SBCT Final EIS - Govsupport.us

Chapter 3 ⎯ Affected Environment• Grading of existing roads to ensure proper drainage;• Installation and maintenance of erosion control structures, such as erosion control dams, rockcheck dams, waterbars, and hardened (bed of rock) crossings in existing drainages at intersectionswith established dirt roads;• Revegetation of disturbed land;• Bank sloping to reduce gully erosion and to increase military training opportunities; and• Installation and maintenance of water diversions.Chemical Constituents in SoilsAs described in the INRMP, FTC and the PCMS have some of the highest naturally occurring documentedlevels of selenium (Se) in the United States. Naturally occurring selenium can acutely andchronically impact both aquatic and terrestrial wildlife when land disturbances, such as militarymechanized maneuvers, and excessive erosion occur. Selenium that has leached into lower soil profilesover millions of years is exposed by land disturbance and taken up by selenium receiving plantsthat are uniquely adapted to these sites. The two most common plants we find as indicators are twonative species, desert princess plume (Stanleya pinnata), and two-grooved milkvetch (Astragalus bisulcatus).When selenium-loaded soils are exposed to water, selenium can directly enter surface watersystems and biologically accumulate in the systems of aquatic and terrestrial animals. Deep-rooted,selenium receptor plants can also redistribute selenium onto the ground surface and into the soil.Other heavy metals naturally occurring at high levels on FTC, such as mercury, follow the same geologicaland biological pathways as selenium.There are no government standards or regulations for terrestrial and non-point source selenium, becausethe understanding of selenium distribution in soil and plant communities is complex and studiesare limited. The DECAM completed and implemented a selenium reception study in 1998 in conjunctionwith the University of Wyoming. The study defined the distribution of selenium in soils andvegetation, and subsequent academic work defined the relationship of selenium concentrations to geologicdistribution (DECAM 2002). Additional academic study is ongoing, including a study conductedby the University of California, Riverside in 1999, for which known selenium plant receptortissues collected from all over the U.S. led to the observation that princess plume plant tissues fromFTC had the highest levels of selenium accumulation. The university then collected genetic materialfrom FTC princess plume populations in 2000 and 2001 to establish a strain of superior selenium receptorsfor use in biological soil amendments. Additional academic work has quantified selenium inaquatic systems at FTC. Selenium study results provide DECAM managers with site-specific seleniumknowledge. Resulting management decisions ensure that land user activities do not create a seleniumenvironmental reception hazard.In 1998, the DECAM initiated its first major selenium remediation project that dramatically reducedaquatic selenium reception in Training Area 11. About 136,000 cubic yards of selenium-contaminatedsoil were buried and stabilized (DECAM 2002a). Selenium management is a byproduct of good watershedmanagement considering current knowledge of the issue. Thus, selenium exposure is controlledthrough the implementation of projects within watershed management plans.Geologic Hazards and SeismicityEarthquake potential for the region that includes the FTC area is classified as Zone 1 on a rating scalefrom 0 to 4, with a rating of 4 indicating the greatest potential. Three main faults — the Oil Creek,Ute Pass, and Rampart Range faults — exist within the FTC area, although none cross into FTC(USGS 2005; Widmann et al. 2002). Documented seismic activity in the region has been limited toFebruary 2008 3–140 2/25th SBCT Final EIS