SBCT Final EIS - Govsupport.us

Chapter 3 ⎯ Affected Environmentlocal areas of disturbed soils resulting from construction of post housing and other support facilities.The range areas (non-cantonment) on FTC cover the majority of land on post and supports the greatestarea of native undisturbed soils because of its lack of development. Severe wind erosion is a problemin the western portion of the range areas, where areas have been cleared, and modified in the caseof berms, for training operations (USACE 2007a). Additional discussion regarding existing soil erosionand ongoing prevention and mitigation activities is presented below in the section on ErosionManagement.Soils occurring at FTC also exhibit high shrink-swell potential because montmorillonitic clays dominatethe composition of most of the soil associations on the installation. Shrink-swell potential is theloss or gain of moisture in soil, which causes the potential for soil to change volume in such a mannerthat increasing soil moisture results in increasing volume and the opposite effect for decreasing soilmoisture. Soils with high shrink-swell potential can result in problems with building foundations andstability (DECAM 2003a).Erosion ManagementRemoval of vegetative cover throughout FTC has caused gully erosion up to 15 feet deep and 20 feetwide on water courses and minor drainages. Sheet and rill erosion also occurs on FTC, which is erosionof soil by concentrated water running through small streamlets, or headcuts. Detachment in a rilloccurs if the sediment in the flow is below the amount the load can transport and if the flow exceedsthe soil’s resistance to detachment. As detachment continues and flow increases, rills become deeperand wider. These erosive features have increased the rates of stormwater runoff, erosion of unstablesoils, and the transport of sediments on FTC (USFWS 1998). Erosive areas on the Range are typicallyassociated with current military training operations including troop, mechanized, and live-fire trainingevents (USACE 2007a).FTC currently follows regulations and implements management plans that include BMPs designed tosustain training resources and offset or reduce adverse effects to soils on the post associated withmilitary training. For example, approximately 350 erosion control dams have been constructed tomitigate erosion on FTC (DECAM 2002a). In addition, the USGS monitors four erosion control reservoirson FTC, as funding resources are available (USACE 2007a). Information on sediment monitoringassociated with these erosion control reservoirs is detailed in the FTC Master Final TransformationEIS (USACE 2007a).The major plans and regulations implemented to reduce the effects of erosion and sedimentation onFTC are FTC Regulations 350–10, 385–63, and 350–19; AR 350–9; the INRMP and EA 2002 – 2006(DECAM 2002a); the Fugitive Dust Control Plan (DECAM 2004b); and the Section 404 RegionalPermit (USACE 2002b). The 2007–2011 INRMP was finalized in July 2007. In addition, the EA forthe Erosion and Sediment Control Program at FTC (USFWS 1998) identifies mitigation measuresthat would minimize erosion on the installation. FTC implements erosion control BMPs and specificmitigation measures on the installation under the direction of these plans and regulations, which aredetailed in the INRMP (DECAM 2002a).In addition to the programs described in the INRMP, DECAM’s Resource Sustainment Team conductserosion control management projects at FTC under specific work plans as erosion control needsare identified (USACE 2007a). Prior to implementing erosion control projects, the work is subject toenvironmental review, which may include a Categorical Exclusion/Record of Environmental Consideration,EA, EIS, and/or permitting (USACE 2007a). BMPs implemented by DECAM include, butare not limited to:February 2008 3–139 2/25th SBCT Final EIS