Go to Sustainability homepage

You are here: Home » What We Work On » Purchasing » Success Stories in Purchasing » Level 3 Diesel Particulate Filters

Photo of Public Works Agency diesel truck.

The Public Works Agency has reduced the emissions of particulate matter from its heavy equipment diesel fleet by 85% by installing California Air Resources Board certified level 3 diesel particulate filters.

Level 3 Diesel Particulate Filters

Particulate matter from diesel vehicles has been identified by the State of California as a toxic air contaminate that impacts air quality and contributes to public health issues including asthma, heart disease, and cancer. In 2008, the California Air Resources Board (CARB) announced requirements that level 3 Diesel Particulate Filters (DPFs) must be installed on all heavy duty diesel trucks in the State, including those owned by the County. The Alameda County Public Works Agency (PWA) managed the process of installing DPFs on the County's fleet of heavy duty diesel trucks in order to comply with CARB regulations.

How We Did It

In this contract, we require the vendor to:

  • Guarantee that each filter is certified by CARB to meet Level 3 standards when using a B20 bio-diesel blend fuel (20% bio-diesel, 80% diesel).
  • Perform the installations at County sites in order to reduce the impact on our employees.
  • Perform all testing and submit to the County all documentation necessary to verify CARB certification requirements.


At the time of the bid in early 2009, CARB was in the process of promulgating more stringent regulations. In order to account for the incremental increase in cost for those filters, the County included an escalation clause within the final contract in order to eliminate the need to rebid during the contract term.


  • Emissions of particulate matter from County fleet vehicles were reduced by 85% with the installation of this technology.
  • The County met CARB requirements through this contract in a timely and cost efficient manner.