS Standard. doc
System Control Services, Inc.
Attn: Mr. Ron Smith
366 Prior Avenue North - Suite 206
Saint Paul, MN 55104
Phone: 651-647-9955
3. Provide 24" wide by 30" high by 10" deep unobstructed space within the
pump control panel for installation of the SCADA equipment by the
SCADA equipment supplier.
4. Provide the following signals wired to terminal strips for monitoring by
the SCADA system:
a. Wetwelllevel (4-20mA analog signal).
b. Wetwell High Level Alarm
c. Wetwell Low Level Alarm
d. Power Failure / Phase Failure
e. Pump No. 1 Alarm
f. Pump No.2 Alarm
g. Pump No.3 Alarm (if applicable)
h. Pump No. 1 Running
1. Pump No.2 Running
J. Pump No.3 Running (if applicable)
k. Control Panel Low Temperature Alarm
1. Control Panel High Temperature Alarm
m. Engine-Generator Running (if applicable)
n. Engine-Generator Alarm (if applicable)
K. Spare Parts
1. A spare parts package shall be provided for each lift station. The spare
parts package shall contain the following items:
· One set of each, upper and lower seals.
· Spare fuses and lamps, consisting of a minimum of 10% spare each
type used, or quantity six (6) of each type used, whichever is
greater.
Page 33
F:\WPWIM1244-08\Prior Lake LS Standard. doc
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