Virginia Capes Range Complex Final Environmental Impact Statement

VACAPES Range Complex FEIS/OEISChapter 3 Affected Environment andEnvironmental Consequences3.2 – Haz Materials/Haz WasteAn estimated 540 non-explosive, practice, 40-mm grenades would be used each year. A grenade is aboutthe same size and shape as a chicken egg, contains high explosives in an inert dye in a metal shell, anduses a variety of fuzes.Small-Arms and Close-In Weapons System Ammunition Fate and TransportExpended .50-caliber and 7.62-mm bullets may release small amounts of iron, aluminum, copper, andtungsten into sediments and the overlying water column as bullets corrode. All of these are elements thatexist naturally in the environment. Their presence in water is mainly the result of erosion of soils androcks. Increased concentrations of metals in sediments would be restricted to a small zone around thebullet, and releases to the overlying water column would be quickly diluted (DoN, 2005c). Refer toSection 3.3, Water Resources, for details regarding water quality.ChaffCharacteristics and Numbers of ChaffRadio frequency chaff (chaff) is an electronic countermeasure designed to reflect radar waves and obscureaircraft, ships, and other equipment from radar-tracking sources. Chaff is non-hazardous and consists ofaluminum-coated glass fibers (about 60% silica and 40% aluminum by weight) ranging in lengths from0.3 to 3 inches with a diameter of about 40 micrometers. Chaff is released or dispensed from militaryvehicles in cartridges or projectiles that contain millions of chaff fibers.For each chaff cartridge used, a plastic end-cap and Plexiglas piston is released into the environment inaddition to the chaff fibers. The end-cap and piston are both round and are 1.3 inches in diameter and0.13 inches thick (Spargo, 2007).Chaff would be used during chaff exercises throughout the VACAPES Study Area. Under the No ActionAlternative, it is estimated that 1,821 chaff exercises would be held per year, releasing about18,198 rounds (150-gram cartridges) of chaff in the VACAPES Study Area.Chaff Fate and TransportWhen deployed, a diffuse cloud of fibers undetectable to the human eye is formed. Chaff is a very lightmaterial that can remain suspended in air anywhere from 10 minutes to 10 hours. It can travelconsiderable distances from its release point, depending on prevailing atmospheric conditions (Arfsten etal. 2002).Based on the dispersion characteristics of chaff, large areas of open water within the VACAPES StudyArea would be exposed to chaff, but the chaff concentrations would be low. For example, Hullar et al.(1999) calculated that a 4.97-mile by 7.46-mile area (37.1 square miles or 28 square nautical miles) wouldbe affected by deployment of a single cartridge containing 150 grams of chaff. The resulting chaffconcentration would be about 5.4 grams per square nautical mile. This corresponds to fewer than179,000 fibers per square nautical mile or fewer than 0.005 fibers per square foot, assuming that eachcanister contains five million fibers.The fine, neutrally buoyant chaff streamers act like particulates in the water, temporarily increasing theturbidity of the ocean’s surface. However, they are quickly dispersed and turbidity readings return tonormal.The end-caps and pistons would sink; however, some may remain at or near the surface if it were to falldirectly on a dense Sargassum mat. The expended material could also be transported long distancesbefore becoming incorporated into the bottom sediments.3-27 March 2009