Primary Clarifier Mechanism (Circular Plow Type)

PRIMARY CLARIFIER MECHANISM (CIRCULAR PLOW TYPE)

PART 1 GENERAL

1.01 REFERENCES A. The following is a list of standards that may be referenced in this section:

1. American Bearing Manufacturers Association (ABMA). 

2. American Gear Manufacturers Association (AGMA):

a. 2001, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth.

b. 2004, Gear Materials and Heat Treatment Manual. 

c. 6022, Design Manual for Cylindrical Wormgearing. 

d. 6034, Practice for Enclosed Cylindrical Wormgear Speed

Reducers and Gearmotors. 

e. 9005, Industrial Gear Lubrication.

3. American Institute of Steel Construction (AISC). 

4. American Iron and Steel Institute (AISI). 

5. American Society of Mechanical Engineers (ASME): B29.100,

Precision Power Transmission Double-Pitch Power Transmission, and

Double-Pitch Conveyor Roller Chains, Attachments, and Sprockets. 

6. American Water Works Association (AWWA): C200, Steel Water

Pipe – 6 In. (150 mm) and Larger. 

7. American Welding Society (AWS):

a. D1.1/D1.1M, Structural Welding Code – Steel.

b. QC 1, Standard for AWS Certification of Welding Inspectors. 

8. ASTM International (ASTM):

a. A36/A36M, Standard Specification for Carbon Structural Steel. 

b. A48/A48M, Standard Specification for Gray Iron Castings. 

c. A148/A148M, Standard Specification for Steel Castings, High

Strength, for Structural Purposes. 

d. A283/A283M, Standard Specification for Low and Intermediate

Tensile Strength Carbon Steel Plates. 

e. A285/A285M, Standard Specification for Pressure Vessel Plates,

Carbon Steel, Low- and Intermediate-Tensile Strength. 

f. A536, Standard Specification for Ductile Iron Castings.

9. National Electrical Manufacturers Association (NEMA): 

a. 250, Enclosures for Electrical Equipment (1000 Volts Maximum). 

b. MG 1, Motors and Generators.

10. The Society for Protective Coatings (SSPC): SP 7, Brush-off Blast Cleaning.

Underwriters Laboratories (UL: 674, Standard for Safety, Electric Motors and Generators for Use in Division 1 Hazardous (Classified) Locations.

1.02 DEFINITIONS 

A. Alarm Torque:120 percent of Design Running Torque. 

B. Certified Welding Inspector (CWI): As defined in AWS QC 1. 

C. Cutout Torque: 140 percent of Design Running Torque.

D. Design Running Torque: Torque used to select size, strength, and type of materials and components for mechanism and drive system, and at which or below will provide continuous 24 hour per day clarifier operation for period of not less than 20 years at design torque condition and rotational speed specified herein, without damage, permanent deformation or overload, and equal to 50 percent on overload device scale.

E. Slenderness Ratio: Ratio of unbraced length to least radius of gyration.

F. Submerged Metal: Metal below gear head drive and plane 18 inches above weir elevation indicated.

G. Ultimate Torque: 200 percent of Design Running Torque and below which no portion of mechanism will be damaged if operated for only short period of time (a few seconds) and equal to 100 percent on overload device scale.

1.03 SUBMITTALS

A. Action Submittals:

1. Shop Drawings: 

a. Product Data:

1) Make, model, weight, and horsepower. 

2) Descriptive literature, specifications, dimensional layout,

identification of materials of construction, and specialized

equipment assembly cuts. 

3) Painting/Coating System(s): Manufacturer’s descriptive

technical catalog literature and specifications. 

4) Anchorage and bracing data sheets and drawings as required

by Section 01 88 15, Anchorage and Bracing. 

b. Detailed Drawings:

1) Structural, mechanical, and electrical showing equipment fabrications and interface with other items including dimensions, size, and locations of connections to other work, and weights of associated equipment.

2) Structural and Mechanical: Details of influent column, center torque cage, center pier, walkway bridge, influent well with energy dissipating inlet, flocculation well, sludge collection box, rotating rake arm trusswork, scum skimmer, and scum trough.

3) Scum Trough Flushing Valve Details: Method of operation and flushing water flow adjustment, and flow rate calculations.

4) Diameter of ball race. 

c. Design Details:

1) Running, Alarm, Cutout, and Ultimate Torque ratings of drive unit assembly.

2) Ultimate Torque load capabilities of drive unit assembly, torque cage, and, rotating rake arm trusswork.

d. Hydraulic Calculations: Minimum average, normal maximum, and instantaneous flows and data.

e. Certification of Structural Calculations: Letter of certification for structural design of mechanism, signed and sealed by Registered Professional Engineer. Copies of detailed structural design calculations shall not be submitted for review. If submitted, calculations will be returned without review.

f. Structural Loads: Static, dynamic, and torque reaction loads to be transferred into structure at center column and access bridge support locations.

g. Details of torque sensing and load indication device. 

h. External utility requirements such as air, water, power, and drain

for each component. 

i. Power and control wiring diagrams, including terminals and

numbers. 

B. Informational Submittals:

1. Designer’s qualifications.

2. Anchorage and bracing calculations as required by Section 01 88 15, Anchorage and Bracing.

3. Certificates: 

a. Manufacturer’s Certificate of Compliance, in accordance with

Section 01 43 33, Manufacturers’ Field Services. 

b. Manufacturer’s certificate that coating system(s) meet or exceed specified requirements. 

4. Special shipping, storage and protection, and handling instructions. 

5. Test procedures. 

6. Test results, reports, and certifications. 

7. Operation and Maintenance Data: As specified in Section 01 78 23, Operation and Maintenance Data.

8. Manufacturer’s Certificate of Proper Installation, in accordance with Section 01 43 33, Manufacturers’ Field Services.

1.04 QUALIFICA TIONS 

A. Designer: Registered Professional Engineer.

1.05 EXTRA MATERIALS

A. Provide recommended list of spare parts in the Operations and Maintenance Manual, in accordance with Section 01 78 23, Operation and Maintenance Data.

PART 2 PRODUCTS

2.01 MANUFACTURERS

A. Materials, equipment, and accessories specified in this section shall be products of:

1. Hi-Tech Environmental, Inc. 

2. Ovivo USA. 

3. Siemens. 

4. Walker Process Equipment/Division of McNish Corporation.

2.02 SERVICE CONDITIONS

A. Material Handled: Screened and degritted raw sewage and settled tertiary return sludge.

B. Influent Liquid Temperature Range: 35 degrees F, minimum to 85 degrees F.

C. Influent pH Range: 6.3, minimum to 7.5, maximum.

D. Sludge Solids Concentration Range, Dry Weight Basis: 5,000 mg/L, minimum, 10,000 mg/L, average, 40,000 mg/L, maximum.

E. Site Conditions:

1. Mechanism and bridge design shall be in accordance with conditions and requirements stated in Section 01 61 00, Common Product Requirements.

2. In addition, design shall accommodate the following Site conditions: a. Exposure: Ultraviolet radiation of sun on drive and walkway

components. Remaining components are under cover and subject to sewer gases including hydrogen sulfide.

2.03 MANUFACTURED UNITS

b. Chemicals: Tertiary sludge contains alum and polymer may be added to the primary influent to provide chemically enhanced primary treatment.

c. Ambient Temperature Range: Minimum minus 20 degrees F to 110 degrees F, maximum.

d. Ambient Humidity Range: Minimum 10 percent to 98 percent relative humidity, including rain, snow, and ice.

e. Spray Water: Plant effluent available at 120 psig. 

A. Provide units meeting performance and design requirements as specified below.

B. General:

1. Suitable for installation in 135-foot inboard launder diameter by 14-foot sidewall water depth (SWD) clarifier having floor slope of 1:12. Clarifier inside wall diameter is 141 feet, with a 14-inch exterior wall, and the sidewall depth is 17 feet.

2. Center pier supported, center drive type. 3. Furnished complete, including drive motor, gearing, center influent well

with energy dissipation inlet, flocculation well, bridge, walkway, platforms, scraper mechanism, skimmer mechanism, scum trough with flushing device, and other necessary parts, including anchor bolts.

4. Direction of mechanism rotation shall be clockwise. 5. Scum baffles and effluent weirs shall be provided under

Section 44 42 28, Weir and Baffle Plates. 6. Compatible with low profile aluminum dome cover system provided

under separate contract. 

C. Performance Requirements:

1. Collect and convey settled sludge to center solids hopper. 

2. Collect, convey, and discharge floating scum from surface of clarifier and from inside flocculation well, to defined area at outside perimeter of unit.

3. Operate satisfactorily under the following conditions:

Design Flow Rates

Minimum

Average

Normal Maximum

Peak Instantaneou s

Sludge Flow Rate (mgd)

0.20

0.25

0.36

0.40

Clarified Effluent Flow Rate (mgd)

5.0

12.1

27.2

34.1

Influent Flow Rate (mgd)

5.2

12.3

27.6

34.5

D. Design Requirements:

1. Gears, Bearings, Chains and Sprockets: Above clarifier water surface. 

2. Drive Mechanism: Easy removal of internal gears, balls, and strip liners

without walkway bridge removal. 

3. Mechanism Construction: Welded, except at locations requiring

periodic field adjustment and as approved. 

4. Stresses: Maximum 90 percent of material yield strength at Ultimate

Torque load in members. 

5. Maximum Slenderness Ratio: 200 for compression member and 240 for

tension member. 

6. Design Running Torque: 50,000 foot-pounds minimum. Drive unit shall

be sized such that worm gear, spur gear, and pinion meet Design

Running Torque in accordance with AGMA 2001 and AGMA 6034. 

7. Rotational Speed: Between 0.018 and 0.023 rpm. 

8. Capable of withstanding, without failure or permanent deformation of

any part, torque load of minimum twice Design Running Torque. 

2.04 CENTER PIER AND INFLUENT COLUMN

A. Steel: ASTM A36/A36M, 54-inch minimum outside diameter, wall thickness not less than 1/4 inch, extending continuously from clarifier base slab.

B. Ports:

1. Minimum four in top of column to release liquid flow and entrapped scum. Size and location determined by manufacturer.

2. Sized to limit velocity to 1.5 feet per second at peak flow.

C. Minimum 3/4-inch-thick flange at base of pier for anchoring to clarifier foundation by not less than 12 anchor bolts; size as determined by manufacturer. Coordinate influent column with 36-inch diameter influent pipe, a 6-inch diameter sludge pipe, and a 6-inch diameter drain pipe.

2.05 INFLUENT STILLING WELL

A. Steel plate, ASTM A36/A36M, minimum 3/16 inch thick and minimum 1/4-inch thick shapes.

B. Energy Dissipating Influent Well:

1. Supported from centerwell support structure. 

2. Function: Enhance flocculation and diffuse influent liquid into clarifier. 

3. Size and Dimensional Design Details: As required to dissipate energy and promote even distribution of flow to the clarifier. 

4. Equip with multiple outlet ports. Ports shall be arranged to create flow impingement, dissipate energy and promote flocculation. 

2.06 FLOCCULATION WELL

A. Configuration:

1. Center of basin shall be separated from settling zone by minimum 27-foot diameter cylindrical baffle wall. 

a. Constructed of reinforced steel plate, ASTM A36/A36M. 

b. Plates minimum 3/16 inch thick and shapes minimum 1/4 inch thick. 

2. Extend from 8 feet below to 1⁄2 inch below the designed clarifier water

surface. 

3. Minimum Submerged V olume: 3,600 cubic feet.

B. Baffle Wall:

1. Rigidly supported from walkway bridge or drive cage. 

2. Designed to withstand wind load of 20 pounds per square foot on projected area when well is not full of water.

3.  Baffle Plate: Along bottom periphery of baffle wall to direct flow currents down inside face of baffle wall toward center of basin and to prevent short-circuiting. 

4. Ports: a. Eight minimum. b. At 45-degree points around circumference to allow scum to pass

into skimming area of clarifier. c. Approximately 12 inches square. d. Opening shall extend to top of baffle plate.

2.07 CENTER DRIVE UNIT ASSEMBLY

A. Ultimate Torque Rating: Not less than 2 times Design Running Torque.

B. Motor, Primary and Secondary Speed Reducers: Mount separately and independently at center gear head drive platform. Mounting configurations that piggyback or otherwise vertically stack these components are not acceptable. Cycloidal reducer directly coupled to motor is not acceptable.

C. Electric Drive Motor: In accordance with Section 26 20 00, Low-Voltage AC Induction Motors, and Induction Motor Data Sheet located in Supplements following End of Section.

D. Primary Speed Reducer:

1. Horizontally mounted cylindrical-worm or helical-worm gear motor type with gears supported by antifriction bearings. Planetary gear units will not be acceptable. Connect to secondary speed reducer via chain or belt or direct coupled drive system with drive sprocket or pulley directly mounted on its output shaft.

2. AGMA 6034 and AGMA Service Classification II. 3. Overhung Load Rating: Exceed chain pull by minimum 1.75 based upon

Ultimate Torque. 4. Oil Fill, Drain and Level Indicator Devices, and Lubricant:

AGMA 9005. E. Chain or Belt Drive:

1. Roller Chain: Standard, ASME B29.100. 2. Standard single V-belt. 3. Connect drive sprocket or pulley on primary speed reducer to driven

sprocket or pulley on secondary speed reducer input shaft. 4. Steel Sprockets: Minimum of 12 teeth. 5. Chain or Belts:

a. Service Factor: Minimum L: 4.0. b. Power Transmission Rating: 1.75 based on pull and power

required respectively at Design Torque Rating. F. Secondary Speed Reducer:

1. Cylindrical-Worm and Worm-Gear Type: a. Shafts supported by antifriction bearings and output shaft directly

driving pinion gear of low speed main bearing assembly. 

2. Load Capacity and Torque Rating: AGMA 6034. 

3. Design: AGMA 6022. 

4. Service Factor: Minimum 1.25 based upon Design Running Torque.

5. Output Shaft: One-piece output extending through worm-gear and low speed main gear drive pinion without intermediate couplings.

6. Worm: Steel, heat treated, AGMA 2004, ground and polished. 

7. Worm-Gear: Centrifugally cast, high silicon bronze copper alloy, or ductile iron. 

8. Bearings: ABMA L-10, life of 180,000 hours minimum. 

9. Oil Fill, Drain and Level Indicator Devices, and Lubricant:

AGMA 9005. 

10. Enclosure: ASTM A48/A48M, Class 40 minimum housing, and

registered fit mounted to gear head drive platform. 

G. Low Speed Final Reduction Unit:

1.

2.

3.

Enclosed turntable, balls in main bearing annular radial thrust raceway type, balls in compression and renewable strip liners. 

a. Ring Gear: Internal or External toothed, spur pinion gear driven,

attached to secondary speed reducer output shaft. 

b. Precision bearing designs are not acceptable. Low Speed Gearset: a. Designed and Rated: AGMA 2001. b. Power Rating:

1) Lower of pitting resistance and bending strength ratings for pinion and gears.

2) Based upon continuous 24 hours per day service at Design Running Torque for 180,000 hours minimum.

c. Spur Pinion Gear: 1) Steel: Heat treated; integral with or keyed to its shaft. 2) Wall Thickness (Above Keyway): Minimum depth of one tooth. d. Ring Gear:

1) Solid one-piece or split construction of ductile (nodular) iron (ASTM A536).

2) Split Gear Construction: Machined, minimum two alignment dowels, joined with high strength galvanized steel bolts.

3) Bolt to center torque cage that supports and rotates collection mechanism.

e. Teeth: Full-depth, AGMA 2001; stub-pitch and undercut gear teeth not acceptable.

Main Bearing: 

a. Ball Raceway Diameter: Minimum 65 inches, low unit ball load

and stability without guide shoes or steady bearings. 

b. Raceways and Balls: ABMA L-10 life of minimum 180,000 hours

when operating continuously at Design Running Torque.

c. Load Carrying Balls:

1) Steel: Chrome alloy, hardened to 60-65 Rockwell C. Diameter: Minimum 1-1/2 inches. 

2) If all balls are load- carrying, 1-inch diameter balls are acceptable. Crushing Strength: Minimum 120,000 pounds.

3) Spacer Balls (if required): 1/16-inch lesser diameter than, and of

same material as, load carrying balls. e. Raceways:

1) Four vacuum degassed high carbon steel renewable liner strips force fit (pin or cap screw attachments not acceptable) into base and ring gear, and specially hardened to 38-46 Rockwell C. Strips shall have minimum dimensions of

1/4 inch by 1/2 inch. 4. Ring Gear, Pinion Gear, and Main Bearing Ball Races:

a. Oil bathed and steel dust shield and felt seal protected. b. Oil Fill, Drain and Level Indicator Devices, and Lubricant:

AGMA 9005-E02. c. Casing with manual condensate drain.

5. Oil filling and level pipe, drain plug, and sight gauge. Attach pipe to turntable bottom within base center for easy access.

H. Turntable Base and Housing:

1. Bolt to center column, support entire rotating collector mechanism, transmit mechanical design strengths, support main bearing assembly, and one end of access walkway, and form center platform for convenient access to drive unit components.

2. Platform: 32-inch minimum clearance walking and working surface outside drive unit components mounted at platform.

3. Cast Iron: Grey, ASTM A48/A48M, Class 40 minimum. I. Mechanism Overload Device:

1. Mechanical or Hydraulic: Actuate integral contacts to indicate impending overload and shutoff drive motor at predetermined load.

2. Impending Overload Contact (Alarm Torque): Actuate at 100 percent of Design Running Torque.

3. Motor Shutdown Contact (Cutout Torque): Actuate at 120 percent of Design Running Torque.

4. Contacts: Single-pole, double-throw rated 5 amps, 120V ac. 

5. Enclosure: NEMA 250, Type 4X, Type 316 stainless steel. 

6. Indicating Pointer: Indicate relative load on graduated scale up to Ultimate Torque.

7. Provide shear pins in the drive assembly for additional protection above the shut-off torque rating. 

a. Shear pins shall function at approximately 125 percent of the continuous running torque 

b. Shear pins shall be corrosion resistant material 

c. Provide limit switch that indicates breakage of the sheer pin due to any circumstance. Shear pin limit switch shall be interlocked with motor controls to prevent mechanism from operating with a broken shear pin.

2.08 ACCESS WALKWAY

A. General: Provide access walkway from side of clarifier to center drive unit and access platform around center drive unit.

B. Support System:

1. All-welded steel, hot-dip galvanized rolled wide flange beam or truss beam type bridge construction rigidly supported on center pier and at access end on clarifier wall with thermal expansion compensating anchorage.

2. Diagonally cross brace and space beams as necessary to carry loads and produce required clear walkway width. Extend full radius.

C. Bridge Design:

1. Maximum Vertical Deflection: 1/360 of span under uniform 50 pound per square foot of walkway surface live load, plus dead load. 

2. Camber for 1/3 live load plus dead load.

3. Maximum Horizontal Deflection: 1/360 of span under uniform horizontal loading of 50 pounds per linear foot.

4. Horizontal and vertical design live loads need not be applied simultaneously. 

5. Walkway Surface Elements: Do not utilize to reduce calculated bridge deflections.

Steps:

a. b. c.

Provide as necessary at outboard end of bridge to allow access from walking surface adjacent to clarifier at top of wall elevation. Equally spaced to provide equal risers at maximum 7 inches from access landing to bridge surface. Stair Tread:

1)

2) 3)

12 inches with 1-inch nosing to provide effective 11-inch tread. Attach to web of bridge support beams. In accordance with Section 05 53 00, Metal Gratings, and fabricated of same grating as walkway system.

6. Coordinate requirements with low profile dome cover provided under separate specification.

D. Surface:

1. Material: a. Walkway: Aluminum grating as specified in Section 05 53 00,

Metal Gratings. b. Center Drive Platform: Hot dip galvanized checkered plate as

specified in Section 05 50 00, Metal Fabrications. 2. Thickness: Minimum, 1/4 inch.

3. Width: Extend minimum to guardrail/handrail supports. E. Width:

1. 42 inches minimum clear between kickplates. 2. 32 inches minimum clear working space around center drive unit.

F. Kickplates:

1. In accordance with Section 05 52 00, Metal Railings. 2. Anodized Aluminum: 4 inches high by 1/4 inch minimum thickness. 3. Fasteners: Type 316 stainless steel. 4. Locate full length of both sides of access walkway.

2.09 CENTER TORQUE CAGE

A. All-welded steel, ASTM A36/A36M, box truss design, minimum 6 feet square and components minimum 1/4 inch thick.

B. Supports and rotates influent stilling well, rake arms, and skimming devices, and fastens to main ring gear with machine screws or bolted connections.

C. Designed with sufficient strength and rigidity such that with 60/40 percent load imbalance at Ultimate Torque Load; no member will be stressed to a level beyond allowable maximums set forth in AISC Specifications.

D. Connections to Rake Arms: Adjustable, bolted, and seal welded after alignment.

2.10 RAKE ARMS

A. Full- and half-radius, all-welded steel triangular or diagonally braced box truss design that supports and rotates sludge scraper blades, and skimming devices. Support from center torque cage. Use of tie rod supports is not acceptable.

B. Quantity: Two full radius and two half radius rake arms per clarifier.

C. Sludge scraper configuration shall be spiral. Spiral blade shall be continuous from center hopper to half-radius and from half-radius to clarifier perimeter and shall provide an angle relative to direction of travel along its length to effectively and continuously convey sludge toward center of clarifier as rake arm rotates.

D. Sufficient strength and rigidity such that at Ultimate Torque no member will be stressed to a level beyond maximums allowed by current AISC Specifications.

E. Rake arms shall not be used to sweep in grout, but rather shall be used as guide for grout placement.

F. Truss Width: Same as center torque cage or as needed to adequately support rake.

G. Steel: ASTM A36/A36M, angular and round rectangular tubular elements. 1. Maximum Allowable Horizontal Deflection: L/200 at Cutout Torque.

H. Squeegees:

1. Materials: 20-gauge Type 316 stainless steel. 2. Attached to stainless steel sludge scraper blades. 3. Bolts, Nuts and Washers: Type 316 stainless steel. 4. Vertical Alignment: Between 1/2-inch minimum and 1-1/2-inch

maximum clearance above grouted clarifier bottom.

I. Counterweight Assembly: Designed by mechanism manufacturer to balance weight of scum skimmer components or other appurtenances as necessary of one of following designs:

1. Welded steel box filled with proper quantity of steel punchings and topped with 2 inches minimum of grout.

2. Multiple steel plates of various thicknesses and quantities supported by baseplate and forming a stack bolted together by at least two Type 316 stainless steel bolts.

2.11 SCUM SKIMMING SYSTEM

A. Mechanically collect and discharge surface scum from annular space between center influent flocculation stilling well and outer perimeter scum baffle, with positive means for moving scum from influent well to outer clarifier surface.

B. Skimming Arm and Skimmer Blade Assemblies: Support from rake arms.

1. Quantity: Two. 2. Supports: Maximum 10-foot centers. 3. Bolted Connections: Permit plate removal.

C. Skimming Arm:

1. Extend from, but not necessarily attached to, center influent stilling well at an aggressive attack angle outward to skimmer blade assembly at perimeter of clarifier.

2. Type 316 stainless steel plate and shapes, minimum thickness 1/4 inch. 

3. Extend plate from 3 inches above to 3 inches below static liquid level

(weir invert elevation) in clarifier. 

D. Skimmer Blade Assembly:

1. Traps scum at perimeter scum baffle and discharge it into scum trough. 

2. Hinged, adjustable unit designed such that when passing over scum trough bottom, blade edge is always in contact with trough even if trough is not horizontal or plumb. 

3. Lockout Device: Permits unit to be raised and maintained out of liquid. 

4. Lift Mechanism: Operable from exterior walkway or bridge deck. 

5. Blade:

a. b. c.

Extend full width of scum trough. Bottom and Edges: Replaceable neoprene seal strips to ensure continued entrapment and discharge of scum into scum trough. Inner and Outer Edges: Suitable, separate wearing surfaces.

6. Adjustable, spring-loaded device, minimum applied force of 5 pounds,

or flexible neoprene wiper to constantly force seal with perimeter scum baffle.

E. Scum Trough Assembly:

1. One per clarifier, including horizontal submerged shelf and inclined beach.

2. Steel: ASTM A36/A36M, plate and shapes, minimum thickness 1/4 inch.

3. Radial Width: Minimum 6 feet. 

4. Circumferential Length (Including Inlet and Outlet Beaches): Minimum 6 feet. 

5. Inlet Inclined Beach Length: Minimum 65 percent of total

circumferential length of trough. 

6. Trough Opening: Minimum 12 inches wide, sloped bottom, with 8-inch

outlet.

7. Support from basin weir wall and connect to scum baffle with adequate supports.

8. Support of skimming blade as it passes over scum trough opening shall be provided by support bars over opening or roller and track assembly.

9. Track: Vertically and horizontally adjustable, arranged to properly engage roller assembly on skimmer blade assembly at outside perimeter edge.

10. Support Bars: Maximum of three per scum trough, sized to provide adequate support for skimmer blade.

11. Containment/Training Baffle Assembly: a. At inside perimeter edge. b. Extend minimum 6 feet in front of shelf/beach leading edge. c. Extend 1 foot below and 8 inches above static liquid level (weir

invert elevation) in clarifier. d. Support from basin wall.

12. Trough Flushing Weir a. 12 inch long weir that uses clarifier liquid to flush trough

continuously. b. Weir shall have two 3-inch V-notch openings, 6 inches on center.

The top of the V-notch opening shall align with the entrance ramp top elevation.

2.12 SCUM BAFFLES

A. Molded fiberglass plate in accordance with Section 44 42 28, Weir and Baffle Plates.

B. Minimum 1/4 inch thickness. 

2.13 WEIR PLATES

A. Molded fiberglass plate in accordance with Section 44 42 28, Weir and Baffle Plates.

B. Minimum 1/4 inch thickness. 

2.14 INSTRUMENTATION AND CONTROLS

A. Provide local control panel with control components and protective devices, as specified herein and in accordance with Section 40 99 90, Package Control Systems.

1. Clarifier control panel elements:

a. ON-OFF selector switch.

b. RESET pushbutton.

c. RUN indicator pilot light

d. 120 percent torque alarm pilot light. 

e. 100 percent torque warning pilot light.

f. Shear pin fail alarm pilot light

g Power ON indication pilot light

2. Clarifier starter furnished by others. 

3. Provide contacts for remote alarm monitoring by plant control system.

2.15 DISSIMILAR METALS

A. Isolate dissimilar metals or connectors to prevent direct contact and electrical conductivity.

1. Use 1/8-inch thick continuous neoprene gasket to insulate aluminum grating, checker plate, and handrail post bases from access walkway support bridge and other components.

2. Use insulating washer and Teflon sleeves at bolted connections. 

2.16 ACCESSORIES

A. Anchor Bolts: Provide coated Type 316 stainless steel bolts, sized by equipment manufacturer and at least 3/4 inch in diameter or as shown. Coating shall be as specified in Section 09 90 00.01, Painting and Coating for Equipment Prepurchase.

B. Equipment Identification Plates: 16-gauge, Type 316 stainless steel, securely mounted on the drive unit and control panel in readily visible location. Plate shall bear 3/8-inch high engraved block type black enamel filled equipment identification number and letters.

2.17 FABRICATION

A. Fabricate bridge beam or stringer sections in continuous unbroken pieces.

B. Shop fabricate and assemble mechanism components in largest sections practicable and permitted by transportation carrier regulations.

C. Divide large assemblies such as center torque cage, rake arms, influent well, access walkway bridge, and energy dissipation inlet into flanged sections. Bolt together with Type 316 stainless steel fasteners.

D. Hot-Dip Galvanize After Fabrication: Steel access walkway support/bridge system in accordance with Section 05 50 00, Metal Fabrications. Field cutting or welding of galvanized parts will not be permitted.

E. Welded Construction: As specified in Section 05 05 23, Welding.

F. Shop/Factory Finishing:

1. Shop prime ferrous metal in accordance with and as specified in Section 09 90 00.01, Painting and Coating for Equipment Prepurchase, for submerged surfaces and for all nonsubmerged, nongalvanized surfaces.

2. Exposed metal surfaces of motors, gear reducers, and assemblies shall be factory prepared and primed and field finish coated in accordance with Section 09 90 00.01, Painting and Coating for Equipment Prepurchase.

3. Surfaces inaccessible subsequent to erection, shall be prepared, primed, and finished with the applicable coating prior to erection.

4. Seal welding shall be provided for submerged welded joints. Skip welds are not acceptable.

2.18 SOURCE QUALITY CONTROL

PART 3

A. Factory Inspections: Inspect control panels for required construction, electrical connection, and intended function.

B. Factory Adjustments: Calibrate torque controls.

EXECUTION

3.01 INSTALLATION

A. In accordance with manufacturer’s written instructions.

B. Anchor Bolts: Place using steel templates furnished by manufacturer and as specified in Section 05 50 00, Metal Fabrications.

3.02 FIELD FINISHING (BY OTHERS)

A. Paint ferrous metal in accordance with and as specified in Section 09 90 00.01, Painting and Coating for Equipment Prepurchase. Shop primed mechanism shall be prepared for field priming and finish coating by brush-off blasting in accordance with SSPC SP 7.

1. Completely remove shop primer to expose shop-blasted surface and apply specified coating system.

2. Provide supplemental heating and environmental controls as required to obtain complete curing.

B. Touch up paint exposed metal surfaces of motors, gear reducers, and assemblies in accordance with Section 09 90 00.01, Painting and Coating for Equipment Prepurchase.

3.03 FIELD QUALITY CONTROL

A. Before placing clarifiers into service, check weir plate settings by filling clarifiers with water to design water elevation indicated by CH2M HILL. Readjust as required by CH2M HILL.

B. Weirs: Level to within plus or minus 1/16 inch of design elevation. 

C. Functional Tests:

1. Conduct on each mechanism. 

2. Test for continuous 3-hour period without malfunction.

D. Performance Test:

1. Conduct on each completed assembly in accordance with accepted test procedures.

2. Perform under actual or approved simulated operating conditions. 

3. Perform to confirm mechanical and structural compliance with specified

torque requirements. 

a. Load each mechanism to 120 percent of Design Running Torque

to demonstrate mechanism’s structural capability to withstand resulting loads. 

1) Apply loads to mechanism’s rake arms through cables or

other means anchored to basin floor or wall. Utilize a hydraulic cylinder, springs, or other means that allows machine to rotate for a peripheral distance of at least 3 feet under load.

2) Accomplish testing with machine in operation. b. Demonstrate mechanism overload devices; verify actual torques at

which Alarm and Cutout (shutdown) contacts and load limiting

device are actuated. c. Correlate with scale indications.

4. Replace shear pins after torque testing is completed. 

3.04 MANUFACTURER’S SERVICES

A. Manufacturer’s Representative: Present at Site or classroom designated by Owner, for minimum person-days listed below, travel time excluded:

1. 1 person-day for installation assistance and inspection. 

2. 1 person-day for functional and performance testing and completion of

Manufacturer’s Certificate of Proper Installation. 

3. 0.5 person-day for prestartup classroom or Site training. 

4. 1 person-day for facility startup.

5. 0.5 person-day for post-startup training of Owner’s personnel. Training shall not commence until accepted detailed lesson plan for each training activity has been reviewed by Owner.

B. See Section 01 43 33, Manufacturers’ Field Services, and Section 01 91 14, Equipment Testing and Facility Startup.

3.05 SUPPLEMENT

A. The supplement listed below, following End of Section, is a part of this Specification.

1.

Primary Clarifier Nos. 1 and 2 Induction Motor Data Sheet.

END OF SECTION