Brownfields Broadband Deployment Act This bill excludes projects to deploy or modify communications facilities from specified environmental and historic preservation review requirements if they are carried out entirely within a brownfield site (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). In particular, it specifies such projects are not considered major federal actions under the National Environmental Policy Act of 1969 or undertakings under the National Historic Preservation Act. This excludes the projects from relevant reviews that are required under those acts.