Brownfields Improvement Act of 2005

Brownfields Improvement Act of 2005 - Amends the Public Works and Economic Development Act of 1965 to require the Secretary of Commerce to coordinate activities relating to the redevelopment of brownfield sites and the promotion of eco-industrial development under such Act with other Federal agencies, States, local governments, consortia of local governments, Indian tribes, nonprofit organizations, and public-private partnerships.

Authorizes the Secretary to make grants for projects to alleviate or prevent conditions of excessive unemployment, underemployment, blight, and infrastructure deterioration associated with brownfield sites through projects involving: (1) the development of public facilities or services; (2) business development; (3) the development of affordable housing; (4) planning; (5) technical assistance; (6) training; and (7) the purchase of environmental insurance with respect to certain of these activities.

Sets forth grant criteria. Authorizes assistance under this Act for activities identified by a community, the economy of which is injured by one or more brownfield sites.

Authorizes appropriations for brownfield site redevelopment grants for FY 2006 through 2010.

Limits the Federal share of costs for activities funded by such grants to 75 percent of the total.

Defines "brownfield site" by reference to the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) as real property the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant (subject to certain exclusions), and with respect to which an entity has received or is eligible to receive CERCLA funding for site characterization, assessment, or remediation.