Contra Costa County only accepts online applications. When viewing a job posting for a currently open examination, you can select the option that says 'Apply'.You may complete an on-line application at the Contra Costa Human Resources Department at 651 Pine St., 2nd Floor, Martinez, CA 94553. I would like to inform you that I would like to cancel my resignation, which I had applied for on January 30, 2022. Fictitious Business Name Abandonment and Withdrawal of Partnership Form(Opens in a new window). Contact Us. Registrar of Voters. 925-335-7800. The Board will go into closed session pursuant to Govt. Fill in the date and the person's name who is completing the mailing. The principa l office of the MBNC shall be loca ted in the County of Contra Costa. Prior to joining the District, he worked at Central Contra Costa Sanitary.