If it was based on age the (EEOC) Equal Employment Opportunity commission enforces the Age Discrimination in Employment Act of 1967 .(ADEA)

It protects individuals who are 40 years of age or older from employment discrimination based on age. The ADEA's protections apply to both employees and job applicants. Under the ADEA, it is unlawful to discriminate against a person because of his/her age with respect to any term, condition, or privilege of employment, including hiring, firing, promotion, layoff, compensation, benefits, job assignments, and training.

A link to the act online: http://www.eeoc.gov/policy/adea.html

Charges can be filed with the EEOC. Information on filing charges can be found here: http://www.eeoc.gov/charge/overview_charge_filing.html

Charges can be brought against the local as well as the contractor. Ultimately it is the local's responsibility to see that discrimination does not occur. Therefore it is their duty to you to see that the contractor does not discriminate.