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HomeMy WebLinkAboutCT 00-13; TABATA PROPERTY; DRAINAGE STUDY; 2002-05-09/ J • DRAINAGE STUDY FOR TABATA PROPERTY CT 00-13 Job No. 00-1003 May 9, 2002 Prepared by: O'DAY CONSULTANTS, INC. 5900 Pasteur Court Suite 100 Carlsbad, California 92008-7317 Tel: (760)931-7700 Fax: (760) 931-8680 Patrick N. O'Day RCE 27214 Date TABLE OF CONTENTS SECTION 1 HYDROLOGY FOR ON-SITE SYSTEM INTRODUCTION Purpose of Study Scope STUDY AREA Soils Groups Land Uses HYDROLOGY Rational Method Description CONCLUSION SECTION 2 SECTION 3 Vicinity Map USGS Quad Sheet Soil Classification Map Intensity/Duration Chart (XI A) Isopluvial Maps Runoff Coefficients Time of Concentration for Natural Watershed (X-C) Hydrology Existing Condition Basin 100 & 200 Basin 300 & 400 SECTION 4 Pre Drainage Area Map - Existing Condition - Fig. 1 Post Drainage Map - Proposed Condition - Fig. 2 SECTION 1 INTRODUCTION The site consists of a ridge running from south to north through the center of the property and drains to the northeast and southwest from the ridgeline. Previous use was farming and has been cultivated however at present it is vacant. Purpose of Study This drainage smdy was prepared to determine the runoff quantities for our site and determine the adequacy ofthe existing and proposed drainage facilities. Scope This study analyzes the 100-year flow for the pre and post condition ofthe drainage areas. STUDY AREA Soils Groups For on-site and off-site, a worst-case condition was assumed by using soil type D for this study. Land Use For all drainage areas, residential land use was utilized. HYDROLOGY The rational method for storm water runoff was used for this study according to the County of San Diego Hydrology Manual and Design Procedure Manual. Rational Method Description The rational method, as described in the 1985 San Diego County Flood Control/Hydrology Manual, is used to estunate surface runoff flows. The basic equation: Q = CIA C = runoff coefficient (varies with surface) I = intensity (varies with time of concentration) A = area in acres The design storm for this project is the 100-year event; the corresponding 6-hour and 24-hour rainfall is used to determine the storm intensity. CONCLUSION We analyzed the on-site Storm Drain system and based on our results we concluded that: For the 100-year storm The total Q for our site (existing conditions) = 10.50 cfs The total Q for our site (proposed conditions) = 14.45 cfs There is an increase of 3.95 cfs for the proposed site. SECTION 2 arr or OCEANSIDE HIGHWAYj—^ SITE arr or SAN MARCOS PACIFIC OCEAN CITY OF ENCINITAS VICINITY MAP NO SCALE A- 20 )n\to D A A 27 oS ^ G O ^7 /V DV, .26 35 \ JNTENSITY-DUPATION DESIGN CHART {TriTnTn.til i i-i-n-«<iilnii(iiiii.ii.ii.itr=. . Y i;i.iu.i ui.niniiliri .J ;-j Equation: I « 7.44 D -.645 I = Intensity (In./Hr.) « 6 Hr. Precipitation (In.) 0 a Duration (Min.) mrn I CTl I w C "D -J n n rt cu ft O 3 Z3 O m ut Directions for Application: 1) From precipitation naps detemiine 6 hr. and 24 hr. amounts for the selected frequency. These maps are printed in the County Hydrology Manual (10, 50 and 100 yr. maps included in the Design and Procedure Manual). 2) Adjust 6 hr. precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr. precipitation. (Not applicable to Desert) 3) Plot 6 hr. precipitation on the right side of the chart. 4) Draw a line through the point parallel to the plotted lines. 5) This line is the intensity-duration curve for the location being analyzed. Application Form: 0) Selected Frequency /^>a yr. 1) Pe ' ^'^ i"-• ^24' -^'^ ' \ ' Z.7 2) Adjusted *Pg= 3) t^ = min. 4) I = ^in/hr. 24 in. *Not Applicable to Desert Region 1 /or courrrv OF SAN OIEGO DEPARTMENT OF SANITATION 6 FLOOD CONTROL 100-YEAR 6-HOUR PRECIPiTATIOii ^20^ ISOPLUVIALS OF 100-YEAR 6-HOUR PKECIPITATIOn IfJ mim CF AH i::csi 33" Prep«»;il by U.S. DEPARTMENfr OF COMMERCE NATIONAL OCEANIC AND ATlJuSPllEKIC ADMINISTRATION SPECIAL STUDIES DRANCH, OFFICE OF lljuROLOGY, NATIONAL WEATHER SERVICE 30' k r»r»r*\Tr\T v VT r* COUNTY OF SAN DIEGO DEPARTMENT OF SANITATION & FLOOD CONTROL ^5 33' 30' 15 fttp U.S. DEPARTMtN 100-YEAn 24-IIOl)R PRECIPITATION ''20^ISOPtUVIAtS 0 PRECIPITATIOH IH 100 -YEAR 24-HOUR ENTIIS OF AN INCH 4 by r OF COMMERCE NATIONAL OCEANIC AND AT.'JoiiPllEKIC ADMINISTRATION DKOLOGY, NATIONAL WEATHER SEKVICE SPECIAL STUDIES BKANCII, OFFICE OF II 30' lur 30' 117' i,r,( :in' 116" AnnpunTV VT_I4 RUNOFF COEFFICIENTS (RATIONAL METHOD) LAiN'D USE Coefficient, C Soil Group (1) A B C D Undeveloped .30 .35 .40 .45 Residential: Rural .50 . 53 .40 . •* 5 Single Family . 40 .45 .50 . 55 Multi-Units .45 .50 .60 . 70 Mobile Homes (2) .45 .50 .55 .55 Commercial (2) 30% Impervious . 70 .75 .80 .35 Industrial (2) .80 .85 .90 .95 90% Impervious -NOTES: Cl) Obtain soil group from maps on file with the Department of Sanitation and Flood Control. (2) Where actual conditions deviate significantly frora the tabulated imperviousness values of 80% or 90%, the values given for coefficient C, may be revised by multiplying 80% or 90% by the ratio of actual imperviousness to the tabulated imperviousness. However, in no case shall the final coefficient be less than 0.50. For example: Consider commercial property on D soil group. Actual imperviousness = 50% Tabulated imperviousness = 80% Revised C = |° X 0.85 = 0.53 APPENDIX IX £Qa/pr/oA/ £40 SAN DIEGO COUNTY DEPARTMENT OF SPECIAL DISTRICT SERVICES DESIGN MANUAL APPROVED ^•3'// NOMOGRAPH FOR DETERMINATTON OF TIME OF CONCENTRATION (Tc) FOR NATURAL WATERSHEDS DATF /2///^9 r SECTION 3 5 1 1 H i ! —^M H • ! i -B a -line Of ^ndlP^cmAnohJ 1 i • i 1 1 - 3(J i !• ^ : ) i ! —M 11 Cf r?. fbtt tJArvk^Jk /AVteKSNecK /Am X-A) i f H- ——— • mmJi —' -. ^ \ r -X • i! 77.= |! '~iHi 1 ^ • ! ' • H H-ji -fl il • HI i i U-'— • •• — ~ H -B H-! ! S li H-jj. • ~~ — • — ____ • -• rH * f ~~ ~ ——————— • ———- - : i ©=^://4 •• -H H4 I I -444- rhjtJTi OF SM pmp A^m^K Xl ! 1 ! TTT A'- 4-0 Ar San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2 Rational method hydrology program based on San Diego County Flood Control Division 1985 hydrology manual Rational Hydrology Study Date: 05/09/02 HYDROLOGY STUDY - TABATA PROPERTY BASINS 100 & 200 J.N. 000040 MAY 9, 2002 FILE: 0040DS BY:CSO ********* Hydrology Study Control Information ********** O'Day Consultants, San Diego, California - S/N 10125 Rational hydrology study storm event year is 100.0 Map data precipitation entered: 6 hour, precipitation(inches) = 2.700 24 hour precipitation(inches) = 4.300 Adjusted 6 hour precipitation (inches) = 2.700 P6/P24 = 62.8% San Diego hydrology manual 'C values used Runoff coefficients by rational method +++++++++-f-t-+++++++++++++++++++++++++++++++++++-f++++++++-f-(-++ + Process from Point/Station 102.000 to Point/Station 104.000 **** INITIAL AREA EVALUATION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Initial subarea flow distance = 150.00(Ft.) Highest elevation = 365.50(Ft.) Lowest elevation = 361.95(Ft.) Elevation difference = 3.55(Ft.) Time of concentration calculated by the urban areas overland flow method (App X-C) = 9.10 min. TC = [1.8*(l.l-C)*distance'".5)/(% slope'^ (1/3) ] TC = [1.8*(l.l-0.5500)*(150.00^.5)/( 2.37"(1/3)]= 9.10 Rainfall intensity (I) = 4.835 for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.550 Subarea runoff = 0.718(CFS) Total initial stream area = 0.270(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 104.000 to Point/Station 106.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** Top of street segment elevation = 360.490(Ft.) End of street segment elevation = 356.820(Ft.) Length of street segment = 252.500(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 18.000(Ft.) Distance from crown to crossfall grade break = 16.500(Ft.) Slope from gutter to grade break (v/hz) = 0.020 Slope from grade break to crown (v/hz) = 0.020 Street flow is on [2] side(s) of the street Distance from curb to property line = 10.000(Ft.) Slope from curb to property line (v/hz) = 0.020 Gutter width = 1.500(Ft.) Gutter hike from flowline = 2.000(In.) Manning's N in gutter = 0.0150 Manning's N from gutter to grade break = 0.0150 Manning's N from grade break to crown = 0.0150 Estimated mean flow rate at midpoint of street = 1.303(CFS) Depth of flow = 0.233(Ft.), Average velocity = 1.952(Ft/s) Streetflow hydraulics at midpoint of street travel: Halfstreet flow width = 4.809(Ft.) Flow velocity = 1.95(Ft/s) Travel time = 2.16 min. TC = 11.25 min. Adding area flow to street Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [COMMERCIAL area type ] Rainfall intensity = 4.215(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.850 Subarea runoff = 1.577(CFS) for 0.440(Ac.) Total runoff = 2.295(CFS) Total area = 0.71(Ac.) Street flow at end of street = 2.295(CFS) Half street flow at end of street = 1.147(CFS) Depth of flow = 0.267(Ft.), Average velocity = 2.173(Ft/s) Flow width (from curb towards crown)= 6.522(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 106.000 to Point/Station 106.000 * * * * SUBAREA FLOW ADDITION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Time of concentration = 11.25 min. Rainfall intensity = 4.215(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method, Q=KCIA, C = 0.550 Subarea runoff = 1.623(CFS) for 0.700(Ac.) Total runoff = 3.917(CFS) Total area = 1.41(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 106.000 to Point/Station 106.000 **** SUBAREA FLOW ADDITION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Time of concentration = 11.25 min. Rainfall intensity = 4.215(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.550 Subarea runoff = 1.924(CFS) for 0.830{Ac.) Total runoff = 5.842(CFS) Total area = 2.24(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 206.000 to Point/Station 206.000 **** CONFLUENCE OF MINOR STREAMS **** Along Main Stream number: 1 in normal stream number 1 Stream flow area = 2.240(Ac.) Runoff from this stream = 5.842(CFS) Time of concentration = 11.25 min. Rainfall intensity = 4.215(In/Hr) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 202.000 to Point/Station 204.000 **** INITIAL AREA EVALUATION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [COMMERCIAL area type ] Initial subarea flow distance = 155.00(Ft.) Highest elevation = 369.92(Ft.) Lowest elevation = 366.96(Ft.) Elevation difference = 2.96(Ft.) Time of concentration calculated by the urban areas overland flow method (App X-C) = 4.52 min. TC = [1.8*(l.l-C)*distance''.5)/(% slope'^ (1/3) ] TC = [1.8*(l.l-0.8500)*(155.00'^.5)/( 1. 91'^ (1/3) ] = 4.52 Setting time of concentration to 5 minutes Rainfall intensity (I) = 7.114 for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.850 Subarea runoff = 0.605(CFS) Total initial stream area = 0.100(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 204.000 to Point/Station 206.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** Top of street segment elevation = 366.960(Ft.) End of street segment elevation = 357.350(Ft.) Length of street segment = 119.000(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 18.000(Ft.) Distance from crown to crossfall grade break = 16.500(Ft.) Slope from gutter to grade break (v/hz) = 0.020 Slope from grade break to crown (v/hz) = 0.020 Street flow is on [1] side(s) of the street Distance from curb to property line = 10.000(Ft.) Slope from curb to property line (v/hz) = 0.020 Gutter width = 1.500(Ft.) Gutter hike from flowline = 2.000(In.) Manning's N in gutter = 0.0150 Manning's N from gutter to grade break = 0.0150 Manning's N from grade break to crown = 0.0150 Estimated mean flow rate at midpoint of street = Depth of flow = 0.198(Ft.), Average velocity = Streetflow hydraulics at midpoint of street travel: Halfstreet flow width = 3.060(Ft.) Flow velocity = 4.32(Ft/s) Travel time = 0.4 6 min. TC = 5.4 6 min. Adding area flow to street Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 group C = 0.000 group D = 1.000 0.847(CFS) 4.316(Ft/s) for a 100.0 year storm Decimal fraction soil Decimal fraction soil [COMMERCIAL area type Rainfall intensity = 6.722(In/Hr) Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = Subarea runoff = 0.457(CFS) for 0.080(Ac.) Total runoff = 1.062(CFS) Total area = 0.18(Ac.) Street flow at end of street = 1.062(CFS) Half street flow at end of street = 1.062(CFS) Depth of flow = 0.212(Ft.), Average velocity = 4.372(Ft/s) Flow width (from curb towards crown)= 3.74 6(Ft.) 0.850 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 206.000 to Point/Station 206.000 **** CONFLUENCE OF MINOR STREAMS **** Along Main Stream number: 1 in normal stream number 2 Stream flow area = 0.180(Ac.) Runoff from this stream = 1.062(CFS) Time of concentration = 5.4 6 min. Rainfall intensity = 6.722(In/Hr) Summary of stream data: Stream No. Flow rate (CFS) TC (min) Rainfall Intensity (In/Hr) 1 2 Qmax(1) .842 ,062 Qmax(2) = 1.000 0.627 1.000 1.000 11.25 5.46 1.000 * 1.000 * 0.485 * 1.000 * 4.215 6.722 5.842) + 1.062) + 5.842) + 1.062) + 6.508 3.896 Total of 2 streams to confluence: Flow rates before confluence point: 5.842 1.062 Maximum flow rates at confluence using above data: 6.508 3.896 Area of streams before confluence: 2.240 0.180 Results of confluence: Total flow rate = 6.508(CFS) Time of concentration = 11.254 min. Effective stream area after confluence = 2.420(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 206.000 to Point/Station 208.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** Top of street segment elevation = 357.350(Ft.) End of street segment elevation = 34 6.150(Ft.) Length of street segment = 165.000(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 18.000(Ft.) Distance from crown to crossfall grade break = 16.500(Ft.) Slope from gutter to grade break (v/hz) = 0.020 Slope from grade break to crown (v/hz) = 0.020 Street flow is on [1] side(s) of the street Distance from curb to property line = 10.000(Ft.) Slope from curb to property line (v/hz) = 0.020 Gutter width = 1.500(Ft.) Gutter hike from flowline = 2.000(In.) Manning's N in gutter = 0.0150 Manning's N from gutter to grade break = 0.0150 Manning's N from grade break to crown = 0.0150 Estimated mean flow rate at midpoint of street = 6.642(CFS) Depth of flow = 0.340(Ft.), Average velocity = 5.852(Ft/s) Streetflow hydraulics at midpoint of street travel: Halfstreet flow width = 10.161(Ft.) Flow velocity = 5.85(Ft/s) Travel time = 0.47 min. TC = 11.72 min. Adding area flow to street Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [COMMERCIAL area type ] Rainfall intensity = 4.106(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area, Rational method,Q=KCIA, C = 0.850 Subarea runoff = 0.349(CFS) for 0.100(Ac.) Total runoff = 6.857(CFS) Total area = 2.52(Ac.) Street flow at end of street = 6.857(CFS) Half street flow at end of street = 6.857(CFS) Depth of flow = 0.343(Ft.), Average velocity = 5.896(Ft/s) Flow width (from curb towards crown)= 10.298(Ft.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 208.000 to Point/Station 208.000 SUBAREA FLOW ADDITION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Time of concentration = 11.72 min. Rainfall intensity = 4.106 (In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.550 Subarea runoff = 0.881(CFS) for 0.390(Ac.) Total runoff = 7.737(CFS) Total area = 2.91(Ac.) End of computations, total study area = 2.91 (Ac.) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software, (c) 1993 Version 3.2 Rational method hydrology program based on San Diego County Flood Control Division 1985 hydrology manual Rational Hydrology Study Date: 05/09/02 HYDROLOLGY STUDY - TABATA PROPERTY BASINS 300 & 400 J.N. 000040 MAY 9, 2002 FILE: 0040D2 BY:CSO ********* Hydrology Study Control Information ********** O'Day Consultants, San Diego, California - S/N 10125 Rational hydrology study storm event year is 100.0 Map data precipitation entered: 6 hour, precipitation(inches) = 2.700 24 hour precipitation(inches) = 4.300 Adjusted 6 hour precipitation (inches) = 2.700 P6/P24 = 62.8% San Diego hydrology manual 'C values used Runoff coefficients by rational method +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++4-+^ Process from Point/Station 302.000 to Point/Station 304.000 **** INITIAL AREA EVALUATION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Initial subarea flow distance = 140.00(Ft.) Highest elevation = 373.70(Ft.) Lowest elevation = 371.86(Ft.) Elevation difference = 1.84(Ft.) Time of concentration calculated by the urban areas overland flow method (App X-C) = 10.69 min. TC = [1.8*(l.l-C)*distance'^.5)/(% slope-^ (1/3) ] TC = [1.8*(l.l-0.5500)*(140.00'^.5)/( 1.31"(l/3)]= 10.69 Rainfall intensity (I) = 4.357 for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.550 Subarea runoff = 0.503(CFS) Total initial stream area = 0.210(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 304.000 to Point/Station 306.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** Top of street segment elevation = 371.420(Ft.) End of street segment elevation = 367.580(Ft.) Length of street segment = 213.000(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 18.000(Ft.) Distance from crown to crossfall grade break = 16.500(Ft.) Slope from gutter to grade break (v/hz) = 0.020 Slope from grade break to crown (v/hz) = 0.020 Street flow is on [2] side(s) of the street Distance from curb to property line = 10.000(Ft.) Slope from curb to property line (v/hz) = 0.020 Gutter width = 1.500(Ft.) Gutter hike from flowline = 2.000(In.) Manning's N in gutter = 0.0150 Manning's N from gutter to grade break = 0.0150 Manning's N from grade break to crown = 0.0150 Estimated mean flow rate at midpoint of street = Depth of flow = 0.208(Ft.), Average velocity = Streetflow hydraulics at midpoint of street travel Halfstreet flow width = 3.575(Ft.) Flow velocity = 2.05(Ft/s) 0.946(CFS) 2.055(Ft/s) TC A = 0.000 0.000 0.000 1.000 Travel time = 1.73 min. Adding area flow to street Decimal fraction soil group Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [COMMERCIAL area type Rainfall intensity = Runoff coefficient used for sub-area, Subarea runoff = 1.24 4(CFS) for Total runoff = 1.747(CFS) Street flow at end of street = Half street flow at end of street 12.42 min. ] 3.955(In/Hr for a 100.0 year storm Rational method,Q=KCIA, C = 0.370(Ac.) Total area = 0.58(Ac.) 1.747(CFS) 0.874(CFS) 0.850 Depth of flow = 0.244(Ft.), Average velocity = 2.246(Ft/s) Flow width (from curb towards crown)= 5.352(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 306.000 to Point/Station 306.000 **** SUBAREA FLOW ADDITION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Time of concentration = 12.42 min. Rainfall intensity = 3.955(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.550 Subarea runoff = 1.371(CFS) for 0.630(Ac.) Total runoff = 3.118(CFS) Total area = 1.21(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 306.000 to Point/Station 306.000 **** SUBAREA FLOW ADDITION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Time of concentration = 12.42 min. Rainfall intensity = 3.955(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.550 Subarea runoff = 1.827(CFS) for 0.840(Ac.) Total runoff = 4.945(CFS) Total area = 2.05(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 404.000 to Point/Station 404.000 **** CONFLUENCE OF MINOR STREAMS **** Along Main Stream number: 1 in normal stream number 1 Stream flow area = 2.050(Ac.) Runoff from this stream = 4.945(CFS) Time of concentration = 12.42 min. Rainfall intensity = 3.955(In/Hr) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 402.000 to Point/Station 404.000 **** INITIAL AREA EVALUATION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [COMMERCIAL area type ] Initial subarea flow distance = 48.00(Ft.) Highest elevation = 369. 92(Ft.) Lowest elevation = 368.03(Ft.) Elevation difference = 1.89(Ft.) Time of concentration calculated by the urban areas overland flow method (App X-C) = 1.97 min. TC = [1.8*(l.l-C)*distance'^.5)/(% slope"(l/3)] TC = [1.8* (1.1-0.8500) * ( 48.00'^.5)/( 3 . 94(1/3) ] = 1.97 Setting time of concentration to 5 minutes Rainfall intensity (I) = 7.114 for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.850 Subarea runoff = 0.181(CFS) Total initial stream area = 0.030(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 404.000 to Point/Station 404.000 **** CONFLUENCE OF MINOR STREAMS **** Along Main Stream number: 1 in normal stream number 2 Stream flow area = 0.030(Ac.) Runoff from this stream = 0.181(CFS) Time of concentration = 5.00 min. Rainfall intensity = 7.114(In/Hr) Summary of stream data: Stream No. Flow rate (CFS) TC (min) Rainfall Intensity (In/Hr) 1 4 . 945 12 42 3 955 2 0. 181 5 00 7 114 Qmax 1) = 1. 000 * 1 000 * 4 . 945) + 0. 556 * 1 000 * 0 .181) + = Qmax 2) = 1. 000 * 0 403 * 4 . 945) + 1. 000 * 1 000 * 0 .181) + 5.046 2.172 Total of 2 streams to confluence: Flow rates before confluence point: 4.945 0.181 Maximum flow rates at confluence using above data: 5.046 2.172 Area of streams before confluence: 2.050 0.030 Results of confluence: Total flow rate = 5.046(CFS) Time of concentration = 12.421 min. Effective stream area after confluence = 2.080(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 404.000 to Point/Station 406.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** Top of street segment elevation = 368.030(Ft.) End of street segment elevation = 352.280(Ft.) Length of street segment = 196.000(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 18.000(Ft.) Distance from crown to crossfall grade break = 16.500(Ft.) Slope from gutter to grade break (v/hz) = 0.020 Slope from grade break to crown (v/hz) = 0.020 Street flow is on [1] side(s) of the street Distance from curb to property line = 10.000(Ft.) Slope from curb to property line (v/hz) = Gutter width = 1.500(Ft.) Gutter hike from flowline = 2.000(In.) Manning's N in gutter = 0.0150 Manning's N from gutter to grade break = Manning's N from grade break to crown = Estimated mean flow rate at midpoint of street = Depth of flow = 0.317(Ft.), Average velocity = Streetflow hydraulics at midpoint of street travel Halfstreet flow width = 9.013(Ft.) Flow velocity = 5.97(Ft/s) Travel time = 0.55 min. TC = Adding area flow to street Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 0. 020 0.0150 0.0150 5.458(CFS) 5.967(Ft/s) 12.97 min. Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [COMMERCIAL area type ] Rainfall intensity = 3.847(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area, Rational method, Q=KCIA, C = 0.850 Subarea runoff = 1.112(CFS) for 0.340(Ac.) Total runoff = 6.158(CFS) Total area = 2.42(Ac.) Street flow at end of street = 6.158(CFS) Half street flow at end of street = 6.158(CFS) Depth of flow = 0.327(Ft.), Average velocity = 6.135(Ft/s) Flow width (from curb towards crown)= 9.493(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 406.000 to Point/Station 406.000 **** SUBAREA FLOW ADDITION **** Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [SINGLE FAMILY area type ] Time of concentration = 12.97 min. Rainfall intensity = 3.847(In/Hr) for a 100.0 year storm Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.550 Subarea runoff = 0.550(CFS) for 0.260(Ac.) Total runoff = 6.708(CFS) Total area = 2.68(Ac.) End of computations, total study area = 2.68 (Ac.) SECTION 4