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Home My WebLink About03 - Design Report - The Village Downtown - Stormwater c.,.� C� $0cd 2 t J(d STORM WATER MANAGEMENT DESIGN REPORT "THE VILLAGE DOWNTOWN" Prepared for: Delaney & Company Inc. 101 East Main, Bozeman, MT 59715 Prepared by: C & H]Engineering and Surveying, Inc. 205 Edelweiss Bozeman, MT 59718 (406) 587-1115 Project Number: 02026.3 December, 2003 STORM WATER MANAGEMENT Summary STORM WATER run-off from the public right-of-way will be directed to two storm water detention areas. One of these areas will be located on Lot#2 adjacent to Mill Creek(Detention Pond #1). This area will detain storm water run off from the public right-of-way and a portion of Lot#1 and #2. The other detention area will be constructed on Lot#4 east of the cul-de-sac adjacent to the emergency access road and easement(Detention Pond#2). This area will detain storm water run off from the public right-of-way and a portion of Lots #3, #4 and 45. The drainage areas contributing to each of the storage areas are highlighted on the overall grading/drainage plan enclosed in Appendix A. The storm water runoff rate was calculated with the rational formula as shown. A runoff coefficient (C) of 0.90 applicable to hard surfaces, a runoff coefficient(C) of 0.85 for house development, and a runoff coefficient of 0.30 for residential lawns/landscaping was used for the system. For portions of the drainage areas found on individual lots without building layouts a runoff coefficient of 0.50 was used. This is the runoff coefficient recommended in the City of Bozeman Storm water Master Plan for high density residential areas. For portions of the drainage areas in which building layouts are predetermined(on Lots 1 &2) the runoff coefficient was calculated as follows: Individual Lots Impervious Area(C=0.90) =410 ft2 Roof Area(C=0.85) =2,556 ft2 Grass and Landscaping(C=0.30) = 1,714 ft2 Total =4,680 ft2 Mean C = [(0.90x410 ft2)+(O.g5x2,556 ft2)+(0.30x1,714)]/4,680 ft2 = 0.67 Design Report-Page I of 10 Detention Area#1 Detention Area#1 handles the runoff generated from Drainage Area#1 and#3. Please see the grading and drainage plan (Appendix A). The storm water runoff surface areas for Drainage Area#1 were calculated as follows: CONTRIBUTING AREAS Impervious Area(C=0.90) = 55,333 ft2 Grass and Landscaping(C=0.30) =49,564 ft2 Lot Area(C=0.67) = 60,840 ft2 Total = 165,737 ft2 =3.8048 acres The storm water runoff surface areas for Drainage Area#3 were calculated as follows: CONTRIBUTING AREAS Impervious Area(C=0.90) =9,896 ft2 Grass and Landscaping(C=0.30) =48,436 ft2 Lot Area(C=0.67) =30,420 ft2 Total =88,752 ft2 =2.0375 acres Mean C= [(0.90x65,229 ft2)+(0.3008,000 ft2)+(0.67x91,260))/254,489 ft'- = 0.59 Overland travel time is based upon the length of time it would take a drop of water to travel from the furthest point in the drainage area to Detention Area#1. In this case the furthest point is the high point located in the center of the subdivision. The time of concentration is calculated on Figure I-1 in Appendix A. The travel time is calculated to be 30.5 minutes, or 0.5083 hours. Using the formula for the 10 year storm event a storm intensity and flow is calculated in the following formulas: Design Report-Page 2 of 10 I,o =0.64X-_65 = 0.64 (0.5083)-65 = 0.9935 in/hr The storage basin located in the detention structure can have a release rate of pre-development flow. The C coefficient for predevelopment is 0.20 and the release rate is calculated as follows: Qlo= CIA = 0.20 (0.9935 in/hr)(5.8423)= 1.16 cfs *111, Release rate The maximum required storage is calculated below by varying the storm duration and holding the release rate at 1.16 cfs and using a C of 0.59. Detentioni Pond #1 c = 0.59 A= 5.8423acres release = 1.16cfs Storm Storm Runoff Release Required length(min)len th hrs Intensity Q future Volume Volume Storage 28 0.466667 1.05033 3.620441 6082.34 1948.8 4133.54 29 0.483333 1.026643 3.538795 6157.504 2018.4 4139.104 30 0.5 1.004268 3.461667 6231.001 2088 4143.001 31 0.516667 0.98309 3.388668 6302.923 2157.6 4145.323 32 0.533333 0.96301 3.319454 6373.352 2227.2 4146.15 33 0.55 0.94394 3.253719 6442.364 2296.8 4145.564 34 0.566667 0.9258 3.191191 6510.031 2366.4 4143.631 35 0.583333 0.908519 3.131626 6576.415 2436 4140.415 36 0.6 0.892035 3.074805 6641.578 2505.6 4135.978 37 0.616667 0.876289 3.020529 6705.575 2575.2 4130.375 Detention Pond#1 will be constructed to a depth of 1.5 feet with a mid-depth surface area of 2,770 square feet. With 4:1 side slopes the detention pond will contain a volume of 4,155 cubic feet. OUTLET CONTROL STRUCTURE SIZING The outlet control structure for Detention Pond#1 needs to limit the release rate to the predevelopment runoff rate of 1.16.cfs. The slot width is sized using the following equation: Q= CLH3iz Where:Q=Discharge(efs) C =Weir Coefficient=3.33 L=Horizontal Length (feet) Design Report-Page 3 of 10 H=Head (feet) For the outlet control structure detailed in Appendix B. L= (L 16 cfs)/(3.33 x 1.5"') = 0.155 feet= 1.86 inches The weir needs to be 1.86" wide in order to limit the release rate to 1.16 cfs. STORM SEWER INFRASTRUCTURE 15" RCP crossing Village Boulevard This pipe carries the storm water flowing down the south side of Village Boulevard under the road towards detention pond#1(%2 of Drainage Area#1). Furthest point in drainage area=lots adjacent to high point on Village Boulevard Size of Drainage Area = 82,868 ft' = 1.9024 acres Mean C = 0.64 Time of Concentration Overland flow(100 ft @ 1.0%, C=0.30)= 13.5 min.(see Figure I-1, Appendix A) Gutter flow(697 ft @ 0.90% avg.slope) V= (1.486/n)R"'S'/2 (n=0.013, A=1.24 ft, P=9.23, R2/1=0.2623, S'/2=0.0949) `J=2.85 ft/s T= 697 ft/2.85 ft/s/60s/min =4.08 min Total Time of Concentration = 17.58 minutes(0.293 hours) For a 25-year storm event I25 =0.78X-.64 =0.78(0.293)-.64= 1.7112 in/hr Q25 =CIA= 0.64(1.7112 in/hr)(1.9024 acres) =2.08 cfs Calculations are enclosed in Appendix A for a 15" PVC pipe at 0.40% slope. The 15-inch pipe will flow at a depth of 7.58 inches with a velocity of 3.34 ft/sec. 18" RCP from Village Boulevard to Detention Area This pipe carries the storm water from all of Drainage Area#1(3.8048 acres). The time of concentration for all of Drainage Area#1 is identical to the time of concentration for the south half Design Report-Page 4 of 10 of the drainage area calculated above. Total Time of Concentration = 17.58 minutes(0.293 hours) For a 25-year storm event Its= 0.78X-•64=0.78(0.293)-.64= 1.7112 in/hr Q25 =CIA=0.64(1.7112 in/hr)(3.8048 acres) =4.17 cfs Calculations are enclosed in Appendix A for an 18"PVC pipe at 0.50% slope. The 18- inch pipe will flow at a depth of 9.65 inches with a velocity of 4.32 ft/sec. Swale from Private Road to Detention Area#1 The swale constructed from the private road on the north side of Village Boulevard to Detention Area#1 must be large enough to handle the runoff generated.by all of Drainage Area'#3. Furthest point in drainage area= eastern end of Drainage Area#3 Size of Drainage Area = 88,752 ft2=2.0375 acres Mean C =0.49 Time of Concentration Overland flow(500 ft @ 1.25%,C=0.30)=31.5 min.(see Figure I-1, Appendix A) =0.525 hours For a 25-year storm event I25=0.78X--"=0.78(0.525)-.14= 1.178 in/hr Q25=CIA= 0.49(1.l 78.int )(2.0375 acres) = 1.18 cfs Calculations are enclosed in Appendix A for swale I' deep with a P wide bottom and 4:1 side slopes. The swale will flow at a depth of-74U inches with a velocity of 3.34 ft/sec. Detention Area #2 Detention Area#2 handles the runoff generated from Drainage Area#2 and#7. Please see the grading and drainage plan (Appendix A). The storm water runoff surface areas for Drainage Area#2 were calculated as follows: CONTRIBUTING AREAS i Impervious Area(C=0.90) =99,136 ft2 Grass and Landscaping(C=0.30) =70,277 ft2 Design Report-Page 5 of 10 Lot Area(C=0.67) =32,760 ft2 Future Lot Area(C=0.50) =25,382 ft2 Total =227,555 ft2 = 5.2239 acres The storm water runoff surface areas for Drainage Area#7 were calculated as follows: CONTRIBUTING AREAS Future Lot Area(C=0.50) = 109,498 ft2 =2.5137 acres Mean C = [(0.90x99,136 ft2)+(0.30x70,277 ft2)+(0.67x32,760)+(0.50x134,880)j/337,053 ft2 =0.59 Overland travel time is based upon the length of time it would take a drop of water to travel from the furthest point in the drainage area to Detention Area#2. In this case the furthest point is the high point located in the center of the subdivision. The time of concentration is calculated on Figure I-1 in Appendix A. The travel time is calculated to be 35 minutes, or 0.5833 hours. Using the formula for the 10 year storm duration a storm intensity and flow is calculated in the following formulas: I10 =0.64X--65 = 0.64 (0.5833)-.61=0.9085 in/hr The storage basin located in the detention structure can have a release rate of pre-development flow. The C coefficient for this is 0.20 and the release rate is shown in the following: For pre-development, the C coefficient=0.20 Q,o= CIA=0.20 (0.9085 in/1-ir)(7.7377) = 1.40 efs *111, Release rate The maximum required storage is calculated below by varying the storm duration and holding the Design Report-Page 6 of 10 release rate at 1.40 cfs and using a C of 0.59. Detention Pond #2 c = 0.59 A = 7.7377acres release = 1.4cfs Storm Storm Runoff Release Required lenoth(min)len th hrs Intensity Q future Volume Volume Storage 34 0.566667 0.9258 4.2265 8622.06 2856 5766.06 35 0.583333 0.908519 4.14761 8709.982 2940 5769.982 36 0.6 0.892035 4.072354 8796.285 3024 5772.285 37 0.616667 0.876289 4.00047 8881 044 3108 5773 04 38 0.633333 0.86123 3.931722 8964.327 3192 5772.327 39 0.65 0.846811 3.865896 9046.197 3276 5770.197 40 0,666667 0.832989 3.802797 9126.714 3360 5766.714 41 0.683333 0.819726 3.742249 9205.932 3444 5761.932 42 0.7 0.806986 3,684089 9283.905 3528 5755.905 43 0.716667 0.794738 3.628171 9360.68 3612 5748.68 Detention Pond#2 will be constructed to a depth of 1.5 feet with a mid-depth surface area of 3,850 square feet. With 4:1 side slopes the detention pond will contain a volume of 5,775 cubic feet. OUTLET CONTROL STRUCTURE SIZING The outlet control structure for Detention Pond#2 needs to limit the release rate to the predevelopment runoff rate of 1.40 cfs. The slot width is sized using the following equation: Q = CLH3i2 Where:Q=Discharge(cfs) C=Weir Coefficient= 3.33 L=Horizontal Length(feet) H=Head (feet) For the outlet control structure detailed in Appendix B. L=(1.40 cfs)/(3.33 x 1.53r2) = 0.187 feet=2.24 inches The weir needs to be 2.24" wide in order to limit the release rate to 1.40 cfs. Design Report-Page 7 of 10 STORM SEWER INFRASTRUCTURE 18" PVC from east end of Village Boulevard to Detention Area #2 This pipe carries the storm water from the eastern half of Village Boulevard(Drainage Area#2). Furthest point in drainage area=lots adjacent to high point on Village Boulevard Size of Drainage Area =227,555 ft2= 5.2239 acres Mean C = 0.64 Time of Concentration Overland flow(100 ft @ 1.0%, C=0.30)= 13.5 min.(see Figure I-1, Appendix A) Gutter flow(300 ft @ 1.50% avg.slope) V=(1.486/n)R213S'l2 (n=0.013; A=1.24 ft, P=9.23, R2/3=0.2623, S 1/2=0.1225) V=3.67 ft/s T=300 ft/3.67 ft/s/60s/min = 1.36 min Gutter flow(660 ft @ 4.7% avg.slope) V= (1.486/n)R2/3S'/2 (n=0.013, A=1.24 ft, P=9.23, R2/3=0.2623, S'/2=0.2168) V=6.5 ft/s T= 660 ft/6.5 ft/s/60s/min = 1.69 min Total Time of Concentration = 16.55 minutes(0.2758 hours) For a 25-year storm event I25 = 0.78X-.G4=0.78(0.2758)-G4= 1.78 in/hr Q25 = CIA= 0.64(1.78 in/hr)(5.2239 acres) = 5.95 cfs Calculations are enclosed in Appendix A for a 18" PVC pipe at 0.50% slope. The 18-inch pipe will flow at a depth of 12.19 inches with a velocity of 4.67 ft/sec. Retention Pond#3 Retention Pond#3 handles the runoff from Drainage Area#4 Design Report-Page 8 of 10 CONTRIBUTING AREAS Future Lot Development(C=0.50) =213,501 ft2 =4.9013 acres For a 10-yr 2-hr storm event: V= CdA V=0.50 x 0.068 ft x 213,501 ft2 =7,259 ft' =volume to be retained The proposed pond has a mid-depth surface area of 4,840 ft2. At a depth of 1.50 feet, the pond has a storage volume of 7,260 ft'. Retention Pond #4 Retention Pond#4 handles the runoff from Drainage Area#5 Impervious Area(C=0.90) =9,506 ft2 Grass and Landscaping(C=0.30) =40,780 ft2 Lot Area(C=0.67) =25,614 ft2 Total =75,900 ft2 = 1.7424 acres Mean C = [(0.90x 9,506ft2)+(0.30x40,780 ft2)+(0.67x25,614)]/75,900 ft2 = 0.50 For a 10-yr 2-hr storm event: V= CdA V= 0.50 x 0.068 ft x 75,900 ft2=2,581 ft' =volume to be retained The proposed pond has a mid-depth surface area of 1,622 ft2. At a depth of 1.50 feet, the pond has a storage volume of 2,433 ft'. Design Report-Page 9 of 10 Retention Pond #5 Retention Pond#5 handles the runoff from Drainage Area#6 CONTRIBUTING AREAS Future Lot Area(C=0.50) = 134,483 ft' =3.0873 acres For a 10-yr 2-hr storm event: V=CdA V = 0.50 x 0.068 ft x 134,483 ft' =4,572 ft' =volume to'be retained The proposed pond has a raid-depth surface area of 3,050 ft2. At a depth of 1.50 feet, the pond has a storage volume of 4,575 ft3. CAPACITY OF CURB & GUTTER The curb section with the largest contributing area is located at the east end of Village Boulevard. Each curb carries %2 of the drainage from Drainage Area#2 with a minimum slope of 1.23%. The capacity of the curb and gutter at 1.23% slope with a depth of water 0.15'below top of curb is calculated as follows: Q=(1.486/n)AR2i3S1/2 n= 0.013 for Concrete A= 1.24 ft2 P = 9.23 ft R=A/P = 1,24/9.23 =0.1343 ft R2/3 =0.2623 .ft S = 0.0123 ft/ft SI/2= 0.1109 ft/ft Q=(1.486/0.013)(1.24)(0.2623)(0.1109)=4.12 cfs. The maximum flowrate for all of Drainage Area#2, for a 25-year event, was previously calculated to be 5.95 cfs. The flow within each curb section is equal to 5.95cfs/2 or 2.98 cfs. 2.98 cfs < 4.12 cfs — Gutter capacity is adequate 02026.3/office/design report Design Report Page 10 of 10 APPENDIX A ♦JI♦� \ C i It 1 \ \•l� , \ \\\\ F / ♦` 1 1 t A NO jJ AuI tn� �II 3¢ ✓ley✓/+®�' ®!p y�oe �.�, !�i1 /%"s� '\ \\ III 8s°+®�\ II \\ \� iAi 1200 I 140 I I I I I I I I I I I I 120 Li I I t o I I I I I I I I I II 11 I I I IIIIIII uj 800 ! I I I i I I I I ( I I I i I CO s II II I III II � I ! I l I I I I I I I I I I I I z booLu I Iui z o LL- 40o `' j7- < . � � I � I I I I i I-- ' 1 ► I I I I ► I I I I I !,� I I Q 0o 9 I I I I I I I. �" I J I I X > 20 � � ' � i I I ! ! I ► I � I I i l l I I I I I 0 FIGURE I-1 TIME OF CONCENTRATION (Rational Formula) 2Do v 1200 140 P I( I 1000 I i ° 10 ° I I I I I I 120 i o I II 1Y I I W 600 1 i ) I i 100 z Z LLJ LLJ 1 i I11I 600 I I I I �o z W U " I I I i o i G i o Q 4 00 -) I I I I I s0 i o Z J a I _ I I I I LJ 200 40 0o s 1 I XI ► I i I � 0 I I I - 20 I i FIGURE I-I TIME OF CONCENTRATION (Rational Formula) 26 15" PVC crossing village Boulevard Manning Pipe Calculator Given Input Data: shape. . . . . . . . . . . . . . . . . . . . . . . . . . . Circular solving for . . . . . . . . . . . . . . . . . . . . . Depth of Flow Diameter . . . . . . . . . . . . . . . . . . . . . . . . 15.0000 in Flowrate . . . . . . . . . . . . . . . . . . . . . . . . 2.0800 cfs slope . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.0040 ft/ft Manning's n . . . . . . . . . . . . . . . . . . . . . 0.0130 Computed Results: Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5804 in Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2272 ft2 wetted Area 0.6220 ft2 wetted Perimeter . . . . . . . . . . . . . . . . 23.7228 in Perimeter. . . . . . . . . . . . . . . . . . . . . . 47.1239 in Velocity . . . . . . . . . . . . . . . . . . . . . . . . 3.3442 fps Hydraulic -Radius 3.7754 in Percent Full . . . . . . . . . . . . . . . . . . . . 50.5361 Full flow Flowrate . . . . . . . . . . . . . . 4.0855 cfs Full flow velocity . . . . . . . . . . . . . . 3.3292 fps Critical information Critical depth . . . . . . . . . . . . . . . . . . 6.9013 in Critical slope . . . . . . . . . . . . . . . . . . 0.0055 ft/ft Critical velocity . . . . . . . . . . . . . . . 3.7730 fps Critical area . . . . . . . . . . . . . . . . . . . 0.5513 ft2 Critical perimeter . . . . . . . . . . . . . . 22.3632 in Critical hydraulic radius . . . . . . . 3.5498 in Critical top width . . . . . . . . . . . . . . 14.9521 in specific energy 0.8055 ft Minimum energy . . . . . . . . . . . . . . . . . . 0.8627 ft Froude number 0.8358 Flow condition . . . . . . . . . . . . . subcritical 18" PVC from village Boulevard to Detention Area #1 Manning Pipe Calculator Given Input Data: shape . . . . . . . . . . . . . . . . . . . . . . . Circular solving for . . . . . . . . . . . . . . . . . . . . . Depth of Flow Diameter . . . . . . . . . . . . . . . . . . . . . . . . 18.0000 in Flowrate . . . . . . . . . . . . . . . . . . . . . . . . 4.1700 cfs slope . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.0050 ft/ft manning's n . . . . . . . . . . . . . . . . . . . . . 0.0130 computed Results: Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6462 in Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7671 ft2 wetted Area 0.9643 ft2 wetted Perimeter 29.5678 in .Perimeter 56.5487 in velocity . 4.3245 fps Hydraulic Radius . . . . . . . . . . . . . . 4.6962 in Percent Full . . . . . . . . . . . . . . . . . . . . 53.5898 Full flow Flowrate . . . . . . . . . . . . . . 7.4277 cfs Full flow velocity . . . . . . . . . . . . . . 4.2032 fps Critical Information Critical depth . . . . . . . . . . . . . . . . . . 9.3909 in Critical slope . . . . . . . . . . . . . . . . . . 0.0055 ft/ft Critical velocity . . . . . . . . . . . . . . . 4.4722 fps Critical area . . . . . . . . . . . . . . . . . . . 0.9324 ft2 Critical perimeter . . . . . . . . . . . . . . 29.0562 in Critical hydraulic radius . . . . . . . 4.6211 in Critical top width . . . . . . . . . . . . . . 18.0000 in specific energy . . . . . . . . . . . . . . . . . 1.0944 ft Minimum energy . . . . . . . . . . . . . . . . . . 1.1739 ft Froude number ' . . . . . . . . . . . . . . . 0.9509 FTow"condition .. . . . . . . . . . . . . . . . . . subcritical 1200 140 I I I I ( 1000 11 I I ° I o I I I I 120 + I w I o� I i o I I so o 1 I I I I I 1- I I oo z _ I � z I I 1 1 i I I a 600 I I I 1 I I i ao W i I I z z _ o } 400 I I 1 1 1 I I 60 ►- - ' Z a o o 40 G I I I i l l 0 I i 20 I � � � I I I I ( 0 FIGURE I-I TIME OF CONCENTRATION (Rational Formula) 26 Swale from Drainage Area #3 to Detention Pond #1 Channel Calculator Given Input Data: shape . . . . . . . . . . . . . . . . . . . . . . . . . . . Trapezoidal solving for . . . . . . . . . . . . . . . . . . . . . Depth of Flow Flowrate . . . . . . . . . . . . . . . . . . . . . . . . 1.1800 cfs Slope . . . . . . . . . . . . . . . . . . . . . . . . 0.0050 ft/ft Manning's n . . . . . . . . . . . . . . . . . . . . . 0.0350 Height . . . . . . . . . . . . . . . . . . . . . 12.0000 in Bottom width . . . . . . . . . . . . . . . . . . . . 12.0000 in Left slope . . . . . . . . . . . . . . . . . . . . . . 0.2500 ft/ft (v/H) Right slope . . . . . . . . . . . . . . . . . . . . . 0.2500 ft/ft (v/H) Computed Results: Depth 4.7409 in velocity . . . . . . . . . . . . . . . . . . . . . 1.1575 fps Full Flowrate . . . . . . . . . . . . . . . . . . . 9.9635 cfs Flow area 1.0194 ft2 Flow perimeter . . ... . . . . . . . . . . . . . . 51.0941 in Hydraulic radius . . . . . . . . . . . . . . . . 2.8730 in Top width . . . . . . . . . . . . . . . . . . . . . . . 49.9269 in Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0000 ft2 Perimeter . . . . . . . . . . . . . . . . . . . . 110.9545 in Percent full . . . . . . . . . . . . . . . . . . . . 39.5072 Critical Information Critical depth . . . . . . . . . . . . . . . . . . 3.0298 in critical slope . . . . . . . . . . . . . . . . . 0.0332 ft/ft Critical velocity . . . . . . . . . . . . . . . 2.3252 fps critical area . . . . . . . . . . . . . . . . . . . 0.5075 ft2 critical perimeter . . . . . . . . . . . . . . 36.9844 in Critical hydraulic radius . . . . . . . 1.9759 in Critical top width . . 36.2385 in Specific *energy . . ... . . . . . . . . ... . . ` 0.4159 ft Minimum energy . . . . . . . . . . . . . . . . . . 0.3787 ft Froude number . . . . . . . . . . . . . . . . . . . 0.4123 Flow condition . . . . . . . . . . . . . . . . . . Subcritical � r f ( LI 1200 140 1000 0 � ° I 120 lu o\ O Boo &0 z Li Li T 600 so LIJ o 0 G J ` ti uj 400 I � I I � � � I 60 0 o z '20�J 1--` I J i + J� r'r r' I i L OI 40 0 v f 20 I 0 FIGURE I-1 TIME OF CONCENTRATION (Rational Formula) 26 18" PVC from east end of village Boulevard to Detention Area #2 Manning Pipe Calculator Given Input Data: shape . . . . . . . . . . . . . . . . . . . . . . . . . . . Circular Solving for . . . . . . . . . . . . . . . . . . . . . Depth of Flow Diameter 18.0000 in Flowrate . . . . . . . . . . . . . . . . . . . . . . . . 5.9500 cfs Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.0050 ft/ft Mann-ing`s n . . . . . . . . . . . . . . . . . . . . . 0.0130 computed Results: Depth 12.1903 in Area . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7671 ft2 wetted Area . . . . . . . . . . . . . . . . ... . . . 1.2738 ft2 wetted Perimeter 34.7968 in Perimeter . . . . . . . . . . . . . . . . . . . . . . . 56.5487 in velocity 4.6709 fps Hydraulic Radius . . . . 5.2716 in Percent Full 67.7240 Full flow Flowrate . . . . . . . . . . . . . . 7.4277 cfs Full flow velocity 4.2032 fps Critical Information Critical depth . . . . . . . . . . . . . . . . . . 11.3857 in Critical slope . . . . . . . . . . . . . . . . . 0.0060 ft/ft Critical velocity . . . . . . . . . . . . . . . 5.0347 fps Critical area . . . . . . . . . . . . . . . . . . . 1.1818 ft2 Critical perimeter 33.0458 in Critical hydraulic radius . . . . . . . 5.1498 in Critical top width . . . . . . . . . . . . . . 18.0000 in Specific energy . . . . . . . . . . . . . . . . . 1.3485 ft Minimum energy . . . . . . . . . . . . . . . . . . 1.4232 ft Froude number . . . . . . . . . . . . . . . . . . . 0.8992 Flow condition . . . . . subcritical 0 v, p � a � y zd II _ c;o p II ti w ti .-3 i i