Final Supplemental Environmental Impact Statement Guam and CNMI
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Guam and CNMI Military Relocation (2012 Roadmap Adjustments) SEIS Final July 2015 CHAPTER 3 RESOURCE DEFINITIONS AND APPROACH TO ANALYSIS This chapter lays the foundation for understanding each of the 18 environmental resources that were analyzed for this SEIS and summarizes the approach taken to evaluate potential impacts to each resource. These same resources were also analyzed in the 2010 Final EIS and much of the summary information presented in this chapter incorporates by reference the more detailed resource descriptions in the 2010 Final EIS. As applicable, this chapter highlights any changes in resource characteristics, regulations, or analytical approach that has occurred since publication of the 2010 Final EIS. Each resource is discussed in terms of a definition, the regulatory framework, and the approach to analysis used this SEIS. Each resource definition summarizes key components and characteristics that are explored as appropriate in the environmental consequences sections later in this SEIS (Chapters 4, 5, 6, and 7). The regulatory framework describes the relevant laws and government regulations that pertain to each resource, particularly with regard to identifying impacts to the resource and determining thresholds for significance of those impacts. The approach to analysis describes in general terms the methodology and impact assessment criteria used to identify and categorize resource impacts in this SEIS, and review the key concerns and issues raised about each resource during the two public scoping periods. 3.1 GEOLOGICAL AND SOIL RESOURCES 3.1.1 Definition The comprehensive description of the geological and soil resources of Guam in this SEIS is the same as that provided in the 2010 Final EIS (Volume 2, Chapter 3: Geological and Soil Resources, Section 3.1: Affected Environment, pages 3‐1 to 3-30). This SEIS includes any relevant geological or soils resources information that may have changed or been updated since the 2010 Final EIS was completed. 3.1.1.1 Geological Setting of Guam Guam is located on a volcanic arc adjacent to the Mariana subduction boundary and comprises a volcanic core partially overlain with limestone (karst). The entire island is a potentially active seismic area. Geologic hazards on Guam include the potential for earthquakes that can cause liquefaction (loss of soil cohesiveness and stability in response to earthquake ground motion) and tsunamis; regional volcanism; steep slopes where landslides can occur due to earthquakes or heavy rainfall; and sinkholes associated with the limestone karst. Sinkholes range from a few feet (1 m) to about 75 feet (23 m) deep over most of the limestone plateau on Guam (Tracey et al. 1964). Other characteristics of the limestone plateau (related to its tendency to be dissolved by groundwater and rainwater) are enclosed depressions that may be up to a 0.5 mile wide (0.8 km) and 40 to 50 feet (12 to 15 m) deep (Tracey et al. 1964). 3-1 Guam and CNMI Military Relocation (2012 Roadmap Adjustments) SEIS Final July 2015 3.1.2 Regulatory Framework The National Coastal Zone Management Program is a voluntary partnership between the federal government and U.S. coastal states and territories and Great Lakes states authorized by the Coastal Zone Management Act (16 USC §§ 1451 et seq.) to address national coastal issues. Federal consistency is a unique aspect of coastal zone management under the Act that ensures that federal actions with reasonably foreseeable effects on coastal uses and resources must be consistent with the enforceable policies of a state’s or territory’s National Oceanic and Atmospheric Administration (NOAA)-approved coastal management program. This also applies to federally authorized and funded non-federal actions. NOAA approved Guam’s Coastal Management Program in 1979 (NOAA 2014). The Guam Coastal Management Program requires consistency with its Erosion and Siltation development policy for applicable federal activities on Guam. The policy states that “development shall be limited in areas of 15% or greater slope by requiring strict compliance with erosion, sedimentation, and land use regulations, as well as other related land use guidelines for such areas.” The laws and regulations that follow describe the networked management framework that all non-exempted federal actions, including the proposed actions, must be consistent with to the maximum extent practicable as required by the Coastal Zone Management Act. GEPA administers portions of federal statutes via a Memorandum of Agreement with the USEPA Region 9. GEPA issues Clearing, Grubbing, Grading, and Stockpiling Permits under the Guam Soil Erosion and Sediment Control Regulations (22 Guam Administrative Rules and Regulations [GAR] Chapter 10). In addition to compliance with the USEPA NPDES program, federal projects must also comply with local requirements (e.g., “respecting the control and abatement of water pollution”) per Section 313(a) of the Clean Water Act (CWA). Environmental Protection Plans (EPPs) are specifically identified in 22 GAR, Division II, Chapter 10, § 10103.C.5 (d). EPPs would include nonpoint source control management measures including but not limited to erosion and sedimentation control and fugitive dust control, as necessary, depending on the work, project, activity, and facility function. Section 10106F of 22 GAR Chapter 10 prohibits earth-moving within sinkholes that threaten their viability, function, or the conveyance of surface water into such features. Modifications or use of sinkholes must be authorized by GEPA and must include an assessment to ensure adverse effects to sinkholes do not occur. Section 3406 of 18 GAR, Chapter 3, Article 4, Standards for Flood Hazard Area Management specify measures that are applicable to managing activities that are located in areas subject to flooding hazards or may increase the severity of flooding. Flooding includes tsunamis and storm surge, overflow from rivers and streams, and excessive ponding of storm water within sinkholes. Although permitting under the Flood Hazard regulation is not likely to apply to federal activities outside local jurisdiction, consistency to the greatest extent practicable with regulatory performance standards is required by the Coastal Zone Management Act. Laws, regulations, and design criteria respecting the control of water pollution applicable to floodplains are discussed in the Water Resources regulatory framework. Structural design and facility function considerations related to geological and soil resources include potential mitigation of geologic hazards. For example, seismic, liquefaction, and ground shaking effects are reduced by following UFC 3-310-04, which specifies DoD requirements for earthquake-resistant designs for new buildings, and evaluating and rehabilitating existing buildings for earthquake resistance. 3-2 Guam and CNMI Military Relocation (2012 Roadmap Adjustments) SEIS Final July 2015 3.1.3 Approach to Analysis 3.1.3.1 Methodology The methodology used for identifying and evaluating impacts to geology and soil resources in this SEIS is consistent with the methodology described in the 2010 Final EIS (Volume 2, Chapter 3: Geological and Soil Resources, Section 3.2: Environmental Consequences, pages 3‐31 to 3‐32), and includes consideration of available geologic and soil studies, federal laws and regulations, state and local building codes and grading ordinances, and previously published NEPA documents containing relevant information. An indispensable resource for this analysis was an inventory of closed-contour depressions and known karst formations on Guam: UoG Water and Environmental Research Institute of the Western Pacific (WERI) Technical Report No. 112 (Taborosi 2006). Additionally, Light Detection and Ranging contour data were used to identify potential sinkholes on proposed sites. Analyses of topography, soil, and vegetation were considered during site characterization and planning of the proposed action using Light Detection and Ranging contour data, geotechnical reports, and site visits in an effort to minimize impacts to geological and soil resources during the design of the proposed action. The construction and operational footprints of the proposed action include areas not identified in the 2010 Final EIS. The analysis of potential impacts to geology and soils considers both direct and indirect impacts. Direct impacts result from physical soil disturbances or topographic alterations, while indirect impacts include risks to individuals from geologic hazards, as well as impacts to water or marine biological resources away from the construction/operation site. 3.1.3.2 Impact Assessment Criteria The impact assessment for geological and soil resources considered the following: Substantial alteration of surrounding landscape. Effects on important geologic features (including large-scale soil or rock removal). Filling sinkholes that adversely effects site drainage. Diminished slope stability. A change to soil and/or bedrock conditions that increases vulnerability to a geologic hazard (e.g., seismic activity, flood, tsunami, liquefaction), and the probability that such a hazard could result in injury and property damage. Physical disturbance that substantially increases the rate of erosion and soil loss. Reduced amounts of productive soils. Threats of pollution to soil or groundwater. Quantitative thresholds for impact assessment criteria are not available for most components of geological and soil resources analysis. Therefore, the significance of potential