SOW Sludge Holding Tank Aerator and Instal for sams.pdf

UNITED STATES DEPARTMENT OF AGRICULTURE

BELTSVILLE AGRICULTURAL RESEARCH CENTER

FACILITIES SERVICE

UTILITIES MANAGEMENT UNIT

BUILDING 426A, BARC-EAST

10300 BALTIMORE AVENUE

BELTSVILLE, MARYLAND 20705-2350

STATEMENT OF WORK

November 2021

STATEMENT OF WORK

PROJECT LOCATION:

Beltsville Agricultural Research Center (BARC), Bldg. 015, USDA Westside Wastewater Treatment Plant (Westside WWTP), Beltsville, Maryland.

DESCRIPTION OF WORK:

BARC Westside WWTP Sludge Holding Tank Aerator. To furnish and install a Submersible Aerator complete with electrical cables, lifting cables, controls, and motor starter for aerating the plant’s Sludge Holding Tank.

The project will include purchase of supplies; installation services; and minor construction (as needed with installation).

1.0 GENERAL

1.1 Background

USDA, Beltsville Agricultural Research Center’s (BARC) Westside WWTP was built in 1993. It is a small, activated sludge package plant with an average daily flow of 0.26 MGD. Waste activated sludge from the activated sludge treatment process is transferred into an aerobic digester within the treatment unit where it is aerated for about 15 days. Digested sludge is then pumps to a sludge holding tank for further processing and disposal.

1.2 Overview and Purpose of Statement of Work:

The Westside WWTP Sludge Holding Tank is a 20 ft diameter glass-lined steel bolted tank. Walls of the tank are 15 ft high with 3 ft of free board. Maximum design capacity of the tank is approximately 28,200 gallons. The sludge in the tank is mixed and further aerated using a Submersible Aerator which is currently not operating due to mechanical and electrical problems. Furnishing and installing a new aerator system for this tank is the scope of this project.

2.0 SCOPE OF WORK:

2.1 General Requirements

2.2 The contractor shall furnish and install ONE (1) submersible aerator complete and operational with all mechanical appurtenances and air piping as well as all electrical and control equipment including wiring, and control panels.

2.3 Work shall include all labor, materials, equipment, and incidentals necessary and required for the aeration system to be complete and operational as specified.

2.4 Performance Requirements

2.4.1 The submersible aerator shall be capable and completely aerate and mix the sludge inside the sludge holding tank with the following criteria:

Number of Tanks: 1 Nominal Capacity 28,200 gallons Tank Type: Glass-lined steel, bolted Tank Manufacturer: US Filter Tank Inside Diameter: 20 feet

Tank Walls Height: 15 feet Maximum Liquid Depth 12 feet @ side wall Material Stored: Aerobically Digested Sludge Specific Gravity: 1.02 Sludge Content: 1.5% – 3% Number of Aerators: 1 Air Application Rate: 20 Cubic feet per minute per 1000 cubic feet of tank volume Aerator Minimum Oxygen Transfer Rate: 5 pounds O2/HR Aerator Minimum Horsepower: 7.5 Aerator Speed: 1770 RPM

SPECIFICATIONS

1.0 GENERAL

1.1 Work Included

A. The contractor shall furnish and install ONE (1) submersible aerator complete and operational with all mechanical appurtenances and air piping as well as all electrical and control equipment including wiring, and control panels.

B. Work shall include all labor, materials, equipment, and incidentals necessary and required for the aeration system to be complete and operational as specified.

1.2 Unit Responsibility

A. The Aerator, complete with motor, shafting, necessary guards and all other accessories and appurtenances shall be furnished by the aerator manufacturer to ensure compatibility and integrity of the individual components and provide the specified warranty for all components.

1.3 Qualifications and Quality Assurance

A. The Aerator Unit specified shall be the products of a reputable manufacturer who has been regularly engaged in the design, manufacture and furnishing of Wastewater Submersible Aeration Equipment for at least ten (10) years. The manufacturer shall have installed similar aerators, performing similar duty, for at least three (3) other installations in Mid Atlantic area.

Each such installation shall have performed satisfactorily for at least five (5) years and be still in operation.

1. The manufacturer shall provide references and their contact details to verify these successful installations.

2. Aerators shall be engineered and manufactured under the certification of ISO-9001.

3. All manufacturer parts and components shall be engineered for long, continuous, and uninterrupted service. Provisions shall be made for easy lubrication, adjustment, or replacement of all parts.

4. All stages of the manufacturing process shall be carefully inspected at the factory by manufacturer’s inspectors who shall use whatever means necessary to assure the proper fit of all field connections and compliance with all material and fabrication requirements of the specifications.

5. The aerator and control panel shall be factory wired and assembled. Assembly and wiring shall be to the point where the only field interconnections to numbered terminal blocks are required.

1.4 Factory and Performance Testing

A. The aerator shall be factory tested for sound component and optimum operation parameters including temperature, proper assembly, non-clog impeller and performance under operating conditions. The manufacturer shall provide factory testing results to the owner for verification.

Performance testing shall also be administered onsite after installation, the manufacturer representative shall be available onsite for such testing with the appropriate equipment to measure oxygen transfer rate and mixing capabilities.

1.5 Submittals

A. General:

1. Schedule submittals well in advance of the need for the material or equipment for construction.

Allow time to make delivery of material or equipment after submittal is approved

2. Develop a submittal schedule that allows sufficient time for initial review, correction, resubmission, and final review of all submittals. The OWNER will review and return submittals to the CONTRACTOR as expeditiously as possible and within a maximum period of two weeks.

3. Provide Shop Drawings, administrative, quality control, and contract closeout submittals in accordance with the requirements of this specification.

4. The OWNER’S review of submittals covers only general conformity to the contract documents.

The CONTRACTOR is responsible for any errors, omissions, or deviations from the Contract requirements; review of submittals in no way relieves the CONTRACTOR from his obligation to furnish required items according to the contract documents.

5. Submit five (5) copies of documents unless otherwise specified in the Submit five (5) copies of documents unless otherwise specified in the contract documents. In addition, one electronic copy of each submittal shall be furnished to the OWNER.

6. Action Submittal Dispositions: OWNER will review, mark, as appropriate, and distribute marked-up copies as noted:

APPROVED: CONTRACTOR may incorporate product(s) or implement Work covered by submittal.

APPROVED AS NOTED: CONTRACTOR may incorporate product(s) or implement Work covered by submittal, in accordance with ENGINEER’s notations.

PARTIAL APPROVAL, RESUBMIT AS NOTED: Make corrections or obtain missing portions, and resubmit. Except for portions indicated, CONTRACTOR may begin to incorporate product(s) or implement Work covered by submittal, in accordance with OWNER’s notations.

REVISE AND RESUBMIT: CONTRACTOR may not incorporate product(s) or implement Work covered by submittal.

7. Distribution of all submittals will be made as follows: Four copies of the furnished submittal will be retained in OWNER’s file. Remaining copy returned to CONTRACTOR appropriately annotated.

8. Apply CONTRACTOR'S stamp, certifying that the items have been reviewed in detail and are correct and in accordance with Contract Documents, except as noted by any requested variance.

As a minimum, Contractor's Stamp shall include:

• CONTRACTOR'S name.

• Certification statement that the CONTRACTOR has reviewed the submittal and it is in compliance with the Contract Documents.

• Signature line for CONTRACTOR.

B. Shop Drawings as a minimum shall include:

1. Make, model, weight, and horsepower of the equipment assembly.

2. Complete catalog information, descriptive literature, dimensions, and drawings, cut sheets, Specifications, identification of materials of construction.

3. Performance data curves showing oxygen transfer rates, minimum submersion depth, submersion depth for automatic start, and horsepower demand over the entire operating range. Performance data shall also include schematics of the active mixing zones/areas of the aerator.

4. Power and control wiring diagrams, including terminals as well as Instrumentation and control data.

5. Complete motor nameplate data, as defined by NEMA, motor manufacturer, and including any motor modifications. List any motor special features being provided.

6. Information on bearing life and type of bearing lubrication recommended.

7. Factory-finish system including epoxy coating system for cast iron and steel components.

Include the manufacturer’s descriptive technical catalog literature and specifications and hazardous communication data sheets.

C. Provide Quality Control Submittals as follows:

1. Operations and Maintenance Data and manuals.

2. Manufacturer’s Certification of Compliance that the factory finish system is identical to the requirements of these specifications.

3. Manufacturer’s Certificate of Proper Installation.

4. Manufacturer’s Training Program.

5. Equipment Testing and Field Startup Report.

2.0 PRODUCTS

2.1 Performance Requirements

A. The submersible aerator shall be capable and completely aerate and mix the sludge inside the sludge holding tank with the following criteria:

Number of Tanks: 1 Nominal Capacity 28,200 gallons Tank Type: Glass-lined steel, bolted Tank Manufacturer: US Filter Tank Inside Diameter: 20 feet Tank Walls Height: 15 feet Maximum Liquid Depth 12 feet @ side wall Material Stored: Aerobically Digested Sludge Specific Gravity: 1.02 Sludge Content: 1.5% – 3% Number of Aerators: 1 Air Application Rate: 20 Cubic feet per minute per 1000 cubic feet of tank volume Aerator Minimum Oxygen Transfer Rate: 5 pounds O2/HR Aerator Minimum Horsepower: 7.5 Aerator Speed: 1770 RPM

2.2 Approved Manufacturers

A. Fluence – Hurricane Aerators

B. Aerator Solutions

C. Approved Equal

2.3 Aerator Requirements

A. General: The aerator shall be of a submersible type, complete with cables, lifting chains or cables.

Each aerator shall consist of a submersible electric motor directly coupled to an impeller. The impeller shall be housed in a replaceable stator assembly beneath the submersible motor. The stator assembly may be designed to distribute air and water efficiently throughout the basin. A stationary air intake pipe shall be provided to draw atmospheric air from above the water surface into the aerator where it is thoroughly mixed by the impeller and stator into the wastewater/sludge. This aeration shall occur without the use of a separate air blower or compressor.

B. Site Specific Requirements: The aerator weight shall be sufficient to keep the aerator grounded, balanced and stationary during operations as the aerator will be installed/removed during full tank operations and without the need for anchor bolts. The air intake pipe will be anchored to the sludge holding tank platform, but that anchoring is only to hold the intake pipe vertical and shall not affect the performance or anchoring of the aerator itself.

C. Impeller: A non-clog, non-fouling, high-efficiency impeller shall be used. The impeller body shall be constructed with stainless steel and hardening treatment for maximum strength, minimum corrosion, and maximum abrasion resistance. The impeller shall be dynamically balanced for minimum vibration and maintenance free operation. The impeller shall rotate within a stator assembly to maximize air to water interface and to provide the desired amounts of air required for aerating the sludge holding tank on its entirety. The non-clog feature of the impeller and its operation within the stator shall provide a free passage of solids up to 2” diameter and to have the ability to further chop/grind solids to further improve wastewater treatment.

D. Stator: The stator shall be a one-piece stainless-steel design hardened similar to the impeller. The stator shall be easily replaceable without the need to replace other components of the aerator assembly. The stator shall accommodate the optimum number of air diffuser pathways to distribute the air/water mixture away from the aerator assembly along the radial plane of the aerator, a minimum of at least eight (8). The stator shall incorporate threaded openings to allow the installation of air diffuser tubes of varying lengths and diameters to optimize the distribution of oxygen and mixing in the basin.

E. Motor: The submersible aerator motor shall be explosion proof built to U.L. standards for use in Class I Groups C & D hazardous locations. The motor shall have a cast iron housing coated with epoxy paint to withstand corrosion in the wastewater/sludge environment, a 416 stainless steel motor shaft, oil-filled chamber with double mechanical seals, a seal minder (moisture detector), and thermal overload protection. The outer seal shall be constructed from a silicon carbide and withstand pressures up to 20 bar g. The outer seal shall have no exposed spring or seal faces on which debris may collect and be designed for use in applications involving extreme solids and grit.

Each motor shall have thirty-five (35) feet of submersible power cable attached at the factory. The cable entry seal shall be watertight and submersible. The motor shall incorporate a sensor to detect water leakage through the outer seal. A separate electrical lead from the motor shall provide a signal from the leakage sensor to the control panel.

F. Aerator Base Assembly: The aerator base assembly shall be constructed of 304 stainless steel. A bronze wear bushing shall be pressed into the base assembly, providing an air seal and deflection protector for the rotating impeller. The aerator base assembly shall include extended legs with adjustable vibration-dampening feet to allow the aerator to be leveled on most basin bottom surfaces and to absorb vibration during operation.

G. Ancillary Equipment

1. Air Intake Pipe and Strainer: The aerator shall be equipped with an air intake pipe of at least 17 feet to be mounted on the aerator and anchored to the aerator assembly as well as to the sludge tank platform above the tank. The air intake pipe shall be stainless steel and constructed of flanged joint connection to the aerator assembly. The air intake pipe shall be attached to the aerator base via a heavy-duty stainless steel bolted flange and gasket. An air inlet strainer shall be supplied for the top of the air intake pipe to prevent infiltration of airborne debris and particulates. The air inlet strainer shall be of non-corrosive material and shall have a total open area of at least twice the open area of the air inlet pipe.

2. Air Diffuser Tubes: If required by the design of the manufacturer for optimum air distribution, the air diffuser tubes shall be constructed from 304 stainless steel.

3. Spare Parts: The manufacturer shall submit recommended spare parts as part of the shop drawings and provide such parts as part of the supply.

2.4 Aerator Control System

A. Control Panel

1. One (1) control panel shall be furnished, completely pre-wired and tested.

2. The control panel shall adhere to the following specifications:

a. Enclosure Rating: NEMA 4X

b. Material: 304 SS

c. Voltage: 480 Volt

d. Phase: 3 Phase

e. Frequency: 60 Hz

f. Load: 11 Amps

g. Logic: Programmable Relay

3. The Control panel shall contain all timers, switches, indicator lights, and other components necessary to operate the aerator

4. The control panel shall be supplied with applicable control relays and time delay relays with a minimum one extra normally closed and one extra normally opened contact is provided for each relay.

5. At this facility, remote monitoring is currently limited, but it will be expanded soon, accordingly, the panel shall be provided with Form C contacts for all dry contacts necessary. Remote monitoring and control shall include monitoring the aerator run status, run hours, remote starting and stopping and automatic operations based on level and timer.

6. The motor starter shall be NEMA rated size 1 minimum with adjustable solid-state overload protection

7. The control panel operator device shall be rated 4X, heavy duty, 30.5 mm, lights to be LED Push-to-Test type.

8. The panel door layout shall include the following items:

a. Front panel mounted main disconnect switch

b. Motor circuit breaker

c. Back lit Power Maintained 2-way switch

d. System three position HOA switch

e. System Emergency Stop push button

f. System Alarm Reset push button (optional)

g. Aerator running light

h. Aerator fail indicating light

i. Aerator manual START push button

j. Aerator manual STOP push button

2.5 Sequence of Operation

A. The system shall be controlled in either automatic or manual mode including manual starting, stopping and system shut down when a fault is detected.

1. Wastewater sludge shall be pump fed into the sludge holding tank from the plant’s aerobic digesters.

2. When the sludge level at the tank reaches the aerator safe start level, the aerator shall start automatically (aerator manufacturer determines that level and shall provide the level sensing device). After the initial start, the aerator shall start/stop based on a timer. A time clock (TC) shall dictate the start/stop cycle. The time clock shall be adjustable to initiate cycles up to every 15 to 20 minutes.

3.0 EXECUTION

3.1 Installation

A. Aerator shall be installed in the basin at closest location to the center of the tank and at a safe distance from sliding into the sludge hopper. The cables shall be of sufficient length for connection to the edge of the basin.

B. Lifting chains/cable shall be provided as part of the assembly and shall be used to install the aerator.

3.2 Field Services

A. The manufacturer shall provide one (1) day of field service by a qualified service engineer to inspect and test for lubrication, alignment, free operation, and to instruct the Owner's personnel in the proper operation and maintenance of the equipment. Instructions for long-term storage and maintenance of the aerators and motors shall be provided.

B. Manufacturer's field engineer or representative shall certify that the aerator has been installed in accordance with the manufacturer's instructions and that trial operation of the aerators has been satisfactorily completed and that the aerators had met performance requirements.

3.3 Startup and Testing

A. All cost of testing and instructions shall be at no cost to the Owner.

PROJECT CONDITIONS AND SPECIFICATIONS

1.0 PROJECT COORDINATION

1.1 Communications

1.1.1 All communications shall be through the Project CO and the Project COR

1.1.2 Acceptable forms of communications include Emails, Letters, and Telephone

Memoranda

1.2 Project Schedule

1.2.1 Within a week of project award, the contractor shall submit project schedule following the Milestones below:

1.2.1.1 Shop drawings submittal within 2 weeks

1.2.1.2 Equipment delivery within 8 weeks

1.2.1.3 Installation, certification of installation and owner’s training within 10 weeks

1.2.2 Progress Meetings & Reporting

1.2.2.1 A Progress Report shall be submitted to BARC Representatives monthly and/or with each billing cycle/invoice.

1.2.2.2 A Progress Meeting shall be held with BARC Representatives at every Project

Milestone

1.2.3 Quality Requirements

1.2.3.1 Quality procedures outlined on the project specifications plan shall be followed and records submitted to BARC Representatives with every milestone.

1.2.4 Change Management

1.2.4.1 No changes to the scope of work will be accepted without a written approval of

BARC Representatives

1.2.5 Project Resource Management

1.2.5.1 Changes to project team personnel shall be approved in advance by BARC Representatives

1.3 SAFETY SUBMITTALS

1.4 CONSTRUCTION SECURITY REQUIREMENTS

1.5 FIRE SAFETY

1.6 OPERATIONS AND STORAGE AREAS

1.7 ALTERATIONS

1.8 DISPOSAL AND RETENTION

1.9 PROTECTION OF EXISTING VEGETATION, STRUCTURES, EQUIPMENT, UTILITIES,

AND IMPROVEMENTS

1.10 RESTORATION

1.11 AS-BUILT DRAWINGS

1.12 USE OF ROADWAYS

1.13 TEMPORARY TOILETS

1.14 AVAILABILITY AND USE OF UTILITY SERVICES

1.15 TESTS AND BALANCING

1.16 INSTRUCTIONS

1.17 RELOCATED EQUIPMENT AND ITEMS

1.18 HISTORIC PRESERVATION

-End-