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Last modified
1/26/2010 10:08:01 AM
Creation date
10/5/2006 4:04:55 AM
Metadata
Fields
Template:
Floodplain Documents
County
Logan
Community
Sterling
Basin
South Patte
Title
Sterling Flood Control Interceptor Channel Project
Date
4/1/2002
Prepared For
Sterling
Prepared By
URS
Floodplain - Doc Type
Project
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<br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />SEma.THREE Affected Environments and Environmental Consequences <br /> <br />Practices (BMPs), such as silt curtains and/or hay bales, would be employed by the contractor. <br />Because the floodwaters would be conveyed within the constructed flood channel, soil erosion in <br />the project area would be reduced during future flood events. <br /> <br />As previously stated, soils within the project area have one or more characteristics that would <br />require special consideration during the construction of the conveyance channel, maintenance <br />access road, extension ofthe county road, and other project features. Both the AIda loam and the <br />Fluvaquents soil mapping units are quite susceptible to water erosion, and cutbanks frequently <br />cave. Both of these mapping units are generally located near the South Platte River, and the <br />banks of the conveyance channel within these mapping units would need to be hardened (rock <br />riprap, soil cement, etc.) or vegetated with plant species that form dense root systems. Soils <br />within the other mapping units (Haverson loam, Hayford silty clay loam, Lebsack silty clay <br />loam, Nunn clay loam, Nunn loam, and Satanta loam) have low strength and/or are subject to <br />shrink-swell, which can contribute to problems if used for road construction. It would be <br />expected that mixing these soils with soils with higher contents of silt and/or loam would allow <br />these soils to be used in the construction of the proposed roads. <br /> <br />3,1,3 Alternative 3 -Improve Routing of Pawnee Creek Flood Flows <br /> <br />The berm and channel construction activities associated with this alternative would not impact <br />the geology of the project area. Overall, approximately 33 acres of soil would be disturbed <br />during vegetation removal, grading, and berm and channel construction. Ofthe disturbed soils, <br />approximately 3 acres have previously been disturbed by road or railroad development activities <br />and 33 acres are within cultivated cropland. Disturbance of approximately 33 acres of soil does <br />not represent a significant impact because none ofthe affected soils are unique or have limited <br />abundance in Logan County. In addition, topsoil within the cropland areas would be stockpiled <br />and spread back over the disturbed areas after construction has been completed to allow them to <br />be returned to production. To reduce soil erosion during construction and to reduce the amount <br />of silt entering local streams, BMPs, such as silt curtains and/or hay bales, would be employed <br />by the contractor. Because the floodwaters would be conveyed within the constructed flood <br />channel, soil erosion in the project area would be reduced during future flood events. <br /> <br />As previously stated, soils within the project area have one or more characteristics that would <br />require special consideration during the construction of the conveyance channel, maintenance <br />access road, extension ofthe county road, and other project features. Both the Aida loam and the <br />Fluvaquents soil mapping units are quite susceptible to water erosion, and cutbanks frequently <br />cave. Both of these mapping units are generally located near the South Platte River, and the <br />banks of the conveyance channel within these mapping units would need to be hardened (rock <br />riprap, soil cement, etc.) or vegetated with plant species that form dense root systems. Soils <br />within the other mapping units (Haverson loam, Hayford silty clay loam, Lebsack silty clay <br />loam, Nunn clay loam, Nunn loam, and Satanta loam) have low strength and/or are subject to <br />shrink-swell, which can contribute to problems if used for road construction. It would be <br />expected that mixing these soils with soils with higher contents of silt and/or loam would allow <br />these soils to be used in the construction of the proposed roads. <br /> <br />3-2 <br />
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