Amendment_1_and_Attachments.pdf

Mission Beach Wastewater

Treatment Facility

Improvements Project

Construction Stormwater Pollution Prevention Plan

September 2014

IHS - Tulalip Tribes

Mission Beach Wastewater Treatment

Facility Improvements

Construction Stormwater Pollution Prevention Plan

Table of Contents Introduction

Existing Site Conditions

Adjacent Areas

Critical Areas

Soils

Erosion /Contaminant Discharge Problem Areas

Construction Stormwater Pollution Prevention BMP Elements

Mark Clearing Limits

Establish Construction Access

Control Flow Rates

Install Sediment Controls

Stabilize Soils

Protect Slopes

Protect Drain Inlets

Stabilize Channels and Outlets

Control Pollutants

Control Dewatering

Maintain BMPs

Manage the Project

Wastewater Treatment Facilities

Improvements

Construction Stormwater Pollution Prevention Plan

Introduction

This Stormwater Pollution Prevention Plan (SWPPP) has been prepared for submittal to the Government as required per the specifications of IHS project Number PO-10-L17, Tulalip tribes Mission Beach Wastewater Treatment Plant Improvements. The project is located at the site of the existing Mission Beach Wastewater Treatment Plant (WWTP) and the current site of the influent lift station serving the plant, Lift Station No. 3. (Note that this SWPPP applies only to stormwater runoff and dewatering operations from the construction site and not to sewage discharges. Untreated sewage shall not be discharged from the site under any circumstances). It is the overall intent of the SWPPP to manage runoff and dewatering flows such that the water infiltrates into the soil rather than entering surface waters, and if any flows must enter surface waters that the turbidity and contaminants have been removed prior to discharge.

Construction activities will include demolition, excavation, trenching and minor grading. The purpose of this SWPPP is to describe the proposed construction activities and all Temporary and permanent Erosion and Sediment Control (TESC) measures, pollution prevention measures, inspection monitoring activities, and record keeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to:

1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity.

2. Prevent violations of surface water quality, ground water quality, or sediment management standards.

3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff/dewatering flows at the Permittee's (contractor’s) outfalls and downstream of the outfalls (outfall meaning any location where surface water is traced to the construction site).

Existing Site Conditions

The WWTP site is slightly less than 1 acre with 75% of the surface area paved.

Runoff from the WWTP site is collected in catch basins and conveyed west toward the tide flats of Tulalip Bay.

Adjacent Areas

No upstream areas contribute flow to the site.

Critical Areas

Wetlands are present in the Lift Station No. 3 area.

Soils

The NRCS Snohomish County Soil Survey identifies the predominant soil type on the site as Kitsap silt loam: very deep, moderately well drained, on 0 to 8 percent slopes; on terraces from lacustrine sediments. The soils have slow permeability and the hazard of water erosion is slight.

Erosion /Contaminant Discharge Problem Areas

There are currently no known erosion problem areas within the clearing limits of the site. However, erosion is a possibility during construction and contaminant discharges are a significant risk. Since rainfall on the site is likely to be the principal cause of erosion and transport of sediment and contaminants to surface waters, this risk will be reduced by scheduling earthwork for the dry summer season.

If this project continues into the winter season, the following wet weather precautions will be practiced.

Prevention of tracking mud onto roads through the use of equipment sweeping onsite and if necessary, a wheel wash installed near the construction entrance.

Geotechnical fabric shall be installed under all construction entrances with quarry spall rock surfaces.

Exposed portions of the site shall be adequately covered by straw or mulch material based upon the weather. Straw or approved equivalent material will always be available on site and ready to use. Exposed areas will be adequately covered when raining and at the end of the day if the next day is a “non-working” day. Weather forecasts shall be used to govern whether work will commence or stop for the day.

All site work generating exposed soil (with the exception of installation and maintenance of erosion control BMPs) shall cease during weather conditions when rain generates runoff and causes erosion.

If necessary, earthwork shall be phased to minimize areas of exposed soil.

The Contractor will devise a maintenance and inspection schedule with an identified erosion control specialist responsible for these items.

A Certified Erosion and Sedimentation Control Lead (CESCL) is recommended but not required for this project. However, the contractor shall designate an employee to be present or on-call throughout the project duration to ensure the BMPs are working appropriately and are well maintained (erosion control specialist). This erosion control specialist will monitor the discharge after each storm event that generates runoff. They will also conduct site inspection reports on the installed BMPs. These reports will be available on site and provided to the Contracting Officer’s Representative (COR) on a monthly basis with progress payment requests and/or when requested.

Vegetated buffers and forest areas shall be protected, especially through the use of silt fences or compost socks, and minimization of soil exposure.

If necessary, dirty water shall be filtered through an approved device such as a Baker tank, prior to releasing it. Particularly for dewatering operations that may be needed during construction at Lift Station No. 3.

Open drainage ditches shall have a method of slowing the surface flow of water through the use of stilling pools created with sand bags or quarry spalls (along Mission Beach Dr. and Mission Ave.).

Catch basins within the treatment facility drain to the influent lift station No.3 which pumps directly back into treatment facility processes.

Contaminants that enter catch basins will be discharged to the Puget Sound and cause a violation of the Tribes NPDES permit. The Contractor shall control discharges from the treatment facility at all times.

Construction Stormwater Pollution Prevention BMP Elements

Mark Clearing Limits

The clearing limits will be established prior to beginning land disturbing activities by placing high visibility fence around the areas indicated on the plans.

Establish Construction Access

A quarry spall construction access with geotextile fabric under the rock will be installed at the entrance of the Lift Station No. 3 site. If necessary during wet weather, a wheel wash facility may be constructed to minimize the impact of construction on nearby streets. As an additional measure, street sweeping will be performed when required.

Control Flow Rates

All drainage from the site will be directed to an on-site infiltration structure or level spreader designed to infiltrate the runoff/dewatering flows into the soil.

Any flows that can not be infiltrated into the soil will be treated prior to discharge from the site. No sediment laden or contaminated runoff will enter surface waters under any circumstances.

Install Sediment Controls

Sediment controls include a silt fence or compost sock along the perimeter of the site, interceptor ditch, covering of soil stockpiles, and installation of straw or mulch when necessary. Erosion control BMPs shall be installed prior to land disturbing activities as noted on the plans. Catch Basin filters are a requirement.

Stabilize Soils

To protect soil stockpiles from erosive forces such as rain, plastic sheeting, jute mats or similar BMPs will be placed upon exposed and non-worked soil throughout construction. Per wet weather requirements, these BMPs will be placed within 2 days of stockpiling the soil from October 1st through April 30th or if raining.

Protect Slopes

Slopes are not anticipated to be damaged from concentrated flows. Stockpile slopes shall be protected as mentioned in the “Stabilize Soils” section.

Protect Drain Inlets

To prevent sediment from moving off the site, catch basin inlet protection shall be used for any catch basins downstream of work areas and on new catch basins as they are installed. Inlets will be inspected weekly at a minimum and daily during storm events as noted on the plans. Sediment shall not accumulate greater than three inches in depth within the inlet protection device.

NOTE: catchbasins within the WWTP yard drain back into the influent lift station No. 3 wet well and then through the wastewater treatment system. Catch basin inlet protection filters will be monitored and replaced frequently to eliminate any sediment from entering the treatment processes.

Stabilize Channels and Outlets

Where site runoff is to be conveyed in channels such as along Mission Ave., or discharged to some other natural drainage point, efforts will be taken to prevent downstream erosion.

Control Pollutants

Good housekeeping practices and appropriate BMPs will be utilized to control pollutants on site. Any water used to clean equipment or pumped from the existing drainage facilities shall be filtered through an approved filtering device and tested prior to discharging to an undeveloped portion of the site.

Control Dewatering

Any water from dewatering operations that may occur throughout this project, will be conveyed to an approved filter such as a Baker tank and then released to an undisturbed area on site. All measures shall comply with Tulalip Tribe and Washington State Department of Ecology requirements.

Maintain BMPs

The BMPs shown on the plans will be maintained and repaired as needed.

Specific maintenance requirements are listed in the notes and/or details on the plans. Monitoring will be conducted by the designated erosion control specialist and the COR to ensure BMPs are working effectively and are not damaging facilities or waterways downstream of the site.

Manage the Project

Erosion Control Specialist: The contractor shall provide the name and phone number of an erosion control specialist that will verify that the actions noted in this Stormwater Pollution Prevention Plan and on the drawings will be implemented. This person will be contacted in the event of an erosion control/ contaminant discharge problem outside of normal work hours and during weekends and Holidays, and it will be their responsibility to address the erosion/sediment/contaminant discharge problem immediately.

Phasing of Construction: The first order of work will include establishing clearing limits, installing appropriate BMPs for erosion control and clearing sediment. The remaining site will then be cleared and project development will commence. The site shall be protected as described in this Plan and on the drawings. Throughout the work, the contractor is responsible for maintaining all BMPs. Upon completion of the work, temporary BMPs shall be removed as necessary.

Seasonal Work Limitations: Work should be scheduled for the dry season however, it may be conducted during the wet weather season of October 1 through March 31st. Construction entrances consisting of a wheel wash facility and/or underlying geotextile fabric will be utilized to minimize the disturbance from transporting soils from the existing site. All stockpiles shall be covered with plastic sheeting, straw (or equal) to minimize any loss of soil during the wet weather. The Contractor will be responsible for consistently monitoring any outfall to ensure all applicable requirements are met and that water quality downstream is not being compromised throughout this process.

In addition, the contractor’s erosion control specialist will be responsible for ensuring that proper BMP maintenance is conducted throughout the season as well as ensuring the local requirements are met through testing and other appropriate methods.

Coordination with Utilities and Other Contractors: As stated on the plans and in the specifications, the contractor shall be responsible for coordinating any utility work with the appropriate agencies.

Inspection and Monitoring: Inspection and monitoring as well as compliance will occur in accordance with the Washington State Department of Ecology (DOE) Stormwater Management Manual for Western Washington. The COR and/or Tulalip Natural Resources Department staff will provide regular inspections of the effectiveness of the erosion and contaminant discharge measures and a written report. The contractor shall immediately address any ineffective BMP that allows erosion or the discharge of contaminants to surface waters.

At any location where runoff will enter surface waters, a runoff sample will be obtained by the COR and tested for turbidity and pH by a state certified laboratory. If the contractor wishes to use their own turbidity meter, they must demonstrate calibration for the COR prior to use. The COR will obtain samples after significant rainfall or spill events.

The contractor’s erosion control specialist will be present or on-call throughout the project duration to insure the BMPs are working appropriately and are well maintained. The specialist and the Contracting Officers Representative (COR) will choose appropriate monitoring sites and note them on the field copy of the plans. Sampling points will be determined during the pre-construction meeting and after observing movements of runoff as work progresses and shall be marked with a stake. They will monitor the discharge from this site after each storm event that generates runoff as well as once per month if flow is occurring. They will also conduct site inspection reports on the installed BMPs. The monitoring and sampling shall be done in a professional manner consistent with current DOE sampling protocols and reporting requirements. A turbidity value greater than 25 NTUs indicates erosion/sedimentation control measures are not adequate. A turbidity value greater than 250 NTUs indicates a significant problem and the contractor shall stop work and focus efforts on erosion/sedimentation control.

Reporting: All spills or discharge of pollutants shall be reported within 24-hours to the COR and the Tribe. Discharge samples shall be tested for turbidity during or immediately after significant precipitation events and the results reported to the COR. A turbidity level of 250 NTUs requires the contractor to contact the Tulalip Tribes Natural Resources Department and the Washington State Department of Ecology following the instructions on the DOE website:

http://www.ecy.wa.gov/programs/wq/stormwater/construction/.

Site inspection reports will be available on site and provided to the COR on a monthly basis and/or when requested by the COR or the Tribe. An NPDES Construction Stormwater General Permit is not required for this project. A Notice of Intent is not required for this project, however the contractor shall follow the reporting requirements of the Tulalip Tribes Natural Resources Department.

http://www.ecy.wa.gov/programs/wq/stormwater/construction/

Maintenance: No maintenance on heavy equipment is expected to occur on site throughout the project. Any spilled equipment fluids such as hydraulic fluid or oil shall be immediately absorbed, contaminated soil excavated, and the absorbent and/or soils disposed of at a disposal site equipped to accept such wastes. Spill response kits will be present on-site at all times during the performance period.

Maintenance of the Construction SWPPP: This plan will be located on site at all times. The plan will be revised accordingly if significant changes have been made to the design, construction, operation, or maintenance of any BMPs.

ADDENDUM NO. 1

(G&O #12563.01) 11331-2R

1.4 PERFORMANCE REQUIREMENTS

The mechanical fine screen shall meet the following design conditions:

Parameter Performance Requirement

Mechanical Fine Screen Maximum Hydraulic Capacity (mgd) 2.97 Maximum Upstream Liquid Level (inches) 13.75 Maximum Head Loss at Maximum Capacity (inches) 8 Wash water requirement (gpm) 20 Wash water requirement (psi) 60 Bar Spacing (inches) 0.25 Nominal Screening Basket Diameter (inches) 31 Screening Chamber Width (inches) 38 Minimum Screen Invert to Discharge Height (inches) 89 Screening Screw Conveyor Diameter (inches) 10

1.5 QUALITY ASSURANCE

The equipment manufacturer’s shop welds, welding procedures, welders, and welding operators shall be qualified and certified in accordance with the requirements of the latest edition of ANSI/AWS D1.1 “Structural Welding Code – Steel” published by the American Welding Society.

Fabricate all parts and assemblies from sheets and plates of Type 304 stainless steel with a 2D finish conforming to ASTM A666, unless noted otherwise.

Fabricate all tubular products and fittings to conform to ASTM A269, A351, and A403.

All welding in the factory shall be accomplished using shielded arc, inert gas, MIG or TIG method. Add filler wire to all welds to provide for a cross section and weld metal equal to or greater than the parent metal. Fully penetrate butt welds to the interior surface and provide gas shielding to interior and exterior of the joint.

Bolts, nuts, and washers shall be Type 304 stainless steel furnished in accordance with ASTM A193.

1.6 DELIVERY, STORAGE, AND HANDLING

All equipment shall be completely factory assembled, skid mounted, crated and delivered to protect against damage during shipment.

(G&O #12563.01) 11331-3R

All exposed flanges shall be covered and sealed with shrink-wrap to prevent the entrance of moisture. Finished iron or steel surfaces not painted shall be properly protected to prevent rust and corrosion.

All equipment delivered to the site shall be stored as specified in accordance with the manufacturer’s instructions.

PART 2 PRODUCTS

2.1 APPROVED MANUFACTURERS

The mechanical fine screen shall be a Lakeside Fine Screen, Model 31FS-0.25, or equivalent equipment manufactured by Huber.

The structural, mechanical and electrical designs shown on the Plans are based on the equipment manufactured by Lakeside. Any modifications to the mechanical, structural, electrical, instrumentation and control and other portions of work that may be required to adapt the general layout and details shown on the Plans to the equipment actually furnished shall be at no additional cost to the Owner. All necessary revisions shall be made at Contractor’s sole expense. All redesign information prepared by the contractor shall be submitted for review prior to incorporating the redesign into the work.

In order to assure uniform quality, product functionality, and ease of maintenance;

all of the equipment specified in this Section shall be supplied by one manufacturer.

2.2 SCREEN

The screen unit shall consist of a screen basket, rotating rake, cleaning comb, concentric screw conveyor, dewatering and compaction section, drive assembly, and pivoting support structure.

The screen shall be complete with electrical control panel, motor starter and level sensing system.

The system shall be explosion proof, with the exception of the control panel.

Systems for this project, other than cylindrical bar screens with integral screening, screenings washing, transport, and compaction/dewatering, using a single motor drive system, will not be considered.

The bar spacing specified shall be clear opening between the fixed bar elements only. Screen designs which account for the specified spacing between a fixed bar element and adjacent rake element will not be acceptable for this project. Screens

(G&O #12563.01) 11331-4R using perforated plate, traveling filter media, fabric wire or wedge wire will not be acceptable for this project.

The screen shall operate intermittently based on level measurement and a timer.

The average bar screen flow through velocity shall not exceed 3.3 ft/sec under any flow condition up to the maximum hydraulic capacity. The screen hydraulics shall be designed to minimize solids deposition in the channel.

The operation of the rake cleaning mechanism shall be automatically initiated at a preset high liquid level. Screens that operate continuously or via timer only will not be acceptable. The rake shall remove solids from the screenings basket and deposit them into the concentric screw conveyor trough after passing through a cleaning comb, where reverse movement of the rake shall provide positive cleaning of the rake mechanism. The screenings shall be transported up the screw conveyor and through a compression chamber.

The screening equipment shall produce dewatered screenings capable of passing the EPA Paint Filter Test as described in method 9095 of EPA Publication

SW-486.

Due to the high solids loadings in wastewater, the entire screen basket shall be completely cleaned to ensure minimum headloss and rapid cleaning of the screen.

All open spaces of the screen shall be positively cleaned via teeth that pass through the full depth of the bars during each cleaning cycle. Spray wash water or screw flights with brushes will not be an acceptable method of cleaning the screen.

The control system shall be designed so that the cleaning characteristics of the screen and spray wash systems can be changed via the programmable controller.

Systems that do not offer this feature will not be considered for this project.

To minimize odors and nuisance inspect populations, the screen transport system and compaction/dewatering system shall be completely enclosed.

The spray wash systems shall be completely enclosed to prevent spray, aerosols, and leakage from coming in contact with the operating floor.

The bar screen shall be designed and built to withstand maximum possible static and hydraulic forces exerted by the liquid to the screen. All structural and functional parts shall be sized for the loads encountered during the screening, conveying and pressing operations. All submerged components and all components of the screen in contact with the screened solids shall be of stainless steel construction.

(G&O #12563.01) 11331-5R

The screen basket shall be of a cylindrical shape that shall be open at the top. The screen bars shall be perpendicular to the centerline of the screen. The basket ring support bars shall have adequately machined slots so that the rake teeth can penetrate the basket ring bars to ensure proper cleaning of the full basket depth.

The screen basket shall use graduated depth bars to provide three distinct screening planes (bar heights) on the screen interior to provide superior solids capture and removal from the flow. Designs that utilize a single bar height will not be acceptable for this project. The bar spacing shall be 1/4 inch. Perforated plate, fabric wire, wedge wire or lamella plates will not be acceptable screen media.

Each ring shall be fabricated from sections that have been cut from flat cold rolled stainless steel sheet to minimize warping of the rings. Basket ring designs manufactured from rolled bar stock into rings will not be acceptable for this project. Each basket ring section shall be provided with an integral strengthening gusset at each attachment point to the support bars for added basket strength. The stainless steel support bars shall be machined with slots to provide the proper bar spacing as specified. Each basket ring shall be inserted into the machined slot of the basket support bars and then welded to the support bars to provide a superior strength basket design.

A hinged protective guard fabricated of 12-gauge minimum thick stainless steel or FRP shall be provided to cover the open top of the screen basket. Hinges and mounting hardware shall be stainless steel.

The screen shall be provided with a pivoting support stand allowing for easy removal of the screen basket from the channel for maintenance purposes. To ensure operator safety during servicing of the screen, supports and support stand shall be fabricated from 1/4-inch minimum stainless steel shapes and plates.

The main screen basket upper support ring shall be a minimum of 5/8-inch thick and shall be machined to match the transport tube main support flange to ensure proper alignment of the basket and the rotating rake arm. The main screen basket lower support ring shall be 7/8-inch minimum thickness.

The minimum diameter of the screening basket shall be 31 inches. The basket diameter shall be matched with a sufficient number of bar spacings to ensure the maximum hydraulic capacity flow rate and to provide less than the maximum headloss.

Side seal plates shall be provided to enclose the circular screen and the rectangular concrete channel. Side seal plates shall be two-piece fabricated of 10 gauge minimum stainless steel and shall be of sufficient height to prevent bypassing of flow around the screen at the maximum hydraulic capacity flow rate.

(G&O #12563.01) 11331-6R

A set of stainless steel lower screen basket support brackets fabricated by 1/4-inch sections shall be provided to support the basket in the channel. Support brackets shall allow vertical adjustment of the screen basket so that it does not rest on the channel floor.

2.3 ROTATING RAKE AND CLEANING COMB

The rotating rake assembly shall penetrate the depth of the bar screen to ensure positive solids removal. Rake shall be cast stainless steel or water-jet cut stainless steel for superior life. Designs using a fabricated rake head or that use a screw conveyor with a brush to clean the screen will not be acceptable for this project.

Rake tooth root design shall match the 3-plane design of the basket rings to ensure proper cleaning of the screen bars.

The rake shall reverse at least once during the cleaning cycle to pass through the topmost position where it shall be cleaned by a cast stainless steel or water-jet cut stainless steel hinged cleaning comb installed at the top of the screen basket.

Fabricated cleaning comb designs will not be acceptable for this project. The cleaning comb shall be designed to match the rake profile to ensure cleaning of the spaces to the root of each tooth in the 3-plane rake design. Cleaning comb shall be supported at both ends by a nylon bearing and shall pivot and return to the standby position without the use of counterweights.

The rotating rake and the screw conveyor shall be fixed to the same shaft and driven by a common drive.

A stainless steel backed nylon brush shall be attached to the rake arm and positioned to make contact with the screening trough to sweep material caught on the edges of the trough.

2.4 SCREENINGS CONVEYOR AND DEWATERING PRESS

The screenings screw conveyor transport tube shall have a minimum Schedule 10S wall thickness. A minimum of three anti-rotation bars with 1/4-inch minimum thickness shall be welded to the inside of the transport tube along the longitudinal axis from the compaction zone to the beginning of the screenings collection trough.

The screenings screw conveyor shall not depend on support from the anti-rotation bars during normal operation.

A basket support plate flange shall be a minimum of 3/4-inch and shall be welded to the lower end of the screenings transport tube to attach the screen basket and to provide for attachment of the screenings collection hopper. A 1/2-inch minimum thick drive support flange shall be welded to the upper end of the screenings transport tube for attachment of the drive assembly. After all welding of

(G&O #12563.01) 11331-7R components to the screenings transport tube have been completed the fabrication shall be placed in a lathe to machine the face of the upper drive flange, to machine the face of the lower basket support plate flange for mating the basket and to machine the lower bearing housing. A 1/2-inch-thick minimum drive assembly adaptor stainless steel flange shall be provided to bolt to the upper drive support flange.

The dewatering screw shall be designed to transport and dewater the screened material. Screw flights shall be all AISI Type 304 stainless steel construction with a minimum thickness of 3/16-inch with increased 3/8-inch thick minimum thickness in the screenings collection trough and in the compaction and dewatering zone. Flight pitch distance shall be a maximum in the screenings collection hopper and shall be reduced along the length of the screenings transport tube to a minimum pitch distance in the compaction zone. Constant pitch screenings screw conveyor designs will not be acceptable for this project.

The upper and lower screenings conveyor torque tube shall be fitted with a solid stainless steel stub shaft. The shafts and screenings screw conveyor torque tube shall be accurately machined to allow a close running fit for the upper stub shaft and a shrink-fit for the lower stub shaft. The upper screenings conveyor torque tube shall be fitted with a bolted removable stainless steel stub shaft that may be changed for adapting to speed reducers that are produced by various manufacturers.

Welding the upper stub shaft to the screening transport screw conveyor torque tube will not be acceptable for this project.

The lower end of the screenings conveyor shall be supported by a sealed, water-flushed, self-lubricated lower polymeric composite sleeve bearing with stainless steel wear sleeve. The lower bearing shall not take any thrust load from the screw conveyor. Flush water shall be furnished with a stainless steel water feed line connected to the lower bearing housing to maintain a positive pressure in the bearing cavity. A minimum of two seals shall be provided each with a UHMW polyethylene seal retainer plate. The stainless steel bearing housing shall be field replaceable and shall be machined to mate with the screenings collection housing by a bolted connection. Designs in which the bearing housing is welded directly to the screen body will not be acceptable for this project.

A compaction zone shall be an integral part of the screenings screw conveyor and transport tube design. The compaction zone shall be designed to form a screenings plug of material and to return water released from the screened material back to the wastewater channel. The compaction zone shall be fabricated from 12 gauge minimum thick stainless steel welded to the screenings transport tube to provide a watertight screenings pressate collection chamber. Compaction zone housing shall be furnished with a hinged and sealed access cover held in place with stainless steel latches as well as a removable dewatering section panel inside the dewatering

(G&O #12563.01) 11331-8R chamber to allow direct access to the screw conveyor should the compaction zone ever become plugged.

2.5 DRIVE

The rake mechanism and transport screw shall be driven by a direct-connected cycloidal-helical hollow-shaft high-thrust in-line speed reducer. The speed reducer shall have an AGMA Class I or II rating.

2.6 SCREENINGS CHUTE

The discharge chute shall be fabricated of stainless steel. The screenings chute shall be designed to discharge to the existing screening collection dumpster.

2.7 SPRAY WASH SYSTEMS

Three automatic spray wash systems shall be provided for the screen. Each spray wash system shall be furnished with a control solenoid valve, stainless steel piping and fittings, flexible reinforced PVC hose and nozzles. Piping, fittings, and valves shall be 3/4-inch diameter minimum.

The lower spray wash system shall be located near the upper end of the screenings basket just prior to where screenings enter the screw conveyor transport tube and shall include a minimum of one stainless steel header assembly that shall span the full length of the basket with a minimum of six spray nozzles. A stainless steel spray wash header cover shall be provided for the spray header.

The screenings spray wash system shall be located in the upper section of the transport tube no more than 17 inches from the beginning of the compaction zone, to break up and return organic materials to the flow stream and to ensure maximum screenings washing. A minimum of one spray nozzle shall be provided. The screenings spray wash system and screenings screw conveyor shall be designed to prevent washing screenings down the center of the screw conveyor.

The dewatering chamber flush water system shall periodically clean the compaction and dewatering zone via a stainless steel wash nozzle located in the compaction/dewatering chamber. The dewatering chamber flush water system shall not be a substitute for the screenings spray wash system.

The solenoid valves shall be 3/4-inch minimum, brass body suitable for 120 Vac operation with an explosion-proof rating. Solenoid valves shall be normally closed and rated for up to 100 psig. Solenoid valves shall be slow close type to minimize water hammer. Solenoid valve electrical connectors shall be a metallic

(G&O #12563.01) 11331-9R design. Solenoid valves that use plastic connectors will not be acceptable for this project.

Solenoid valves shall be factory installed to a piping manifold to ensure even pressure distribution to each spray wash system. The solenoid valve wiring shall be factory installed to a common junction box on the spray wash manifold for wire nut connection to external power. Conduit and fittings shall be factory installed between the solenoid valves and junction boxes. Junction box, conduit, and fittings shall be rated for an explosion-proof environment.

Isolation ball valves shall be 3/4-inch minimum, bronze body with chrome plated ball complete with reinforced Teflon seats and adjustable stop lever.

A 3/4-inch stainless steel body Y-strainer with replaceable stainless steel internals shall be provided for the incoming plant water supply. Strainer shall be heat traced and accessible to operator.

2.8 ULTRASONIC LEVEL SENSOR

An ultrasonic level sensor with associated transmitter/display equipment and appurtenances shall be provided by the screen manufacturer. The ultrasonic level sensor shall be a HydroRanger 200 with XPS sensor as manufactured by Siemens (Milltronics). The level sensor will initiate the operation cycle of the screen. The unit shall be flush mounted in the door of the screen control panel. The ultrasonic level sensor shall conform to the requirements of Section 13425 of the Specifications.

2.9 CONTROLS

All controls necessary for the fully automatic operation of the screen shall be provided. The electrical control system shall provide for control of the screen via a high liquid level using a liquid level control system in connection with an adjustable time clock. The screen shall operate at a high liquid level and/or a predetermined time sequence to provide a variable time between cleaning operations.

A. CONTROL PANEL

The screen shall be furnished with a 240/120-volt 3-phase primary control panel in a NEMA 4X stainless steel enclosure suitable for mounting as shown on the Plans. The control panel shall be constructed in accordance with Divisions 13 and 16 of these Specifications. It shall contain the following items:

(G&O #12563.01) 11331-10R

1. Door interlocked circuit breaker disconnect lockable in the off position. The breaker shall not be larger than the feeder breaker (by others), 20A at 240/120V, 3 phase.

2. Process controller complete with LCD operator interface panel providing field settable/adjustable/access to process parameters and for providing specific indications of each type of fault that may occur. Controller RAM shall be backed up with non-volatile memory which will load automatically if RAM is corrupted.

3. Control power transformer fused primary and secondary with

120 Vac surge protection device (SPD).

4. Full voltage LED pilot lights for the following:

a. Control power on pilot light (White)

b. Multifunctional overload shutdown/screen motor fault pilot light (Red)

c. Screw convey motion detector senses no movement/conveyor failure pilot light (Red)

d. High level pilot light (Amber)

5. E-stop push button (Red).

6. Reset push button (Black)

7. Hand-Off-Auto selector switches for the following

a. Screen drive

b. Common wash system solenoid valves

8. Forward-Off-Reverse selector switch (spring return to center) for screen drive

9. Door mounted elapsed time meter

10. Running counter of motor starts

11. Remote dry contact outputs for the following:

a. Screen Running

(G&O #12563.01) 11331-11R

b. Malfunction alarm

c. High water level alarm

12. Two weather protection system heat tracing circuit breaker.

13. Circuit breaker and power to manufacturer-supplied ultrasonic transmitter

14. VFD motor starter with overload

15. Set spare fuses (two of each size used)

16. Flashing alarm light

17. White phenolic nameplates with black lettering.

18. UL panel label per the application.

19. NEMA 4X Stainless steel enclosure

20. Analog terminals in layout and quantity as shown in the Plans

B. SCREEN SEQUENCE OF OPERATION

1. Screen Hand Operation

When the control station HOA selector switch is in the Hand position, the screen will run continuously. Turning the HOA selector switch to Off will stop the unit.

2. Screen Automatic Operation

When the screen selector switch is in the Auto position, the screen will cycle on demand by the level sensor or repeat cycle timer.

After the level sensor condition has cleared, the screen shall continue to run for an off delay time to prevent excessive starting and stopping of the unit. The repeat cycle timer shall reset after the screen is called to run by the level sensor.

(G&O #12563.01) 11331-12R

3. Lower Spray Wash Hand Operation

When the lower spray selector switch is in the Hand position, the spray wash will run continuously. Turning the selector switch to Off will stop the spray wash.

4. Lower Spray Wash Automatic Operation

When the lower spray selector switch is in the Auto position, the spray wash will cycle on and off per the settings of the lower spray wash repeat cycle timer.

5. Screenings Spray Wash Hand Operation

When the screenings spray selector switch is in the Hand position, the spray wash will run continuously. Turning the selector switch to Off will stop the spray wash.

6. Screenings Spray Wash Automatic Operation

When the screenings spray selector switch is in the Auto position, the spray wash will cycle on and off per the settings of the lower spray wash repeat cycle timer.

7. Dewatering Chamber Spray Wash Hand Operation

When the dewatering chamber spray selector switch is in the Hand position, the spray wash will run continuously. Turning the selector switch to off will stop the spray wash.

8. Dewatering Chamber Spray Wash Automatic Operation

When the dewatering chamber spray selector switch is in the Auto position, the spray wash will cycle on and off per the settings of the lower spray wash repeat cycle timer.

C. FAULTS

1. Excessive motor current will trip the starter overload relays, immediately stop the drive motor, and illuminate the alarm indicating light. This fault must be reset by depressing the motor starter overload reset, accessible without opening the control panel.

Dry contact provided for remote sensing.

(G&O #12563.01) 11331-13R

2. Momentary motor over or under current will trip the current monitor, immediately stop the drive motor, and illuminate the alarm indicating light. Pushing the reset pushbutton will reset this fault.

The screw conveyor will initiate run cycle when the control station HOA selector switch is in the HAND position, the screw conveyor will run continuously. Turning the HOA selector switch to OFF will stop the unit.

3. Screw Conveyor Automatic Operation

When the screw conveyor selector switch is in the AUTO position, the screw conveyor will initiate run cycle(s) with time delay after the screen starts.

D. EMERGENCY STOP

The unit can be deactivated at any time by pressing the control panel mounted or emergency stop pushbutton.

2.10 ANCHOR BOLTS

The equipment manufacturer shall furnish all anchor bolts of ample size and strength required to securely anchor each item of equipment. Anchor bolts, hex nuts, and washers shall be Type 316 stainless steel unless noted otherwise.

Anchor bolts shall be L-type embedded. Expansion-type anchors will not be acceptable.

Anchor bolts shall be set by the Contractor. Equipment shall be placed on the foundations, leveled, shimmed, bolted down, and grouted with a non-shrinking grout.

2.11 OUTDOOR WEATHER PROTECTION

The screenings transport tube and unit supplied wash water piping shall be furnished with a heat tracing system for outdoor weather protection, which shall enclose the screenings, transport tube, compaction and dewatering zone and all spray wash piping, ball valves and solenoid valves.

The outdoor weather protection system shall include self-regulating heat tracing, adjustable thermostat, insulation and a fiberglass protective jacket. The area classification for the heat tracing shall be Class 1, Division 2, Group C and D.

(G&O #12563.01) 11331-14R

The heat tracing system shall be suitable for operation down to a minimum temperature of -25 degrees C (-13 degrees F) and shall be powered from the main control panel.

Weather protection system protective cover shall be molded fiberglass reinforced polyester laminate, with the exterior surface gel coated for ultraviolet radiation protection. Fiberglass shall have a glass content of not less than 30 percent, a tensile strength of not less than 22,000 psi, a flexural strength of not less than 25,000 psi and Barcol hardness of not less than 40. Finished fiberglass must withstand a temperature of 200 degrees F without blistering, pinholes, warping or other defects. Gel coat shall be provided with impregnated pigment for exterior light gray color. The weather protection package cover shall be designed to support a wind load of 30 pounds per square foot.

Weather protection system fiberglass cover sections shall be split into two sections when mounted axially along the transport tube. Weather protection system fiberglass cover sections shall extend from the discharge chute over the compaction and dewatering zone and down to the main basket support flange gussets. Each split fiberglass cover section shall be connected via fiberglass flanges and no more than six stainless steel thumb screws for ease of operator access. Each fiberglass cover section shall be designed so that the insulation is completely encapsulated within the fiberglass to prevent water intrusion and damage. Designs utilizing loose fiberglass or foam insulation that are not encapsulated in FRP will not be acceptable for this project. Each fiberglass half section shall be approximately 2-feet long with molded fiberglass flanges.

Individual sections shall be connected via fiberglass flanges and a stainless steel V-ring captive clamping system for easy installation and removal.

All fasteners to assemble the fiberglass cover components shall be stainless steel.

Wiring from the heat trace cable shall terminate in a factory-mounted junction box for field connection by the Contractor.

Where flexible water supply lines and electrical wiring penetrates the jacket, bulkhead adapters or grommets shall be provided.

An ambient sensing control thermostat shall be mounted to the unit with adjustable set point dial, preset for 40 degrees F, with a conduit connection for wiring by the contractor to the screen control panel. The thermostat shall be suitable for installation in a Class I Division 2 Groups C and D environment.

Electrical power for the heat tracing and thermostat shall be by the screen main control panel.

(G&O #12563.01) 11331-15R

2.12 MOTOR

A. APPROVED MANUFACTURERS

Motors shall be by Baldor, US Motors, Reliance, Flygt, or Toshiba/Houston. No other manufacturers shall be accepted.

B. MOTOR PERFORMANCE CHARACTERISTICS

Parameter Specification [01 MTR 01], Fine Screen Drive Unit Motor Size 2 hp Operating Voltage 240 VAC Phase 3 Frequency 60 Hz Synchronous Speed 1,750 rpm Inverter Duty? Yes (VFD) Motor Overtemperature Protection? No Classified Environment? No

C. GENERAL MOTOR REQUIREMENTS

The motors shall be standard TEFC premium efficiency, electric induction motors meeting NEMA MG-1 and other applicable NEMA, ANSI, and IEEE standards. Motors shall be constructed with Class H insulated windings, Class B 30,000 anti-friction bearings, cast iron frame and end bells. The motor nameplates shall be rated for continuous duty at 40 degrees C ambient temperature with a 1.15 service factor. The rotors and short-circuit rings shall be made of copper. Motor design shall be Type B (Standard).

Motors shall meet the efficiency requirements of the Washington State Energy Code (Washington Administrative Code, Title 51, Chapter 51-11) Table 14-4, regardless of whether or not a particular motor is exempted from meeting this efficiency by the Washington State Energy Code.

Motors shall be recognized or labeled and listed by a recognized electrical testing laboratory approved by the Washington State Department of Labor and Industries, or the motor shall be specifically approved by the Washington State Department of Labor and Industries for installation on the project.

Motor manufacturer shall verify that the submitted motor is suitable for use with the motor starting method shown in the Plans.

(G&O #12563.01) 11331-16R

If any motor fails during the warranty period, the Contractor shall replace the motor with a new motor. Rewinding a failed motor shall not be acceptable.

D. MOTORS USED WITH VARIABLE FREQUENCY DRIVES

Motors being used in conjunction with variable frequency drives shall be inverter duty rated and shall meet the requirements of NEMA MG-1 Parts 30 and 31. They shall be coordinated with the thermal, electrical, and mechanical characteristics of the variable frequency drives actually supplied in accordance with Division 16, Electrical.

E. MOTORS IN CLASSIFIED ENVIRONMENTS

Motors shall mounted outside of the classified area.

2.13 MOTOR PROTECTIVE DEVICE COORDINATION AND

DOCUMENTATION

Motor overcurrent protection shall be sized by the motor manufacturer. The Screen manufacturer shall list the motor characteristics that are necessary to size, select, and/or set the various motor protective devices, such as thermal overloads, breaker trip devices, motor protection relays, etc., for inclusion in the O&M manuals.

This list shall also include any additional information needed to setup, program or adjust the variable frequency drive, or solid state drive (soft start) which serves motor driven equipment.

In addition, the Contractor shall take a digital photo of each motor nameplate when the motor arrives at the jobsite.

Spreadsheet of motor nameplate information, motor settings, drives configuration (if applicable), and photo of each nameplate shall be included in the O&M manuals.

2.14 SPARE PARTS

The Contractor shall provide the manufacturer’s recommended spare parts and special tools. All parts and tools shall be suitably identified and effectively protected from moisture and corrosion with appropriate wrappings or coatings or a combination thereof. All parts and tools shall be furnished in sturdy labeled boxes. At a minimum these shall include all special tools and appliances necessary to service, repair, and adjust the equipment, and the following spare parts items:

(G&O #12563.01) 11331-17R

Solenoid valve assembly .............................one Solenoid valve rebuild kit ...........................one Lower bearing composite sleeve bearing ....one Lower bearing seals ....................................one set Conveyor lower shaft wear sleeve ..............one Proximity sensor .........................................one

2.14 PAINTING

Clean all stainless steel surfaces by either brushing with Type 304 stainless steel brushes (metal materials only), or blasting with glass beads followed by chemical treatment of all non-wetted stainless steel materials to a uniform finish.

Units, motors, and accessories shall be painted in accordance with Section 09900- 2.2C of these specifications. Nameplates, drain holes, vent opening or lubrication fittings shall not be painted.

2.15 FACTORY TESTING

The equipment shall be fully tested at the manufacturer’s plant before shipment. Tests shall consist of checking the unit at its rated speed, pressure, capacity, efficiency and at such other conditions and capacity to properly ensure that the system will perform as desired. Certified copies of test results and a report shall be submitted to the Engineer prior to shipment.

PART 3 EXECUTION

3.1 INSTALLATION

Screen shall be installed as shown on the Plans and in strict conformance with the manufacturer’s instructions and recommendations. The equipment shall be secured using Type 316 stainless steel fasteners.

3.2 FIELD TESTING

The Contractor shall perform the field testing described in Section 01800 and 11000.

The field test shall be made by the Contractor in the presence of and as directed by the Engineer. Voltage, amperage draw, flow capacity, discharge pressure and other significant parameters shall be recorded. The manufacturer shall provide a formal test procedure and report forms for recording data. The Contractor shall submit the report forms to the Engineer prior to operational testing.

(G&O #12563.01) 11331-18R

Any defects in the equipment or failure to meet requirements of the Specification shall be promptly corrected by the Contractor.

3.3 MANUFACTURER’S SERVICES

The services of a factory-trained representative of the equipment manufacturer shall be provided by the Contractor. Services shall include 2 days (two visits) onsite for the supervision of equipment startup, testing and instruction of the Owner’s personnel in the operation and maintenance of the equipment. One trip (1 day) shall be for installation inspection, certification and testing; and one trip (2 days) shall be for startup and training.