City of Oak HarborClean Water Facility

NW Biosolids Presentation – September 9, 2019

Brett Arvidson PECity of Oak Harbor

• Oak Harbor is a city of 22,000 located on Whidbey Island

• Since 2005 all wastewater treatment was at a lagoon

• 2010 NPDES permit included a deadline for developing a facilities plan

• The facilities plan resulted in the decision to build a new treatment plan

Project Background

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What is Oak Harbor CWF?• Liquid Stream

• Flow• Startup: 1.9 MGD Average Annual• Buildout: 3.7 MGD AA

• Coarse/Fine Screening + Grit Removal• Membranes• UV Disinfection

• Solid Stream• Load

• Startup: 2,500 PPD AA• Buildout: 5,500 PPD AA

• No anaerobic digesters• Centrifuge dewatering• Belt dryer to produce Class A

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• In 2014 design started on the treatment plant with Carollo Engineers

• In 2014 the city selected Hoffman Construction as the GC/CM contractor

• 2015 Construction begins• 2018 city began liquid stream treatment operation• 2019 biosolids operations started

Project History

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Aerial View June 2015

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Aerial View July 2019

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Site Layout: Compact, Efficient, Accessible

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• Design-Bid-Build – Traditional Public Works Process

• General Contractor / Construction Manager (GC/CM) – Alternative Public Works Process

General Contractor /Construction Manager

Design Bid Build

DesignBring on Contractor

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Biosolids

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• The city did not have a biosolids program• The city would have to design and build a new

biosolids facility from scratch• Beyond technology installation, the city would have to

implement a beneficial reuse system• Operator training, SCADA implementation and neighbor

relations were primary concerns.

Oak Harbor’s Decision Drivers• Cost• Site Issues-geotechnical, area, surrounding uses, aesthetics, and

archaeology• Odors• Washington State beneficial use requirement for their biosolids. • Oak Harbor is located on an island which increases biosolids

handling costs.• Drying biosolids reduces biosolids volume and weight.• Class A solids allows Oak Harbor the most flexibility in disposal of

biosolids. Provides a hedge against future cost or disposal location risks.

What alternatives were considered?• “Base Case”: Beneficial Reuse of Class A Biosolids- Construct on-site dewatering and thermal drying to Class A- Beneficial reuse of biosolids on Whidbey Island

• Alternative 1: Beneficial Reuse of Class B Biosolids- Construct on-site dewatering- Digestion had high capital cost- Construct off-site treatment with lime stabilization to Class B- Haul lime-stabilized biosolids for beneficial reuse in Eastern

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Summary of Solids Alternatives

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Oak Harbor Biosolids Building Odor Control

Centrifuges

Dryer Feed Hopper

Biosolids Dryer

Dryer Room Truck Bay

To Biofilter

600 CFM

200 CFM

750 CFM

800 CFM (all conveyors)

500 CFM

2,350 CFMTo Strobic Fans

17,300 CFM (6 ACH)

To Strobic Fans

4,750 CFM

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Oak Harbor Belt Dryer Concerns and Decisions

Concerns• Heating Method and

Operation Temperature• Odor and Dust Control• Footprint• Operation Shift Duration

Decision• Any heating method.• Point instead of area

treatment with dust collector.• Tight facility was expected.• Hold off on continuous

operation till the future.

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Dryer System Overview

Burner

Extruder

Discharge Conveyor

Centrifuge

Dryer Feed Hopper

Dryer Belts Condenser

Fuel/Air

Crusher

Hauling Truck

Plant Drain

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• The CC/CM contractor solicited proposals from manufacturers• Four manufacturers provided proposals to Hoffman• Proposals were evaluated by a selection committee• Proposals are for equipment and design services only• Installation was part of a future contract (GMP)• Proposals evaluated based on:

Equipment Procurement

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• Capital Costs• Operation Costs• Overall Footprint• Product Quality

• Heating Source• US Installations• Technician Location

Proposal Results

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Manufacturer AmountHaarslev Industries $ 1,879,205 Huber Technologies $ 2,650,000 Andritz $ 3,964,685 J. Kruger $ 5,119,000 Package Estimate $ 3,500,000

Biosolids Site Plan

WAS STORAGE

SOLIDS BUILDING

TRUCK LOADING

DEWATERING

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December 2015 January 2018

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December 2015 January 2018

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December 2015 January 2018

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December 2015 January 2018

Results

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• GC/CM proved successful for Oak Harbor• Dryer system proved more complex to install than anticipated• Issues with the dryer have delayed implementation of the

biosolids program• City is in the process of eliminating odors from solids system• Material produced has been classified as Class A• The dryer has not achieved reliable operation but we are

working to resolve those concerns.• Despite implementation problems, the city is feeling positive

about the long term use of the dryer

Oak Harbor CWF

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Questions?

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