USACE / NAVFAC / AFCESA / NASA UFGS-44 42 23 (April 2006)
------------------------------
Preparing Activity: NAVFAC Replacing without change
UFGS-11338 (August 2006)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 44 42 23
CIRCULAR CLARIFIER
04/06
NOTE: This guide specification covers the requirements for circular clarifier
for use in sewage treatment plants.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
NOTE: This guide specification is for treatment of domestic sewage only. Special
consideration must be given to sewage containing industrial wastes.
NOTE: The following information shall be shown on the project drawings or provided
by the project designer:
1. Type of clarifier: primary or secondary
2. Dimensions of clarifier tank
3. Whether clarifier is of center feed/peripheral overflow type or peripheral
feed/center overflow type
4. Whether influent enters through side of tank or through center column when
clarifier is center feed/peripheral overflow type
5. Whether rapid sludge removal system is to be used and the number and size
of the sludge uptake pipes
6. Size of influent well when clarifier is center feed/peripheral overflow
type
7. Size and section of effluent trough when clarifier is peripheral feed/center
overflow type
8. Size and section of weirs and baffles; and anchorage details
9. Electrical characteristics for motor
10. Sizes of piping, points of connection to plant piping, and types of joints
for wall castings and sleeves
NAVFAC Definitive Designs, P-272, drawing number 1402886, "Primary and Final
Settling Tanks, Circular up to 11 m 35 Feet Diameter" and 1402887, "Primary
and Final Settling Tanks, Circular More Than 11 m 35 Feet Diameter" show the
general layout and arrangement of components and may be used as design guides.
This guide specification may be used to prepare specifications for either primary
or secondary clarifiers; where both are used on a project, a separate section
should be prepared for each type.
NOTE: Reliability and Maintainability (RAM) Data: A survey by the Naval Facilities
Engineering Service Center (NFESC) collected RAM data on 278 collectors at 134
plants nationwide. The report of survey contains general statistical data rating
manufacturers' equipment in terms of the average time of operation between breakdowns.
Information included in the report may be obtained by calling Dr. D. B. Chan,
DSN 551-4191, or commercial (805) 982-4191; or by writing to: Commanding Officer,
Naval Facilities Engineering Service Center, Code 411, 560 Center Drive, Port
Hueneme, CA 93043-4328.
PART 1 GENERAL
1.1 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
of the Section's Reference Article to automatically place the reference in the
Reference Article. Also use the Reference Wizard's Check Reference feature
to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
The publications listed below form a part of this specification to the extent referenced. The publications are
referred to within the text by the basic designation only.
[ALUMINUM ASSOCIATION (AA)AA DAF-45(2003) Designation System for Aluminum Finishes][AMERICAN BEARING MANUFACTURERS ASSOCIATION (ABMA)ABMA 11(1990; R 1999) Load Ratings and Fatigue Life for Roller BearingsABMA 9(1990; R 2000) Load Ratings and Fatigue Life for Ball Bearings][AMERICAN GEAR MANUFACTURERS ASSOCIATION (AGMA)AGMA 2009(2001b) Bevel Gear Classification, Tolerances and Measuring MethodsAGMA 2011(1998a) Cylindrical Wormgearing Tolerance and Inspection MethodsAGMA 2015/915-1(2002a) Supplement Tables - Accuracy Classification System - Tangential Measurement Tolerance Tables for Cylindrical GearsAGMA 6001(1997d; R 2003) Design and Selection of Components for Enclosed Gear DrivesAGMA 6013(2006) Standard for Industrial Enclosed Gear DrivesAGMA 6034(1992b; R 2005) Practice for Enclosed Cylindrical Wormgear Speed Reducers and GearmotorsAGMA 6113(2006) Standard for Industrial Enclosed Gear Drives (Metric Edition)AGMA 9000(1990c; R 2001) Flexible Couplings - Potential Unbalance ClassificationAGMA 9002(2004b) Bores and Keyways for Flexible Couplings (Inch Series)AGMA 908(1989b, R 1999) Information Sheet: Geometry Factors for Determining the Pitting Resistance and Bending Strength of Spur, Helical and Herringbone Gear Teeth][AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC)AISC 360(2005) Specification for Structural Steel Buildings, with Commentary][AMERICAN WATER WORKS ASSOCIATION (AWWA)AWWA C104/A21.4(2003) Cement-Mortar Lining for Ductile-Iron Pipe and Fittings for WaterAWWA C110/A21.10(2008) Ductile-Iron and Gray-Iron Fittings for WaterAWWA C111/A21.11(2000) Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and FittingsAWWA C115/A21.15(2005) Flanged Ductile-Iron Pipe With Ductile-Iron or Gray-Iron Threaded FlangesAWWA C151/A21.51(2002; Errata 2002) Ductile-Iron Pipe, Centrifugally Cast, for WaterAWWA C600(2005) Installation of Ductile-Iron Water Mains and Their Appurtenances][ASME INTERNATIONAL (ASME)ASME B17.1(1967; R 2008) Keys and KeyseatsASME B17.2(1967; R 2008) Woodruff Keys and KeyseatsASME B18.21.1(1999; R 2005) Lock Washers (Inch Series)ASME B18.21.2M(1999; R 2005) Lock Washers (Metric Series)ASME B18.22.1(1965; R 2008) Plain WashersASME B18.22M(1981; R 2005) Metric Plain WashersASME B29.100(2002; Errata 2004) Precision Power Transmission, Dbl-P-Power Transmission, Dbl-P-conveyor Roller Chains, Attachments and Sprockets][ASTM INTERNATIONAL (ASTM)ASTM A 153/A 153M(2005) Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel HardwareASTM A 325(2007a) Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile StrengthASTM A 325M(2008) Standard Specification for Structural Bolts, Steel, Heat Treated, 830 Mpa Minimum Tensile Strength (Metric)ASTM A 36/A 36M(2008) Standard Specification for Carbon Structural SteelASTM A 48/A 48M(2003; R 2008) Standard Specification for Gray Iron CastingsASTM A 53/A 53M(2007) Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and SeamlessASTM A 563(2007a) Standard Specification for Carbon and Alloy Steel NutsASTM A 563M(2007) Standard Specification for Carbon and Alloy Steel Nuts (Metric)ASTM B 209(2007) Standard Specification for Aluminum and Aluminum-Alloy Sheet and PlateASTM B 209M(2007) Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate (Metric)ASTM B 221(2008) Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and TubesASTM B 221M(2007) Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes (Metric)ASTM D 1784(2008) Standard Specification for Rigid Poly(Vinyl Chloride) (PVC) Compounds and Chlorinated Poly(Vinyl Chloride) (CPVC) CompoundsASTM D 2241(2005) Standard Specification for Poly(Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)ASTM D 256(2006e1) Determining the Izod Pendulum Impact Resistance of PlasticsASTM D 3034(2008) Standard Specification for Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and FittingsASTM D 635(2006) Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Self-Supporting Plastics in a Horizontal PositionASTM D 638(2008) Standard Test Method for Tensile Properties of PlasticsASTM E 84(2008a) Standard Test Method for Surface Burning Characteristics of Building MaterialsASTM F 593(2002; R 2008) Stainless Steel Bolts, Hex Cap Screws, and StudsASTM F 594(2008) Standard Specification for Stainless Steel Nuts][NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)NEMA ICS 1(2000; R 2005; R 2008) Standard for Industrial Control and Systems General RequirementsNEMA ICS 2(2000; Errata 2002; R 2005; Errata 2006) Standard for Industrial Control and Systems: Controllers, Contractors, and Overload Relays Rated Not More than 2000 Volts AC or 750 Volts DC: Part 8 - Disconnect Devices for Use in Industrial Control EquipmentNEMA MG 1(2007; Errata 2008) Standard for Motors and Generators][NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA 70(2007; AMD 1 2008) National Electrical Code - 2008 Edition][THE SOCIETY FOR PROTECTIVE COATINGS (SSPC)SSPC SP 10(2007) Near-White Blast Cleaning][U.S. DEPARTMENT OF DEFENSE (DOD)MIL-P-24441(Rev C; Supp 1; INT Am 1) Paint, Epoxy-Polyamide]1.2 DEFINITION
a. Year 2000 compliant - means computer controlled facility components that accurately process
date and time data (including, but not limited to, calculating, comparing, and sequencing) from,
into, and between the twentieth and twenty-first centuries, and the years 1999 and 2000 and
leap year calculations.
1.3 RELATED REQUIREMENTS
Section 23 03 00.00 20 BASIC MECHANICAL METARIALS AND METHODS, applies to this section, with the additions and
modifications specified herein.
1.4 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are [for Contractor Quality Control approval.][for information only. When used, a designation following the
"G" designation identifies the office that will review the submittal for the Government.] The following shall
be submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-02 Shop Drawings
Circular clarifier system
SD-03 Product Data
Clarifier mechanism
Grout Materials
Electrical control system
SD-07 Certificates
SD-08 Manufacturer's Instructions
Circular clarifier
SD-10 Operation and Maintenance Data
Circular clarifier, Data Package 3[; G][; G, [_____]]
Submit in accordance with Section 01 78 23 OPERATION AND MAINTENANCE DATA.
SD-11 Closeout Submittals
Posted operating instructions for motor and gear motor
1.5 DELIVERY, STORAGE, AND HANDLING
Equipment and parts shall be packaged for shipment to prevent breakage and damage to components. Deliver materials
to the site, inspect for damage, unload and store with a minimum of handling. Store materials off the ground
and under a weathertight covering.
1.6 MANUFACTURER'S REPRESENTATIVE
Furnish the service of the clarifier equipment manufacturer's representative or technician, experienced in installation
and operation of the type of systems being provided, to supervise the erection, start-up, acceptance tests, and
final inspection.
1.7 POSTED OPERATING INSTRUCTIONS
Provide, in accordance with Section 23 03 00.00 20 BASIC MECHANICAL MATERIALS AND METHODS.
1.8 WARRANTY
1.9 QUALITY ASSURANCE
1.9.1 Drawing Requirements
Show the complete assembly of the circular clarifier system with all components, mechanisms, and parts; each
with an assigned number corresponding to the equipment manufacturer's parts list. Show details for each component
of the clarifier mechanism including installation of piping, anchorage, wiring, and tank floor surfacing.
PART 2 PRODUCTS
2.1 CIRCULAR CLARIFIER, GENERAL
NOTE: The concrete section of the project specification should provide for
the clarifier tank to be constructed in accordance with Section 03 31 00.00
10, CAST-IN-PLACE STRUCTURAL CONCRETE, Section 03 30 00 CAST-IN-PLACE CONCRETE.
Concrete should be 25 MPa 3500 psi minimum 28-day compressive strength with
50 mm 2 inch maximum aggregate size and 22.70 liters 6 gallon per bag maximum
water-cement ratio. Walls should have smooth form finish. Floor should have
base slab poured to a minimum of 50 mm 2 inches below indicated finish elevation;
and then be given a screed finish followed by raking to roughen the surface.
NOTE: When center feed/peripheral overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
center column used as influent pipe, influent well, and (peripheral) weirs and
scum baffles.
NOTE: When peripheral feed/center overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
influent skirt, and effluent trough and weir assembly.
Clarifier equipment shall include clarifier mechanism [with effluent trough and weir assembly], [weirs and baffles,]
[influent skirt,] and piping. Structural steel shall conform to ASTM A 36/A 36M. Completely or intermittently
submerged steel members shall have a minimum thickness of 6 mm 1/4 inch. Cast iron shall conform toASTM A 48/A 48M
, Class 30 minimum.
2.2 CLARIFIER MECHANISM
NOTE: Delete requirements for and references to rapid sludge removal system
when this system is not included in the project.
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
NOTE: When center feed/peripheral overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
center column used as influent pipe, influent well, and (peripheral) weirs and
scum baffles.
NOTE: When peripheral feed/center overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
influent skirt, and effluent trough and weir assembly.
NOTE: Use first bracketed wording in the second sentence when rapid sludge
removal system is not included in the project; use second bracketed wording
in this sentence when rapid sludge removal system is included.
NOTE: Other items associated with the circular clarifier, but not covered in
this section, include (when used) valves, sluice gates, and perimeter handrail.
These items should be covered in the appropriate sections of the project specification.
Shall include sludge collector assembly [with rapid sludge removal system]; drive assembly; [supporting bridge
or] center column and access bridge; operating platform and access walkway thereto; influent [well] [skirt and
effluent trough and weir assembly]; scum removal assembly; overload protection and alarm; and electrical control
equipment. The drive shall rotate the sludge collector assembly, which shall be designed to [move settled sludge
to a centrally located sludge hopper] [concentrate settled sludge ahead of pipes for rapid sludge removal system].
Mechanism shall be so designed that there will be no chains, sprockets, bearings (except sleeve bearings when
used), or operating mechanism below the liquid surface or in contact with the liquid. The mechanism shall be
assembled in the shop to ensure proper fitting of parts, match-marked for erection, and disassembled for shipment.
2.2.1 Design
NOTE: Insert torque value(s) as follows: bridge-supported mechanisms for tanks
of 6-8.5 m 20-28 feet diameter, use 2,710 joules 2,000 foot-pounds; bridge-supported
mechanisms for tanks of 9-12 mm 30-40 feet diameter, use 5,420 joules 4,000
foot-pounds; bridge-supported mechanisms (peripheral feed/center overflow type
only) for tanks of 13-18 m 42-60 feet diameter, use 8,130 joules 6,000 foot-pounds
; center-column-supported mechanisms for tanks less than 16.8 mm 55 feet diameter,
use 27,100 joules 20,000 foot-pounds; center-column-supported mechanisms for
tanks 16.8 to 23 m 55 to 75 feetdiameter, use 40,650 joules 30,000 foot-pounds
.
This guide specification is written for one clarifier. If the project includes
more than one circular clarifier, all necessary pluralizations should be made
or use made of the word "each."
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
NOTE: Use peripheral speed of 0.04 to 0.06 meter per second 8 to 12 fpm for
primary clarifier, 0.035 to 0.05 meter per second 7 to 10 fpm for secondary
clarifier.
NOTE: Use recommended values from NAVFAC Design Manual DM-2.2, Structural Engineering
Loads, for wind load and ice load.
Clarifier mechanism shall be designed to have a minimum continuous output torque rating of [_____] joules foot-pounds
[for center-column-supported units and [_____] joules foot-pounds for bridge-supported units] with the scraper
arms rotating at a constant speed which will produce a peripheral speed of [_____] meter per second fpm. Clarifier
mechanism and its component parts shall be designed, with a safety factor of 2.5, to withstand all structural
and mechanical stresses brought about by the following loadings: continuous output rated torque load; dead load;
wind load of [_____]; ice load of [_____] (except on scum skimmer); and a live load of 2.5 kPa 50 psf on the
access bridge [or on access section of supporting bridge]. Under maximum load, deflection of access bridge shall
not exceed 1/240 of span [; deflection of supporting bridge shall not exceed 1/360 span]. Clarifier mechanism
shall be designed for continuous 24-hour service under design load without excessive wear, damage, or failure.
Stresses developed under aforementioned operating conditions and loads shall not exceed stresses allowed under
AISC 360.
2.2.2 Sludge Collector Assembly
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
NOTE: Delete requirements for and references to rapid sludge removal system
when this system is not included in the project.
Shall include scraper arms, scraper blades, [and] center drive cage/drum [or center shaft] [, and rapid sludge
removal system].
2.2.2.1 Scraper Arms
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
NOTE: Use first bracketed wording in the second sentence when rapid sludge
removal system is not included in the project; use second bracketed wording
in this sentence when rapid sludge removal system is included.
NOTE: Fiberglass reinforced plastic grating squeegees, weirs and baffles are
available but require special consideration for anchorage and expansion. Fiberglass
reinforced plastic may be allowed as an optional material provided that the
necessary requirements for anchorage of these items, including provision for
expansion and contraction, are incorporated in the project specification or
shown on the project drawings.
Shall be fabricated of structural steel, using welded truss construction of triangular or box section [; or shall
be structural steel shapes or closed end pile supported either by steel guy-rods or steel tie-rods or both].
Steel scraper blades, with attached squeegees, shall be welded or bolted to underside of scraper arms and shall
be designed to [move settled sludge to a centrally located sludge hopper] [concentrate settled sludge ahead of
pipes for rapid sludge removal system]. Scraper arms shall be connected to [center shaft or] center drive cage/drum
by bolted or welded connections. Scraper blades shall be steel plate having a minimum thickness of 6 mm 1/4 inch
. Squeegees shall be of bronze [, fiberglass reinforced plastic,] or stainless steel having a minimum thickness
of 3 mm 1/8 inch [for metal, 6 mm 1/4 inch for fiberglass reinforced plastic], and shall be connected to scraper
blades with bronze or stainless steel bolts and nuts with provision for vertical adjustment of not less than
50 mm 2 inches.
2.2.2.2 Center Drive Cage/Drum
Shall be fabricated of structural steel, using box truss or cylindrical drum construction. Center drive cage/drum
shall be connected to drive assembly with machine screws or by a bolted connection.
2.2.2.3 Center Shaft
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/ center overflow type clarifier is
larger than 18 m 60 feet in diameter, delete requirements for and references
to bridge-supported clarifier mechanisms and those components peculiar thereto,
including support bridge, center shaft, and scraper arms of structural shapes.
Shall be a solid steel shaft or steel pipe conforming to ASTM A 53/A 53M, Schedule 40. Steel pipe shall have
solid shaft stub ends or machined flange at top and steel cap at bottom.
2.2.2.4 Rapid Sludge Removal System
NOTE: Delete requirements for and references to rapid sludge removal system
when this system is not included in the project.
Rapid sludge removal system shall include [_____] mm inch diameter sludge uptake pipes of PVC 1120 or PVC 1220
conforming to ASTM D 1784, ASTM D 3034, SDR 35 or ASTM D 2241, SDR-26, attached to the scraper arms and arranged
so that the flow from each can be observed, adjusted, and sampled in the sludge well. Lower end of the uptake
pipes shall be attached to scraper arms with steel clamps or O-ring fittings. Uptake pipe system shall include
all necessary intermediate clamps and supports and shall terminate in a suitable fitting or flexible coupling
in sludge well. Discharge end of each uptake pipe shall be provided with an adjustable slip tube or orifice control
gate to permit flow adjustment. Sludge well shall be of structural steel plate having a minimum thickness of
6 mm 1/4 inch and shall include a stationary and rotating section separated by a chloroprene seal.
2.2.3 Drive Assembly
NOTE: Delete reference to chain drives when clarifier tank is more than 12
m 40 feet in diameter. Check with manufacturer.
Shall include motor, speed reduction and turntable gearing, turntable bearing assembly, drive assembly bearings,
and belt drives [or chain drives, or both]. Design of drive assembly shall be such as to permit sustained operation
at the continuous output torque rating without excessive wear and to develop twice the continuous output torque
rating without damage to or failure of drive assembly components.
2.2.3.1 Motor
NOTE: Use first bracketed wording when considered necessary to specify minimum
wattage horsepower; otherwise, use second bracketed wording (adequate motor).
NOTE: Delete reference to chain drives when clarifier tank is more than 12
m 40 feet in diameter. Check with manufacturer.
Motor shall be constant speed, totally-enclosed, fan-cooled, horizontal vertical type, suitable for outdoor service,
and conforming to NEMA MG 1. Motor wattage horsepower shall be [_____] [watts minimum] [HP minimum] [adequate
to drive the sludge collector assembly continuously at the maximum load encountered under any operating condition
without overloading or exceeding the nameplate rating of the motor.] Motor shall be suitable for operation on
[_____] volt, [_____] phase, [_____] hertz service. Motor shall be protected against overload, low voltage,
and unbalanced voltage. Motor shall provide the starting torque needed to move sludge collector assembly from
a dead stop in a dewatered clarifier tank as well as torque needed to move it from a dead stop under the maximum
loading specified in paragraph entitled "Design," without overloading. Motor shall be close-coupled to or on
input shaft of primary speed reducer; or shall drive speed reducer by a belt [or chain drive]. Flexible coupling
for connecting shafts of close-coupled motor and speed reducer shall conform to the applicable requirements of
AGMA 9002, and AGMA 9000. Motor position shall be adjustable to increase or decrease belt [or chain] tension.
2.2.3.2 Speed Reduction and Turntable Gearing
NOTE: Delete references relating to pinion-and-spur-gear reduction unit and
intermediate speed reducer when clarifier tank is less than 11 m 35 feet in
diameter.
NOTE: Delete reference to worm-gear reduction unit when clarifier tank is more
than 11 m 35 feet in diameter.
Speed reduction and turntable gearing for primary [and intermediate] speed reducer[s] shall be worm or helical
or a combination thereof. Gearing for turntable shall be [a worm gear reduction unit] [or] [a pinion-and-spur-gear
reduction unit]. Speed reduction and turntable gearing shall be designed with a AGMA service factor as recommended
in the applicable AGMA Standards AGMA 6113 AGMA 6013, AGMA 6034 or when drive is operating at full load motor
wattage horsepower, 24 hours a day continuous running. Gearing shall be designed to withstand any loadings
produced by thrust, out-of-balance, and vibration resulting from operating conditions and shall operate from
zero rpm to a speed consistent with the maximum peripheral speed specified in paragraph entitled "Design." All
component parts of the speed reduction and turntable gearing shall be designed to permit sustained operation
at the continuous output torque rating for the life expectancy specified without excessive wear and to develop
twice the continuous output torque without damage to or failure of any component part. Gears shall conform to
applicable requirements of the following AGMA Standards (AGMA 908, AGMA 2009, AGMA 2011, AGMA 6034, AGMA 2015/915-1
). Gears for primary [and intermediate] reducer[s] shall be not less than AGMA Quality 10, AGMA 2015/915-1,
AGMA 2009, AGMA 2011, or AGMA 6113 AGMA 6013. Gears for turntable shall be not less than AGMA Quality 6, AGMA 2009
, AGMA 2011. Gears shall be certified as meeting the specified quality. Worm gears shall be of cast bronze
or shall have bronze rim with inner portion of cast steel or nodular cast iron. Worms shall be of hardened ground
alloy steel or high-test heat-treated nodular cast iron. Helical gears shall be of cast or forged alloy steel;
helical angle shall not exceed 0.31 rad 18 degrees. Spur gear shall be internal or external; shall be of cast
iron, nodular cast iron, heat treated cast alloy steel, or heat-treated forged steel; and shall have an endurance
and strength rating of 1,000,000 cycles. Spur gear teeth shall be hardened by the through-hardening, contour-induction-hardening,
nitriding, or carburizing processes; flame-hardened gears will not be acceptable. Shafts, bolting, and keys for
gears shall conform to AGMA 6001; shafts shall be of structural steel. An oil or grease lubrication system shall
be provided for speed reduction gearing. Bath lubrication using oil seals for containment or lubrication systems
which rely upon an oil circulating pump shall include means to stop drive motor in event of insufficient lubrication.
Pressure indicating devices influenced by oil sludge or changes in oil viscosity will not be acceptable. Speed
reduction and turntable gearing shall be fully enclosed in cast iron or fabricated steel housings provided with
dust and oil seals. [Mating surfaces of turntable and intermediate gear reducer housing shall be machined in
such manner and to such tolerances that accurate alignment of the pinion will be assured.]
2.2.3.3 Gearmotor
Gearmotor, where practicable, may be used in lieu of separate motor and primary speed reducer. Motor component
of gearmotor shall be as specified in paragraph entitled "Motor." Speed reducing component of gearmotor shall
conform to the applicable requirements specified in paragraph entitled "Speed Reduction and Turntable Gearing,"
and in AGMA 6113 AGMA 6013 and AGMA 6034.
2.2.3.4 Turntable Bearing Assembly
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
Turntable bearing assembly shall include the turntable bearings upon which the turntable and attached sludge
collector assembly are supported; the turntable; and the drive assembly/turntable support base. Assembly shall
be designed for all radial and axial loads imposed by drive assembly and sludge collector assembly. Arrangement
of component parts shall permit replacement of balls or rollers, or the bearing raceways, or complete bearing
unit. Bearing raceway material shall have adequate strength to withstand all radial and axial loads and shall
have a Rockwell "C" hardness of not less than 58. Turntable bearing assembly [for a center-column-supported
clarifier mechanism] shall also be designed to support, where applicable, drive assembly, turntable, spur gear,
and one end of access bridge. [A bridge-supported clarifier mechanism may incorporate a submerged split-case,
water-lubricated bottom guide bearing or an intermediate steady bearing where manufacturer's design requires
use of such bearing in addition to turntable bearings.] A design incorporating a bottom support bearing will
not be acceptable. Bearing shall run in an oil bath or be grease-lubricated. Turntable and drive assembly/turntable
base shall be of cast iron, nodular cast iron, or steel; if of steel, these parts shall have sufficient thickness
to provide the rigidity necessary to maintain alignment of sludge collector assembly. Turntable shall be cast
integrally with spur gear or be fastened to the spur gear with machine screws or bolts.
2.2.3.5 Drive Assembly Bearings
Drive assembly bearings shall be ball or roller bearings having a minimum rated life expectancy (L10) as specified
in this paragraph when clarifier mechanism is operating continuously at torque rating specified in paragraph
entitled "Design." Load rating and fatigue life shall be based on ABMA 9 and ABMA 11, as applicable. Bearings
shall be either oil lubricated or grease lubricated.
Worm and primary helical gearbox bearings L10 100,000 hours
Gearmotor, direct drive L10 100,000 hours
NOTE: Delete references relating to pinion-and-spur-gear reduction unit and
intermediate speed reducer when clarifier tank is less than 11 m 35 feet in
diameter.
[Spur and intermediate helical gearbox bearings L10 17,000 hours]
Gearmotor, indirect drive L10 17,000 hours
2.2.3.6 Chain Drives and Belt Drives
NOTE: Delete reference to chain drives when clarifier tank is more than 12
m 40 feet in diameter. Check with manufacturer.
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
Belt drives [and chain drives] incorporated in drive assembly shall include V-belt-and-pulley [and chain-and-sprocket]
arrangements, except that belt drives shall not be used directly on the [center shaft or on the] center drive
cage/drum. Belt drives [and chain drives] shall be designed with a minimum safety factor of 4 as applied to
ultimate breaking or transmission strength of the belt [or chain] with respect to loads transmitted at twice
the continuous output torque rating of the clarifier mechanism. Belts shall be rayon corded with heat- and -oil-resistant
rubber covering. [Chain shall be roller type conforming to ASME B29.100 and shall have steel links. Sprockets
shall conform to ASME B29.100 and shall be of heat-treated ground alloy steel or of high-test cast iron conforming
toASTM A 48/A 48M, Class 40 minimum, cast in a chill mold; teeth bearing surfaces shall have a Brinell hardness
of not less than 360 and a minimum hardened zone depth of 5 mm 3/16 inch. Sprockets shall be stress relieved
before machining. Sprocket teeth shall be accurately ground to fit the chain.] Pulleys [, sprockets,] and other
motive power transmitting connections shall be key mounted. Drive pulley [or drive sprocket] on output shaft
of primary speed reducer shall be connected to shaft by a shear-pin hub arrangement designed to protect motor
against overload [; sprocket shall have a bronze bushing with grease lubrication]. Design of shear-pin hub arrangement
shall be such that it will not bind or freeze into position, preventing it from performing its intended function.
Machinery guards shall be fabricated of steel and weatherproof.
[2.2.4 Scum Removal Assembly
NOTE: Select the applicable paragraphs(s) from the following:
NOTE: When center feed/peripheral overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
center column used as influent pipe, influent well, and (peripheral) weirs and
scum baffles.
NOTE: In cold climates where ice build-up is a problem, require heated scum
trough and hinged or pivoting skimming blades in lieu of fixed blades.
Shall include skimmer assembly and [heated] scum trough. Skimmer assembly shall continuously move surface scum
to tank periphery and automatically flush the scum into scum trough. Assembly shall discharge scum with a minimum
discharge of water.
2.2.4.1 Skimmer Assembly
NOTE: In cold climates where ice build-up is a problem, require heated scum
trough and hinged or pivoting skimming blades in lieu of fixed blades.
NOTE: Delete references to and requirements for aluminum wherever a corrosion
problem with aluminum may be anticipated.
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
Skimmer assembly shall include a [fixed] [hinged or pivoting] skimming blade, a hinged or pivoting plow blade
with wiper blades, and support legs. Skimming blade shall be of structural steel and shall extend from influent
well to scum trough. Plow blade shall be structural steel [or aluminum], shall be the width of the scum trough,
and shall have grease- and oil-resistant chloroprene wiper blades securely clamped in position with a bronze
[or aluminum] backing plate. The plow blade and its hinged or pivoted connections shall be designed so as to
assure proper alignment and continuous contact between wiper blades, scum trough approach ramp, and scum baffle.
Plow blade shall have provision for field adjustment in the vertical plane. Suitable means shall be provided
to carry plow blade smoothly over the scum trough. Corrosion-resistant materials shall be used for moving parts
within the skimming assembly in such manner as to ensure that corrosion will not freeze joints, springs, and
other moving or adjustable parts into position. Blades shall be adequately supported from one scraper arm [or
by center shaft and a grooved roller on the scum baffle]; bracing shall be provided where necessary to maintain
rigidity of assembly. Support legs shall be of structural steel.
2.2.4.2 Scum Trough
Scum trough shall be welded structural steel, minimum thickness 6 mm 1/4 inch; shall have a flanged connection
for the scum discharge pipe; and shall be supported from the tank wall. The inclined approach ramp leading to
discharge section of scum trough shall be shaped to contain the scum as it is moved up the incline to the trough
by the plow blade.
NOTE: When peripheral feed/center overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
influent skirt, and effluent trough and weir assembly.
NOTE: In cold climates where ice build-up is a problem, require heated scum
trough and hinged or pivoting skimming blades in lieu of fixed blades.
a. Scum Removal Assembly: Shall include scum skimmer and [heated] scum trough. Scum skimmer
shall continuously move surface scum around influent raceway to scum trough.
b. Scum Skimmer: Scum skimmer shall include skimming blade and support leg[s] and shall be
mounted on the one scraper arm. Skimming blade and support leg[s] shall be of structural steel.
The skimming blade shall extend from clarifier tank wall to influent skirt. Scum skimmer shall
be hinged and counter weighted to provide for passing under scum trough, piping, and other obstructions
within clarifier tank. The skimming blade shall have provision for field adjustment in the
vertical plane.
c. Scum Trough: Scum trough shall be of the adjustable dipping weir type and shall include
collector pipe and operator. Scum trough shall be provided in peripheral raceway where indicated.
(1) Collector pipe shall be steel pipe conforming to ASTM A 53/A 53MSchedule 20 minimum. Pipe
shall have a 1.05 rad 60 degree wide slot cut symmetrically about the vertical axis, with the
horizontal edges of the slot parallel to the longitudinal axis of the pipe. At maximum intervals
of 750 mm 30 inches, a 50 mm 2 inch wide band of full circumference shall be left for stiffness.
The pipe shall be plugged on inboard end and open on effluent end. End supports shall include
a rolled steel collar welded to an adjustable steel end plate. A grease and oil-resistant,
watertight seal shall be provided, so constructed that it will allow smooth motion of the rotating
pipe; seal shall be readily renewable without removing pipe. End supports shall be secured
to concrete tanks walls by stainless steel anchor bolts of 16 mm 5/8 inch minimum diameter.
(2) Operator: A manual operating lever shall be mounted on the collector pipe. Lever shall
be steel pipe having a minimum diameter of 31 mm 1 1/4 inches and shall be secured to collector
pipe with a chain or bolted connection. Lever shall extend at least 0.91 m 3 feet above the
top of the tank wall and shall permit rotation of collector pipe at least 0.52 rad 30 degrees
each side of the vertical axis.
]2.2.5 Center Column
NOTE: When center feed/peripheral overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
center column used as influent pipe, influent well, and (peripheral) weirs and
scum baffles.
Shall be of structural steel, shall be cylindrical in shape, and shall support entire clarifier mechanism, including
inboard end of access bridge. [Center column shall also serve as influent pipe and shall have large openings
at its upper end to direct influent flow into influent well at a low velocity.] Top of center column shall be
machined to provide an accurate fit with the drive assembly. Center column shall be attached to drive assembly
with bolts or machine screws. Bottom of center column shall have a bolting flange with minimum of four equally
spaced holes for anchorage to the concrete tank. The equipment manufacturer shall supply a template to accurately
locate anchor bolts for center column.
2.2.6 Access Bridge, Walkway, and Operating Platform
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
NOTE: Delete "raised pattern floor plate" or "grating." Grating is recommended
when snow or ice build-up is anticipated; otherwise, use floor plate.
NOTE: Fiberglass reinforced plastic grating squeegees, weirs and baffles are
available but require special consideration for anchorage and expansion. Fiberglass
reinforced plastic may be allowed as an optional material provided that the
necessary requirements for anchorage of these items, including provision for
expansion and contraction, are incorporated in the project specification or
shown on the project drawings.
Access bridge shall be of structural steel and shall extend from tank sidewall to the center and beyond sufficient
to support walkway and operating platform. [Where bridge supported unit is used, the supporting bridge shall
be used as the access bridge.] Walkway and operating platform shall be skidproof galvanized steel [raised-pattern
floor plate] [grating] [or fiberglass reinforced plastic]. Walkway and operating platform shall have a double
railing not less than one m 3 feet 6 inches in height on both sides of walkway and around outside of operating
platform; railing shall be of galvanized structural steel section or of standard 38 mm 1 1/2 inch galvanized
pipe conforming to ASTM A 53/A 53M. Walkway shall be not less than 750 mm 30 inches wide. [Raised-pattern floor
plate] [Grating] shall be of a design and material thickness necessary to keep deflection to less than 6 mm 1/4
inch with a uniform load of 5 kPa 100 pounds per square foot.
2.2.7 Supporting Bridge
NOTE: When center feed/peripheral overflow type clarifier is larger than 11
m 35 feet in diameter or peripheral feed/center overflow type clarifier is larger
than 18 m 60 feet in diameter, delete requirements for and references to bridge-supported
clarifier mechanisms and those components peculiar thereto, including support
bridge, center shaft, and scraper arms of structural shapes.
Shall include two structural steel beams and braces of sufficient depth and thickness to support entire clarifier
mechanism within the specified maximum allowable deflection.
2.2.8 Influent Well
NOTE: When center feed/peripheral overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
center column used as influent pipe, influent well, and (peripheral) weirs and
scum baffles.
The center influent well shall be structural steel, 6 mm 1/4 inchminimum thickness, reinforced and stiffened
with structural sections. The well shall project below and 100 mm 4 inches above the water level and shall be
designed to radially diffuse and dampen the influent liquid without inhibiting the clarifier process. A slot
with a baffle shall be provided at water level to permit escape of floating material. Where required by manufacturer's
design, a standard bolted flange shall be provided for connection of the influent pipe.
2.2.9 Influent Skirt
NOTE: When peripheral feed/center overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
influent skirt, and effluent trough and weir assembly.
NOTE: Delete references to and requirements for aluminum wherever a corrosion
problem with aluminum may be anticipated.
The tangential inlet shall be curved sheet steel shaped to direct influent liquid through the influent raceway.
Influent skirt shall be steel sheet [or aluminum sheet, minimum thickness] 1.8 mm 14 gage, with bars or structural
shapes at top and bottom for rigidity. [Aluminum shall conform ASTM B 209M ASTM B 209 or ASTM B 221M ASTM B 221
, Alloy 6061, Temper T6.] Sheets shall be prepunched and structural shapes shall be predrilled for ease of field
installation. Influent skirt shall be located where indicated and shall be supported by adjustable galvanized
hanger rods, hung from structural tees or shapes welded to anchor plates bolted to tank wall. Supporting assembly
shall be capable of a minimum horizontal and vertical adjustment of one inch for final location and leveling
of influent skirt. [Dielectric insulators shall be provided where aluminum and ferrous metals are in contact.]
2.2.10 Effluent Trough and Weir Assembly
NOTE: When peripheral feed/center overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
influent skirt, and effluent trough and weir assembly.
NOTE: Use square effluent trough when clarifier tank diameter is larger than
8.5 m 28 feet; for smaller tanks, use circular effluent trough. However, a
weir length longer than usual in a smaller tank may require a square trough
(Insert a minimum weir length equal to clarifier tank circumference unless it
is determined that a longer weir length is required.).
NOTE: Delete fourth sentence when circular effluent trough is specified (Use
square effluent trough when clarifier tank diameter is larger than 8.5 m 28
feet; for smaller tanks, use circular effluent trough. However, a weir length
longer than usual in a smaller tank may require a square trough (Insert a minimum
weir length equal to clarifier tank circumference unless it is determined that
a longer weir length is required.)).
NOTE: Insert a minimum weir length equal to clarifier tank circumference unless
it is determined that a longer weir length is required.
NOTE: Fiberglass reinforced plastic grating squeegees, weirs and baffles are
available but require special consideration for anchorage and expansion. Fiberglass
reinforced plastic may be allowed as an optional material provided that the
necessary requirements for anchorage of these items, including provision for
expansion and contraction, are incorporated in the project specification or
shown on the project drawings.
Assembly shall include effluent trough, effluent weirs, and supporting members. Effluent trough shall be [square]
[or] [circular] and of sufficient size for length of weir specified in this paragraph. Effluent trough sections
shall be of welded structural steel construction. [Trough sections shall not end at corners; all corner joints
shall be welded.] Joints between sections shall have bolted connections with suitable rubber gaskets. Weir plates
shall be attached to each side of the effluent trough; not less than [_____] mm feet of weir length shall be
provided. Weir plates shall be structural steel [or fiberglass reinforced plastic]. Weir plates shall be V-notched
and of size and section as indicated. Weir plates shall be bolted to effluent trough and shall have slotted
or oversize holes and plate washers to permit horizontal and vertical adjustment of weir. Weirs shall have overlapping
splice plates to ensure proper alignment. Effluent trough and weir shall be supported from bridge structure;
outrigger beams shall be provided where necessary. Supporting members shall be of sufficient cross section to
prevent vertical movement due to the flotation forces developed with trough empty and liquid level in tank at
base of V-notch weir. Supporting assembly shall be capable of a minimum vertical adjustment of 75 mm 3 inches
to permit leveling of trough.
2.2.11 Electrical Control System
Shall include enclosure; main and branch circuit breakers; starter, contactors, and reset buttons; pushbuttons;
and all necessary wiring. Electrical control system shall be in accordance with NEMA ICS 1 and NEMA ICS 2. Design,
fabrication, and installation of electrical components shall be in accordance with requirements of NFPA 70. Electrical
controls shall be mounted in outdoor weatherproof enclosure, NEMA 3R. Electrical control system components shall
be completely wired and mounted in the enclosure at the manufacturer's plant and tested prior to shipment from
the factory. The electric service available is [_____] volts, [_____] phase, [_____] Hertz, [_____] wire. Pushbuttons
and reset switches shall be installed on the outside of the door, properly identified with laminated phenolic
name plates. Components on outside of enclosure and on internal panels shall be identified by engraved laminated
phenolic legend plates. Connecting electrical wiring and related equipment are specified in Division entitled
"Electrical."
2.2.11.1 Control System Enclosure
Electrical control system enclosure shall be outdoor unit with support legs and shall be constructed of sheet
steel. Screened ventilating openings shall be installed in the enclosure. Enclosure shall have rubber-gasketed
door provided with continuous piano hinge and cylinder locking type door latch. A copy of the external wiring
connections and a circuit breaker index print shall be secured to the inside of door. Control panel shall be
mounted on legs formed from steel angles welded to the bottom of the enclosure. The legs shall have bottom plates
drilled with holes for securing the panel to access bridge at or near the drive assembly.
2.2.11.2 Circuit Breakers
Circuit breakers shall be thermal magnetic type. Main circuit breaker shall have a maximum capacity of 150 percent
of the electrical load. The main circuit breakers shall be an external handle mechanism, with positive locking
device, mounted outside the enclosure to permit operation of breaker from outside the enclosure. Branch circuit
breakers shall be E-frame bolt-on type mounted on interior bus bar. Branch circuit breakers shall be provided
for each drive motor, control circuit, [trough heating device,] and receptacle. Panel shall include spaces for
two additional circuit breakers.
2.2.11.3 Motor Starter [, Contactors,] and Pushbutton Station
A pushbutton actuated magnetic motor starter with overload and undervoltage protection shall be provided for
the motor. Starter shall have thermal overload protection in each phrase and short circuit protection. Overload
protective devices shall give adequate protection to motor windings, shall be of thermal inverse-time-limit type,
and shall include manual-reset type pushbutton. Pushbutton station shall be 2-button Start-Stop. [Provide contactors
for trough heating devices.]
2.2.11.4 Overload Protection and Alarm Device
Clarifier mechanism shall have an overload protection and alarm device designed to indicate load on the mechanism
at all times, to surround an alarm in case of impending excessive load, and to stop the mechanism when such load
is reached. Device shall be of the torque-actuated or indicating-ammeter type, mounted except for alarm, in
enclosure. Overload alarm shall include an industrial-type horn or 150 mm 6 inch bell, relay, reset button,
test circuit, and an independent On-Off switch. Horn or bell shall be constructed of noncorrodible material
and shall be suitable for remote mounting. [Provide auxiliary contacts in alarm circuit for transmission of
signal to existing alarm system.]
2.2.11.5 Wiring
Control circuits shall be wired with 1.8 mm No. 14 gage stranded, 1 mm 2/64 inch insulation machine-tool wire
with ring tongue compression type lugs and number tags on both ends of wires. Circuit breakers and power circuits
shall be wired with necessary gauge wire, minimum size 2.5 mm No. 12 gage with wire lugs and number tags. Wires
shall be secured with either plastic ties or wiring duct, or both. Wires going to components mounted on the
enclosure door shall be secured in a cable-like bundle and strapped to the door and the enclosure with sufficient
slack to allow easy operation of the door. Circuits requiring field connection shall be terminated on panel
terminals.
2.2.12 Lubrication Fittings
Bearings and other moving parts subject to wear shall be provided with adequate means for lubrication. Lubrication
shall be by grease or oil, as suitable. Greased bearings shall be provided with fittings suitable for grease
gun service. Where grease fittings would not be easily accessible, grease tubing shall be extended to a convenient
location. Grease fittings shall be of a type that prevents overlubrication and build-up of pressure injurious
to the bearings. Each oil reservoir shall be liberal in size and provided with an opening for filling, an overflow
opening at the proper location to prevent overfilling, an oil-level sight glass, and a drain at the lowest point.
2.2.13 Key Mounted Connections
Where connections between shafts and sprockets, gears, pulleys, and other component parts are specified to be
key mounted, keys and keyways shall conform to ASME B17.1 or ASME B17.2.
2.2.14 Weir Plates and Scum Baffles
NOTE: When center feed/peripheral overflow type clarifier is not specified
for the project, delete references to this type and the requirements for those
components peculiar thereto, including scum removal assembly (for this type),
center column used as influent pipe, influent well, and (peripheral) weirs and
scum baffles.
NOTE: Delete references to and requirements for aluminum wherever a corrosion
problem with aluminum may be anticipated.
NOTE: Fiberglass reinforced plastic grating squeegees, weirs and baffles are
available but require special consideration for anchorage and expansion. Fiberglass
reinforced plastic may be allowed as an optional material provided that the
necessary requirements for anchorage of these items, including provision for
expansion and contraction, are incorporated in the project specification or
shown on the project drawings.
Shall be steel [or aluminum conforming to ASTM B 209M ASTM B 209 or ASTM B 221M ASTM B 221, Alloy 6061, Temper
T6] [or fiberglass reinforced plastic]. Weirs shall be V-notched and of size and section as indicated. Scum
baffles shall be of size and section as indicated. Weir plates and baffles or their supports shall have slotted
or oversize holes and plate washers as indicated to permit horizontal and vertical adjustment of the weir and
baffle. Weirs and baffles shall have overlapping splice plates as indicated to ensure proper alignment. [Splice
plates, washers, and baffle supports used with fiberglass reinforced plastic shall be fiberglass reinforced plastic.]
There shall be no projection of bolts, nuts, or splice plates on inboard side of the scum baffle. Sealant for
mounting weir plates shall be a two-component polysulfide-rubber-base sealant.
2.3 CLARIFIER PIPING
NOTE: Delete piping applications not covered in this section. In general,
piping external to the clarifier tank which is part of the sewage plant interconnecting
piping system should be covered in a separate piping section in the project
specification.
INFLUENT[,] [SLUDGE REMOVAL,] [SCUM REMOVAL,] [EFFLUENT,] [AND] [TANK DRAIN] PIPING:
2.3.1 Pipe and Fittings
NOTE: Delete piping applications not covered in this section. In general,
piping external to the clarifier tank which is part of the sewage plant interconnecting
piping system should be covered in a separate piping section in the project
specification.
NOTE: Delete bracketed items if not included in project.
Pipe and fittings [, except as otherwise specified [in this section] [in Section 22 00 00 PLUMBING SYSTEMS,]]
shall be ductile iron, of sizes as indicated. Pipe within clarifier tank [and above ground] shall be flanged
pipe conforming to AWWA C115/A21.15. Flanges shall be plain-faced without projection. Bolts, nuts, and gaskets
for flanged joints shall be as set forth in Appendix to AWWA C115/A21.15. [Buried pipe shall conform to AWWA C151/A21.51
, using push-on or mechanical joints conforming to AWWA C111/A21.11.] Fittings shall conform to AWWA C110/A21.10
. Pipe and fittings shall be cement-mortar lined, double thickness, as specified in AWWA C104/A21.4 with tolerance
of plus 3 mm 1/8 inch permitted. Connecting pipe and fittings [valves] [and] [sluice gates] are specified in
Division entitled "Mechanical."
2.3.2 Sleeves and Wall Castings
Shall conform to AWWA C110/A21.10, with sizes and joints as indicated.
2.4 ANCHOR AND CONNECTING BOLTS, NUTS, AND WASHERS
Iron and steel shall be attached with zinc-coated steel, stainless steel bolts. Aluminum [fiberglass reinforced
plastic] shall be attached with stainless steel machine bolts. Steel bolts shall conform to ASTM A 325M ASTM A 325
, Type 3, maximum hardness of Rockwell "C" 32. Nuts shall conform to ASTM A 563M ASTM A 563, Grade as specified
for the bolt material used. Zinc coating shall be in accordance with ASTM A 153/A 153M. Stainless steel bolts
and nuts shall conform to ASTM F 593 and ASTM F 594, respectively. Stainless steel shall be AISI Type 302.
Circular washers shall conform to ASME B18.22M ASME B18.22.1, lock washers to ASME B18.21.1 ASME B18.21.2M.
Bolt sizes and locations shall be as shown on the approved shop drawings for the equipment [, except as otherwise
indicated]. Steel anchor bolts for center column shall be 16 mm 5/8 inch diameter minimum with 64 mm 2 1/2 inch
projection, 225 mm 9 inch embedment, and 75 mm 3 inch hook on embedded end. Templates shall be furnished for
accurate positioning of anchor bolts.
[2.5 FIBERGLASS REINFORCED PLASTIC
NOTE: Fiberglass reinforced plastic grating squeegees, weirs and baffles are
available but require special consideration for anchorage and expansion. Fiberglass
reinforced plastic may be allowed as an optional material provided that the
necessary requirements for anchorage of these items, including provision for
expansion and contraction, are incorporated in the project specification or
shown on the project drawings.
Isophthalic polyester resins reinforced with a minimum of 30 percent (by weight) glass fibers, with edges sealed
and thermally cured in molds, free of voids and porosity. Grating bearing and cross bars shall be molded at
the same time or pultruded and bonded into one-piece construction. Grating shall be square or rectangular mesh
capable of supporting 5 kPa 100 pounds per square foot on a 1200 mm 48 inch span with a maximum deflection of
7.5 mm 0.303 inch. Sheet goods shall be two stage compression molded laminates with 6 mm 1/4 inch minimum thickness;
70 MPa 10,000 pounds per square inch minimum tensile strength when tested in accordance with ASTM D 638 ASTM D 638
; and 16 to 19 joules per 25 mm 12 to 14 foot pounds per inch of notch (Izod) impact resistance when tested in
accordance with ASTM D 256. Fiberglass reinforced plastic shall have a flame spread rating of 25 or less and
fuel contributed rating of zero when tested in accordance with ASTM E 84, and rated as self-extinguishing when
tested in accordance with ASTM D 635. Color blue-green.
]2.6 GROUT MATERIALS
Cement, fine aggregate, and water shall be as specified in Section 03 30 00 CAST-IN-PLACE CONCRETE.
2.7 SPARE PARTS
Spare parts shall be identical and interchangeable with original parts and shall be furnished in clearly marked
containers. Spare parts shall be the standard ones recommended by the manufacturer in his operation, maintenance,
or instruction manual, furnished in the number recommended.
2.8 TOOLS
Special tools necessary for the proper maintenance and operation of the equipment shall be furnished together
with a properly identified hardwood or metal box for their storage.
2.9 MATERIALS PROTECTION
NOTE: The field painting section of the project specification should provide
for repair of damaged coat after erection.
Sandblast exposed surfaces of ferrous metals, including those to be submerged, in accordance with SSPC SP 10;
and apply a four-coat system conforming to MIL-P-24441. Apply the system in the following order: one coat of
Formula 150, one coat of Formula 151, one coat of Formula 156, and one coat of Formula 152. Final total dry
film thickness shall be not less than 0.25 mm 10 mils. Maximum time between coats shall be 72 hours. The following
items shall be finished in accordance with the manufacturer's standard practice suitable for end use environment:
Motors, gearmotors, speed reducers, chains, sprockets, shafts, exposed drive train elements, and pushbutton stations.
Aluminum shall have an AA-MM10-C22-A41 finish, as defined in AA DAF-45. [Treat machined or cut edges of fiberglass
reinforced plastic with resin sealer as recommended by the fiberglass reinforced plastic product manufacturer.]
PART 3 EXECUTION
3.1 GENERAL
NOTE: Delete bracketed portions when services of an engineer representative
of the clarifier equipment manufacturer are not desired. It is generally recommended
that these services be furnished for navy projects.
Install clarifier equipment in accordance with the recommendations of the manufacturer of the clarifier mechanism,
as approved. Take special care to correctly align equipment components. [After final positioning of center
column, provide full bearing under base plate using non-shrink grout.] For equipment utilizing V-belt drives,
adjust sheave alignment and belt tension in accordance with equipment manufacturer's recommendations. [The Contractor
shall procure the services of an engineer representative of the manufacturer of the clarifier mechanism to inspect
the equipment after erection, for final inspection, startup, and acceptance tests. The representative shall
also be available at the clarifier site for a period of not less than one day to instruct operating personnel
during initial operation period.]
3.2 SURFACING OF CLARIFIER TANK FLOOR
NOTE: Delete bracketed portions when services of an engineer representative
of the clarifier equipment manufacturer are not desired. It is generally recommended
that these services be furnished for navy projects.
Following installation of the clarifier mechanism, bring clarifier tank floor to finish grade by means of cement-mortar
grout surfacing swept into place by use of the sludge collector arms, as herein specified. Do not begin surfacing
operation until after [the installed equipment has been inspected by the engineer representative of the manufacturer
and] scraper arms and scraper blades have been adjusted to give correct clearance above final floor elevation.
Perform surfacing operation in accordance with the approved recommendations of the manufacturer of the clarifier
equipment, except as otherwise specified. If grout proportions for the surfacing are not given in the manufacturer's
recommendations, use a cement-mortar grout composed of one part cement and three parts fine aggregate with sufficient
water as needed for conditions of placement and with one teaspoon of powdered aluminum added per bag of cement.
Immediately before the surfacing operation is begun, clean the floor of all dirt, soil, and other substances
which would prevent the proper bonding of the surfacing to the concrete subfloor. Bring the grout surfacing
to finish grade, as near as possible, by hand. If the manufacturer's recommended procedure calls for use of
straightedges attached to scraper arms, fasten a 50 by 150 mm 2 by 6 inches metal clad wooden straightedge to
each scraper arm approximately 6 mm 1/4 inch below the scraper blade to form a suitable screed; rotate scraper
arms manually to complete the surfacing operation; use of drive unit to move the arms will not be permitted.
Prevent grout from entering sludge cone; immediately remove any grout which falls in the sludge cone or on clarifier
tank walls. Immediately after surfacing operation is complete, clean clarifier tank floor and circular clarifier
equipment of deposits of excess grout. Remove screeds and install squeegees.
3.3 PIPING
NOTE: Delete piping applications not covered in this section. In general,
piping external to the clarifier tank which is part of the sewage plant interconnecting
piping system should be covered in a separate piping section in the project
specification.
Make flanged joints up tight, taking care to avoid undue strain on flanges. Align bolt holes for each flanged
joint. Use full size bolts for the bolt holes; use of undersized bolts to make up for misalignment of bolt holes
or for any other purpose will not be permitted. Install flanged pipe so that adjoining flange faces are not
out of parallel to such degree that the flanged joint cannot be made watertight without overstraining the flange.
Replace by one of proper dimension any flanged pipe or fitting whose dimensions do not allow the making of a
proper flanged joint as specified herein. Provide hangers and supports where necessary to support piping. [For
buried piping, use push-on joints or mechanical joints, and make in accordance with AWWA C600; for mechanical
joints, also follow recommendations of Appendix A to AWWA C111/A21.11. Replace by one of proper dimensions any
pipe or fitting that does not allow sufficient space for proper installation of jointing materials.]
3.4 WEIRS
Mount weir plates against a double bead of the sealant previously specified for this purpose. Use sufficient
thickness of sealant to fill all voids between concrete tank and weir plates.
3.5 REPAIR PAINTING
Inspect painted surfaces for holidays, scratches, chipping, and other damage. Refinish imperfections by cleaning
burrs and rough surfaces and sanding to a smooth finish, prime and repaint.
3.6 FIELD TESTS AND INSPECTIONS
3.6.1 General
The Contractor shall perform all field tests and provide all labor, equipment, and incidentals required for tests.
The Contracting Officer will witness field tests and conduct all field inspections. The Contractor shall give
the Contracting Officer ample notice of dates and times scheduled for tests.
3.6.2 Tests
Test circular clarifier mechanism as in operation to demonstrate correct alignment, smooth operation, proper
adjustment of flow distribution, freedom from vibration, and freedom from noise and overheating of moving machinery.
Include in test at least two full cycles of successful operational sequences to demonstrate that the system continues
to function satisfactorily after meeting all operational requirements.