Treatment Plant Specifications

EXTENDED AERATION FACTORY BUILT PACKAGE PLANT
WITH HOPPER CLARIFIER(S)
GENERAL
In accordance with these specifications and drawings, the Contractor shall furnish and install one (1) wastewater treatment system. The system shall be an activated sludge process operated in the extended aeration mode. The system shall be a 12,000 Gallon per Day treatment Unit.
The system shall be capable of treating a total flow of 12,000 gallons per day (24 hours) of domestic waste. The plant shall operate efficiently if the average daily flow rate fluctuates within 60% to 100% of design flow and peak hourly flow rates not to exceed 250% of design. The complete wastewater treatment plant shall consist of the necessary tankage and components for proper operation of process.
The plant shall be factory assembled and shipped to the job site in the fewest number of pieces to facilitate ease of installation. Larger treatment plants will require field assembly of tanks, including bolting or welding by Contractor.
CONSTRUCTION
The treatment plant side walls, bottoms and partitions shall be constructed of minimum 1/4-in. thick structural grade low carbon ASTM A-36 steel plate, joined together by arc welding with fillets of adequate strength for the joint involved. All welds above and below water level shall be seat welded. The use of caulking, or other sealants for this purpose is prohibited. The tankage shall be adequately reinforced to withstand normal pressures inside and outside of (above/be/ow) grade installations. All partition wails shall be reinforced to withstand hydraulic differentials when dewatered. The tanks shall be constructed in accordance with the latest requirements of AISC Specification for Buildings and the American Welding Society's Code.
All piping shall be minimum Schedule 40 painted steel. All control valves, where possible, shall be located on the outer perimeter of the tank wall, and shall be easily accessible without the use of walkways or extension handles. The influent and effluent pipe connections shall be grouted. The grout rings shall be an integral part of the tank structure.
INFLUENT BAR SCREEN
If necessary to remove obtrusive debris which may clog piping or pump, a bar screen device shall be furnished at the inlet to the aeration chamber. The bar screen shall remove debris larger than 1- in. diameter. The bars shall be steel flat bar 3/8-in. by 1-in, with a 1-in. opening. The bar screen shall be an integral part of the treatment plant The bar screen shall be sloped for ease of cleaning, and shall have a drying tray. The bar screen shall be readily accessible from the perimeter of the tank service walkway.

SPECIFICATIONS

AERATION CHAMBER
The aeration chamber shall have a minimum capacity of 12,000 gallons providing a 24 hour retention based on a 24 hour average flow rate, and/or a maximum organic loading of 15 lbs. of 5 day BOD per 1,000 cubic feet of tank volume. The tank profile shall eliminate sludge accumulation, and enhance rotation of the tank contents plus prevent any froth or scum

	

accumulation. The chamber shall have a 1-ft. 6-in. freeboard. To insure adequate circulation velocity the proportion of the chamber width to depth, in the direction of rotation, shall not exceed 1.33 to 1. The velocity of rotation shall be sufficient to scour the bottom and prevent sludge filleting.
The chamber shall be equipped with two (2) types of baffles. Flow control baffles shall be provided to enhance the spiral rotation of the contents of the chamber. To help eliminate floating debris from entering the settling tank a baffle shall be provided at the transfer port between the aeration and settling chambers.
AIR DIFFUSION SYSTEM
An air diffusion system shall be an integral part of the aeration chamber. The aeration system shall be located longitudinally along one side of the basin to insure maximum hydraulic retention and eliminate short circuiting of the organic particles. The aeration system shall provide the needed kinetic energy to "rolr the tank contents at a velocity to prevent the escape to the surface of minuscule air diffusion bubbles, causing their entrapment to provide maximum oxygenation efficiency.
The air diffusion system is made up of various components consisting of: an air manifold, air regulation/shut-off valves, disconnecting unions, stainless steel drop pipes, diffuser header, and non-clog type diffusers with a diaphragm type check valve. All diffuser components shall be properly sized to distribute the volume of air required for biological treatment with minimum pressure drop throughout the system.
The air distribution header shall be installed longitudinally along one side at the top of the aeration chamber. The header shall be rectangular shaped, capped at each end, and provided with couplings for riser connections. The risers shall be adequately spaced along the length of the chamber. Attached to the bottom of each riser pipe is a diffuser header with diffuser nozzles spaced approximately 6-in. on center. The header shall be spaced approximately 12-in. from the side wall and 12-in, from the bottom of the tank which will ensure optimum diffusion and mixing of the tank contents. Each diffuser assembly shall be light enough for one man to remove without the aid of lifting device. Each diffuser nozzle shall be constructed of corrosion resistant PVC. Each diffuser shall be capable of operating at a flow rate of 1 to 5 cubic feet per minute. The oxygen transfer capacity of each diffuser shall be such that an adequate supply of oxygen will be maintained in the aeration chamber to meet treatment requirements of the design sewage load.

SPECIFICATIONS

CLARIFIER CHAMBER
A clarifier chamber shall be provided to operate as a quiescent zone to permit settleable solids in the mixed liquor to be removed by gravity. The clarifier shall have a capacity of 2000 gallons which will provide a 4 hour retention at the average design flow rate. The effective volume of the clarifier shall include the upper one third of the hopper plus the area above the hopper. The bottom two thirds of the hopper shall not be considered as part of the effective volume. The bottom of the clarifier shall be formed into an inverted pyramidal hopper or hoppers. The hoppers shall not exceed a slope of 1.7 vertical to 1.0 horizontal. The bottom of each hoppers shall form a flat area of one square foot.

	 

The clarifier shall have baffling to enhance the operation of the settling zone. The inlet of the clarifier shall have a stilling baffle designed to absorb hydraulic shocks and ,disperse the flow uniformly along one side of the clarifier without short circuiting. A scum baffle shall be located longitudinally with the effluent trough. The baffle shall prevent floating debris which may enter the clarifier from passing over the effluent weir plate.
An effluent trough with adjustable steel weir plates shall be provided to ensure a uniform collection of the effluent flow. The weir plate shall have machine cut V-notches and slotted holes for adjustment. The weir plate shall be fastened to the effluent trough with stainless steel fasteners. The trough and weir plate shall be sized to accommodate the flow rate.
SLUDGE RECIRCULATION SYSTEM
The activated sludge which settles to the bottom of the clarifier, shall be recycled and/or disposed of by means of air operated pump. The airlift pump shall provide a positive means of transfening the sludge to the inlet end of the aeration chamber where it will seed the incoming raw sewage with an active culture of bacteria or to the sludge holding tank for further digestion_

SPECIFICATIONS

The airlifts eductor shall be a minimum 4-in. diameter Schedule 40 painted steel pipe. The airlift shall provide a recirculation capacity of 0% to 150% of the average daily flow. The airlift shall be designed for high efficiency by utilizing the maximum submergence possible. The air supply line to the eductor shall inject air at the same elevation as the discharge point of the aeration diffusers to ensure a uniform pressure drop throughout the air supply system. The air supply line shall have a needle valve to accurately adjust the volume of air to the eductor pipe. At the top of the airlift pump a cleanout plug shall be provided for easy dean out and maintenance.
SCUM RECIRCULATION SYSTEM
A system to remove floating debris in the clarifier chamber shall be provided. The system shall provide a positive method of returning the floating debris to the aeration chamber by means of an airlift pumps. There shall be two (2) airlifts provided constructed of 2-1/2-in. diameter Schedule 40 steel pipe with an adjustable steel inlet cone which will enable exact positioning to the water level. The airlifts shall be located strategically to provide maximum surface skimming. The airlifts shall provide a recirculation from 0% to 150% of the average daily flow. The variable flow rate is accomplished by changing the air rate to the airlift by means of a needle valve. The airlifts shall be furnished with a dean-out plug for easy cleaning and maintenance.
PLANT AIR SUPPLY
The air required for biological process and operation of the various airlift pumps shall be supplied by a dual blower system consisting of two (2) property sized positive displacement blowers. The blowers shall be located on the treatment plant or in a blower building supplied by the owner. Each blower/motor assembly shall consist of a positive displacement blower, motor 00P (TE) sheaves, V-belts, base, belt guard, inlet air filter silencer, pressure relief valve, pressure gauge, adjustable motor base, vibration dampeners, check valve, and flexible discharge coupling.
Each blower shall provide 100% of the air required for proper plant operation. The blower units shall be manufactured by Roots, Sutorbitt, Spencer or approved equal. The blower shall 

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be capable of delivering 2100 cubic feet per minute of air per pound BOD per day.
Each motor shall be open drip-proof, 1750 rpm, operating on 3 phase, 230/460 volts, 60 HZ. The motor shall be mounted on an adjustable base for proper tensioning of the belts. The motor shall be connected to the blower by means of belts and sheaves. The blower/motor assemblies which do not have a cover shall be provided with an OSHA approved belt guard.
Each blower assembly shall be equipped with an inlet air filter/silencer to reduce noise levels and protect the blower from abrasive air particles. Vibration dampeners and a flexible rubber discharge coupling shall also be furnished to protect the assembly from excessive vibrations.

SPECIFICATIONS

AIR REQUIREMENTS
The amount of air required for biological treatment shall be based on 2,100 cubic feet per minute of air per day per pound of 5 day minimum BOD or the amount of air needed to thoroughly mix the contents of the aeration chamber. The amount of air to mix the aeration tank contents shall be 3 cubic feet per minute per foot of aeration tank length. The larger of the two air requirements shall be the basis for sizing the blowers. The sludge return airlifts shall require 5- 20 cfm of air per airlift. The scum return airlifts shall require 5-10 c-fm of air per airlift The air required for a sludge holding tank shall be 30 cfm per 1000 cubic feet of tank volume. The total sum of air required for the venous components and auxiliary tanks shall equal the capacity of each blower assembly_
ELECTRICAL CONTROLS
An electrical control system shall be provided to operate the motors and other electrical devices. The control system shall be located on the top of the plant or (optional) remotely located as required by the owner_
The control shall be enclosed in a NEIVIA 3R panel for outdoor service or NEMA 12 for indoor installation. The enclosure shall be adequately supported by steel angles of floor mounting legs. The enclosure shall be mounted on an elevation to permit bottom entrance of all electrical connections.
The control system shall be in accordance with the recent design and wiring practices required in the National Electiical Code. The electrical components wiring and other appurtenances shall be mounted on a removable subpanel. The controls shall be protected by an adequately sized magnetic-circuit protection device which is also utilized as the main disconnect. The blower/motor units and any other automatically controlled motors shall be supplied with acrossthe-line magnetic starters or magnetic contractors with overload protection. Any equipment which operates automatically shall be furnished with HAND-OFF-AUTO selector switches. All redundant equipment shall be automatically alternated to ensure equal operational use.
A timer shall be provided for the blower units. This timer shall permit the operator to adjust the amount of air required in a 24 hour period for biological treatment and operation of airlift. The
, timer shall be a 1-day 24 hour timer with 96 incremental adjustment points of 15 minutes each. The timer shall also include a skip-a-day feature which will allow a separate program for weekends (when required).

	 

The control system shall be completely factory wired and tested. The enclosure shall have a pocket to store color coded electrical schematic. The terminal blocks shall be numbered for easy wiring connections. The main power supply shall be 230 volts, 3 phase, 80 cycle. The control circuitry shall operate on 120 volt, 1 phase_
The Contractor shall provide all electrical wiring, conduit and other appurtenances from the control panel to the electrical power service. AU wiring and conduit from the control panel to the various electrical components shall be supplied by the Contractor.
SURFACE PREPARATION AND COATING
All steel fabrications shall be surface prepared in accordance with the coating manufacturers requirements. All 'painting shall be done in a building under controlled environmental conditions. The tankage shall be thoroughly dean of any abrasive materials used for surface preparation prior to applying any coatings. The use of any filler materials such as putty or caulking is not permitted. All tank seams shall be seal welded to prevent corrosion. The manufacturer shall certify that the tankage has been tested for voids and holidays and verify the actual dry film thickness of the coating. All surfaces with the exception of stainless steel, fiberglass, aluminum, galvanized, PVC, or components such as blowers and motors shall be coated with Bitumastic coal tar or equal applied with a total dry thickness of 8-10 mils DFT. The manufacturer shall supply touch up paint to recoat surfaces marred during installation_
CATHODIC PROTECTION (for below grade installation)
To minimize corrosion due to electrolytic reaction with the soil the plant snail be furnished with sacrificial anodes. There shall be four (4) cathodic anode bags furnished. Each bag shall be a 35 lb. magnesium anode with copper leads fastened to a core packed in its own low resistant backfill material. The anode bags shall be securely attached to the tank with stainless fasteners. The anodes shall be buried approximately 4 to 5 feet from the tank at about 5 feet depth. The anodes shall be installed equally spaced around the tank perimeter.
FOUNDATION AND ANCHORAGE
The Contractor shall provide a reinforced concrete pad in accordance with the proiect Engineers design requirements. The concrete pad shall stabilize the plant and prevent flotation as necessitated by the soil conditions and the ground elevation. Anchorage rods (re- bars) supplied by the Contractor shall be cast into the concrete slab and welded to the anchor clips on the treatment plant. The number and spacing of the anchor rods shall be in accordance with the anchorage drawing supplied by the manufacturer of the treatment plant After attaching the anchor rods to the treatment plant the Contractor will clean the welded area and recoat with the same coating as originally supplied. Touch up paint shall be supplied by the manufacturer.

SPECIFICATIONS

FIELD ASSEMBLY
The treatment plant shall be factory built and pre-assembled prior to shipment In most cases, due to shipping limitations, some of the ancillary equipment will be shipped unattached. This will require minor assembly on the job site Utilizing bolted connections. Other fragile items may be shipped unattached because of special crating or packaging.

	 

The control system shall be completely factory wired and tested. The enclosure shall have a pocket to store color coded electrical schematic. The terminal blocks shall be numbered for easy wiring connections. The main power supply shall be 230 volts, 3 phase, 80 cycle. The control circuitry shall operate on 120 volt, 1 phase_
The Contractor shall provide all electrical wiring, conduit and other appurtenances from the control panel to the electrical power service. AU wiring and conduit from the control panel to the various electrical components shall be supplied by the Contractor.
SURFACE PREPARATION AND COATING
All steel fabrications shall be surface prepared in accordance with the coating manufacturers requirements. All 'painting shall be done in a building under controlled environmental conditions. The tankage shall be thoroughly dean of any abrasive materials used for surface preparation prior to applying any coatings. The use of any filler materials such as putty or caulking is not permitted. All tank seams shall be seal welded to prevent corrosion. The manufacturer shall certify that the tankage has been tested for voids and holidays and verify the actual dry film thickness of the coating. All surfaces with the exception of stainless steel, fiberglass, aluminum, galvanized, PVC, or components such as blowers and motors shall be coated with Bitumastic coal tar or equal applied with a total dry thickness of 8-10 mils DFT. The manufacturer shall supply touch up paint to recoat surfaces marred during installation_
CATHODIC PROTECTION (for below grade installation)
To minimize corrosion due to electrolytic reaction with the soil the plant snail be furnished with sacrificial anodes. There shall be four (4) cathodic anode bags furnished. Each bag shall be a 35 lb. magnesium anode with copper leads fastened to a core packed in its own low resistant backfill material. The anode bags shall be securely attached to the tank with stainless fasteners. The anodes shall be buried approximately 4 to 5 feet from the tank at about 5 feet depth. The anodes shall be installed equally spaced around the tank perimeter.

SPECIFICATIONS

FOUNDATION AND ANCHORAGE
The Contractor shall provide a reinforced concrete pad in accordance with the proiect Engineers design requirements. The concrete pad shall stabilize the plant and prevent flotation as necessitated by the soil conditions and the ground elevation. Anchorage rods (re- bars) supplied by the Contractor shall be cast into the concrete slab and welded to the anchor clips on the treatment plant. The number and spacing of the anchor rods shall be in accordance with the anchorage drawing supplied by the manufacturer of the treatment plant After attaching the anchor rods to the treatment plant the Contractor will clean the welded area and recoat with the same coating as originally supplied. Touch up paint shall be supplied by the manufacturer.
FIELD ASSEMBLY
The treatment plant shall be factory built and pre-assembled prior to shipment In most cases, due to shipping limitations, some of the ancillary equipment will be shipped unattached. This will require minor assembly on the job site Utilizing bolted connections. Other fragile items may be shipped unattached because of special crating or packaging.

	 

Shipping limitations may require the treatment plant to be shipped in sections and on special lowboy- trailers requiring a permit for over width or height loads. The Contractor shall provide an adequately sized crane to lift and set the tanks on the foundation slab. The manufacturer shall provide lifting lugs. The Contractor shall be given the weight of the heaviest piece prior to shipment The manufacturer shall coordinate shipment of the tanks with the Contractor and freight company to minimize time required for crane services. The freight company shall be responsible for delivering the tankage to the nearest accessible roadway.
The following is a general overview of the responsibilities of the Contractor during the installation of the equipment
•	Site preparation including excavation, concrete foundation, electrical utilities, dewatering and accessible roadway.
•	Unloading and storage of equipment in accordance with the manufacturers requirements.
•	Position tankage on the foundation and splice by welding or bolting as required by the specifications.
•	Fasten anchorage in accordance with the manufacturers instructions_
•	Supply and install all yard piping and valves including interconnecting process piping between the various tanks.
•	Provide electrical service including power pole, transformers, electrical meters, wiring all necessary appurtenances to supply power to the treatment control panel. Connect wiring and conduit to the control panel_ Provide and install wiring and conduit from the control panel to the motors and other elecuical devices.
•	Install all ancillary equipment such as blower units, comminutor handrail, service walkway, etc.
•	Prior to backfilling install drain plugs, and fill tanks with clean water to prevent flotation.
•	Install anode bags.
•	Inspect tanks for surface scratches and repair with touch-up paint
•	Backfill around the treatment plant with care to avoid damaging the tank wall_
•	Check oil levels and lubricate all mechanical equipment.
•	

Check motors for proper rotation and electrical connections.
•	Level and seal the weir plates with caulking (provided by Contractor).
FIELD SERVICE AND COMMISSIONING
The Contractor shall notify the Engineer and the manufacturer after the treatment plant has been completely installed. The manufacturer shall provide the service of a factory trained representative or factory technician to inspect the installation. The technician shall make final
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 adjustments on the equipment and instruct the plant operator on the maintenance and operation of the equipment At this time the operator will be presented with two (2) bound copies of the operation and maintenance manuals. The manuals shall include complete operational instructions, trouble shooting charts, parts lists and lubrication schedules. The manuals shall include the phone numbers of the local representative and the manufacturer for assistance in operational difficulties and placing parts orders.