Hawaii-Southern California Training and Testing Final EIS/OEIS October 2018 Final Environmental Impact Statement/Overseas Environmental Impact Statement Hawaii-Southern California Training and Testing TABLE OF CONTENTS 3.2 Sediments and Water Quality .................................................................................. 3.2-1 3.2.1 Introduction and Methods .................................................................................. 3.2-1 3.2.1.1 Introduction ........................................................................................ 3.2-1 3.2.1.2 Methods .............................................................................................. 3.2-5 3.2.2 Affected Environment ......................................................................................... 3.2-8 3.2.2.1 Sediments ........................................................................................... 3.2-8 3.2.2.2 Water Quality.................................................................................... 3.2-22 3.2.3 Environmental Consequences .......................................................................... 3.2-32 3.2.3.1 Explosives and Explosives Byproducts .............................................. 3.2-33 3.2.3.2 Chemicals Other Than Explosives ..................................................... 3.2-42 3.2.3.3 Metals ............................................................................................... 3.2-48 3.2.3.4 Other Materials ................................................................................. 3.2-55 3.2.4 Summary of Potential Impacts on Sediments and Water Quality .................... 3.2-62 3.2.4.1 Combined Impact of All Stressors Under Alternative 1 .................... 3.2-62 3.2.4.2 Combined Impact of All Stressors Under Alternative 2 .................... 3.2-63 3.2.4.3 Combined Impact of All Stressors Under the No Action Alternative 3.2-63 List of Figures Figure 3.2-1: Sediment Particle Size Comparison ................................................................................... 3.2-2 Figure 3.2-2: Sediment Quality Index for the Hawaiian Islands ............................................................ 3.2-10 Figure 3.2-3: Sediment Contaminant Rating for the West Coast Region ............................................. 3.2-14 Figure 3.2-4: Water Quality Index for the Hawaiian Islands ................................................................. 3.2-26 Figure 3.2-5: Water Quality Index for the West Coast Region ............................................................. 3.2-28 List of Tables Table 3.2-1: Sediment Quality Criteria and Index, United States West Coast and Hawaiian Islands ..... 3.2-9 Table 3.2-2: Sediment Screening Criteria and Background Concentrations for Pearl Harbor Sediment Remedial Investigation .................................................................................................... 3.2-12 Table 3.2-3: Contaminant Concentrations in Bottom Sediments Offshore of San Clemente Island .... 3.2-16 i 3.2 Sediments and Water Quality Hawaii-Southern California Training and Testing Final EIS/OEIS October 2018 Table 3.2-4. Mean Concentration of Contaminants in San Diego Bay for Un-Impacted and Impacted Sediments with Comparison to Effects Ranges ............................................................... 3.2-18 Table 3.2-5: Percent of Macro-Debris Found on Seafloor Habitats in the Southern California Bight .. 3.2-20 Table 3.2-6. Extent and Abundance of Micro-Plastics Found on Seafloor Habitats in the Southern California Bight .......................................................................................................... 3.2-21 Table 3.2-7: Water Quality Criteria and Index, United States West Coast ........................................... 3.2-24 Table 3.2-8: Water Quality Criteria and Index, Hawaiian Islands ......................................................... 3.2-25 Table 3.2-9: Water Solubility of Common Explosives and Explosive Degradation Products ................ 3.2-34 Table 3.2-10: Failure and Low-Order Detonation Rates of Military Munitions .................................... 3.2-37 Table 3.2-11: Sinking Exercises in the HSTT Study Area Since 2006 ..................................................... 3.2-40 Table 3.2-12: Constituents in Munitions Other Than Explosives .......................................................... 3.2-44 Table 3.2-13: Concentrations of and Screening Levels for Selected Metals in Marine Sediments, Vieques, Puerto Rico ........................................................................................................ 3.2-51 Table 3.2-14: Summary of Components of Marine Markers and Flares ............................................... 3.2-57 Table 3.2-15: Major Components of Chaff ........................................................................................... 3.2-58 ii 3.2 Sediments and Water Quality Hawaii-Southern California Training and Testing Final EIS/OEIS October 2018 3.2 SEDIMENTS AND WATER QUALITY PREFERRED ALTERNATIVE SYNOPSIS The United States Department of the Navy considered all potential stressors that sediments and water quality could potentially be exposed to from the Proposed Action. The following conclusions have been reached for the Preferred Alternative (Alternative 1): Explosives and explosives byproducts: Impacts from explosives and explosives byproducts would be short-term and local. Impacts from unconsumed explosives and constituent chemical compounds would be minimal and limited to the area adjacent to the munition. Explosives and constituent compounds could persist in the environment depending on the integrity of the undetonated munitions casing and the physical conditions on the seafloor where the munition resides. Chemical and physical changes to sediments and water quality, as measured by the concentrations of contaminants or other anthropogenic compounds, may be detectable and would be below applicable regulatory standards for determining effects on biological resources and habitats. Chemicals other than explosives: Impacts from other chemicals not associated with explosives would be both short term and long term depending on the chemical and the physical conditions on the seafloor where the source of the chemicals resides. Impacts would be minimal and localized to the immediate area surrounding the source of the chemical release. Metals: Impacts from metals would be minimal, long term, and dependent on the metal and the physical conditions on the seafloor where the metal object (e.g., non-explosive munition) resides. Impacts would be localized to the area adjacent to the metal object. Concentrations of metal contaminants near the expended material or munition may be measurable and are likely to be similar to the concentrations of metals in sediments from nearby reference locations. Other materials: Impacts from other expended materials not associated with munitions would be both short-term and long-term depending on the material and the physical conditions on the seafloor where the material resides. Impacts would be localized to the immediate area surrounding the material. Chemical and physical changes to sediments and water quality, as measured by the concentrations of contaminants or other anthropogenic compounds near the expended material, are not likely to be detectable and would be similar to the concentrations of chemicals and material residue from nearby reference locations. 3.2.1 INTRODUCTION AND METHODS 3.2.1.1 Introduction The following sections provide an overview of the characteristics of sediments and water quality in the Hawaii-Southern California Training and Testing (HSTT) Study Area (Study Area), and describe, in general terms, the methods used to analyze potential impacts of the Proposed Action on these resources. 3.2-1 3.2 Sediments and Water Quality Hawaii-Southern California Training and Testing Final EIS/OEIS October 2018 3.2.1.1.1 Sediments The discussion of sediments begins with an overview of sediment sources and characteristics in the Study Area, and considers factors that have the potential to affect sediment quality. 3.2.1.1.1.1 Characteristics of Sediments Sediments consist of solid fragments of organic and inorganic matter forming the bottom, or substrate, of bodies of water. Sediments in the marine environment (e.g., in ocean basins) are either terrigenous, meaning that they originate from land, or are biogenic (i.e., formed from the remains of marine organisms). Terrigenous sediments come from the weathering of rock and other land-based substrates and are transported by water, wind, and ice (glaciers) to the seafloor. Biogenic sediments are produced in the oceans by the skeletal remains of single-celled benthic and planktonic organisms (e.g., foraminiferans and diatoms). When an organism dies, its remains are deposited on the Figure 3.2-1: Sediment Particle Size Comparison seafloor. The remains are composed primarily of either calcium carbonate (e.g., a shell) or silica, and mixed with clays, form either a calcareous or siliceous ooze (Chester, 2003). Sediments in the Atlantic Ocean are predominantly composed of calcareous oozes and the Pacific Ocean has more siliceous oozes (Kennett, 1982). In addition to composition, sediments are also classified by size. Blott and Pye (2012) reviewed commonly used historical classification systems and offered a refined system that is adopted for describing sediments in this section. Sediments are grouped into five size classes: boulders,