Screenings Sluice Trough

SCREENINGS TROUGH


EQUIPMENT NUMBER

T-V200           Screenings Trough

PART 1          GENERAL

1.01       RELATED SECTIONS

A.     Section 44 42 29, Screenings Processing Equipment.
B.     Section 44 42 30, Perforated Plate Screens.

1.02       SUBMITTALS

A.     Action Submittals:

1. Contractor shall review Section 44 42 29, Screenings Processing Equipment, and Section 44 42 30, Perforated Plate Screens, and shall certify that the screenings trough is compatible with both the screenings processors and the fine screens. Contractor shall be responsible for the screen discharge chute, screenings trough, trough rock trap, trough diversion gate, and screenings processor inlet hoppers to ensure continuity between the fine screens and the screenings processors.
2.      Provide submittals in accordance with the requirements of Section 01 33 00, Submittal Procedures.
3. Detailed structural, mechanical, and electrical drawings including dimensional plan and sections of the complete mounted screenings trough, equipment fabrication details (including material thicknesses and structural member sizes) and all interfaces. Include dimensions, size, and details of anchorages and connections. Provide weights of all equipment. See Section 05 50 00, Metal Fabrications, for additional requirements.
4. External utility requirements such as water, power, drain etc., for each component.
5. Detailed descriptive literature and complete specifications on each electrical control, pilot, or monitoring device. Provide detailed description of interlock, control, or protective function provided by each item.
6. Wiring and interconnection diagrams and control elements for all electrical components.
7. Power and control wiring diagrams, including terminals and numbers, point-to-point wiring and control schematic diagrams.
8.      Seismic anchorage and bracing drawings and cut sheets, as required by
Section 01 88 15, Anchorage and Bracing.

B.     Informational Submittals:

1.      Statements of Qualification: Professional structural engineer.
2.      Special shipping, storage and protection, and handling instructions.
3.      Manufacturer’s testing methods, test results, and certification of Source Quality Control.
4.      Manufacturer’s installation instructions.
5.      Manufacturer’s Certificate of Proper Installation, in accordance with Section 01 43 33, Manufacturers’ Field Services.
6. Certification that the following structural calculations have been completed, signed, and sealed by a registered professional engineer, including:
a. Structural calculations for the support and anchorage of all equipment for design loads as specified in Section 01 61 00, Common Product Requirements.

PART 2          PRODUCTS

2.01       QUALIFICATIONS

A.     Registered Professional Civil Engineer in the State of California.

B. Equipment manufacturer shall have at least 5 years of experience in the design, construction, and operation of the screenings conveyance equipment described herein with at least 25 similar equipment installations.

2.02       GENERAL REQUIREMENTS

A. All metallic items routinely wetted during operation shall be Type 316 stainless steel (Type 316L for all welded items) hardened appropriately and as listed to limit abrasive wear, unless otherwise indicated. Where this section requires stainless steel, it shall be Type 316/316L unless otherwise indicated.

B. Equipment Supports: Equipment supports, anchors, and restraints shall be designed for static, dynamic, and seismic loads and structural design requirements as noted in Section 01 61 00, Common Product Requirements. Design shall be stamped and signed by a Civil Engineer registered in the State of California.

C. Service Factors: Service factors shall be applied in the selection and design of components where so indicated in individual sections. When not indicated there, minimum service factors shall be 1.25.

D.     Environmental Requirements: As described in Section 01 61 00, Common Product Requirements.

E. Area Classification: Each of the enclosed spaces within the headworks will be designed for strict compliance with NFPA 820 and NFPA 70 and will include ventilation with a redundant power supply. Therefore, the spaces within the headworks will be classified as Class I, Division 2, with the exception of the pump station dry well which will be unclassified. Provide equipment and controls rated and identified for use in this classification.

F.      Welding:

1.      Comply with applicable ANSI/AWS codes.
2. Qualification of weld procedures, welders, and welding operators shall conform to ANSI/AWS standards.
3. All fixed or movable structural components shall have continuous seal welds and shall prevent entrance of air or moisture.
4. In assembly and during welding, the component parts shall be clamped, supported, and restrained to minimize distortion and for control of dimensions. Weld reinforcement shall comply with the AWS code. Upon completion of welding, weld splatter, flux, slag, and burrs left by attachments shall be removed. Welds shall be repaired to produce a workmanlike appearance with uniform weld contours and dimensions. Sharp corners of material which is to be painted or coated, shall be ground to a minimum of 1/32 inch on the flat.

2.03       SERVICE CONDITIONS

A. The screenings trough will convey wet screenings slurry from two fine screens to one of two screenings processors. The equipment will be exposed to variable concentrations of hydrogen sulfide, chlorine, and other compounds commonly associated with screened raw sewage.

B. The equipment will be contained within an enclosed headworks screen building, as shown on the Drawings. Therefore, equipment enclosures must be watertight and airtight to the extent possible. Odor control covers shall be incorporated into the screenings trough.

C.     Spray Wash Water: Wash water will be available at a working pressure of 60 psi and 60 gpm.

2.04       SYSTEM DEFINITION

A. The screenings trough described herein shall include the necessary equipment to convey wet screenings from two fine screens to one of two screenings processors.

B. The installing Contractor shall be responsible for the screen discharge chutes, screenings trough, rock trap, screenings trough diversion gate, and screenings processor inlet hoppers to ensure continuity between the fine screens and the screenings processors.

C. The major components described in this section are listed by equipment tag number under Equipment Number located at the beginning of this section. Additional components shall include, but shall not be limited to, the following items:

1. Fabricated fine screen discharge chutes, seals, odor control covers, access hatches, rock trap and valves, diverter gate, toggle clamps, spray nozzles, valves, piping and screenings processor inlet hoppers.
2.      Spare parts.

2.05       SYSTEM PERFORMANCE AND FUNCTIONAL REQUIREMENTS

A. General: All equipment and associated components shall be designed, sized, and selected to meet the performance requirements under the full load range of operating conditions.

B.     Performance Requirements:

1. Equipment shall be manual, with the exception of the spray wash system.
2. Equipment shall prevent odors from contaminating the normal operating areas.

C.     Loading Criteria:

1. The screenings trough shall be designed to be full of water up to the top of the trough.
2. The screenings slurry will be wet screenings containing plastics, rags, grit, stones, grease and fecal matter which has been captured using two 6-mm aperture fine screens, each rated for 10 mgd for a combined screen throughput flow of 20 mgd, as specified in Section 44 42 30, Perforated Plate Screens.

D.     Equipment Design and Construction:

1. All materials of construction shall be suitable for the severe environment conditions for operation in contact with the corrosive and abrasive nature of the screenings slurry, as well as corrosive gases associated with septic raw sewage.
2.      Manufactured from corrosion-resistant materials.
3. Abrasion-resistant components and linings in high wear areas and moving parts.
4. The trough interiors shall have polished smooth surfaces. There shall be no projecting fasteners or other protrusions or leading edges that would potentially catch stringy material.
5. Where stainless steel is used, the grade shall be Type 316L, unless otherwise noted. Anchors and fasteners shall be Type 316 stainless steel.

2.06 SCREENINGS PROCESSING COMPONENTS
A. Fine Screen Discharge Chutes:
1. Fine screen discharge chute shall consist of stainless steel attachment flanges connecting a stainless steel or rubber extension chute installed into the fine screen discharge chute flange and shall extend into the screenings trough opening to prevent splashing.
2. Chutes shall be constructed from Type 316L stainless steel and shall be minimum 12-gauge in thickness. Inside surface of chute shall be highly polished.
3.      All interior surfaces of the chutes shall be vertical to the extent possible.
Chutes shall be the same width as the effective screen width and designed to mate with the screen discharge chute.
4. Chute shall have a polished smooth surface. There shall be no projecting fasteners or other protrusions or leading edges that would potentially catch stringy material.

B.     Screenings Trough:

1. Screenings trough shall be manufactured from Type 316L stainless steel, 12-gauge minimum thickness.
2. Screenings trough shall be configured to transport screenings by sluicing from the fine screens specified in Section 44 42 30, Perforated Plate Screens, to the screenings processor inlet hoppers as shown on the Drawings.
3. The trough shall incorporate means to divert wet screenings to either of the two units, as shown on the Drawings.
4. Design condition for the trough shall be for the trough to be completely full of water.
5. Contractor shall certify that screenings trough is compatible with fine screen discharge chute.
6.      Width: 14 inches.
7.      Depth: 12 inches.
8.      Slope: 1.25 percent.
9.      Adjustable pitch.
10.    Welds shall be ground to a minimum of 1/32 inch.
11.    Trough shall have no bends greater than 45 degrees.
12. Trough shall have side flanges for attaching odor control covers and toggle clamps. Closed cell neoprene sponge gaskets shall be placed between the trough and odor control covers.
13. The trough shall have a smooth semicircular flow surface, unless otherwise approved by Engineer.

C.     Trough Supports:

1. The trough shall be furnished with supports suitable for mounting the trough as required by the Contractor’s design. The trough supports shall be manufactured from 10-gauge (minimum) Type 316L stainless steel structural shapes and plates.
2. The trough supports shall be fitted at each end with intermediate supports spaced no greater than 10 feet apart. Fasteners shall be Type 316 stainless steel.
3. Trough supports shall be designed to firmly support the trough when full to the trough top with water.

D.     Trough Odor Control Covers:

1. The trough shall include easily removable odor control covers and screenings shall not be exposed to the atmosphere from the point of connection at the screen discharge chute to the screenings processor inlet hoppers.
2. Odor control covers shall be easily removable and secured to the trough by vertical-handle quick-release toggle clamps. Covers shall be installed in sections no greater than 5 feet in length per section.

E.      Trough Spray Wash System:

1. The screenings trough shall include 1 inch Type 316 stainless steel spray piping and nozzles to convey the screenings without manual operation or assistance. Any makeup water required by the screenings processor wash tank shall come from these sprays. Spray wash water availability is described in Article Service Conditions, Paragraph C.
2. Two spray nozzles shall be installed at the upstream end of the screenings trough, as shown on Drawings. Each nozzle shall supply spray wash water at 1 gpm and 50 psi.
3. Nozzles shall be narrow angle spray with flat spray pattern. One piece design on low-mount on 3/8 inch NPT, adjustable ball fittings, pressure ratings 125 psi. Spraying Systems Co., or equal.
4. Ball valve and solenoid valve shall be installed upstream of the spray nozzles.

F.      Trough Inlets:

1. The trough inlet shall be designed to mate with the fine screen discharge chute. The discharge chute extension shall attach to the trough.
2. Rubber seal shall be installed between the screen discharge chutes and trough inlets.

G.     Trough Manual Diverter Gate:

1. One diverter gate mounted in the screenings trough shall be provided to direct flow to one of two screenings processors and shall provide a water tight seal (zero leakage) and smooth transition to the selected downstream trough. Gate seals shall be made of neoprene. No variations in the smooth flow surface of the screenings trough will be permitted.
2. Gates shall be positioned manually and be lockable. Gate is irregular in shape, see Drawings. Gate height and width shall be coordinated with the screenings trough. Gate bottom elevation to be at invert of screenings trough.
3. Gate shall be piano hinged to the trough at the downstream end of the gate. Contractor shall provide means of securing gate to trough to prevent screenings slurry from altering the position of the gate.

H.     Trough Rock Trap:

1. Rock trap shall be supplied as an integral flanged section of the screenings trough between the fine screens and the screenings processors. The rock trap shall function to separate stones and rocks from other screenings and grit to protect the seals and grinder. The storage volume shall be approximately 5.3 cubic feet (40 gallons). A 4-inch manual knife gate valve shall be included for the purpose of solids removal from the rock trap.
2.      Rock trap shall be used to drain the screenings trough as needed. A 2-inch diameter pipeline shall extend from the side of the rock trap and discharge into the screen forebay by way of the floor trench drain located directly beneath the rock trap, as shown on Drawings.
3.      Dimensions as shown on Drawings.

I.       Screenings Processor Inlet Hopper:
1.      Hoppers shall be manufactured from Type 316L stainless steel, 12-gauge minimum thickness.
2.      Hoppers shall have screenings loaded via screenings trough.
3. Hoppers shall be fully enclosed so that screenings are not exposed to the air.
4. The design shall allow for removal and installation of the screenings processor grinder component without the need to enter the hopper and with all necessary access from the outside.

2.07       ELECTRICAL COMPONENTS AND ACCESSORIES

A. General: Provide all necessary electrical components and wiring for a complete, functional system. Electrical components shall be provided in accordance with the requirements of Division 26, Electrical.

B. Wiring: All wiring shall meet the requirements of Section 26 05 05, Conductors, NFPA 820 and NFPA 70. All insulation shall be rated 600 volts, minimum. Twisted shielded pair cable shall be used for all low-voltage (24V) signals.

C. Electrical Raceways: All electrical wiring shall be installed in conduit meeting the requirements of Section 26 05 33, Raceway and Boxes. All raceways shall be installed in accordance with Section 26 05 33, Raceway and Boxes,
NFPA 820 and NFPA 70.

2.08 INSTRUMENTATION AND CONTROLS
A. General:
1. Provide industrial grade instrumentation and controls, suitable for the intended service and environment. Provide a complete and functional system, including interfaces with instrumentation and controls as specified in other sections. Instrumentation and control components shall be provided in accordance with the requirements of Division 40, Process Integration.
2. Instrumentation and control system requirements specified herein are minimum requirements. Contractor shall provide additional components and features necessary to provide safe and reliable operation of the equipment furnished.

B. Instruments and Control Devices: Provide the following devices in accordance with Section 40 91 00, Instrumentation and Control Components, and
Section 40 27 02, Process Valves and Operators:
1. Ball Valve: Two-piece, standard port, NPT threaded ends, bronze body and end piece, hard chrome-plated solid bronze or brass ball, RTFE seats and packing, blowout proof stem, adjustable packing gland,
zinc-coated steel hand lever operator with vinyl grip, rated 600-pound WOG, 150-pound SWP, complies with MSS SP-110. Conbraco Apollo 70-100, or equal.
2.      High Level Switch:
         a.      Function: Monitor screenings trough water level.
         b. Setpoint: Set to alarm if the water surface rises to within 3 inches of the top of the trough.
         c.      Rating: NEMA X/7 explosion-proof enclosure.
3.      Knife Gate Valve:
        a.      Valve No.: V150
        b. Function: As required in the rock trap to manually and periodically release rocks collected in the         trough.
        c.      Rating: NEMA 4X/7 explosion-proof enclosure.

C.     Functional Requirements:
1. Contractor shall design and provide all trough system components, including but not limited to the trough, spray system nozzles and piping, and trough high water level switch wired to fine screen manufacturer’s control panel located in the electrical room.
2. Screenings trough spray water may be the sole source of water provided to sluice screenings and fill the screenings processor wash tank. Separate fluidization water connections to the wash tank are also permitted.
3. The high level switch shall be set to alarm if the water surface rises to within 3 inches of the top of the screenings trough.

D. Power Requirements: Provide 120 volt control power transformer for 120 volt loads, including solenoid valve and controls.

2.09       ACCESSORIES

A.     Equipment Identification Plate: 16-gauge stainless steel with 1/4-inch die-stamped equipment tag number securely mounted in a readily visible location.

B.     Lifting Lugs: Equipment weighing over 100 pounds.

2.10       FABRICATION

A. The screenings trough shall be factory assembled to the extent possible and delivered to the site for installation in the headworks, with minimal field assembly required.

2.11       SOURCE QUALITY CONTROL

A. All major system components shall be factory tested for compliance with the requirements herein, and a certification of the results of these tests shall be submitted to the Engineer.

B.     Engineer and the District reserve the right to visit the manufacturer’s facility to inspect equipment prior to shipping.

PART 3          EXECUTION

3.01       INSTALLATION

A.     Manufacturer’s recommendations shall be strictly adhered to during installation.

3.02       PRODUCT DELIVERY, STORAGE, AND HANDLING

A.     As specified in Section 01 61 00, Common Product Requirements.

3.03       FIELD FINISHING

A. Touch-up and repair surfaces in accordance with Section 09 90 00, Painting and Coating.

3.04       FIELD QUALITY CONTROL

A.     Functional Testing: Perform in accordance with Section 01 91 14, Equipment Testing and Facility Startup.

3.05       MANUFACTURERS’ SERVICES

A. A Manufacturer’s representative for the equipment specified herein shall be present at the Job Site for the minimum person-days listed for the services herein, travel time excluded. Manufacturer shall provide for a minimum of two trips. The minimum person-days listed herein are additive.

1. 2 person-days for installation assistance, inspection, and certification of the installation. Provide Certificate of Proper Installation for functional and performance testing.

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

END OF SECTION