To assist Contra Costa County in its commitment to Equal Employment Opportunity, applicants are asked to voluntarily provide the following information. An incomplete application packet may disqualify an applicant.You may complete an on-line application at the Contra Costa Human Resources Department at 651 Pine St., 2nd Floor, Martinez, CA 94553. This document is the official Employment Application for Contra Costa County. It includes required personal, educational, and employment information. The process consists of the following steps: Create an Account. Sample Job Application. A cover letter of 300 words or less, explaining why you are the ideal candidate for the students at Contra Costa College. This is a confidential employment application. Please answer all questions as completely and accurately as possible.