SBCT Final EIS - Govsupport.us
SBCT Final EIS - Govsupport.us SBCT Final EIS - Govsupport.us
Chapter 5 – Environmental Consequencesand other land management and restoration projects implemented by the LRAM, TRI, and SRAprograms of the FTC INRMP and ITAM annual work plan.Impact 7: Increased Potential for Slope Failure. Areas of steep slopes and erosive soils that could beprone to slope failure are located in the eastern portion within the Fountain Creek Watershed on FTC.Areas of steep slopes and erosive soils that could be prone to slope failure on PCMS are located onthe steep side slopes of the limestone ridges that cross the northwestern corner of the PCMS, and inthe steep areas of the landscape where the Purgatoire River and associated side canyons form a seriesof rock-strewn cliffs and rolling mesa tops. No landslides are known to have occurred on FTC withinthe past few years (USACE 2007a), although localized slides resulting in slope wash have occurred inthe past given the colluvial nature of soil deposits. A major landslide occurs every 20 to 40 years atthe PCMS affecting soils with slopes that are greater than 30 percent. Landslides tend to occur at thePCMS from approximately the middle of the western boundary, southwest to Dillingham Ridge(USACE 2007a). Stryker vehicle maneuver training tends to avoid slopes greater than 30 percent.Increased potential for slope failure from impacts from maneuver training would be a significantimpact mitigable to less than significant with mitigation measures.Regulatory and Administrative Mitigation 7: The impact is considered less than significant withimplementation of standard road maintenance BMPs other land management and restoration projectsimplemented by the LRAM, TRI, and SRA programs of the FTC INRMP and ITAM annual workplan.Less Than Significant ImpactsVolcanic and Seismic Hazards. As described previously, FTC and PCMS are located within the lowriskSeismic Zone 1 (DECAM 2002a) and there is low potential for significant seismic activity in thevicinity of the installations. The seismic hazards associated with maneuver training are consideredless than significant.5.4.3 Water ResourcesPotential impacts to water resources from the proposed permanent stationing of an SBCT at FTC andPCMS include impacts on surface water quality, floodplains, and groundwater quality and supply(Table 5-38).Table 5-38Summary of Potential Water Resource Impacts from Alternative CLocationActivity Group Fort Carson PCMSImpacts from Cantonment Construction ☼ N/AImpacts from Range Construction ☼ N/AImpacts from Live-Fire Training ☼ N/AImpacts from Maneuver Training ☼ ☼ = Significant + = Beneficial Impact = Significant but mitigable to less than significant N/A = Not Applicable☼ = Less than Significant= No ImpactFebruary 2008 5-138 2/25th SBCT Final EIS
Chapter 5 – Environmental ConsequencesAt FTC, Alternative C may result in impacts to surface water quality due to increased erosion andsedimentation related to training activities and construction of new facilities. Other impacts includeincreased loading to the existing stormwater system, impacts on water quality from munitions use,spills and leaks, and depletion of groundwater resources from staffing increases. At PCMS, impacts tosurface water quality may occur from increased erosion and sedimentation related to maneuvertraining and potential impacts on water quality from spills and leaks. All of these impacts areconsidered less than significant.5.4.3.1 Impacts from Cantonment ConstructionLess Than Significant ImpactsNonpoint source contamination of surface water and groundwater. No cantonment construction toaccommodate the addition of 663 Soldiers, their families, support personnel, and SBCT-specificfacilities would be required at FTC initially to accommodate the permanent stationing of the 2/25 thSBCT at FTC. The initial needs would be met by the facilities being vacated by the 4/4 th IBCT thatthe SBCT would be replacing. The associated facilities needs for the SBCT would not be significantlydifferent from the current needs at FTC that are on going as part of the transformation at FTC and anyfuture construction is likely to occur in previously disturbed areas of the cantonment. Temporarily,Stryker vehicles would be parked in vacant fields within the cantonment area until a future date whenpermanent parking would be developed to make up the identified shortfall of approximately 20,000square yards. Future construction activities and temporary parking could result in short-term,localized increases in erosion and runoff. Use of heavy construction equipment would causecompaction of near surface soils that could result in increased runoff and sedimentation. Clearing andgrading during construction would expose the soils to erosion. Dewatering may also be needed duringconstruction, particularly for the utility trenches. However, engineering controls and BMPs includingSWPP Plan would be used to minimize these potential impacts during construction.Construction and operation of new facilities would increase the use of fuels, solvents, and otherhazardous and toxic substances, which might result in indirect impacts to surface and/or groundwaterif accidentally released into the environment. Fort Carson would implement BMPs and the SPCC toaddress leaks or spills of hazardous materials. Potential spills would be typically small in magnitudeand localized. Even a large, uncontained spill, however, would have a low probability of affectingsurface water, as the streams at FTC are intermittent. In addition, Fountain Creek is on the oppositeside of a major highway (I-25), making it highly unlikely for any spill to directly or indirectly affectthis water body.Groundwater from nine existing wells is used at FTC for natural resource support and rehabilitation,support of training capabilities, and fire suppression. Increase in personnel stationed at FTC related tothe permanent stationing of the 2/25 th SBCT may result in increased groundwater use. This increase,however, would be small enough (16 percent) that it could likely be accommodated under existingsubsurface water rights.Stormwater runoff. The stormwater conveyance system, utilities, and ditches within the cantonmentarea may be unable to handle the increased loading from additional construction and facilitiesoperation, even with the upgrade of the “B” Ditch and the Magrath/O’Connell drainage system.Insufficient capacity in the stormwater conveyance system could result in adverse affects tofloodplains in the cantonment under this alternative. Implementing the remaining phases of theUSACE (2005b) study would address shortcomings in the stormwater system.February 2008 5-139 2/25th SBCT Final EIS
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Chapter 5 – Environmental Consequencesand other land management and restoration projects implemented by the LRAM, TRI, and SRAprograms of the FTC INRMP and ITAM annual work plan.Impact 7: Increased Potential for Slope Failure. Areas of steep slopes and erosive soils that could beprone to slope failure are located in the eastern portion within the Fountain Creek Watershed on FTC.Areas of steep slopes and erosive soils that could be prone to slope failure on PCMS are located onthe steep side slopes of the limestone ridges that cross the northwestern corner of the PCMS, and inthe steep areas of the landscape where the Purgatoire River and associated side canyons form a seriesof rock-strewn cliffs and rolling mesa tops. No landslides are known to have occurred on FTC withinthe past few years (USACE 2007a), although localized slides resulting in slope wash have occurred inthe past given the colluvial nature of soil deposits. A major landslide occurs every 20 to 40 years atthe PCMS affecting soils with slopes that are greater than 30 percent. Landslides tend to occur at thePCMS from approximately the middle of the western boundary, southwest to Dillingham Ridge(USACE 2007a). Stryker vehicle maneuver training tends to avoid slopes greater than 30 percent.Increased potential for slope failure from impacts from maneuver training would be a significantimpact mitigable to less than significant with mitigation measures.Regulatory and Administrative Mitigation 7: The impact is considered less than significant withimplementation of standard road maintenance BMPs other land management and restoration projectsimplemented by the LRAM, TRI, and SRA programs of the FTC INRMP and ITAM annual workplan.Less Than Significant ImpactsVolcanic and Seismic Hazards. As described previo<strong>us</strong>ly, FTC and PCMS are located within the lowriskSeismic Zone 1 (DECAM 2002a) and there is low potential for significant seismic activity in thevicinity of the installations. The seismic hazards associated with maneuver training are consideredless than significant.5.4.3 Water ResourcesPotential impacts to water resources from the proposed permanent stationing of an <strong>SBCT</strong> at FTC andPCMS include impacts on surface water quality, floodplains, and groundwater quality and supply(Table 5-38).Table 5-38Summary of Potential Water Resource Impacts from Alternative CLocationActivity Group Fort Carson PCMSImpacts from Cantonment Construction ☼ N/AImpacts from Range Construction ☼ N/AImpacts from Live-Fire Training ☼ N/AImpacts from Maneuver Training ☼ ☼ = Significant + = Beneficial Impact = Significant but mitigable to less than significant N/A = Not Applicable☼ = Less than Significant= No ImpactFebruary 2008 5-138 2/25th <strong>SBCT</strong> <strong>Final</strong> <strong>EIS</strong>