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Home My WebLink AboutFORT COLLINS COLORADOAN - PDP - 41-03 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT12/15/2003 ' By: meo Proj. No. COD:03-050 11 r I Northern Engineering Services.lnc. COD-Riprap-pipe Coloradoan Riprap-circular Sizing of Riprap Apron for Circular pipe @ Storm Line A Notes: pine and Plnw nata Pipe Diam Area R Slope Capacity Q100 cfs Type Dc ft sf ft ft/ft C-Factor cfs 8.871 ADS1 1.50 1 1.77 1 4.71 0.0050 113.80 8.05 Flow r = x = x/r Theta Theta Area Perim Depth 0.5*D r-Yh (7) Yn ft ft ft deg. rad. sf ft 1.4244 0.75 -0.67 1 -0.90 308.11 5.38 1.73 4.03 Top R C Qd Delta Vel Froude Vel Width n = # head T 0.012 ft ft cfs cfs fps ft 0.656 0.4299 122.29 8.65 -0.22 4.99 0.5410 0.39 STEP 1 Modified Flow Depth if supercritical flow & < full Subcritical flow Dc= 1.50 feet STEP 2 Determine Froude Parameter FPx = integer (FP-6) Q/Dc 2.5 3.22 FPx = 0.00 STEP 3 Determine Type of Riprap Flow depth macro will set Yt to a value which makes Yt/D = 0.40 if Yt unknown or jump expected. Designer can change Yt if known Yt (ft) Yt/Dc Q/DCA1.5 Solving Equation MD-18 0.60 0.40 4.83 D50 = 4.002 inches D50 = 9.00 inches - bury riprap From Figure MD-21 Use Class L Riprap STEP 4 Determine Expansion Factor From Figure MD-23 Q/D'2.5 Interpolation of 1/2Tan(Theta) Yt/D 3.00 3.22 4.00 0.39 4.25 4.06 3.38 0.4000 4.46 4.26 3.54 0.40 4.46 4.26 3.54 1/2TAN(THETA) = 4.26 STEP 5 Determine Required Length of Protection Allowable Velocity =(Va) 5.00 fps At = Q/Va = 1.77 sf L=(1/2TAN(THETA))*(At/Yt-Da)= 6.20 ft Minimum Length= 3D = 4.50 ft Max Length(Lmax)= 10D+(FPx*0.25*1 15.00 ft Conclude: Riprap Geometry Apron Length D50 FES width ft inches width ft ft 7.00 9.00 4.17 6.00 Make Longer ' Page 2 of 2 I I 1 [1 I] r I 1 I 12/15/2003 By: meo Proj. No. COD:03-050 Northern Engineering Services Inc. COD-Riprap-pipe Coloradoan Summary Riprap Schedule Storm Line Q100 cfs Pipe Diam ft 1 Riprap Clas D50 inches Length ft Width ft 1 A 8.70 1.50 L 9.00 7.00 6.00 I Page 1 of 2 I I J I I I I 1 u 11 L 1 12/15/2003 Northern Engineering Services Inc. By: meo Coloradoan Proj. No. COD:03-050 Determine Required width of curb cut to pass Q100 @ Maximum Head COD -curb cuts Broadcrested Weir Design Point Q cfs Maximum Head (H) ft C Req'd Width ft (Lr) Design Width (Ld ft Actual Head ft 1 2.69 1.00 3.00 0.90 2.00 0.59 2 13.67 1.00 3.00 4.56 5.00 0.94 4 - 5.27 1.00 3.00 1.76 2.00 0.92 Formula : Q = CLHA�V2 L = Q/CH^12 H = (Q/CL)^vs Page 1 of 1 12/15/2003 Northern Engineering Services Inc. By: meo Coloradoan Proj. No. COD:03-050 Design of Triangular of Trapezoidal Swale Swale Description Ex.Swale along south prop.line Channel Configuration Trapezoidal Channel Lining Grass Design Storm 100 year Q Design Storm (Qds) 13.67 cfs Design Q = Qds* 1.33 18.19 cfs Da Db Dc Sc n W ft ft ft ft/ft ft 12.00 12.00 2.00 0.0160 0.032 1.00 0.17 Left Bank Slope 6.0 :1 Side Slope 0.17 Right Bank Slope 6.0 :1 Side Slope Legend Input Calculation Error Check Title I ft 0.25 COD -Swale Channel Dc Top Width Area Perim R 2/3 Sc 1/2 Q V ft. ft. sf ft. (A/P) cfs ft/sec 2.00 25.00 26.00 25.33 1.02 0.1265 155.40 5.98 Froude # Formula Q = 1.486*A*RA2/3*5A0.5/n Conclude: Swale is adequate for flows Page 2 of 2 12/15/2003 Northern Engineering Services Inc. By: meo Coloradoan Proj. No. COD:03-050 Design of Triangular of Trapezoidal Swale Swale Description Swale along Railroad Channel Configuration Trapezoidal Channel Lining Grass Design Storm 100 year Q Design Storm (Qds) 8.87 cfs Design Q = Qds* 1.33 11.80 cfs Da Db Dc Sc n W ft ft ft ft/ft ft 3.00 5.00 1.00 0.0040 0.032 2.00 0.33 Left Bank Slope 3.0 :1 Side Slope 0.20 Right Bank Slope 5.0 :1 Side Slope Legend Input Calculation Error Check Title I ft 0.25 Top Dc Width Area Perim R 2/3 Sc 1/2 Q V ft. ft. sf ft. (A/P) cfs ft/sec 1.00 10.00 6.00 10.26 0.70 0.0632 12.32 2.05 Froude # Formula Q = 1.486*A*RA2/3*SA0.5/n Conclude: Swale is adequate for flows COD -Swale Channel Page 1 of 2 Culvert Designer/Analyzer Report ' Parking Lot Culvert ' Component:Culvert-1 Culvert Summary Computed Headwater Elew 4,947.09 It Discharge 8.87 cfs ' Inlet Control HW Elev. 4,947.08 ft Tailwater Elevation N/A ft Outlet Control HW Elev. 4,947.09 It Control Type Outlet Control Headwater Depth/Height 1.34 1 Grades Upstream Invert 4,945.08 ft Downstream Invert 4,944.55 It ' Length 106.00 ft Constructed Slope 0.005000 ft/ft Hydraulic Profile ' Profile M2 Depth, Downstream 1.15 ft Slope Type Mild Normal Depth N/A It Flow Regime Subcritical Critical Depth 1.15 ft ' Velocity Downstream 6.09 ft/s Critical Slope 0.006915 ft/ft ' Section Section Shape Circular Mannings Coefficient 0.012 Section Material Concrete Span 1.50 ft Section Size 18 inch Rise 1.50 ft ' Number Sections 1 Outlet Control Properties Outlet Control HW Elev. 4,947.09 ft Upstream Velocity Head 0.43 ft Ke 0.50 Entrance Loss 0.21 It Inlet Control Properties Inlet Control HW Elev. 4,947.08 It Flow Control Submerged ' Inlet Type Square edge w/headwall Area Full 1.8 ft2 K 0.00980 HDS 5 Chart 1 M 2.00000 HDS 5 Scale 1 ' C 0.03980 Equation Form 1 Y 0.67000 Project Engineer: Mark d:\...\culverts\cod-parking lot culvert.cvm 12/15/03 03:58:41 PM ®Haestad Methods, Inc. Northern Engineering Services Inc 37 Brookside Road Waterbury CulvertMaster v3.0 [3.0003] , CT 06708 USA +1-203-755-1666 Page 2 of 2 Culvert Designer/Analyzer Report ' Parking Lot Culvert Analysis Component Storm Event Design Discharge 8.87 cfs ' Peak Discharge Method: User -Specified Design Discharge 8.87 cfs Check Discharge 8.87 cfs Tailwater Tailwater Conditions: Constant Tailwater Elevation N/A ft Name Description Discharge HW Elev. Velocity Culvert-1 1-18 inch Circular 8.87 cfs 4,947.09 ft 6.09 ft/s ' Weir Not Considered N/A N/A N/A Project Engineer: Mark d:\...\culverts\cod-parking lot culvert.cvm Northern Engineering Services Inc CulvertMaster v3.0 [3.0003] ' 12/15/03 03:58:41 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 2 12/16/2003 Northern Engineering Services Inc. By: meo Coloradoan Proj. No. COD:03-050 Size overflow weir from WQ pond Design Design Q Maximum C Req'd Design Actual Storm yr Head (H) Width ft Width Head ft ft (Lr) (Ld ft 100 10.26 0.3 2.6 24.01 25.00 0.29 Conclude: Design the weir to split the flow along the south and east retaining walls Elevation of overflow weir is 4948.00 ft Top of Wall is 4948.30 WQCV overflow weir Page 3 of 3 12/16/2003 Northern Engineering Services Inc. By: meo Coloradoan Proj. No. COD:03-050 Determine Volume for WQ pond using Average Area End Method Top of Overflow Pond Weir Pond Increment First Even Elevation elevation Bottom ft ft Contour ft ft ft 4944.10 1.00 4945.00 4948.30 4948.00 Stage ft Elev (E) ft Area (A) sf Volume (V1) cf Cum Volume (Vc) cf Cum Volume (Vc) AF 0.00 4944.10 0 0 0 0.00 0.90 4945.00 376 169 169 0.00 1.90 4946.00 1795 1086 1255 0.03 2.90 4947.00 4633 3214 4469 0.10 3.90 4948.00 6519 5576 10045 0.23 4.20 4948.30 6789 1996 12041 0.28 Pine Volume Pipe Pipe Pipe Area Pipe Length ft Diam ft sf Volume cf 106 1.5 1.77 187.32 Determine Reouired WSEL for WO Volume Required Volume cf WSEL ft Depth ft 2233.05 4946.30 2.20 Volume cf Stage ft 4469 2.90 2233.05 2.20 1255 1.90 WSEL = 4946.30 ft WQCV Pond Volume Page 2 of 3 I 1 11 I 12/16/2003 By: meo Proj. No. COD:03-050 Reference Northern Engineering Services Inc. Coloradoan Urban Storm Drainage Criteria Manual, Volume 3 - Best Management Practices, Urban Drainage and Flood Control District, September 1999. Project Coloradoan Expansion Location Fort Collins, CO REQUIRED STORAGE & OUTLET WORKS: BASIN AREA = 1.250 <-- INPUT from impervious calcs BASIN IMPERVIOUSNESS PERCENT = 91.00 <-- INPUT from impervious talcs BASIN IMPERVIOUSNESS RATIO = <-- CALCULATED WQCV (watershed inches) _ <-- CALCULATED from Figure EDB-2 WQCV (ac-ft) _ = <-- CALCULATED from UDFCD DCM V.3 Section 6.5 cf WO Depth (ft) = 2.730 <-- INPUT from stage -storage table AREA REQUIRED PER ROW, a (in) =<-- CALCULATED from Figure EDB-3 ' CIRCULAR PERFORATION SIZING: dia (in) = 5/16 <-- INPUT from Figure 5 S, (in) = 2 <-- INPUT from Figure 5 n = 3 <-- INPUT from Figure 5 1 t (in) = number of rows = 3/8 <-- INPUT from Figure 5 <-- CALCULATED from WO Depth, row spacing, and channel thickness ' round to lowest whole -number =M<-- total outlet area (in2) _ <-- INPUT from above cell CALCULATED from total number of wholes TRASH RACK DESIGN: Trash Rack Open Area Ratio = <-- CALCULATED from Figure 7 Required Trash Rack Open Area (in2) _ <-- CALCULATED from UDFCD DCM V.3 Section 6.6 ' Wconc (In) = 3 <-- INPUT from Table 6a-1 Wopenin9 (in) = 9 <-- INPUT from Figure 4 ' DON'T FORGET WELL -SCREEN " N/A <-- INPUT from Table 6a-2 I 1 WQCV EDB Page 1 of 3 Ml� M M M M M M r M M M MI M M M 12/15/2003 Northern Engineering Services Inc. COD -rational By: meo Coloradoan DQ-basin-Minor Proj. No. COD:03-050 MINOR STORM - 2-YEAR EVENT Town of Wellington. Colorado Overland Flow Time of Con .en ra ion: Intensity, 1 From Figure 3-1 Ti = (0.395`(I . I -CCf)"L ^ 0.5)/5 ^ 0.33 Rational Equation: Q = CiA (Equation RO-1) u er/ wale Flow. Time of .on..n.ra ion• Tt = L / GOV Velocity (Gutter Flow), V = 20 5u,' T� = T, + Tt (Equation RO-2) Velocity (Swale Flow), V = 15 5"'' Note: Actual Tc rounded to the nearest 0.5 minutes C5 assumes all overland flow 15 grass unless otherwise noted Slopes for Travel times are average slnhPa nver i he traval Sub -basin Info Overland Flow Gutter Flow Swale Flow Tc Intensity, Length, Slope, Length, Slope, Vel, Length, Slope, Vel, Comp. Travel Actual Sub- Area L S T, L S V Tt L 5 V Tt T, Length U 1 80+ T� I Flow, Q Basin acres C2 CCf (ft) (%) (min) (ft) (%) (ft/5) (min) (ft) (%) (ft/5) (min) (min) (ft) 10 (min) (in/hr) (cfs) Developed flows 1 0.27 0.87 0.95 83 2.00 2.0 0 0.00 0.00 0.0 27 1.0 1.50 0.3 5.0 110 10.61 5.0 2.85 0.67 2 1.51 0,85 0.95 50 2.00 1.5 457 0.50 1.41 5.4 O 0 1.50 0.0 6.9 507 12.82 7.0 2.52 3.22 3 0.45 0.85 0.95 15 25.00 0.4 O 0.00 0.00 0.0 293 0.5 1 .06 4.6 5.0 308 1 5.0 2. 85 1.09 4 0.53 0.52 0.95 E2G 2.00 2.5 0 0.50 1.41 0.0 O 0.0 0.00 N/A 5.0 126 .71 10.70 5.0 2.85 1.39 5 0.52 0,8g 0.20 2.00 6.7 463 0.50 41 5.5 O 0.0 0.00 WA 12. I 489 12.72 12.0 2. 05 0.94 Page 7 of 7 r aAMl 12/15/2003 Northern Engineering Services Inc. COD -rational By: meo Coloradoan DQ-basin-Major Proj. No. COD:03-050 MAJOR STORM - 100-YEAR EVENT Town of WPlhnQon Colorado Overland Flow Time- of Concentration: Intensity, i From Figure 3-1 Ti _ (0.355*(1 . I-CCf)'L ^ 0.5)/5 ^ 0.33 Rational Ecivation: Q = CiA (Equation RO-1) Gutter/Swale- Floe Time of Conr n ra ion• Tt = L / GOV Velocity (Gutter Flow), V = 20 5"' T, = T, + Tt (Equation RO.2) Velocity (Swale Flow), V = 15 5"' Note: Actual Tc rounded to the nearest 0.5 minutes Pipe C factor = 1 .48GAR2/3/n C5 assumes all overland flow 15 grass unless otherwise noted 51one5 for Travel times are averaae shops over tha trnvvl Aiafnnro Sub -basin Info Overland Flow Gutter Flow Swale Flow Tc Sub- Area Basin acres C 100 Developed flows CCf Length, L (ft) Slope, S (%) T, (min) Length, L (ft) Slope, 5 (%) Vel, V (ft/5) Tt (min) Length, L (ft) Slope, 5 (%) Vel, V (ft/5) Tt (min) Comp. T� (min) Travel Length (ft) U 1 80+ 10 Actual T, (min) Intensity, I (m/hr) Flow, Q (cfs) 1 2 3 4 5 1 0.27 1.51 0.45 0.53 0.52 11.00 1.00 1.00 1.00 1.00 1.00 1.00 0.25 1.00 0.25 83 50 15 26 26 2.00 2.00 25.00 2.00 2.00 1.3 1.0 2.1 1.6 6.3 O 457 0 0 463 0.00 0.50 0.00 0.50 0.50 0.00 1.41 0.00 1.41 1.1. 0.0 5.4 0.0 0.0 5.5 27 0 293 0 O 1.00 1.00 0.5- 0.00 0.00 1.50 1.50 06 0.00 0.00 0.3 0.0 4.6 0.0 O.O 5.0 6.4 6.7 5.0 11.8 110 507 308 26 489 10.61 12.82 I I.7I 10.70 2.72 5.0 6.5 6.5 5.0 12.0 9.95 9.06 9.06 9.95 7.16 2.69 13.67 4.07 5.27 3.72 Page 6 of 7 M M M M M M M M M M M M r r M M M M a 12/15/2003 Northern Engineering Services Inc. con -rational By: meo Coloradoan Proj. No. COD: 03-O50 DP- Tc TIME OF CONCENTRATION TO DESIGN POINTS FROM MOLTIPLS BASINS Town of Wellington Colorado Overland Flow Time. of Canceatrnt,nn. Velocity (Gutter Flow), V = 20 50.5 Ti = (0.395'(I.I-05)'L^0.5)/5^0.33 Velocity (5wale Flow), V = 15 50.5 Gutted2wale Flow TutTuta of o n - Pipe C factor = 1 .48GARy3/n Tt = L / GOV Pipe Velocity based on 1 8" pipe T, = T, + Tt (Equation RO.2) Note: Actual Tc rounded to the nearest 0.5 minutes C5 assumes all overland flow is grass unless otherwise noted Overland Flow Gutter Flow 5wale Flow Pipe Flow 70 Des n 9 CCf Len th+Slope. gLength, (ft)M 5 T, (min) L (ft) Slope, 5 M Vel, V UVS) Tr (min) Length, L 00 Slope, 5 M Val, V (ft/5) T, (min) Length, L (ft) Slope, 5 M Val. V (fy5) Tt (min) Comp. T� (min) Travel Length (ft) U180+T�Point 10 Actual (min) 1 2 3 p 5 I.00 I.00 I.00 1.00 0.25 126 50.00 126.00 126.00 26.00 2.00 2.00 2.00 2.00 2.00 1.6 1.0 1.6 1.C' 6.3 O 457.00 0 0.00 463.00 0.00 0.50 0.00 0.50 0.50 0.00 ).41 0.00 ).41 1.41 O.O 5.4 0.0 0.0 5.5 ggs.00 0.00 309.00 0.00 0.00 0.50 L00 0.50 0.00 0.00 1.0E 1.50 1.0E 0.00 0.00 7.0 O.O 4.9 0.0 O.0 0.0 0.0 0.0 0.0 0.0 0.0 O.O 0.0 0.0 0.0 0.0 0.0 0.0 O.O 0.0 0.00 0.00 0.00 0.00 0.00 8.7 6A 6.5 5.0 11.8 574 507 435 )26 489 13.19 12.82 12.42 10.70 12.72 5.5 6.5 6.5 5.0 12.0 Page 5 of 7 i r r 1 r r r r 12/15/2003 By: meo Proj. No. COD:03-050 Northern Engineering Services Inc. Coloradoan Determine Percent Imnerviovs fnr each Ragin Sub- basin %im ery Paved/ Concrete ac Landscaping ac Roof ac Total 100% 096 100% 1 89% 0.24 0.00 0.00 0.24 2 86% 1.10 0.00 0.20 1.30 3 8716 0.14 0.00 0.25 0.39 4 96% 0.51 0.00 0.00 0.51 5 90% 0.47 0.00 0.00 0.47 6 0% 0.00 0.00 0.00 0.00 7 0% 0.00 0.00 0.00 0.00 8 0% 0.00 0.00 1 0.00 0.00 COD -rational C-dbasins Page 4 of 7 I I I 1 11 1 I 1 I I I 11 12/15/2003 Northern Engineering Services Inc. COD -rational By: meo Coloradoan C-dbasins Proj. No. COD:03-050 Determine Composite Runoff Coefficient for Sub -basins Parrantano of 1anei naa hraAkAnu Sub- basin Area ac Paved/ Concrete ac Landscaping ac Roof ac Check 1 0.27 88.9% 11.1% 0.0% loops 2 1.51 72.8% 13.9% 13.2% 100% 3 0.45 31.1% 13.3% 55.6% 100% 4 0.53 96.2% 3.8% 0.0% 100% 5 0.52 90.4% 9.6% 0.0% 100% 6 0.05 0.0% 100.0% 0.0% loops 7 0.04 0.0% 100.0% 0.0% 100% 8 0.01 0.0% 100.0% 0.0% 100% Sub- basin Area ac Paved/ Concrete ac Landscaping ac Roof ac Total Area ac 1 0.27 0.24 0.03 0.00 0.27 2 1.51 1.10 0.21 0.20 1.51 3 0.45 0.14 0.06 0.25 0.45 4 0.53 0.51 0.02 0.00 0.53 5 0.52 0.47 0.05 0.00 0.52 6 0.05 0.00 0.05 0.00 0.05 7 0.04 0.00 0.04 0.00 0.04 8 0.01 0.00 0.01 0.00 0.01 Determine Runoff Coefficient for 2 yr storm Sub- basin C Paved/ Concrete ac Landscaping ac Roof ac Total 0.95 0.20 0.95 1 0.87 0.23 0.01 0.00 0.23 2 0.85 1.05 0.04 0.19 1.28 3 0.85 0.13 0.01 0.24 0.38 4 0.92 0.48 0.00 0.00 0.49 5 0.88 0.45 0.01 0.00 0.46 6 0.20 0.00 0.01 0.00 0.01 7 0.20 0.00 0.01 0.00 0.01 8 0.20 0.00 0.00 0.00 0.00 I Page 3 of 7 I I 12/15/2003 Northern Engineering Services Inc. COD -rational By: meo Coloradoan Dbasins-Summary Proj. No. COD:03-050 Sub -basin Information For Storm Sewer and Street Capacity Calculations Area Area C2 C10 C100 Travel%imp Raain cf arraR ft 1 11865 0.27 0.87 0.87 1.00 574 89% 2 65960 1.51 0.85 0.85 1.00 507 86% 3 19439 0.45 0.85 0.85 1.00 435 87% 4 23270 0.53 0.92 0.92 1.00 126 96% 5 22673 0.52 0.88 0.88 1.00 489 90% 6 2192 0.05 0.20 0.20 0.25 0% 7 1555 0.04 0.20 0.20 0.25 0% 8 305 1 0.011 0.20 1 0.20 1 0.25 1 1 0% Average C 1 0.68 1 0.68 1 0.85 1 1 0.64 Sub- basin Paved/ Concrete ac Grass ac Roof ac Total Ac Check 1 0.24 0.03 0.00 0.27 OK 2 1.10 0.21 0.20 1.51 OK 3 0.14 0.06 0.25 0.45 OK 4 0.51 0.02 0.00 0.53 OK 5 0.47 0.05 0.00 0.52 OK 6 0.00 0.05 0.00 0.05 OK 7 0.00 0.04 1 0.00 0.04 jOK 8 0.00 0.01 1 0.00 0.01 JOK I Page 2 of 7 12/15/2003 By: meo Proj. No. COD:03-050 Flow ghmmary fnr Northern Engineering Services Inc. COD -rational Coloradoan Flow Summary ('nlnrnrinon Qif. Cvn�..�i.... Design Point Upstream Basins Total Area acres C2 C100 Tc min 12 1100 i h !ph Q2 Q100 cfs cfs Notes Developed Flows 1 1,3,4, 1.25 0.88 1.00 8.50 2.35 8.21 2.60 10.26 WQ pond 2 2, 1.51 0.85 1.00 6.50 2.60 9.06 3.31 13.67 curb cut/ WQ swale 3 3,4, 0.98 0.89 1.00 6.50 2.60 9.06 2.26 8.87 WQ swale 4 4, 0.53 0.92 1.00 5.00 2.85 9.95 1.39 5.27 curb cut 5 5,6,7,8, 0.61 0.78 0.98 12.00 2.05 7.16 0.98 4.26 Street flows Page 1 of 7 VIII CONCLUSIONS A Compliance with Standards 1 All drainage analysis has been performed according to the City of Fort Collins Standards. B Effectiveness of Design 1 The design of the drainage improvements associated with the Coloradoan will adequately treat the stormwater before it leaves the site. IX REFERENCES Drainage Criteria Manual, Urban Drainage and Flood Control District, Wright Water Engineers, Inc., Denver, Colorado, Updated June 2001. Erosion Control Reference Manual for Construction Sites, City of Fort Collins, Colorado, Hydrodynamics, Inc., January 1991. Storm Drainage Design Criteria and Construction Standards, City of Fort Collins, Colorado, Updated April 1999. VI WATER QUALITY ' A Water Quality Measures and Criteria 1 Water Quality criteria from the Urban Drainage and Flood Control District were used in designing water quality measures. Refer to Appendix B for the Water Quality Calculations. 2 A water quality pond will act in tandem with 2-grassed swales to treat the surface runoff before it leaves the site. The water quality pond has an available volume of 12,041 cf this included available volume in the pond as well as the swale. The required water quality volume for basin 1 is approximately 2233 cf. Basin 1 contributes directly to the pond. Basins 3 and 4 contribute stormwater to the Water ' Quality pond via the water quality swale along the east property line. 3 A water quality outlet structure will be built into the retaining wall that defines the pond. 4 The water quality pond will allow for sediment to settle out in the pond VII EROSION CONTROL ' A Erosion Control Plan ' 1 The erosion control measures shown on the erosion control plan will control both wind and rainfall erosion. ' 2 The following temporary sediment control measures are specified to be put in place and remain until permanent vegetation is established. ' a Gravel bag dikes in swales b Gravel inlet filters on curb cuts ' c Silt fence along the east, south and west property lines. 3 Permanent erosion protection will consist of buried riprap protection at the storm sewer outfalls. A construction schedule for the riprap aprons is shown on the Grading and Erosion Control Plan. A construction detail is provided on the detail sheet. Refer to Appendix F for the riprap design calculations. ' 4 All disturbed areas outside of the parking lots will be seeded and or landscaped to establish permanent ground cover. A seeding table is provided on the grading and erosion control plan. 1 IV DRAINAGE CONCEPTS ' A General Concepts 1 Stormwater is conveyed generally via surface flows across the site to the Water ' Quality pond. 2 Swales are provided in areas where concentrated flows occur outside of the parking lot. There is an existing swale along the south property line that will continue convey flows to the south east corner. A proposed swale will be constructed along the east property line to convey flows from the north parking lot to the southeast corner of the ' building. B On Site Detention 1 Detention is not required for this site. 1 C Floodplain Considerations ' 1 No portion of the site lies within a FEMA or City of Fort Collins delineated floodplain. The FIRM map Community Panel Number 08100102-004C Dated March 18, 1996 is attached in the map pocket. V DRAINAGE DESIGN ' A Storm Sewer ' 1 A culvert is provided under the parking lot along the east property line. Refer to Appendix C for additional detail on the storm sewer design. B Swales 1 A proposed swale will be constructed along the east property line to convey flows from the north parking lot to the southeast corner of the building. Design flows are 133% of the Q100 to the design point. Refer to Appendix D for additional detail on the swale design. C Detention ' 1 No detention is required for this site. 1 1 3 The developed site is subdivided in 8 sub -basins designated 1-8. Basins 1-4 all contribute runoff to the southeast corner of the site. Basins 5-8 contribute runoff to the street at the southwest corner of the site. Refer to Appendix A for the rational calculations. Table 1 summarizes the drainage information for the sub -basins. Table 1 Basin Summary Basin Area ac C2 C10 C100 % Imp 1 0.27 0.87 0.87 1.00 89% 2 1.51 0.85 0.85 1.00 86% 3 0.45 0.85 0.85 1.00 87% 4 0.53 0.92 0.92 1.00 96% 5 0.52 0.88 0.88 1.00 90% 6 0.05 0.20 0.20 0.25 0% 7 0.04 0.20 0.20 0.25 00/0 8 0.01 0.20 1 0.20 0.25 1 0% 4 Basins 1,3 and 4 contribute stormwater to a proposed Water Quality pond in the ' southeast corner of the site. Basins 3 and 4 will be routed to the pond via a grassed swale and storm sewer along the east property line of the site. Basin 2 contributes stormwater to an existing grassed swale along the south property line. Both swales ' will act as water quality devices. Basin 5 consists of the existing half ROW along the frontage of the site. Basins 6-8 consist of portions of proposed landscape areas along Riverside Drive. 1 III DEVELOPED DRAINAGE 1 A Design Criteria and References 1 Drainage criteria City of Fort Collins Rainfall IDF curves were used in conjunction with the Rational Method to determine peak flows at design points on the site. ' B Project Constraints ' 1 All grading on the site will have to match the existing or proposed grades at the limits of the site. ' 2 Detention is not required for this site. Measures to improve the water quality are required for this site. ' Final Drainage Report for Coloradoan Fort Collins, Colorado ' December 16, 2003 ' I INTRODUCTION ' 1 This Final Drainage Report summarizes the drainage design for the proposed development of Coloradoan, an expansion of the existing facilities. All calculations and design associated with this project are done in accordance with the current City of ' Fort Collins Standards. , ' II SITE LOCATION AND DESCRIPTION A Site Location 1 The site is located in Northwest Quarter of Section 18, Township 7 North, Range 68 West of the 6`h Principal Meridian, City of Fort Collins, County of Larimer, State of ' Colorado. More specifically, the site is located at 1212 Riverside Avenue. (See Vicinity Map). The site is bounded by BNSF Railroad ROW on the east, Riverside Avenue on the west and developed properties on the north and south. B Site Description 1 1 The site slopes from northwest to southeast with about 6 feet of relief across the site. The site encompasses approximately 2.86 acres. There are existing buildings on the site, which will be removed. A proposed 19,600 sf building will be constructed on the site along with revisions to the existing parking areas. The parking on the south side of the site will be permanent. The parking along the north side of the building will be temporary, as another building will be constructed there in the future. This will not significantly affect the runoff quantities in the future, as it will be replacing one impervious surface with another 2 Historically stormwater from the site leaves the site via surface flow at southeast corner of the site. A site visit on Saturday 12/13/03 showed this to be the case. In ' addition, runoff from the street would only enter the site if the flows in the curb and gutter overtopped the drives at the north and south ends of the site. 11 1 I hereby certify that this report (plan) for the final drainage design of Coloradoan Expansion prepared by me (or under my direct supervision) for the owners thereof and meets or exceeds the City of Fort Collins Criteria. 1 1 1 I 1 1 1 1 1 1 i 1 1 7�Qi OBERS� .9F • NUMBER 3. 35721Oct A• <v 'CAeO• e�,4�� i's�.�'Prr•e• \ Mark Oberschmidt Registered Professional Engineer State of Colorado No. 35721 (Seal) )Zli 6)c3 [1 I I C [1 Table of Contents VICINITY MAP IINTRODUCTION .................................................................................................................. 2 II SITE LOCATION AND DESCRIPTION .............................................................................. 2 ASite Location....................................................................................................................... 2 BSite Description................................................................................................................... 2 III DEVELOPED DRAINAGE............................................................................................... 3 A Design Criteria and References........................................................................................... 3 BProject Constraints.............................................................................................................. 3 IVDrainage Concepts.............................................................................................................. 4 AGeneral Concepts................................................................................................................ 4 BOn Site Detention................................................................................................................ 4 C Floodplain Considerations.................................................................................................. 4 VDRAINAGE DESIGN............................................................................................................ 4 AStorm Sewer........................................................................................................................ 4 BSwales ................................................................................................................................. 4 CDetention .............................................................................................................................4 VIWATER QUALITY............................................................................................................ 5 A Water Quality Measures and Criteria.................................................................................. 5 VIIEROSION CONTROL........................................................................................................ 5 AErosion Control Plan ........................................................................................................... 5 VIIICONCLUSIONS .................................................................................................................6 A Compliance with Standards................................................................................................ 6 B Effectiveness of Design...................................................................................................... 6 IXREFERENCES ................................................................................................................... 6 Appendix A — Hydrology Calculations Appendix B — Water Quality Calculations Appendix C — Culvert Design Calculations Appendix D — Swale Design Calculations Appendix E — Curb Cut Design Calculations Appendix F — Riprap Calculations I OVICINITY MAP 1 "=1000' I NENORTHERN ENGINEERING SERVICES, INC. December 16, 2003 Fort Collins Utilities - Stormwater P.O. Box 580 ' Ft. Collins, CO 80522 Attn Basil Hamdan, RE: Coloradoan Fort Collins, Larimer County, Colorado Project Number: COD:03-050 Dear Basil: Northern Engineering is pleased to submit this Final Drainage Report for the Coloradoan Office Expansion for your review. This report summarizes the final drainage design for Columbine Estates. The design of the drainage infrastructure conforms to the current City of Fort Collins Standard Design Criteria and Standard Construction Requirements dated January 2003. If you should have any questions or comments as you review this report, please feel free to contact me at your convenience. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Mark Oberschmidt, PE Project Engineer 420 SOUTH HOWES, SUITE 202 / FORT COLLINS, COLORADO 80521 / 970.221.4158 / FAX 970.221.4159 Final Drainage Report for Coloradoan Office Expansion Latimer County, Colorado December 16, 2003 Prepared For: Coloradoan 1212 Riverside Avenue Fort Collins, CO 80525 Prepared By: NORTHERN NE ENGINEERING SERVICES, INC. 420 S. Howes, Suite 202 Fort Collins, Colorado W521 Phone:(970) 221-4158 Fox: (970) 221-4159 Project Number: CO13:03-050 Initial Submittal