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15 Civil Engineering Report App B Pond Calculations
Impervious 0.90Lawn/Landscaped 0.10Undisturbed 0.20Pre-Development: Existing ConditionWeighted C-Value (Cw)Area Runoff (AC)CoefficientCalculationsUndisturbed4.39 0.20 0.88Totals4.39 0.88Cw =0.20Post-Development: Existing ConditionWeighted C-Value (Cw)Area Runoff (AC)CoefficientCalculationsImpervious3.01 0.90 2.71Lawn1.38 0.10 0.14Undisturbed0.00 0.20 0.00Totals4.39 1.20 2.85Cw =0.65EAST FRONTAGE DEVELOPMENTWEIGHTED C-VALUEL:\193190\Computations\CITY OF STORMWATER PONDS.xls Existing SituationMinimum VolumeLand Use Open LandArea 4.39 AcresStorm DurationIntensity Future Runoff Rate Runoff VolumeRelease RateRelease VolumeRequired StorageSlope 1 %(Minutes) (in/hr) Q=CiA (cfs) (cf) (cfs) (cf) (cf)C= 0.2012 1.82 5.203743 0.031 22 3,721Overland Flow Distance 300 ft14 1.65 4.703951 0.031 26 3,925Time of Concentration29min16 1.51 4.314140 0.031 30 4,110Design Storm Frequency 10 year (Table I-3)18 1.40 3.994314 0.031 33 4,280Intensity at Tc 1.02 in/hr (Figure I-3)20 1.31 3.734476 0.031 37 4,439Peak Runoff Rate 0.898 cfs22 1.23 3.514628 0.031 41 4,58724 1.16 3.314771 0.031 45 4,726Proposed Situation26 1.10 3.154906 0.031 48 4,858Land Use Commercial28 1.05 3.005035 0.031 52 4,983Area 4.39 Acres30 1.00 2.875158 0.031 56 5,103Slope 1.5 %32 0.96 2.755276 0.898 108 5,168C= 0.6534 0.93 2.645389 0.898 108 5,281Overland Flow Distance 200 ft36 0.89 2.555498 0.898 216 5,283 *Time of Concentration10min38 0.86 2.465603 0.898 323 5,280Design Storm Frequency 10 year (Table I-3)40 0.83 2.385705 0.898 431 5,27342 0.81 2.305803 0.898 539 5,264Intensity at Tc 2.00 in/hr 10-yr (Figure I-3)44 0.78 2.235898 0.898 647 5,2513.27 in/hr 100-yr (Figure I-3)46 0.76 2.175991 0.898 755 5,23648 0.74 2.116081 0.898 862 5,218Peak Runoff Rate 5.71 cfs 10-yr50 0.72 2.066168 0.898 970 5,1989.33 cfs 100-yr52 0.70 2.006253 0.898 1,078 5,17554 0.69 1.966336 0.898 1,186 5,151Percent Inpervious69%56 0.67 1.916418 0.898 1,294 5,12458 0.65 1.876497 0.898 1,401 5,095Runoff Treatment Volume 5346 cf60 0.64 1.836574 0.898 1,509 5,065(RTV)62 0.63 1.796650 0.898 1,617 5,03364 0.61 1.756725 0.898 1,725 5,000Orifice Flowrate 0.031 cfs66 0.60 1.726797 0.898 1,833 4,965Orifice Size1.0 inches68 0.59 1.686869 0.898 1,940 4,92870 0.58 1.656939 0.898 2,048 4,891Weir Flowrate0.898 cfs72 0.57 1.627008 0.898 2,156 4,852Weir Width12.0inches74 0.56 1.597075 0.898 2,264 4,811*10-yr Detention Volume Required - 5283 cfEAST FRONTAGE DEVELOPMENTDETENTION RELEASE RATEL:\193190\Computations\ON-SITE STORM.xls Pond Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v12 Friday, 10 / 16 / 2020 Pond No. 1 - POND A Pond Data Contours -User-defined contour areas. Conic method used for volume calculation. Begining Elevation = 4782.75 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 4782.75 1,863 0 0 0.25 4783.00 3,470 656 656 0.50 4783.25 7,038 1,287 1,944 0.75 4783.50 9,930 2,110 4,054 1.00 4783.75 10,591 2,564 6,618 1.25 4784.00 15,114 3,196 9,815 1.50 4784.25 16,961 4,007 13,821 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise (in)= 1.00 0.00 0.00 0.00 Span (in)= 1.00 0.00 0.00 0.00 No. Barrels = 1 0 0 0 Invert El. (ft)= 4782.75 0.00 0.00 0.00 Length (ft)= 0.10 0.00 0.00 0.00 Slope (%)= 1.00 0.00 0.00 n/a N-Value = .011 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a No No No Crest Len (ft)= 1.00 4.00 0.00 0.00 Crest El. (ft)= 4783.75 4784.00 0.00 0.00 Weir Coeff.= 3.33 2.60 3.33 3.33 Weir Type = Rect Broad --- --- Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 0.50 1.00 1.50 2.00 2.50 3.00 Stage (ft) 0.00 4782.75 0.20 4782.95 0.40 4783.15 0.60 4783.35 0.80 4783.55 1.00 4783.75 1.20 4783.95 1.40 4784.15 1.60 4784.35 1.80 4784.55 2.00 4784.75 Elev (ft) Discharge (cfs) Stage / Discharge Total Q