SCOPE - Supplier shall furnish one (or more) solids contact, sludge recirculation clarifier(s) equivalent to the Graver Reactivator, or approved equal, fabricated by a supplier regularly engaged in the production of water conditioning equipment. The system furnished must be certified by the supplier to have been fabricated entirely at his direction.

PERFORMANCE - Each unit shall be designed for an effluent flow rate of ____ gpm resulting in a rise rate calculated in the clarified water zone immediately below the effluent collecting system, not exceeding ____ gpm/ft2. The minimum detention time at the design flow rate shall be _____ minutes. This detention time shall include the flocculation zone described later. The unit shall be designed for installation in a (circular) (square) tank with (steel) (concrete) side wall measuring _____ inside (diameter) (square) X _____ side depth, with 12" freeboard and concrete bottom sloping 1:12 into a central sludge thickening pit. For design and guarantee purposes, the influent supply quality to be treated shall be considered to have the following analysis:

• Calcium as CaCO3...................................:...................mg/l
• Magnesium as CaC03.................................................. mg/l
• Alkalinity as CaCO3 ....................................................mg/l
• Turbidity ......................................................................NTU
• Total Dissolved Solids ................................................. mg/l
• Silica ...........................................................................mg/l
• Iron as Fe ....................................................................mg/l
• Manganese as Mn .......................................................mg/l
• Suspended Solids ........................................................mg/l
• pH
• Color ..........................................................................Units
• Temperature Range .....................................................° F

With the addition of optimum chemicals to the flash mixing and sludge recirculation zone, and when the unit is operated as a clarifier or softener; the average turbidity of the clarified effluent shall not exceed ____ NTU. When the unit is operated as a softener, the effluent total hardness shall not exceed _____PPM as CaCO3. Performance shall be based upon feeding chemicals of the type and quantity recommended by the Manufacturer or as determined by the Owner from jar tests performed on the raw water. Performance shall also be based on the proper installation, operation and maintenance of the solids contact equipment in accordance with the drawings and the erection, operating and maintenance instructions of the Manufacturer.

FUNCTIONAL CHARACTERISTICS - The solids contact unit shall provide for flash mixing, sludge recirculation, flocculation, settling and sludge removal within a single basin. The unit shall be designed to recirculate sludge at up to five times the inlet flow rate for standard clarification and up to ten (fifteen for silica removal) times the inlet flow rate for lime softening applications. Mixing of the raw water and fresh chemicals with previously formed sludge particles shall be accomplished in the flash mixing zone of the unit. Velocities shall be such that no deposition of solids can occur in the mixing zone.

The water and sludge particles shall then flow into the flocculation zone where intimate contact for at least _____minutes shall be achieved regardless of throughput rate. The flocculation zone shall be separated from the clarification zone by a properly designed cylindrical hood. The water and sludge particles shall then flow to the bottom of the unit where a portion will enter the clarification zone while the remainder shall be recirculated. The water that enters the clarification zone shall then rise and be collected by a radial pipe launder system with submerged orifices designed to produce uniform rising rates over the entire area of the tank.

Sedimentation of heavy sludge shall take place over the entire bottom of the unit and shall be moved by a mechanical scraper into a centrally located concentrator. Scraper arms shall cover entire bottom on each revolution. The sludge scraper shall be driven by a separate motor which shall also drive a positive mechanical thickener. The sludge removal pipe shall be not less than _____ inches in diameter and so designed as to facilitate cleaning. Sludge valves shall be located outside the tank and sludge discharge shall be visible to the operator. The sludge discharge system shall be equipped with a pressure water backflush system.

DESIGN - The unit shall consist of the following:

1. All fabricated steel parts within the basin including pipe connections, which shall terminate 6" outside of the basin when a steel tank is used as a basin and 6" inside of basin when concrete unit is used. Wall fittings and anchor bolts (shall) (shall not) be furnished by the equipment manufacturer when a concrete basin is used. The internal steel plate shall be 3/16" minimum thickness with structural members 1/4" minimum.

2. Steel plate 1/4" minimum thickness (shall) (shall not) be furnished to form a basin for the unit. This steel plate shall be properly stiffened at the top with suitable structural reinforcement. The bottom course of the shell shall be attached to structural steel channel embedded in the concrete bottom. The embedded channel shall be furnished by the equipment manufacturer.

3. ____ chemical solution lines installed in pipe sleeves within the basin terminating at or above the basin wall; all pressure lubrication piping within the basin terminating at the basin wall or top of basin; all fixed sample lines within the basin terminating at basin wall and including manual sampling valves.
force. Smaller components and parts which cannot be marked with painted figures shall be bagged, bundled or crated and tagged with identification referenced to page, item and line number in Manufacturers Bill of Material. The manufacturer shall furnish an instruction booklet to aid in the steel and internal assembly.

4. Effluent collector system consisting of radial pipe launders with submerged orifices.

5. Non-skid diamond plate walkway and 1-1/4" pipe handrail providing access to center of tank and scraper drive equipment. Minimum width of walkway 3'-0".

6. Sludge scraper drive mechanism with motor, gear reducer, bearings, scraper shaft, arms and blades. The drive equipment shall be equipped with a shear pin for fail safe protection. A standard duty start-stop-reverse pushbuttom station with NEMA 4 enclosure shall be furnished by Manufacturer. The drive (shall) (shall not) be furnished with an indicating overload protection device provided with dial type indicator and adjustable alarm and cut-out switches. Motor characteristics shall be __ volt, ____ phase, ____ Hertz. The arrangement of drive for sludge scraper equipment shall afford ready access for inspection and maintenance.

7. Sludge recirculation 'system consisting of a motor, variable speed controller, speed reducer, shaft and high efficiency impeller. Motor characteristics shall be ____ volt, ____ phase, ____ Hertz. The impeller shall be located at the bottom of the draft tube so that it recirculates sludge from the floor of the unit and mixes it with the incoming raw water and coagulant chemicals. Raw water and chemicals shall be introduced just above the eye of the impeller to prevent polymer shearing and to permit flash mixing with the recirculated sludge. The recirculation rate shall be adjustable over its design range to optimize performance.

8. (Proportional to inlet flow) (Time cycle) backflush and desludging control consisting of:

• Two (2) air actuated valves.
• Two (2) weatherproof solenoid valves
• Two (2) frequency duration timers for (time cycle) (proportional to flow) operation.
• One (1) counter (proportional to flow only)

9. Optional equipment and services including:

• Field erection
• Scraper rake lift mechanism
• Chemical feed equipment
• Sludge handling equipment
• Filters
• Dome type cover
• Freeze protection
• Special coatings or materials of construction

SHIPMENT AND IDENTIFICATION - Fabricated steel components shall be shipped in a minimum number of pieces for field assembly. Plates shall be marked with painted figures in accordance with manufacturers drawings, copies of which shall be furnished for use by field erection.

SHOP PAINTING - (All fabricated steel surfaces shall be shipped bare for surface preparation and painting in the field by others) OR (All fabricated steel surfaces shall be made clean and free of loose mill scale and grease by scraping and wire brushing and given one (1) shop coat of red oxide primer. Components requiring field welding shall be left unpainted within 3" of welds.)

START-UP SERVICE - Upon completion of erection and the availability of water, air, electricity and chemicals, the Manufacturer shall provide a Service Engineer to inspect the installed equipment, start unit operating and train the Owner's operator in its operation and maintenance for a period of ____ days and ____ trips. Such services shall be paid for at the per diem rate to be specified at the time of bidding by the Manufacturer plus actual travel and living expenses to and from the plant location for any service required beyond that mentioned above.

DRAWINGS AND DOCUMENTATION -

1. Seller shall furnish four (4) sets of operating manuals prior to shipment of equipment.

2. Seller shall furnish a priced list of all recommended spare parts upon completion of engineering design.

3. Unless stated elsewhere, this specification does not require drawings for engineering approval. Layout and arrangement drawing(s) for equipment supplied are to be submitted for record purposes only.

ITEMS FURNISHED BY OTHERS - The Purchaser shall furnish all external pipe, fittings or valves other than those specified above. Purchaser shall furnish utilities, conveniences, wiring conduit, chemicals, platforms, walkways, ladders, stairways, concrete, labor and erection unless otherwise specified herein. All concrete design to be by Purchaser.

WARRANTY - The Manufacturer shall guarantee the following when the equipment is operated in accordance with the written operating instructions and treating a raw water of the analysis given in the specifications:

1. Equipment furnished by the Manufacturer shall meet all of the requirements stated under PERFORMANCE.

2. Equipment and materials which prove to be defective within one year from date of shipment shall be repaired or replaced at no charge F.O.B. shipping points.

EXCEPTIONS - Any exceptions to the above specifications shall be clearly indicated and stated in proposal or bid.