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Home My WebLink About1.03 Drainage reportDrainage Report for: Mahan Subdivision Black Diamond Mine Road, GARFIELD COUNTY, CO Prepared for: James & Roberta Mahan 0648 County Road 126 Glenwood Springs, CO 81601 Prepared by: Date: May, 2005 MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 8261/2 Grand Avenue Glenwood Springs, CO 81601 ph 97Q 945.5544 fx 970.945.5558 www.mountaincross-eng.com MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826'h Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 R 970.945.5558 www.mountaincross-eng.eom TABLE OF CONTENTS Drainage Report Page 1-4 Basin Delineation, Tc Paths, SCS Soils, & Vegetation Drainage Plan . Figure 1 Figure 2 Report Calculations Appendix Drainage Report Mahan Subdivision May, 2005 Purpose and Scope of Report This study evaluates the Mahan Subdivison project from a storm water management perspective. It supplies data, calculations, and design criteria that were used to evaluate the site concerning storm runoff. Runoff from snowmelt is typically very large in volume but because it happens over a much longer time period, the peak flows are typically much less than a rainfall event. Therefore storm water is defined in this study to be surface water that is a direct result from a rainfall event. Rainfall events are defined from the probability of the magnitude of an event occurring within a given number of years. Storm water management in this study was concerned with the runoff from a large magnitude storm compared to the capacity of the existing culverts. All flows are listed in units of cubic feet per second (cfs) unless otherwise noted. This study will provide a project overview, a brief description of the methodology, a discussion of the analysis performed, and the results of the analysis. Project Overview The Mahan Subdivision project is located to the south of the City of Glenwood Springs, in Garfield County, Colorado. It is located on Black Diamond Mine Road off of Four Mile Road. The project is at an approximate elevation of 6,800 feet, is at approximately latitude N 39°27'20", longitude W 107°19'55", and is in Section 9, of Township 7 South, Range 89 West, in the 6th Principal Meridian. It is a project involving an area of approximately 20.8 acres. The proposed project will divided the property into 2 lots. Lot 1 will contain approximately 5.7 acres on the northeastern portion of the project. Lot 2 will contain approximately 15.1 acres and the remainder of the project. Black Diamond Mine Road creates a natural division between the two proposed lots and each lot currently contains an existing residence with assorted out buildings. No new construction is proposed. It is the intent of this study to evaluate the existing drainage system through the project site using the 25 -year storm event and comment on the 100 -year storm event. Methodology The design of a storm water management plan begins with a calculation of the volume of water that will be produced from a rainfall event. The SCS TR -55 method was used for estimating the amount of runoff that will occur. This method calculates runoff from SCS curve number, basin area, precipitation, and time of concentration. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 '/ Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.thountaincross-eng.com 1 Drainage Report Mahan Subdivision May, 2005 SCS Curve Number A curve number is assigned to a basin that gives a relationship between the amount of precipitation that becomes surface water and the amount of water that is lost to infiltration, evaporation, or transpiration. The SCS curve number is a function of soil type, vegetative-cover/land-use, and antecedent moisture conditions. SCS soils and vegetative-cover/land-use are shown in Figure 1. Because the land -use and the soil types vary through the drainage basin, a composite curve number is assigned based on the weight of the area and its respective curve number. The curve number calculations are attached in the Appendix. Basin Area Drainage basins have the characteristic that any precipitation falling within that area will drain to the same point of discharge. Basins were delineated from project topographic maps as shown in Figure 1. Precipitation Extreme runoff events from urban areas in western Colorado are caused by cloudburst type storms that are characterized by short periods of high intensity rainfall. The SCS Type II 24-hour distribution reflects this and was used for this study. Estimating rainfall for engineering applications is based on the probability of the magnitude of a storm occurring within a return period. Volume III of the NOAA Atlas 2 maps for Colorado was used for defining design storm rainfall depths for modeled events at the Mahan Subdivision. The following table presents total precipitation depths for the 100, 25, and 2 -year, 24-hour events. The NOAA Atlas Maps are attached in the Appendix. DESIGN STORM DEPTHS RETURN PERIOD (years) RAINFALL DEPTH (inches) 2 1.2 25 2.2 100 2.6 Time of Concentration Manning's kinematic flow equation was used to estimate flow velocity. Length and velocity of flow are used to calculate time. Three flow elements are used: overland -flow, collector -channel flow, and main -channel flow. The parameters needed to determine the flow elements include length, slope, Manning's "n" value, and channel shape. These parameters were determined from topography. The time of concentration calculations are attached in the Appendix. Analysis The following table summarizes the existing drainage characteristics for the drainage basins delineated: MOUNTAIN CROSS ENGINEERING, INC. Civil and EnvIronrpental Consulting and Design 826 'h Grand Avenue, Glehi.wed Springs; CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountai ncross-eng.cotn 2 Drainage Report Mahan Subdivision May, 2005 Basin Characteristics Basin Area (ac) CN Tc (min) A 72.67 58 37.8 B 52.79 56 37.0 The flows for the drainage basins were calculated using the SCS TR -55 method described above. The drainage basins, along with the concentration paths, are shown in Figure 1. Since flow is not increased from existing levels, detention is not warranted. The flows are summarized in the following table for the 25 -year and 100 -year storm events. All calculations are attached for review in the Appendix. Basin 25 -Yr 100 -Yr A 1.62 3.63 B 0.79 2.01 Pipe sizes were calculated using the flows generated from the 25 -year storm events listed above and Manning's equation for open channel flow. The existing pipe material, minimum pipe size, and minimum slope for each basin are summarized in the following table. Pipe routing is shown on the Drainage Plan, Figure 2. All calculations are attached for review in the Appendix. Basin 25 -yr Flow Pipe Design Passes 100 -yr A 12" Corr. @ 1% Min 15" Corr. @ 1% Min 18" Corr. @1% Min No Yes Yes B 12" Corr. @ 1% Min Yes Results The drainage study essentially verified the adequacy of the existing drainage system to convey the Garfield County required 25 -year storm. The road side culverts under driveway accesses are 12" culverts that have capacity for the 25 -year storm. During a 100 -year storm these culverts are anticipated to surcharge causing minor flooding on the edges of the road. The road does have a cross slope that is anticipated to control the flooding to some degree to the outside edges. There are two existing pipes beneath the Black Diamond Road one is a 15" culvert and the other is an 18" culvert. Either have the capacity to convey the 25 -year flows. The 15" and the 18" have the capacity for the 100 -year storm but the inlets are not ideal to capture the flows. Some entrance losses are to be expected that may cause some flooding. As a result of this, the subject property would likely experience some flooding because the site is below these culverts. To mitigate this, a berm 12" in height above the top of the 18" pipe, surrounding the inlet would be recommended to capture the surcharged water caused by entrance losses. However, this would be to capture a storm larger than the mandated 25 -year storm and is a recominendation instead of a requirement. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 ''6 Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com: 3 Drainage Report Mahan Subdivision May, 2005 The Black Diamond Road surface is a base course aggregate (gravel) road and a substantial amount has filled the culverts along the sides of the road. Since the culverts in the calculations assume a full diameter available for conveyance, the road fill greatly limits their capacity. With out this capacity, there is a greater probability of flooding during storms of smaller magnitudes than the 25 -year event. These culverts will therefore need to be cleaned. They should also be periodically inspected, cleaned, and maintained. At the time of the preparation of this report the road was being graded and resurfaced by the County. Cleaning of the culverts was anticipated as part of this work but should be verified. There is a certain amount of uncertainty in hydrologic calculations. However, it is our opinion that the existing culverts will safely convey the runoff flows and volume of the 25 -year design storm event for this site. Thank you for the opportunity to provide this report. Feel free to call if you have any questions, concerns, or continents. Sincerely, Mountain Cross Engineering, Inc. ris Hale, PE MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Dlesign •; 826 !/i ghrand Avenue, Glonwood Springs, CO 81601 P: 970;945.5544f: 970.945:5558 www.mountaincross-eng.com DAR 05!13103 SCALE 0161 Ht, OW nu Dr ainPlan ,or 501-001 FIGURE 1 Basin Delineation, Tc Paths, SCS Soils, & Vegetation Mahan Subdivision MOUNTAIN CROSS ENGINEERING, INC. I Civil and Environmental Consulting and Design 826 1/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mounlaincross-eng.com cb Ex. 12" CMP Ex. 15" CMP - Ex. 18" CMP ZG=N14'00;07"W 1 1 CENTERLINE 10' UTILITY EASEMENT BOOK 483 AT PAGE 421 LOT 5,46 AC 1/ L#118.70' I R=88.06' AV 7 7'13' 45'� 1 C LEN=109.92' \BR!-NJ1` ap 422 �ASEM�' A PAGE' rvr &OOk L_T 1 ACES +/-/z EXISTING CULVERTS DRAIN BASIN A TO BE CLEANED OUT FOR CAPACITY -3 AND ROUTINELY MAINTAINED /o i 0 L=124.41\ R=989.34' A=07'12'18" C LEN=124.33' BRG=N38'04'27" FRAMED DUGOUT\, STORAGE BUILDING_ Z (53 CABIN WATER STORAGE SHED SHED 0 0 ICO 24' ROAD EASEMENT BOOK 483 AT PAGE 421 L=107.93' R=122.27' \A=50'34'9" C E 02' BRG 4'099''29" / N20 WATER ANK • WATER ~ OVERHE D POWE ,LINE (TYP ) LINES (.YP) RES +/-/ PROPOSED 20' WATER MAINTEINANCE EASEMENT ®SPRING B CO X / EXISTING SWALE DRAINS BASIN B DRAINS THROUGH PROPERTY BUT / DOES NOT CROSS ROAD ON SITE / r . // L55' A=41'33'1 C LEN -77 8 BRG=N83' DATE 05/13/05 Nati 1' • 100' BMW Chris Has POO MI Drc>nPEan 501-001 FIGURE 2 DRAINAGE PLAN Mahan Subdivision MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 ix 970.945.5558 www.mountaincross-eng.com Appendix Report Calculations Map Number Description Hydrologic Group 8 Ansel-Anvik association, 12% to 25% B 9 Ansel-Anvik association, 25% to 45% B 64 Jerry Loam, 25% to 65% C Basin A Improved Basin B Improved Curve Number Calculations 3165341.56 = Total Area (sf) 72.67 = Total Area (ac) Gravel Roads (lin.ft*width) 68420 85 65.8 Houses (number#impervious area) 10000 98 11.1 Landscaping, Good 10000 74 8.4 2.8% 85.2 Improved Areas 2.8% 85.2 2.4 Oak, Aspen, Mountain Brush: Good, Type B 1.3% 48 0.6 Oak, Aspen, Mountain Brush: Good, Type C 95.9% 57 54.7 100.0% 57.7 = CN 2299743.04 = Total Area (sf) 52.79 = Total Area (ac) Gravel Roads (lin.ft*width) 55550 85 53.4 Houses (number*impervious area) 15000 98 16.6 Landscaping, Good 15000 74 12.6 3.7% 82.6 Improved Areas 3.7% 82.6 3.1 Oak, Aspen, Mountain Brush: Good, Type B 20.0% 48 9.6 Oak, Aspen, Mountain Brush: Good, Type C 76.3% 57 43.5 100.0% 56.2 = CN House Footprint Assumed to be 5000 sq ft./unit Other impervious Assumed to be 5000 sq ft.Iunit Landscaping Assumed to be 5000 sq ft./unit Overland Shallow Channel Basin Length Elv Diff Slope Length Elv Diff Slope Length Elv Diff Slope A 300 60.00 0.20 835 400 0.48 3150 900 0.286 B 300 60.00 0.20 1285 440 0.34 1985 360 0.181 tmp#7.txt Basin A Sheet Flow Description Manning's n 0.4000 Flow Length 300.0000 ft TWO Yr, 24 hr Rainfall 1.2000 in Land slope 0.2000 ft/ft computed Sheet flow time > 0.5603 hrs shallow concentrated Flow Description surface Unpaved Flow Length 835.0000 ft watercourse slope 0.4800 ft/ft velocity 11.1783 fps Computed shallow flow time > 0.0207 hrs Channel Flow Description Flow Area 1.0000 ft2 wetted Perimeter 24.0000 in Flow Length 3150.0000 ft channel slope 0.2860 ft/ft Mannin 's n 0.0280 Hydraulic radius 6.0000 in Velocity 17.8796 fps computed Channel flow time > 0.0489 hrs Total Time of concentration > 0.6299 hrs Page 1 tmp#8.txt Basin B Sheet Flow Description Manning's n 0.4000 Flow Length 300.0000 ft Two Yr, 24 hr Rainfall 1.2000 in Land slope 0.2000 ft/ft Computed sheet flow time > 0.5603 hrs shallow Concentrated Flow Description surface unpaved Flow Length 1285.0000 ft watercourse Slope 0.3400 ft/ft Velocity 9.4079 fps Computed shallow flow time > 0.0379 hrs channel Flow Description Flow Area 1.0000 ft2 wetted Perimeter 24.0000 in Flow Length 1985.0000 ft Channel Slope 0.1810 ft/ft Manning's n 0.0130 Hydraulic radius 6.0000 in Velocity 30.6357 fps computed Channel flow time > 0.0180 hrs . ............4:[w .... a.J.J..4J-...... .i....'..is.A Total Time of Concentration > 0.6162 hrs ........ ... *..***. ... k 41 109 108 107 1 1 106 105 1-..-... 4.1L. Jl _ 7 i ,��.:10RS r ► I� urEfN\ 1 �t%�;\� � _fl�/ b+i. ill%r '6-,)Y rT 1 i \ t2 1 le `�, 104 103 102 2k 4 : �4..' ate}SFry_1s14 L ENVER, 1-3 39 38 11 20 COLORADO 10 0 10 20 30 40 MILES. a 4 1 _ 121416 0 20 22 24 24 2 NOAA ATLAS 2, Volume 111 Prepared by U.S. Department of Commerce NationalOceenic andAtmcaphericAdministration National Weather Service, Office of Kydrolegy n.c Prepared for U.S. Department of Agriculture, Soil Conservation Service, Engineering Dfvis€on Figure 26 ISOPLUVIALS OF 2 -YR 24 -HR PRECIPITATION IN TENTHS OF AN INCH 109 108 107 106 105 104 103 102 E cn rJ 1- ct 0 z '61 Q cc 0 rJ 0 z 0 V♦ CO r� cn z 2 2 109 41 39 38 37 608 107 106 105 104 10; 21 22 4 —_242 2 2- 26� 311 30 30 4 —;•01,00010 41438 1 4r�, 38 1r k; ri s- r ERLI r • _ — I I AKRON GR "tEY �-�-919tF19 ANION 28 I 9 9 T HASWELL PUEBLO f 7 — 1 1 QYJ Vint!' 26 26 24 20 20 22242630 343438 44 4 109 22 / Ic-9---r-1-I +\ 1.-4111-+ COLORADO 10 0 10 20 30 40 I --I I"----1 f----1 9N11.ES. 24 46 44 4 46 50 NOAA ATLAS 2, Volume IH Figure 29 Prepared by U.S. Department of Commerce NationalOceanicandAtmospheric Administration National Weather Service, Office of Hydrology Prepared for U.S. Department of Agriculture, Soil Conservation Service, Engineering Division 102 ISOPLUVIALS OF 25 -YR 24 -HR PRECIPITATION IN TENTHS OF AN INCH 108 107 106 105 104 103 102 4 109 108 107 106 0 2826 24 2 828 3 105 104 103 102 COLORADO ('w -NS PR MSS COLORADO 10 0 10 20 30 40 MILES. 05A Hey./ 2r 30 2 26 262934 42 424650 NOR ATLAS 2. Volume 111 Prepared by 11$, Department of Commerce National Oceanic and Atmospheric Administration National Weather Service, Ofnce of Hydrology Prepared far 11,$. Department of Agriculture, Soil Conservation Smite, Engineering Division )I 106 105 109 108 107 4 jJ 4— 11-r 4 55 60 65 Figure 31 ISOPLU411ALS OF 100 -YR 24 -HR PRECIPITATION IN TENTHS OF AN INCH 104 103 a) E — Z o CN •- (I) C.1 E 3 -10. ❑ 1- i CO a 0 �► a=te az ■ r a›- 2s cc 4 0 T- 0 0 V Hydrologic Summary Basin Area Ex CN Tc acres minutes A 72.67 57.7 37.8 B 52.79 56.2 37.0 tmp#10.txt Graphical Peak Discharge method Given Input Data: Description Basin A, 25 -Year Rainfall distribution Type 11 Frequency 25 years Rainfall, P (24 -hours) 2.2000 in Drainage area 0.1136 mit Runoff curve number, CN 58 Time of concentration, Tc 0.6300 hrs Pond and Swamp Areas 0.0000 % of Area Computed Results: Initial abstraction, Ia 1.4483 in Ia/P 0.5000 Unit peak discharge, qu 202.2327 csm/in Runoff, Q 0.0707 in Pond and swamp adjustment, Fp 1.0000 Peak discharge, qp 1.6242 cfs Page 1 tmp#14.txt Graphical Peak Discharge method Given Input Data: Description Rainfall distribution Frequency Rainfall, P (24 -hours) Drainage area Runoff curve number, CN Time of concentration, Tc Pond and swamp Areas Computed Results: Initial abstraction, la Ia/P unit peak discharge, qu Runoff, Q Pond and swamp adjustment, Fp Peak discharge, qp Basin A, 100 -Year Type II 100 years 2.6000 in 0.1136 mit 58 0.6300 hrs 0.0000 % of Area 1.4483 in 0.5000 202.2327 csm/in 0.1580 in 1.0000 3.6308 cfs tmp#11.txt Graphical Peak Discharge method Given Input Data: Description Basin 8, 25 -Year Rainfall distribution Type II Frequency 25 years Rainfall, P (24 -hours) 2.2000 in Drainage area 0.0825 mit Runoff curve number, CN 56 Time of concentration, Tc 0.6167 hrs Pond and swamp Areas 0.0000 % of Area computed Results: Initial abstraction, Ia 1.5714 in Ia/P 0.5000 Unit peak discharge, qu 204.4490 csm/in Runoff, Q 0.0466 in Pond and swamp adjustment, Fp 1.0000 Peak discharge, qp 0.7853 cfs Page 1 tmp#16.txt Graphical Peak Discharge method Given Input Data: Description Rainfall distribution Frequency Rainfall, P (24 -hours) Drainage area Runoff curve number, CN Time of concentration, Tc Pond and Swamp Areas computed Results: Initial abstraction, Ia Ia/P unit peak discharge, qu Runoff, Q Pond and swamp adjustment, Fp Peak discharge, qp Basin B, 100 -Year Type II 100 years 2.6000 in 0.0825 mit 56 0.6167 hrs 0.0000 % of Area 1.5714 in 0.5000 204.4490 csm/in 0.1191 in 1.0000 2.0082 cfs tmp#13.txt Manning Pipe calculator Given Input Data: Shape Circular Solving for Depth of Flow Diameter 12.0000 in Flowrate 1.6200 cfs Slope 0.0100 ft/ft Mannings n 0.0200 Computed Results: Depth 7.3946 in Area 0.7854 ft2 Wetted Area 0.5079 ft2 wetted Perimeter 21.6644 in Perimeter 37.6991 in velocity 3.1899 fps Hydraulic Radius 3.3756 in Percent Full 61.6214 % Full flow Flowrate 2.3158 cfs Full flow velocity 2.9486 fps critical information Critical depth 6.4918 in critical slope 0.0150 ft/ft critical velocity 3.7354 fps Critical area 0.4337 ft2 Critical perimeter 19.8332 in Critical hydraulic radius 3.1488 in Critical top width 12.0000 in specific energy 0.7731 ft Minimum energy 0.8115 ft Froude number 0.7906 Flow condition Subcritical Page 1 . tmp#12.txt Manning Pipe Calculator Given Input Data: shape circular solving for Depth of Flow Diameter 12.0000 in Flowrate 0.7853 cfs Slope 0.0100 ft/ft Manning's n 0.0200 computed Results: Depth 4.8164 in Area 0.7854 ft2 wetted Area 0.2947 ft2 wetted Perimeter 16.4668 in Perimeter 37.6991 in Velocity 2.6646 fps Hydraulic Radius 2.5772 in Percent Full 40.1371 % Full flow Flowrate 2.3158 cfs Full flow velocity 2.9486 fps Critical Information Critical depth 4.4444 in critical slope 0.0135 ft/ft Critical velocity 2.9686 fps Critical area 0.2645 ft2 Critical perimeter 15.7025 in critical hydraulic radius 2.4259 in Critical top width 11.5897 in Specific energy 0.5117 ft Minimum energy 0.5556 ft Froude number 0.8568 Flow condition Subcritical Page 1 tmp#18.txt Manning Pipe Calculator Given Input Data: Shape Solving for Diameter Flowrate Slope Manning's n computed Results: Depth Area Wetted Area wetted Perimeter Perimeter Velocity Hydraulic Radius Percent Full Full flow Flowrate Full flow velocity Circular Depth of Flow 18.0000 in 3.6300 cfs 0.0100 ft/ft 0.0200 Critical information critical depth Critical slope Critical velocity Critical area Critical perimeter critical hydraulic radius Critical top width Specific energy Minimum energy Froude number Flow condition 9.3341 in 1.7671 ft2 0.9253 ft2 28.9426 in 56.5487 in 3.9230 fps 4.6038 in 51.8560 6.8278 cfs 3.8638 fps 8.7311 in 0.0125 ft/ft 4.2708 fps 0.8500 ft2 27.7365 in 4.4128 in 17.9920 in 1.0170 ft 1.0914 ft 0.8806 Subcritical Page 1 tmp#17.txt Manning Pipe Calculator Given Input Data: Shape Circular Solving for Depth of Flow Diameter 12.0000 in Flowrate 2.0000 cfs Slope 0.0100 ft/ft Manning's n 0.0200 Computed Results: Depth 8.6054 in Area 0.7854 ft2 wetted Area 0.6028 ft2 wetted Perimeter 24.2399 in Perimeter 37.6991 in velocity 3.3179 fps Hydraulic Radius 3.5809 in Percent Full 71.7119 Full flow Flowrate 2.3158 cfs Full flow velocity 2.9486 fps Critical Information Critical depth 7.2768 in Critical slope 0.0159 ft/ft Critical velocity 4.0072 fps Critical area 0.4991 ft2 Critical perimeter 21.4031 in Critical hydraulic radius 3.3579 in Critical top width 12.0000 in Specific energy 0.8792 ft Minimum energy 0.9096 ft Froude number 0.7621 Flow condition Subcritical Page 1 tmp#20.txt Manning Pipe Calculator Given Input Data: Shape Solving for Diameter Flowrate Slope Manning's n Computed Results Depth Area wetted Area Wetted Perimeter Perimeter Velocity Hydraulic Radius Percent Full Full flow Flowrate Full flow velocity Critical Information Critical depth Critical slope Critical velocity Critical area Critical perimeter Critical hydraulic radius Critical top width Specific energy Minimum energy Froude number Flow condition Circular Depth of Flow 15.0000 in 3.6300 cfs 0.0100 ft/ft 0.0200 10.7656 in 1.2272 ft2 0.9427 ft2 30.3195 in 47.1239 in 3.8507 fps 4.4772 in 71.7709 % 4.1989 cfs 3.4215 fps 9.2892 in 0.0149 ft/ft 4.5377 fps 0.8000 ft2 27.1404 in 4.2444 in 15.0000 in 1.1165 ft 1.1612 ft 0.7908 subcritical Page 1 tmp#1.txt Culvert Calculator Entered Data: shape Circular Number of Barrels 1 solving for Headwater Chart Number 1 Scale Number 1 chart Description CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE Scale Decsription SQUARE EDGE ENTRANCE WITH HEADWALL overtopping Off Flowrate 3.6300 cfs Manning's n 0.0240 Roadway Elevation 3.0000 ft Inlet Elevation 0.2500 ft Outlet Elevation 0.0000 ft Diameter 18.0000 in Length 25.0000 ft Entrance Loss 0.0000 Tailwater 1.0000 ft Computed Results: Headwater 1.2949 ft Inlet Control Slope 0.0100 ft/ft Velocity 3.4151 fps Messages: Inlet head > outlet head. Computing Inlet Control headwater. Solving Inlet Equation 26. Solving Inlet Equation 28. Headwater: 1.2949 ft DIS- HEAD- INLET OUTLET CHARGE WATER CONTROL CONTROL FLOW NORMAL CRITICAL OUTLET TAILWATER Flow ELEV. DEPTH DEPTH TYPE DEPTH DEPTH VEL. DEPTH VEL. DEPTH cfs ft ft ft in in fps ft fps ft 0.73 0.73 0.42 0.48 M1 4.34 8.73 0.58 0.36 0.00 1.00 1.45 0.86 0.61 0.55 NA 6.20 5.42 2.69 0.52 0.00 1.00 2.18 1.02 0.77 0.64 NA 7.72 6.69 3.01 0.64 0.00 1.00 2.90 1.16 0.91 0.77 NA 9.11 7.77 3.24 0.76 0.00 1.00 3.63 1.29 1.04 0.94 NA 10.44 8.73 3.42 0.87 0.00 1.00 4.36 1.42 1.17 1.16 NA 11.79 9.61 3.55 0.98 0.00 1.00 5.08 1.65 1.30 1.40 M2 13.26 9.61 4.06 1.10 0.00 1.00 5.81 2.26 1.77 2.01 M2 18.00 9.61 3.29 1.50 0.00 1.00 6.53 2.46 1.84 2.21 M2 18.00 9.61 3.70 1.50 0.00 1.00 7.26 2.56 1.92 2.31 M2 18.00 9.61 4.11 1.50 0.00 1.00 7.99 2.65 1.98 2.40 M2 18.00 9.61 4.52 1.50 0.00 1.00 8.71 2.74 1.96 2.49 M2 18.00 9.61 4.93 1.50 0.00 1.00 Page 1 tmp#1.txt 9.44 2.85 2.13 2.60 M2 18.00 9.61 5.34 1.50 0.00 1.00 10.16 2.97 2.31 2.72 M2 18.00 9.61 5.75 1.50 0.00 1.00 10.89 2.76 2.51 0.00 NA 18.00 18.00 6.16 1.50 0.00 1.00 11.62 2.97 2.72 0.00 NA 18.00 18.00 6.57 1.50 0.00 1.00 Page 2