39 CFR § 775.5 - Classes of actions.
(a) Actions which normally require an environment impact statement. None, however the Postal Service will prepare an EIS when necessary based on the factors identified in 40 CFR 1508.27.
(b) Actions requiring an environmental assessment. Classes of actions that will require an environmental assessment unless categorically excluded include:
(1) Any project that includes the conversion, purchase, or any other alteration of the fuel source for 25 percent or more of USPS vehicles operating with fuel other than diesel or gasoline in any carbon monoxide or ozone non-attainment area;
(2) Any action that would adversely affect a federally listed threatened or endangered species or its habitat;
(3) Any action that would directly affect public health;
(4) Any action that would require development within park lands, or be located in close proximity to a wild or scenic river or other ecologically critical area;
(5) Any action affecting the quality of the physical environment that would be scientifically highly controversial;
(6) Any action that may have highly uncertain or unknown risks on the human environment;
(7) Any action that threatens a violation of applicable federal, state, or local law or requirements imposed for the protection of the environment;
(8) New construction of a facility with vehicle maintenance or fuel dispensing capabilities, whether owned or leased;
(9) Acquisition or lease of an existing building involving new uses or a change in use to a greater environmental intensity;
(10) Real property disposal involving a known change in use to a greater environmental intensity;
(11) Postal facility function changes involving new uses of greater environmental intensity;
(12) Reduction in force involving more than 1000 positions;
(13) Relocation of 300 or more employees more than 50 miles;
(14) Initiation of legislation.