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HomeMy WebLinkAboutFile Documents.993 Moore Dr.0192.2019 (43).ARBK GLENWOOD SPRINGS DURANGO (970) 945-7755 TEL (970) 945-9210 FAX (970) 259-7411 TEL (970) 259-8758 FAX Wright Water Engineers, Inc. 2490 West 26th Ave., Suite 100A www.wrightwater.com Denver, Colorado 80211 e-mail: sschreiber@wrightwater.com (303) 480-1700 TEL (303) 480-1020 FAX March 1, 2018 Via email: selliot@ccyarchitects.com Simon Elliot, AIA CCY Architects 228 Midland Avenue Basalt, CO 81621 Re: Hydrology and Mudflow Considerations for 993 Moore Drive Dear Simon: Wright Water Engineers, Inc. (WWE) has prepared this letter to present results of a mudflow assessment for the 993 Moore Drive property in the Five Trees area of Aspen, Colorado. Figure 1 is a location and vicinity map. Based on our field observations and review of geologic mapping, it does not appear that this property has a high risk of mud and debris flow. The property does not lie on an alluvial fan, and the slopes above the property appear to be well vegetated and stable. As a result, we have not performed detailed mudflood and mudflow modeling of this site. Instead, we have used an approach that estimates potential runoff and sediment flow rates using the Rational Method along with sediment bulking factors, as described below. The following sections provide a summary of the geology and soils in the area, including hydrology developed by Woody Creek Engineering (WCE) and recommendations for hydrologic design criteria to apply to 993 Moore Drive. The purpose of this letter is to satisfy requirements of the City of Aspen Urban Runoff Management Plan (URMP). The proposed Project is in the Highlands/Five Trees Mudflow Zone as shown in Figure 2 – Mudflow Zones, with slopes greater that 30%. The primary potential source of sediment in runoff is erosion from the steep slopes above the project site. Based on current conditions, the slopes are vegetated and do not show signs of excessive erosion. In the future, however, there could be greater potential for erosion if vegetation were impacted by fire and/or pine beetles. The bulking factors, recommended below, are intended to account for potential greater erosion in the future. 993 Moore Drive Geology Bryant (1971) mapped the surficial deposits (Qmb) in the area. This mapping is presented in Figure 3 – Geological Map. The surficial deposits within the drainage area were mapped as poorly sorted marine deposits ranging from silt to boulders. The geology commonly contains boulders derived from valley heads but may also be composed of relatively angular boulders locally derived. In many places the geology has hummocky or ridge-and-trough topography. The geology is locally indistinguishable from landslides containing morainal material or from colluvium developed on Precambrian rocks. The geologic hazard map by Bryant (1972) does not note any geological hazards within the drainage area. See Figure 4 – Geological Hazards Map for additional information. Simon Elliot, AIA March 1, 2018 Page 2 Major soil groups associated with 993 Moore Drive drainage area are shown on Figure 5 – Soils Map (NRCS Web Soil Survey). The predominant soil group for the drainage area is identified as Map Unit 14, which is classified as Callings-Yeljack complex, 25 to 65 percent slopes. The Web Soil Survey classifies this complex as Hydrologic Soil Group C with very high runoff potential. The erosion potential for these soils is high given the steep slopes. Runoff Analysis WCE performed runoff calculation for the site using the Rational Method and calculated peak runoff rates for the 5- and 100-year events. WCE identified offsite drainage basins with a total size of 10 acres. The drainage basins consist of 20% to 40% slopes covered with large evergreens on the upper areas and smaller shrubs and grasses on the lower. The basins drain to the east with Castle Creek being the receiving waters. WWE recommends applying a 20% bulking factor to the peak rates calculated by WCE to account for sediment. This is consistent with the approach used for the Red Butte area in the recently completed Aspen Mud and Debris Flow Study (WWE 2017). Table 1 summarizes peak flow rates calculated by WCE for offsite basins, recommended bulking factors, and resulting bulked flows. Table 6. Unit Rates of Runoff including Bulking Factor Basin Drainage Area Q5 Unbulked Q5 Bulked Q100 Unbulked Q100 Bulked [ac] [cfs] [cfs] [cfs] [cfs] 1 3.9 1.1 1.3 6.9 8.3 2 4.8 1.4 1.7 8.9 10.7 2.1 0.6 0.2 0.3 1.4 1.7 2.2 0.3 0.1 0.1 0.8 0.9 3 0.2 0.4 0.5 1.0 1.2 4 0.1 0.2 0.3 0.5 0.6 5 0.1 0.3 0.4 0.7 0.8 Conclusion Based on WWE’s analysis, there is not a significant mud and debris flow risk for the property located at 993 Moore Drive. The watershed above the site has steep slopes but is well vegetated. Geologic hazard mapping for the area does not indicate the presence of an alluvial fan or other types of geology characteristic of mud and debris flows. Given these factors, WWE analyzed this site using the Rational Method and bulking factors to account for potentially elevated sediment loads in the future if the vegetative cover were to be diminished. WWE recommends that peak flow rates for all off-site, upgradient runoff be bulked by a 20 percent factor to account for Simon Elliot, AIA March 1, 2018 Page 3 sediment. The design of conveyances should use the bulked flows and should provide freeboard above the water surface elevation that is calculated based on the bulked peak flow rates. In addition, the use of inlets and pipe conveyances for routing of off-site flows should be avoided due to the high potential for clogging. WWE appreciates the opportunity to conduct this analysis of potential mud and debris flow hazards. Please feel free to contact us if you have any questions about the analysis described in this letter. Sincerely, WRIGHT WATER ENGINEERS, INC. By ______________________________ Scott Schreiber, P.E. Water Resources Engineer By ______________________________ Andrew Earles, Ph.D., P.E., D.WRE Vice President of Water Resources Attachments Figure 1. Location and Vicinity Map Figure 2. Highlands/Five Trees Mudflow Zones Figure 3. Geological Map Figure 4. Geological Hazards Map Figure 5. Soils Map Figure 6. UDFCD Rational Method Spreadsheets References 1. City of Aspen, 2014. Urban Runoff Management Plan. November. 2. USGS. 1971. Geologic Map of the Aspen Quadrangle, Pitkin County, Colorado. Bryant, Bruce 3. USGS. 1972. Map Showing Selected Potential Geologic Hazards in the Aspen Quadrangle, Pitkin County, Colorado. Bryant, Bruce. 4. Woody Creek Engineering. 2018. UDFCD Rational Method Spreadsheet 5. USGS. 1972 Map Showing Selected Potential Geologic Hazards in the Aspen Quadrangle, Pitkin County, Colorado. Bryant, Bruce. cc: Josh Rice: josh@woodycreekengineering.com PROJECT NO.181-017.000 Path: G:\WWE\181-017\GIS\Maps\Location and Vicinity Map.mxd Castle CreekMarolt DitchStein Arlian Marolt Ditch Castle Creek RoadMoore Drive FIGURE 1993 MOORE DRIVE LOCATION AND VICINITY MAP ASPEN, COLORADO WRIGHT WATER ENGINEERS, INC. ®0 250 500125Feet Project Vicinity 818 COLORADO AVE., SUITE 307GLENWOOD SPRINGS, CO 81601(970) 945-7755 Drainage Area Proposed Project Location City of Aspen Urban Runoff Management Plan Chapter 7 – Mudflow Analysis 7-10 Rev 11/2014 Figure 7.1 e – Highlands/Five Trees Mudflow Zones PROJECT NO.181-017.000 Path: G:\WWE\181-017\GIS\Maps\Geological Map new format.mxd FIGURE 3993 MOORE DRIVE GEOLOGIC MAPMODIFIED FROM BRYANT 1971 ASPEN, COLORADO WRIGHT WATER ENGINEERS, INC. ®0 1,000 2,000500Feet 818 COLORADO AVE., SUITE 307GLENWOOD SPRINGS, CO 81601(970) 945-7755 Drainage Area City of Aspen PROJECT NO.181-017.000 Path: G:\WWE\181-017\GIS\Maps\Geological Hazards Map new format.mxd FIGURE 4993 MOORE DRIVE GELOGIC HAZARD MAPMODIFIED FROM BRYANT 1972 ASPEN, COLORADO WRIGHT WATER ENGINEERS, INC. ®0 1,000 2,000500Feet 818 COLORADO AVE., SUITE 307GLENWOOD SPRINGS, CO 81601(970) 945-7755 Drainage Area Flood Plains; subject to flooding. Alluvial Fans; subject to sediment deposition during mud floods, mudflows, and debris flows. Landslides; areas that slid in the past and may be prone to future movement. Rockfall Areas; areas on or below cliffs that are prone to future rockfall. Potentially Unstable Slopes; areas potentially prone to future land sliding. Legend City of Aspen 9 Custom Soil Resource Report Soil Map 43384204338470433852043385704338620433867043387204338770433882043388704338420433847043385204338570433862043386704338720433877043388204338870340800 340850 340900 340950 341000 341050 341100 340750 340800 340850 340900 340950 341000 341050 341100 39° 11' 4'' N 106° 50' 37'' W39° 11' 4'' N106° 50' 22'' W39° 10' 49'' N 106° 50' 37'' W39° 10' 49'' N 106° 50' 22'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,290 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. 5YR-EB1.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 1 I.Catchment Hydrologic Data Catchment ID =EB : 1 Area =3.853 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.1600 1,029 0.15 N/A 0.78 22.04 1 2 3 4 5 Sum 1,029 Computed Tc =22.04 Regional Tc =15.72 User-Entered Tc =15.72 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =1.48 inch/hr Peak Flowrate, Qp =0.856 cfs Rainfall Intensity at Regional Tc, I =1.87 inch/hr Peak Flowrate, Qp =1.079 cfs Rainfall Intensity at User-Defined Tc, I =1.87 inch/hr Peak Flowrate, Qp =1.079 cfs 5YR-EB2.1.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 2.1 I.Catchment Hydrologic Data Catchment ID =EB : 2.1 Area =0.573 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.4000 300 0.15 N/A 0.57 8.79 1 2 3 4 5 Sum 300 Computed Tc =8.79 Regional Tc =11.67 User-Entered Tc =8.79 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.60 inch/hr Peak Flowrate, Qp =0.223 cfs Rainfall Intensity at Regional Tc, I =2.23 inch/hr Peak Flowrate, Qp =0.192 cfs Rainfall Intensity at User-Defined Tc, I =2.60 inch/hr Peak Flowrate, Qp =0.223 cfs 5YR-EB2.2.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 2.2 I.Catchment Hydrologic Data Catchment ID =PB : 2.2 Area =0.301 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.4000 300 0.15 N/A 0.57 8.79 1 2 3 4 5 Sum 300 Computed Tc =8.79 Regional Tc =11.67 User-Entered Tc =8.79 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.60 inch/hr Peak Flowrate, Qp =0.117 cfs Rainfall Intensity at Regional Tc, I =2.23 inch/hr Peak Flowrate, Qp =0.101 cfs Rainfall Intensity at User-Defined Tc, I =2.60 inch/hr Peak Flowrate, Qp =0.117 cfs 5YR-EB2.3.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 2.3 I.Catchment Hydrologic Data Catchment ID =EB : 2.3 Area =0.316 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.4000 300 0.15 N/A 0.57 8.79 1 2 3 4 5 Sum 300 Computed Tc =8.79 Regional Tc =11.67 User-Entered Tc =8.79 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.60 inch/hr Peak Flowrate, Qp =0.123 cfs Rainfall Intensity at Regional Tc, I =2.23 inch/hr Peak Flowrate, Qp =0.106 cfs Rainfall Intensity at User-Defined Tc, I =2.60 inch/hr Peak Flowrate, Qp =0.123 cfs 5YR-EB2.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 2 I.Catchment Hydrologic Data Catchment ID =EB : 2 Area =4.836 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.2200 907 0.15 N/A 0.81 18.63 1 2 3 4 5 Sum 907 Computed Tc =18.63 Regional Tc =15.04 User-Entered Tc =15.04 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =1.67 inch/hr Peak Flowrate, Qp =1.209 cfs Rainfall Intensity at Regional Tc, I =1.92 inch/hr Peak Flowrate, Qp =1.393 cfs Rainfall Intensity at User-Defined Tc, I =1.92 inch/hr Peak Flowrate, Qp =1.393 cfs 5YR-EB3.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 3 I.Catchment Hydrologic Data Catchment ID =EB : 3 Area =0.097 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.2590 54 0.15 N/A 0.21 4.31 1 2 3 4 5 Sum 54 Computed Tc =4.31 Regional Tc =10.30 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =3.46 inch/hr Peak Flowrate, Qp =0.050 cfs Rainfall Intensity at Regional Tc, I =2.39 inch/hr Peak Flowrate, Qp =0.035 cfs Rainfall Intensity at User-Defined Tc, I =3.29 inch/hr Peak Flowrate, Qp =0.048 cfs 5YR-EB4.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 4 I.Catchment Hydrologic Data Catchment ID =EB : 4 Area =0.334 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.1860 102 0.15 N/A 0.26 6.60 1 2 3 4 5 Sum 102 Computed Tc =6.60 Regional Tc =10.57 User-Entered Tc =6.60 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.96 inch/hr Peak Flowrate, Qp =0.148 cfs Rainfall Intensity at Regional Tc, I =2.36 inch/hr Peak Flowrate, Qp =0.118 cfs Rainfall Intensity at User-Defined Tc, I =2.96 inch/hr Peak Flowrate, Qp =0.148 cfs 5YR-PB1.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 1 I.Catchment Hydrologic Data Catchment ID =PB : 1 Area =3.853 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.1600 1,029 0.15 N/A 0.78 22.04 1 2 3 4 5 Sum 1,029 Computed Tc =22.04 Regional Tc =15.72 User-Entered Tc =15.72 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =1.48 inch/hr Peak Flowrate, Qp =0.856 cfs Rainfall Intensity at Regional Tc, I =1.87 inch/hr Peak Flowrate, Qp =1.079 cfs Rainfall Intensity at User-Defined Tc, I =1.87 inch/hr Peak Flowrate, Qp =1.079 cfs 5YR-PB2.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 2 I.Catchment Hydrologic Data Catchment ID =PB : 2 Area =4.836 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.15 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.2200 907 0.15 N/A 0.81 18.63 1 2 3 4 5 Sum 907 Computed Tc =18.63 Regional Tc =15.04 User-Entered Tc =15.04 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =1.67 inch/hr Peak Flowrate, Qp =1.209 cfs Rainfall Intensity at Regional Tc, I =1.92 inch/hr Peak Flowrate, Qp =1.393 cfs Rainfall Intensity at User-Defined Tc, I =1.92 inch/hr Peak Flowrate, Qp =1.393 cfs 5YR-PB3.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 3 I.Catchment Hydrologic Data Catchment ID =PB : 3 Area =0.228 Acres Percent Imperviousness =74.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.57 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.57 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.5000 5 0.57 N/A 0.14 0.59 1 2 3 4 5 Sum 5 Computed Tc =0.59 Regional Tc =10.03 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.75 inch/hr Peak Flowrate, Qp =0.613 cfs Rainfall Intensity at Regional Tc, I =2.43 inch/hr Peak Flowrate, Qp =0.313 cfs Rainfall Intensity at User-Defined Tc, I =3.29 inch/hr Peak Flowrate, Qp =0.425 cfs 5YR-PB4.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 4 I.Catchment Hydrologic Data Catchment ID =PB : 4 Area =0.095 Acres Percent Imperviousness =91.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.76 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.76 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.5000 5 0.76 N/A 0.22 0.38 1 2 3 4 5 Sum 5 Computed Tc =0.38 Regional Tc =10.03 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.85 inch/hr Peak Flowrate, Qp =0.350 cfs Rainfall Intensity at Regional Tc, I =2.43 inch/hr Peak Flowrate, Qp =0.175 cfs Rainfall Intensity at User-Defined Tc, I =3.29 inch/hr Peak Flowrate, Qp =0.237 cfs 5YR-PB5.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 5 I.Catchment Hydrologic Data Catchment ID =PB : 5 Area =0.108 Acres Percent Imperviousness =100.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.90 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.90 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.5000 5 0.90 N/A 0.37 0.23 1 2 3 4 5 Sum 5 Computed Tc =0.23 Regional Tc =10.03 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.92 inch/hr Peak Flowrate, Qp =0.476 cfs Rainfall Intensity at Regional Tc, I =2.43 inch/hr Peak Flowrate, Qp =0.235 cfs Rainfall Intensity at User-Defined Tc, I =3.29 inch/hr Peak Flowrate, Qp =0.318 cfs 100YR-EB1.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 1 I.Catchment Hydrologic Data Catchment ID =EB : 1 Area =3.853 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.1600 1,029 0.15 N/A 0.78 22.04 1 2 3 4 5 Sum 1,029 Computed Tc =22.04 Regional Tc =15.72 User-Entered Tc =15.72 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.85 inch/hr Peak Flowrate, Qp =5.484 cfs Rainfall Intensity at Regional Tc, I =3.59 inch/hr Peak Flowrate, Qp =6.910 cfs Rainfall Intensity at User-Defined Tc, I =3.59 inch/hr Peak Flowrate, Qp =6.9101 cfs 100YR-EB2.1.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 2.1 I.Catchment Hydrologic Data Catchment ID =PB : 2.1 Area =0.573 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.4000 300 0.15 N/A 0.57 8.79 1 2 3 4 5 Sum 300 Computed Tc =8.79 Regional Tc =11.67 User-Entered Tc =8.79 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.99 inch/hr Peak Flowrate, Qp =1.430 cfs Rainfall Intensity at Regional Tc, I =4.30 inch/hr Peak Flowrate, Qp =1.231 cfs Rainfall Intensity at User-Defined Tc, I =4.99 inch/hr Peak Flowrate, Qp =1.4298 cfs 100YR-EB2.2.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 2.2 I.Catchment Hydrologic Data Catchment ID =PB : 2.2 Area =0.301 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.4000 300 0.15 N/A 0.57 8.79 1 2 3 4 5 Sum 300 Computed Tc =8.79 Regional Tc =11.67 User-Entered Tc =8.79 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.99 inch/hr Peak Flowrate, Qp =0.751 cfs Rainfall Intensity at Regional Tc, I =4.30 inch/hr Peak Flowrate, Qp =0.646 cfs Rainfall Intensity at User-Defined Tc, I =4.99 inch/hr Peak Flowrate, Qp =0.7511 cfs 100YR-EB2.3.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 2.3 I.Catchment Hydrologic Data Catchment ID =EB : 2.3 Area =0.316 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.4000 300 0.15 N/A 0.57 8.79 1 2 3 4 5 Sum 300 Computed Tc =8.79 Regional Tc =11.67 User-Entered Tc =8.79 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.99 inch/hr Peak Flowrate, Qp =0.789 cfs Rainfall Intensity at Regional Tc, I =4.30 inch/hr Peak Flowrate, Qp =0.679 cfs Rainfall Intensity at User-Defined Tc, I =4.99 inch/hr Peak Flowrate, Qp =0.7885 cfs 100YR-EB2.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 2 I.Catchment Hydrologic Data Catchment ID =EB : 2 Area =4.836 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.2200 907 0.15 N/A 0.81 18.63 1 2 3 4 5 Sum 907 Computed Tc =18.63 Regional Tc =15.04 User-Entered Tc =15.04 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =3.20 inch/hr Peak Flowrate, Qp =7.748 cfs Rainfall Intensity at Regional Tc, I =3.69 inch/hr Peak Flowrate, Qp =8.921 cfs Rainfall Intensity at User-Defined Tc, I =3.69 inch/hr Peak Flowrate, Qp =8.9209 cfs 100YR-EB3.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 3 I.Catchment Hydrologic Data Catchment ID =EB : 3 Area =0.097 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.2590 54 0.15 N/A 0.21 4.31 1 2 3 4 5 Sum 54 Computed Tc =4.31 Regional Tc =10.30 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =6.65 inch/hr Peak Flowrate, Qp =0.322 cfs Rainfall Intensity at Regional Tc, I =4.60 inch/hr Peak Flowrate, Qp =0.223 cfs Rainfall Intensity at User-Defined Tc, I =6.33 inch/hr Peak Flowrate, Qp =0.3068 cfs 100YR-EB4.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:EB : 4 I.Catchment Hydrologic Data Catchment ID =EB : 4 Area =0.334 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.1860 102 0.15 N/A 0.26 6.60 1 2 3 4 5 Sum 102 Computed Tc =6.60 Regional Tc =10.57 User-Entered Tc =6.60 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =5.69 inch/hr Peak Flowrate, Qp =0.949 cfs Rainfall Intensity at Regional Tc, I =4.54 inch/hr Peak Flowrate, Qp =0.758 cfs Rainfall Intensity at User-Defined Tc, I =5.69 inch/hr Peak Flowrate, Qp =0.9495 cfs 100YR-PB1.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 1 I.Catchment Hydrologic Data Catchment ID =PB : 1 Area =3.853 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.1600 1,029 0.15 N/A 0.78 22.04 1 2 3 4 5 Sum 1,029 Computed Tc =22.04 Regional Tc =15.72 User-Entered Tc =15.72 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.85 inch/hr Peak Flowrate, Qp =5.484 cfs Rainfall Intensity at Regional Tc, I =3.59 inch/hr Peak Flowrate, Qp =6.910 cfs Rainfall Intensity at User-Defined Tc, I =3.59 inch/hr Peak Flowrate, Qp =6.9101 cfs 100YR-PB2.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 2 I.Catchment Hydrologic Data Catchment ID =PB : 2 Area =4.836 Acres Percent Imperviousness =0.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.50 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.15 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.2200 907 0.15 N/A 0.81 18.63 1 2 3 4 5 Sum 907 Computed Tc =18.63 Regional Tc =15.04 User-Entered Tc =15.04 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =3.20 inch/hr Peak Flowrate, Qp =7.748 cfs Rainfall Intensity at Regional Tc, I =3.69 inch/hr Peak Flowrate, Qp =8.921 cfs Rainfall Intensity at User-Defined Tc, I =3.69 inch/hr Peak Flowrate, Qp =8.9209 cfs 100YR-PB3.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 3 I.Catchment Hydrologic Data Catchment ID =PB : 3 Area =0.228 Acres Percent Imperviousness =74.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.70 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.57 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.5000 5 0.57 N/A 0.14 0.59 1 2 3 4 5 Sum 5 Computed Tc =0.59 Regional Tc =10.03 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =9.12 inch/hr Peak Flowrate, Qp =1.459 cfs Rainfall Intensity at Regional Tc, I =4.67 inch/hr Peak Flowrate, Qp =0.746 cfs Rainfall Intensity at User-Defined Tc, I =6.33 inch/hr Peak Flowrate, Qp =1.0116 cfs 100YR-PB4.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 4 I.Catchment Hydrologic Data Catchment ID =PB : 4 Area =0.095 Acres Percent Imperviousness =91.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.85 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.76 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.5000 5 0.76 N/A 0.22 0.38 1 2 3 4 5 Sum 5 Computed Tc =0.38 Regional Tc =10.03 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =9.32 inch/hr Peak Flowrate, Qp =0.748 cfs Rainfall Intensity at Regional Tc, I =4.67 inch/hr Peak Flowrate, Qp =0.375 cfs Rainfall Intensity at User-Defined Tc, I =6.33 inch/hr Peak Flowrate, Qp =0.5078 cfs 100YR-PB5.xls Page 3 CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title:Harland Leeds Catchment ID:PB : 5 I.Catchment Hydrologic Data Catchment ID =PB : 5 Area =0.108 Acres Percent Imperviousness =100.00 % NRCS Soil Type =C A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =88.80 (input the value of C1) C2=10.00 (input the value of C2) C3=1.052 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.96 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.90 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Paved Areas & Type Meadow Field Pasture/Bare Swales/Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 10 15 20 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.5000 5 0.90 N/A 0.37 0.23 1 2 3 4 5 Sum 5 Computed Tc =0.23 Regional Tc =10.03 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =9.46 inch/hr Peak Flowrate, Qp =0.977 cfs Rainfall Intensity at Regional Tc, I =4.67 inch/hr Peak Flowrate, Qp =0.482 cfs Rainfall Intensity at User-Defined Tc, I =6.33 inch/hr Peak Flowrate, Qp =0.6531 cfs