10.07.2015 Views

BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

4.2.2.5 SLOPE SHAPINGAlternative Names: Slope Stepping, Gradient Terraces, Benching, SurfaceRoughing, Slope Bottom BenchingDESCRIPTIONSlope shaping is a physical modification to a steep slope that alters thegeometry of the slope and/or increases the surface roughness of the soil on theslope. Slope shaping reduces the erosion potential of a slope by reducing runoffvelocities, reducing the concentration of stormwater runoff, and increasinginfiltration and sediment collection. Slope shaping also provides betterconditions for vegetation establishment.APPLICABILITY• Typically used for slopes greater than 3:1 (run to rise) and more than 5 feetin height.• Slope shaping practices should be used in conjunction with other soilstabilization practices described in this Handbook.• Slope stepping practices described are not recommended for decomposedgranitic soils, sandy soils, or other soils with low cohesiveness.Advantages• Helps promote vegetation establishment.• Helps stabilize steep slopes and reduce the erosion potential of a steepslope.• Typically promotes increased infiltration, which reduces surface runoffand may assist with vegetation establishment.• Can be aesthetically pleasing when grading matches surroundingtopography and vegetation is established.<strong>BMP</strong> DESIGN APPROACHPollutant SourceControlHydrologic SourceControlStormwater TreatmentSCALE OF APPLICATIONAll SFR and MFR < 1acreMFR 1-5 Acre andCICU < 5 acresMFR and CICU > 5acres and all WQIPs<strong>BMP</strong> TYPETemporaryPermanentDisadvantages• Slope stepping practices described have limited success in granitic orhighly sandy soils that are common in the Lake <strong>Tahoe</strong> Region.• Drainage structures may be needed for designs that collect runoff.DESIGN AND INSTALLATION CONSIDERATIONSSlope shaping as defined in this Handbook includes the practices of surfaceroughening, slope bottom benching, and slope stepping. Considerations andguidance for each practice are given below.Surface RougheningSurface roughening is the practice of modifying the soil of a compacted slope tocreate a soil surface that is looser and less uniform. Surface roughening canTRPA <strong>BMP</strong> HandbookChapter 4: <strong>BMP</strong> Toolkit2012 4.2.2.5-Slope ShapingPage 1

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!