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Home My WebLink AboutHORSETOOTH EAST BUSINESS PARK, CARRIAGE AUTO SERVICE SHOP - PDP - 43-94I - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTI� 1, Ll 1 1 I I I I 1 11 1 COMPOSITE RUNOFF COEFFICIENT Percent of impervious and pervious were determined based on the proposed layout with areas determined using AutoCad. General formulation: C= { [(% Perv.)(Coef Perv)] + [(% ImPerv.)(Coef. ImPerv)] ) / 1 SUB- BASIN % PERVIOUS C PERVIOUS % IMPERVIOUS C IMPERVIOUS C COMPOSITE 10-A 23.41 0.25 76.59 0.95 0.79 10-B 39.49 0.25 60.51 0.95 0.67 1 2 Effectiveness Calculations 7 LJ r 1_I 1 11 PROJECT: Carriage Auto Service Shop STANDARD FORM B COMPLETED BY: SD DATE: 07/15/03 Erosion Control C-Factor P-Factor Method Value Value Comment Soil Treatment Methods bare soil 1.00 1.00 reseed 0.06 1.00 sod grass 0.01 1.00 pavement 0.01 1.00 Structural Treatment Me h ds no structure 1.00 1.00 gravel filter 1.00 0.60 straw bale 1.00 0.80 silt fence 1.00 0.50 sediment trap 1.00 0.50 Major Basin PS (%) Sub -Basin Area Calculations Soil Treatment Methods: 0 bare soil 0.00 reseed 10-A 0.62 0.14 sod grass 0.48 pavement Structural Methods: 0.5 silt fence 10 91.36% 1 no structure C-FACTOR= 0.01 1 no structure P-FACTOR= 0.50 1 no structure EFF= 99.50% 0.62 = EFF'A,b 1 no structure Soil Treatment Methods: 0 bare soil 0.10 reseed 10-B 0.27 0.10 sod grass 0.17 pavement Structural Methods: 0.5 silt fence 1 no structure C-FACTOR= 0.03 1 no structure P-FACTOR= 0.50 1 no structure EFF= 98.39% 0.26 = EFF'A b 1 no structure Area = 4:89 Sum (AO*EFF,b) = RL. EFF= 882% Performance= 81.4% Design Works ' TST, INC. CONSULTING 7/14/03 ENGINEERS Page 1 of 1 Erosion Control Effectiveness_ phase breakdown.xls I i 11 1 t 11 Performance and Effectiveness Calculations PROJECT: Carriage Auto Service Shop STANDARD FORM A COMPLETED BY: SD DATE: 07/15/03 DEVELOPED SUBBASIN ERODIBILITY ZONE Asb (ac) L8b (ft) Ssb N Lb"ASb Nb'Sb PS (%) 1'O=A"?;,�-;?`w moderate 0.62 160 2.00 99.20 1.24 n moderate 0.27 90 0.70 24.21 0.19 4+]'!�a 4F xw M* 4'91%-M ,01V+NRiia 0.891 1 138.821 1.61 0.7766 PS (after construction)= 0.9136 TST, INC. CONSULTING 7114103 ENGINEERS Page Egfsion Control Effectiveness_ phase breakdown.xls Curb Openine Width for Sub -Basin 10-A Weir Coefficient: C =3.1 According to the street capacity criteria, maximum flow depth on the flow lined + 18" Therefore the curb opening is only designed for the 10-yr return period. Overflow depth: H = 0.5 .ft 10-yr flow: Qlo = 2.33 ft /sec d Qio With of Curb Opening: L= C H3/2 L= 2.5 ft Curb Opening Width for Sub -Basin 10-B Weir Coefficient: C =3.1 According to the street capacity criteria, maximum flow depth on the flow lined + 18" Therefore the curb opening is only designed for the 10-yr return period. Overflow depth: H = 0.5 .ft 10-yr flow: Qto = 0.86 ft3/sec d Qo With of Curb Opening: L = C H3/ z w;d4-. L= 0.80 ft Design of Riprap Channel Cross Section Project: Carriage Auto Service Shop Channel ID:C (RUN DOWN SWALE) mel Invert Slope )m Width Side Slope t Side Slope ;ific Gravity of Rock lus of Channel Centerline Ign Disharge prop Type (Straight Channel) ;ermedlate Rock Diameter (Straight Channel) ilculated Manning's N (Straight Channel) prap Type (Outside Bend of Curved Channel) termediate Rock Dia. (O.B. of Curved Channel) ilculated Manning's N (Curved Channel) ater Depth ip Width of Flow ow Area etted Perimeter /draulic Radius (A/P) rerage Flow Velocity (Q/A) ydraulic Depth (A/T) oude Number (max. = 0.8) hannel Radius /Top Width prap Design Velocity Factor For Curved Channel Iprap Sizing Velocity For Curved Channel Iprap Sizing Paramenter for Straight Channel Iprap Sizing Paramenter for Outside Bend of Curve uperelevation (dh) ischarge (Check) So = 0.0200 B = 0.0 Z1 = 12.0 Z2 = 12.0 Ss = 2.50 Ccr = Q = 1.1 Type=`*4&kV'.L D50 =6 N =,&=52 Type = D50 N y = 0:24 T A =. 0'7 R = U' 1 V = -1.5 s=r. D = 01. Fr = '0.739 Ccr/T = .8:00 Kv 1.00 VKv = 1i'5 K = 057 Kcurve= 7 dh = 0.00 ft/ft ft ft/ft ft/ft ft cfs Inches Inches I ft ft sq ft ft ft fps ft fps ft cfs Analysis of Trapezoidal Grass -Lined Channel Project: Carriage Auto Service Shop Channel ID: B (GRASS SWALE) Grass Type: A B C D E LimitingMannin 's N 0.060 0.040 0.033 0.030 0.024 Soil Type: Max. Velocity (V1718%) Max. Froude No. (Finax) Non -Sandy 7.0 fps 0.80 Sandy 5.0 fps 0.60 gn Information r Grass Manning's N a of Grass (A,B,C,D, or E) nnel Invert Slope )m Width Side Slope it Side Slope Ign Discharge ck one of the following soil types er Depth Width i Area ted Perimeter raulic Radius r Velocity raulic Depth ide Number :harge (Check) N 0:035 Other. Grass So = ,.0E0050 ft/ft B = 3.00 ft Zt = . 4.00 ft/ft Z2 = 4:00 ft/ft Q = 7.7 cfs Sandy Soil X check, OR Non -Sandy Soil check Y = :._ 0 2 ft T = ...:., a:=? .6 ft A = :,< x{,:.:.: ' ;.' .4.23 s ft 9 P = p894 ft R ft V = ,1:83 fps D = x ",048 It Fr = OOA6 cfs I 1 1 1 1 n 1 J L Design of Riprap Channel Cross Section Project: Carriage Auto Service Shop Channel ID: -A (RUN DOWN SWALE) nnel Invert Slope So = 0.0050 ft/ft :)m Width B = 0.0 ft Side Slope Z1 = 12.0 _ft/ft it Side Slope Z2 = 12.0 ft/ft cific Gravity of Rock Ss = 2.50 ius of Channel Centerline Ccr = It Ign Disharge q = 3.1 cfs rap Type (Straight Channel) Type irmediate Rock Diameter (Straight Channel) D50 4Z Inches culated Manning's N (Straight Channel) N=10:03'S2 rap Type (Outside Bend of Curved Channel) Type J ', Prmediate Rock Dia. (O.B. of Curved Channel) D50 `211 inches culated Manning's N (Curved Channel) N ter Depth Y = 0a47 ft i Width of Flow T = 143 ft w Area A =i .::_, 2r7 sq ft tied Perimeter P = _:: r1.3 ft iraulic Radius (A/P) R 02 It ;rage Flow Velocity (Q/A) V fps iraulic Depth (A(r) D = ` 0'i2 ft ude Number (max. = 0.8) Fr =i , 0. 4;44 annel Radius / Top Width Ccr/T = 8:00 crap Design Velocity Factor For Curved Channel Kv = 100 crap Sizing Velocity For Curved Channel VKV _ 11 fps )rap Sizing Paramenter for Straight Channel K )rap Sizing Paramenter for Outside Bend of Curve Kcumq= ':0 35 perelevation (dh) dh 0:00 ft icharge (Check) q cfs 1 m w m m m ems' m i ni m mm m Imo■ mm m m m Figure 2-1 Table 1. HYDROLOGIC CALCULATIONS WORKSHEET OVERLAND FREQ. COEFF. OVERLAND TRAVEL TIME GUTTER BASIN SUB DESIGN AREAFLOW RUNOFF COEFFICIENT FLOW LENGTH Ti Ti BASIN POINT (ac) C Cf Cf LENGTH 10-YR 100-YR 10-YR 100-YR (ft) (�) (min(fps) 10 10-A 1 0.62 0.79 1 1.25 30 2 2.56 160 10-B 2 0.27 0.67 1 1.25 40 1.6 4.32 90 SUB BASIN DESIGN POINT AVERAGE GUTTER SLOPE (%) GUTTER FLOW VELOCITY (fps) GUTTER TRAVEL TIME (min) TIME OF CONCENTRATION RAINFALL INTENSITY PEAK DISCHARGE Tc 10-YR Tc 100-YR I 10-YR I 100-YR Q 10-YR Q 100-YR 10-A 1 2 2.83 0.94 5 5 4.78 9.76 2.33 5.94 10-B 2 1 1.67 1.67 0.90 5.22 5 4.72 9.76 0.86 2.62 Figure 2-2 Table IA. SUMMARY OF ATTENNUATED DEVELOPED RUNOFF FREQ. TIME RAINFALL PEAK CONTRIBUTING COMBINED COEFF. CONCENTRATION INTENSITY DISCHARGE DESIGN CONTRIBUTING AREA RUN OFF Cf Cf I I Q Q BASIN POINT SUB BASIN (ac) COEFF. 10- 100- Tc Tc 10- 100- 10- 100- YR YR 10-YR 100-YR YR YR YR YR 10 3 1 0.62 0.79 1 1.25 102.50 100.89 0.56 1.98 0.27 1.20 3 2 0.27 - - - - - - - 0.86 2.62 TOTAL 3 1,2 0.89 - - - - - - - 1.13 3.83 TST, INC Consulting Engineers 748 Whalers Way Building D Fort Collins, CO 80525.4872 Phone: (970) 226 0557 START ATTENUATION ANALYSIS ADDITIONAL DATA FOR ATTENUATION ANALYSIS DP = CURRENT DESIGN POINT NDP = NUMBER OF INCOMMING DESIGN POINT IDP(l... 5) = INCOMMING DESIGN POINT ( 1 .... 5 )-> IDPI, IDP2...... IDP5 SDP (I ...5) = GUTTER SLOPE FROM DESIGN POINT (1... 5 )� SDPI, ...SDP5 LDP (1 ... 5) = GUTTER LENGTH FROM DESIG14T POINT (I ...5)4 LDP 1, ..LDP5 TTDP( 1..5 ) = TOTAL TRAVEL TIME FROM DP 1, ...DP5 CALCULATE MAXIMUM TRAVEL TIME FOR 2-YR AND 100-YR TTDP = MAX. (TTDP L.5 + LDP 1..5 I (Cv x SDP 1...5 o..$) CALCULATE COMPOSITE C AND RAINFALL INTENSITY FOR 2-YR AND 100-YR CDP= CDPxADP+IADP(1..5)xCDP(1..5) ADP + ADPI + ADP2 + ADP3 + ADP4 + ADP5 I= a R (10+TT,f CALCULATE RUNOFF AT CURRENT DESIGN POINT FOR 2-YR AND 100-YR (/`-' L DP = DP x I DP'x ADP NO YES _I PRINTTABLE ALL DEDIGN POINTS Y TST, INC Consulting Engineers 748 Whalers Way Building D Fort Collins, CO 80525-4872 Phone: (970) 226 0557 2 l CALCULATE GUTTER TRAVEL TIME V, = C.X Ss T = Lz 8 CALCULATE TIME OF CONCENTRATION OR TOTAL TRAVEL TIME Tc—Ti+T, Tc MAX FOR URBAN AREA = WATERWAY LENGTH (feet) /180 + 10 (minutes) Tc MINIMUM = 5 minutes FOR URBAN AREA Tc MINIMUM =10 minutes FOR NON -URBAN AREA CALCULATE RAINFALL INTENSITY AND RUNOFF FOR 2-YR AND 100-YR I= a R (10+T,Y NEXT SUB -BASINS START ATTENUATION ANALYSIS NO ALL SUB -BASINS? YES PRINT HYDROLOGY TABLE TST, INC Consulting Engineers 748 Whalers Way Building D Fort Collins, CO 805254872 Phone: (970) 226 0557 FLOWCHART OF RATIONAL ANALYSIS This flowchart describes the process that was used to determine the hydrologic calculation and the attenuated runoff. HYDROLOGY DATA FOR RATIONAL IW 1= % OF (ROOF AND ROAD) AREA IW2 = % OF GRAVEL AREA IW3 = % OF LOWN OR GRASS AREA A = AREA OF SUB -BASIN ( ACRE) L = OVERLAND FLOW; LENGTH (FEET) S = AVERAGE OVERLAND SLOPE LG = GUTTER FLOW LENGTH (FEET) SG = AVERAGE GUTTER SLOPE Cr=1 FOR 2-YR AND 1.25 FOR 100-YR Cv = CONVEYANCE COEFF. 7 - SHORT PASTURE GUTTER 15 - GRASS GUTTER 20 - PAVE GUTTER PI = I -HOUR RAINFALL DEPTH (INCHES) A, B, C or D HYDROLOGY SOIL TYPE START IST SUB -BASIN CALCULATE COMPOSITE IMPERVIOUSNESS AND CORRECTION FACTOR _ IWIx100+IW2x40+IW3.5 r 100 FOR 2-YR -> KA= 0 Kco = 0 FOR 100-YR -> K.A _ -0.25i + 0.32 KCD =-0.39i+0.46 CALCULATE INITIAL TRAVEL TIME 1.87(l.1-C Cf)J T, = 50.33 Lmax= 500 It for NON -URBAN LAND Lmax = 300 ft for URBAN LAND 2 References 1. RBD, Inc. Engineering Consultant, Final Drainage and Erosion Control Study for the Carriage Wash P.U.D. Fort Collins Colorado, October 2 1995. 2. Stewart & Associates, Inc., Storm Drainage Report of Horsetooth Business Park First Filling, April 5 1991. 3. The City of Fort Collins, Colorado, Storm Drainage Design Criteria and Construction Standards, May 1984, Revised January 1991. 4. The Urban Drainage and Flood Control District, The Urban Storm Drainage Criteria Manual: Volume 1 and 2, 2001. 0 ' facilities during construction and the warranty period. At the end of the warranty period, and ' with the approval of the county, the contractor will be responsible for removing all of the filters, straw bales, and silt fence. The contractor will also be required to flush and remove any sediment that may build up in the culverts prior to final acceptance by the City. The sheets showing the proposed erosion control measures have been included in the back of this report. r i I I FI I I I 7 I I I r8 I ' 3 . 2 Drainage Plan Development ' The proposed drainage plan consists of a combination of overland flow across parking areas and open spaces, and intercepted flow by gutter curb or swales to discharge points. Subbasins ' were delineated based on proposed grading as shown on the Proposed Drainage Plan, which can be found at the end of this report. Storm water from basin 10-A will flows as an overland flow into a rundown riprap swale through ' a curb opening at design point 1. A grass lined swale will convey the storm water to design point 3. The storm water discharges into a small pond at design point 3. ' Storm water from basin 10-B will flows directly into the small pond through a rundown riprap swale. The Storm Water Runoff from proposed drainage system is designed to flow directly into the present drainage network without an additional volume to the present or existing detention pond volume. ' Results of the rational method calculations can be found in Table 1 with supporting calculations located in Appendix A. Table 1a presents the attenuated runoff at key design points on the site. Attenuated runoff was calculated using the highest time of concentration and the total sub -basin area contributing to the design point. The runoff coefficient used represents a composite of the contributing sub - basins. ' 3.2. Curb Opening and Swale Design The grass lined swale and rundown riprap swales were calculated using urban district excel ' worksheet (Channel Design 'UD-Channels v1.00' Jun-2001). The detail results of calculation are attached in Appendix B. 3.3 Erosion/Sediment Control Plan Information obtained from the previous drainage reports indicates the Carriage Auto Service Shop development lies within the Moderate Rainfall and Wind Erodibility Zone. Therefore, soil on the site is easily eroded so slope and velocity controls will be critical. A relatively small portion of the site will be disturbed during grading operations. Sediment transport will be hindered by the fact that it is the center of the site that will be graded while the outlying land will remain undisturbed. ' Once the grading operations have been completed, the parking area will be paved and the entire disturbed area of the site will be reseeded with native dry land grass species. Elimination of bare soils by pavement, riprap, or established vegetation will almost completely eliminate the potential of soil erosion caused by storm runoff. Since it will take at least one growing season for the vegetation to establish itself it will be necessary to leave the structural measures used during construction in place for the duration of the construction and until the vegetation is established. The contractor will be responsible for periodic maintenance of the erosion control 7 Table 1. HYDROLOGIC CALCULATIONS WORKSHEET BASIN SUB BASIN DESIGN POINT AREA (ac) RUNOFF 'J� &T COEFFICIENT C C FREQCOEFF. OVERLAND FLOW LENGTH (ft) OVERLAND TRAVEL TIME GUTTER FLOW LENGTH (fps) C 00- Ti 10-YR (min) Ti 100-YR (min 10 1 -A 10-B 1 2 0.62 1 027 0.79 0 0 0.67 1 1 1.25 1.25 30 40 2 1.6 2.56 4.32 160 90 SUB BASIN DESIGN POINT AVERAGE GUTTER SLOPE M GLITTER FLOW VELOCITY (fps) GUTTER TRAVEL TIME (min) TIME OF CONCENTRATION RAINFALL INTENSITY PEAK DISCHARGE I I 0-YR I 100-YR Q 10-YR Q 100-YR 10-A 10-B 1 2 2 1.67 2.83 1.67 0.94 0.90 5 5.22 5 5 4.78 4.72 9.76 9.76 2.33 0.86 5.94 2.62 Table IA. SUMMARY OF ATTENNUATED DEVELOPED RUNOFF FREQ. TIME RAINFALL PEAK CONTRIBUTING 1 COMBINED COEFF. CONCENTRATION INTENSITY I DISCHARGE DESIGN i CONTRIBUTING AREA RUN OFF BASIN POINT SUB BASIN j (ac) COEFF. Cr I c, 10-YR I 100-YR Tc i Tc 1 i 1 Q Q I 10-YR 100-YR 10-YR f 100-YR 10-YR 100-YR 10 3 1 0.62 0.79 1 1.25 102.50 100-89 0.56 1.98 0.27 1.20 2 0.27 0.86 2.62 TOTAL 3 1,2 0.89 ' All land development or redevelopment sites within the City of Fort Collins must implement Wind ' and Rainfall Erosion control measures. Rainfall erosion control measures shall be used during April through October when precipitation is most likely to occur. I 7 P 5 10 Developed Conditions Plan 3.1 Design Criteria The drainage system presented in this report has been developed in accordance with the guidelines established by the City of Fort Collins Storm Drainage Design Criteria (CFSDDC) dated May 1984. Where applicable, the Urban Drainage Criteria Manual was also referenced. Developed condition storm facilities were evaluated based on the 10-year and 100-year storm frequencies as dictated by Table 3-1 of the CFSDDC. The Rational Method was selected to calculate runoff for the project site. The rainfall intensities used for the rational analysis can be obtained from the following Rainfall Intensity equation. This equation was derived from the City of Fort Collins Rainfall Intensity Duration Curve. 41.2285 p, I (10+TCy.894671 in which: = rainfall intensity (inches per hour) P, = 1-hour point rainfall depth (inches) ' Tc = time of concentration (minutes) To obtain the rainfall intensity, the time of concentration was determined by the following equation: Tr = Ti + Tt ' Where; Tc is the time of concentration in minutes, T; is the initial or overland flow time in minutes, and Tt is the overland travel time in the ditch, channel, or gutter in minutes. ' All hydraulic analyses within this report were prepared in accordance with the City of Fort Collins Drainage Design Criteria. Open channels should be designed such that flows at critical depth or super critical flows are avoided. A channel side slope of 4:1 is the maximum for an open channel, and 4.0 ft is the maximum channel depth. Unlined channels with longitudinal slope less than 2% shall be designed with a trickle channel. V-shape pans with 12:1 side slopes and 3 ft width is the design criteria for the concrete trickle channels in open channels. 1 4 I ' Historic Conditions ' The Carriage Auto Service Shop development site contains approximately 0.89 acres of undeveloped open area. In accordance with the City of Fort Collins Zoning District, the property will be developed consistent with other Horsetooth Business Park fillings. Native and pasture ' grasses presently cover the entire development area. The site generally slopes from west to east and is conveyed through an existing open V ditch to the south. 11 1 1 1 I 1 3 Figure 1. Vicinity Map I 1 100 1 Introduction 1 1.1 Purpose and Scope In accordance with the requirements of the City of Fort Collins Storm Drainage Design Criteria 1 (CFSDDC), the purpose of this report is to present a storm drainage plan that identifies peak runoff conditions and provides a means by which to safely collect and convey runoff across the site. This report evaluates hydrologic conditions for the proposed development and uses that 1 information for hydraulic analysis of the proposed drainage facilities. Because the present calculation of storm water runoff using a detail proposed development plan, the peak storm water runoff is lower compared to the peak storm runoff from the previous drainage analysis of 1 Horsetooth Business Park. Therefore no additional volume of detention is needed. 1 1.2 Project Location and Description This report presents the results of a Final Drainage Evaluation for Carriage Auto Service Shop, which is located in the East part of Horsetooth Business Park Area. The project location can 1 also be described as located in Section 31, Township 7 North, Range 68 West of the 61h Principal Meridian, City of Fort Collins. A vicinity map illustrating the project location is provided in figure 1. 1 1 1 1 1 1 1 1 TABLE OF CONTENTS 1.0 Introduction Page 1.1 Scope and Purpose................................................................................................... 1 1.2 Project Location and Description............................................................................... 1 2.0 Historic Conditions.......................................................................................................... 2 3.0 Developed Conditions Plan 3.1 Design Criteria.......................................................................................................... 3 3.2 Drainage Plan Development..................................................................................... 3.2.1 Street Capacity.............................................................................................. 7 8 3.2.2 Storm Sewer Design...................................................................................... 8 ' 3.2.3 Inlet Design................................................................................................... 3.2.4 Channel and Swale Design.......................................................................... 8 13 3.2.5 Riprap Design.............................................................................................. 13 ' 3.3 3.2.6 Detention Pond Design................................................................................ Erosion Control....................................................................................................... 13 16 Tables ' Table 1 - Hydrologic Calculations Worksheet.......................................................................4-5 Table 1A - Summary of Attenuated Runoff................................................................................. 6 t Table 2 Table 3 - Summary of Street Capacity Analysis....................................................................... - Summary of Storm Sewer Design........................................................................... 9 10 Table 4 - Summary of Inlet Analysis and Design.................................................................... 11 Table 5 -Summary of Inlet Analysis and Design-100yr.......................................................... 12 Table 6 - Summary of Channel Analysis and Design............................................................. 14 Table 7 - Summary of Riprap Design..................................................................................... 15 ' Technical Appendices Appendix A — Hydrologic Analysis Appendix B — Street Capacity Analysis Appendix C — Storm Sewer Design Appendix D — Inlet Analysis and Design Appendix E — Channel Analysis and Design ' Appendix F — Riprap Design Sheets ' Proposed Drainage Plan........................................................................................... Sheet 1 of 1 Proposed Street Sheets............................................................................. Sheets 14 through 17 r July 15, 2003 Mr. Basil Hamden City of Fort Collins Storm Water Division P.O. Box 580 Fort Collins, CO 80522 ' Re: CARRIAGE AUTO SERVICE SHOP ' Project No. 0695-121 Dear Mr. Hamden: We are pleased to submit to you, this Final Drainage Report for Carriage Auto Service Shop. This report was prepared based on Urban Storm Drainage Criteria and City of Fort Collins criteria. We believe it satisfies all criteria for a final report. This report also includes discussion of erosion and sediment control measures that will be utilized during and after construction. ' We look forward to your review and approval and will gladly answer any questions you may have. iSincerely, VSULTING ENGINEERS ' Enclosures 1 A ' TST, INC. 748 Whalers Way - Building D Consulting Engineers Fort Collins, CO 80525 (970) 226-0557 Metro (303) 595-9103 Fax (970) 226-0204 Email info@tstinc.com www.tstinc.com