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Third Rock Consultants

NEPA Documentation

The National Environmental Policy Act (NEPA) requires an evaluation of the environmental effects of federal actions, which include projects that involve federal funding or permits from federal agencies such as the US Army Corps of Engineers (USACE). These projects include highways designed with federal funds, private developments that require USACE permits for stream or wetland impacts, and projects such as sewer or waterline extensions that involve federal funding or other federal actions such as permits.  Several levels of NEPA analysis can occur depending on whether a project may significantly affect the environment. These levels include Categorical Exclusion (CE); Environmental Assessment (EA), Finding of No Significant Impact (FONSI); and Environmental Impact Statement (EIS). For more complex projects, the NEPA process may take years to complete.


Third Rock's professional staff has prepared and coordinated all levels of NEPA documentation, including EIS documents for complicated and controversial projects. Our specialists - engineers, biologists, ecologists, environmental scientists, economists, and technical writers - have extensive experience in preparing NEPA documents and the supporting baseline studies. We recognize that NEPA is an on-going process that begins in the early planning stages of a project, extends through initial and final design phases, and requires continuous reevaluation. Third Rock works directly with design engineers throughout the project development process to minimize project impacts and maintain up-to-date NEPA documentation.


In addition to preparing NEPA documents, Third Rock environmental scientists and engineers prepare baseline studies and other supporting documentation to facilitate the assessment of impacts upon both natural and human environments. We have extensive experience in conducting both the field work and data analysis necessary to assess impacts to water quality, threatened and endangered species, underground storage tanks/hazardous materials, air quality, traffic noise, and the human environment (socioeconomics , Environmental Justice, and Section 4(f).)



Third Rock's engineers and environmental scientists routinely conduct analyses in accordance with the USEPA National Ambient Air Quality Standards (NAAQS) and state conformity requirements. We have the requisite expertise to conduct air quality analyses in an efficient and accurate manner. Our staff has experience in predicting and quantifying carbon monoxide impacts from mobile sources using quantitative modeling analyses.  We are also experienced with qualitative assessment of particulate matter (PM2.5) Mobile Source Air Toxics (MSATs), and other air pollutants.  Our professionals work closely with transportation design engineers to assure that air quality impacts are accurately predicted.



Third Rock's environmental engineers and environmental scientists conduct traffic noise assessments in accordance with the Federal Highway Administration's (FHWA's) current highway traffic noise policy. Third Rock staff is also familiar with the specific regulations of various state agencies and their requirements to perform traffic noise assessments. These assessments begin with field reconnaissance of the project area to identify locations for noise sensitive receivers. Then our staff uses an acoustically calibrated sound level meter to measure existing noise for representative receivers, including residences or other sensitive receptors such as schools or community facilities located near the proposed roadway. We then use these field measurements, along with traffic data, roadway plans, and the current FHWA Traffic Noise Model (TNM) software program to validate the noise reading and predict future traffic noise levels.

The prediction of future traffic noise levels determine if there are any traffic noise impacts. If the analysis identifies traffic noise impacts, Third Rock can determine feasible mitigation measures in coordination with the design engineer. Mitigation may include a roadway design change such as a shift in the centerline or a change in the vertical alignment, which would avoid or minimize impacts. When other mitigation measures are not feasible, a noise barrier analysis is performed. With the use of TNM, Third Rock can determine if a barrier is feasible, by evaluating whether noise can be abated to design goal levels at impacted residences, or reasonable, by analyzing the cost of the noise wall versus the number of residences benefited. Third Rock can model multiple barriers to effectively evaluate all scenarios and develop the most cost-effective design that is acceptable to the community.



Community impact assessments examine an area that is sometimes neglected in environmental documents - the human environment. NEPA requires the consideration of impacts to both the natural environment and social environment. Since the natural environment is more visible and frequently "gets more press," impacts to the social environment are sometimes overlooked. Although these impacts may be less visible because they are indirect or cumulative, they have profound effects on a community.  Socioeconomic analyses traditionally have examined the human environment from a somewhat statistical perspective. Data such as census information, agricultural statistics, and economic data were compiled and presented in tabular form. Future conditions that consider the impacts of a project are compared with existing conditions. In contrast, a community impact assessment provides a more in-depth analysis of impacts to communities, neighborhoods, and people. While socioeconomic baselines do not always rely on interviews with residents, community impact assessments address the community's concerns (mobility, safety, employment effects, relocations, isolation, etc.) through public participation and face-to-face communication methods such as frequent public meetings and door-to-door surveys.  Dozens of Community Impact Assessments and socioeconomic analyses have been prepared by Third Rock's team of environmental analysts and NEPA specialists.




Environmental Justice considerations related to the NEPA process are a direct result of Title VI of the Civil Rights Act of 1964. Environmental Justice, directly mandated by Executive Order 12898, requires that the effects of all programs, policies, and activities on minority and low-income populations be considered. Impacts from any action cannot be disproportionately borne by these groups. Our NEPA specialists regularly deal with Environmental Justice documentation as a component of all community impact assessments and socioeconomic impact studies.


Third Rock has also conducted Environmental Justice assessments as a supplement to the NEPA document process when it was suspected that an at-risk community might bear a disproportionate impact as a result of a proposed project. Since "disproportionate" is not defined in absolute terms, Third Rock's experienced NEPA team can assist agencies with making an appropriate Environmental Justice determination. If there are no prudent or feasible alternatives that will avoid an Environmental Justice impact, Third Rock can assist the project team with creating appropriate mitigation measures that satisfy the requirements of the Civil Rights Act as well as the needs of the impacted community.




Section 4(f) of the 1966 Department of Transportation (DOT) Act applies only to the NEPA process of federally funded transportation projects. Section 4(f) resources include publicly owned parks, recreation areas, or wildlife refuges and sites listed, or eligible for being listed, on the National Register of Historic Properties. Impacts to these sensitive resources must be avoided if there is a prudent and feasible avoidance alternative. Third Rock's NEPA specialists understand the complex regulations and procedures for dealing with Section 4(f) impacts. We prepare Section 4(f) statements for NEPA projects when no viable alternatives can be developed to avoid the resource. Our experienced specialists identify potential Section 4(f) impacts early in the NEPA process to assist planners and designers in avoiding and minimizing adverse impacts.


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