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Snohomish County Reduces Emissions Through Diesel Retrofits and Biodiesel

Bolstered by Washington state funding, Snohomish County officials have enhanced efforts to reduce greenhouse gas emissions from fleet vehicles. The county’s green initiatives also include increased use of biodiesel.

by Lauren Fletcher & Lisajoyce Vergara
March 24, 2009
2 min to read


With the help of state grants, Snohomish County, Wash., fleet officials are aggressively tackling environmentally responsible practices, which include retrofitting diesel-powered vehicles and increasing biodiesel use throughout the fleet. 

132 Vehicles Retrofitted

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Since 2005, Snohomish County has retrofitted 132 diesel vehicles with diesel oxidation catalysts (DOC), reducing greenhouse gas (GHG) emissions. Turning over the fleet with 2007 and newer diesel-powered engines, certified for biodiesel use, achieved additional gains in GHG reduction. 

In 2005, the County secured a grant from the Puget Clean Air Agency to retrofit 24 fleet vehicles with DOCs. In 2006, the state's Department of Ecology Heavy Duty Diesel Retrofit Program awarded the County a $187,800 grant, valid through June 30, 2009. The County used the DOE grant to retrofit an additional 108 fleet vehicles. 

To retrofit a diesel vehicle, a manufacturer designs DOCs for each specific engine/vehicle configuration. Once the County receives the DOCs, a local vendor schedules installations with county shop supervisors. To perform the installation, the original muffler is removed and the new DOC is bolted in its place. 

'Greener' Path Paved

Another element in the county's multifaceted greening effort is a long-term biodiesel conversion program. Currently, 33,000 gallons of B-20 (20-percent biodiesel, 80-percent diesel) are used in approximately 70 percent of county diesel-powered vehicles. In addition, the County is also replacing at least 15 percent of its non-law enforcement vehicles with biofuel or electric-powered units. 

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In 2008, the County reduced its carbon emissions by approximately 925,000 lbs. through B-20 usage. On target to convert its entire diesel fleet to B-20 biodiesel by 2010, the County has pledged to convert to B-40 by 2014. A pilot test on B-40 will begin in 2012. 

"We have the opportunity to set the right tone for future generations to follow," County Executive Aaron Reardon said. "Whether through emission reductions, waste disposal, transportation, or recycling, we are setting Snohomish County on a greener path." WT

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How Snohomish County Secured Grant Funding

To receive the Washington state Department of Ecology's Heavy Duty Diesel Retrofit Program grant, Allen Mitchell, fleet manager for Snohomish County, followed these steps: 

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▲ The County researched two retrofit options. Option 1 included specific types of vehicles and option 2 covered additional vehicle types not listed in option 1. 

▲ The County applied for a combination of the two options. "We prepared a spreadsheet including vehicle type, manufacturer, vehicle year, engine manufacturer, engine model, engine size (HP), odometer reading, vehicle usage per year, and years of use remaining," said Mitchell. 

▲ Mitchell included information in the application on its 2005 Puget Sound Clean Air Agency grant. Mitchell also detailed the county's plan for a B-20 pilot project.

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