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Table 5.11-3. Estimate of Soil Loss by Water Erosion Using Revised Universal Soil Loss Equation (RUSLE2) <br /> Estimates Using Revised Universal Soil Loss Equation <br /> Duration Soil Loss(tons) Soil Loss(tons) Soil Loss(tons/yr) <br /> Feature(acreage)2 Activity (months) without BMPs with BMPs No Project <br /> Site(4.4 acres) Grading 2 0.8 0.010 0.0233 <br /> Construction 22 4.1 0.113 --- <br /> Laydown Areas(A through D-9.8 acres) Grading 1 0.9 0.011 0.0519 <br /> 0 acres exposed;paved or ravelled Construction 23 0.0 0.0 --- <br /> Gas Supply Pipeline <br /> (1.21 acre trench;9.09 acre construction corridor) Grading 3 2.50 0.0318 0.0482 <br /> Construction 3 1.16 0.0318 --- <br /> Transmission Line Pole(0.0004 acre for pole footprint) Grading 0 0.00 0.00 0.0000 <br /> Construction 0 0.00 0.00 --- <br /> Project Soil Loss Estimates JAII activities listed above 20 9.48 0.20 t 0.12 <br /> Notes: <br /> 1.Soil losses(tons/acre/year)are estimated using RUSLE2 software available online[http://fargo.nserl.purdue.edu/rusle2_dataweb/]. <br /> -The soil characteristics were estimated using RUSLE2 soil profiles corresponding to the mapped soil unit. <br /> -Soil loss(R-factors)were estimated using 2-year,6-hour point precipitation frequency amount for the LEC Project site <br /> found at[http://www.nws.noaa.gov/ohd/hdsc/noaaatlas2.htm]. <br /> -Estimates of actual soil losses use the RUSLE2 soil loss times the duration and the affected area.The No Project Alternative estimate does not have <br /> a specific duration so loss is given as tons/year. <br /> Other Project Assumptions as follows: <br /> -It is assumed that 100%of the LEC site and laydown areas will be exposed during grading,and approximately 10%of the site will be bare soil during construction. <br /> -It is assumed that grading the site will take 2 months and construction will take 22 months. <br /> -It is assumed that grading for laydown area will take 1 month and the area will be covered(gravelled or paved)immediately thereafter. <br /> -It is assumed that soil loss will be negligible from the laydown areas once it is covered. <br /> -It is assumed that the 2.5-mile gas pipeline will be installed within a 4-ft wide trench and a 30-ft construction corridor along existing roadways. <br /> -It is assumed that the gas pipeline will take 3 months to construct and will take another 3 months before permanent cover is established. <br /> -The water and sewer lines will be completed on-site,so no additional soil losses are estimated for them. <br /> -It is assumed that no new off-site transmission poles are required. <br /> RUSLE2 Assumptions as follows: <br /> 100-ft slope length. Estimated soil unit slope is the midpoint of the minimum and maximum of the unit slope class. <br /> Construction soil losses assume the following inputs:Management-Bare ground;Contouring-None,rows up and down hill; <br /> Diversion/terracing-None;Strips and Barriers-None. <br /> Grading soil losses assume the following inputs:Management-Bare ground/rough surface;Contouring-None,rows up and down hill; <br /> Diversion/terracing-None;Strips and Barriers-None. <br /> Construction with BMP soil losses assume the following inputs:Management-Silt fence;Contouring-Perfect, no row grade; <br /> Diversion/terracing-None;Strips and Barriers-2 fences, 1 at end of RUSLE slope. <br /> No Project soil losses assume the following inputs:Management- Dense grass,not harvested;Contouring-None,rows up and down hill; <br /> Diversion/terracing-None;Strips and Barriers-None. <br /> 9/2/2008 <br />