Environmental Assessment / EA, FONSI, EIS

What is an Environmental Assessment?


Having its basis in the National Environmental Policy Act (NEPA), an Environmental Assessment (EA) is performed under U.S. environmental law to determine the need for an Environmental Impact Statement (EIS).  The purpose of the NEPA process is to ensure that the decision maker is able to determine if the impacts of the proposed action will be significant.


An EIS is required if a proposed action has the potential to “…significantly affect the quality of the human environment”.  If the proposed action does not meet the criteria for Categorical Exclusion, it is reviewed to determine if an EIS is required.  The EA is used for this purpose. 


Usually, an agency will release either a Draft Environmental Assessment (Draft EA) or a Draft Environmental Impact Statement (DEIS) for comment. Interested parties and the general public have the opportunity to comment on the draft, after which the agency will approve the “Final Environmental Assessment” (Final EA) or Final Environmental Impact Statement (FEIS).


The EA will document the need for either an EIS or document and justify a Finding of No Significant Impact (FONSI), and the EA will end with either a FONSI or a determination that an EIS is required.  A FONSI describes why an action will not have a significant impact on the environment.  Since the NEPA regulations do not prescribe a public review period for a FONSI, it is imperative that parties who may be negatively affected by a proposed action offer technical comments during the EA phase and before the Environmental Assessment (EA) is finalized. 


Williams Aviation Consultants, Inc has the specialized expertise to review and provide technical comments during the public comment period required of the Draft EA and EIS.  The unique background and experience of Williams Aviation Consultants, Inc allows us to look beyond the data in order to analyze the adequacy of noise modeling methodology, noise data, noise contours and associated conclusions to provide our clients with an assessment of the validity of projections of noise impacts as set forth in the EIS  and the resulting implications for restricted land use.  


The adequacy of an EIS can be challenged in federal court and some large projects have been blocked because of an agency’s failure to prepare an acceptable EIS.


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