You may complete an on-line application at the Contra Costa Human Resources Department at 651 Pine St., 2nd Floor, Martinez, CA 94553. How will I be informed of the results of a hiring interview?We can help you discover rewarding career paths, find a job, write your resume and cover letters and even get ready for interviews. An incomplete application packet may disqualify an applicant. Click on the job title, and then Apply, to complete the application. You can use Remove if you want to delete an application without completing it. Contra Costa County is seeking talented and qualified individuals to fill clerical vacancies throughout the County! 3 months to post the job. 3 months to interview. Many schools offer career-guidance tools.