July 15, 2015 Bellecci & Associates, Inc Summary of Detention Pond Calculation Canyon Estates American Canyon, California 1. Methodology: Method: Unit Hydrograph Software: Bentley Pond Pack Version 8i Modeled: 100-year storm event, 24-hour duration Storm Drain layout Hydrology Map dated April 2015 Rainfall Distribution Type IA (Haestad's Stormwater Conveyance Modeling & Design - 5th Edition). Rainfall 6.0 inches (From NOAA Atlas 2, Vol XI) Time of Concentration Figure 1 Travel Time for Overland Flow (American Canyon Dept. of Public Works - Engineering Standard Plans and Specifications for Public Improvements) Roof to Gutter Time 9 mins. 2. Pre-Development Condition: Longest Time of Concentration 0.40 hours (24 mins.) Existing peak flow rate 28.96 cfs 3. Post-Development Condition: Longest Time of Concentration 0.50 hours (30 mins.) Proposed peak flow rate 18.09 cfs 4. Storage: Detention Pond o Top of Pond 11 o Bottom of Pond 117.0 o 21" Dia Outlet Pipe Invert In 112.0 o Pipe Outfall Invert 104.0 o Pond Bottom Dimensions 70 ft x 100 ft o Side Slopes 3:1 o Peak Water Surface Elevation 114.97 o Peak Storage Volume 0.578 ac-ft o Peak Inflow 22.79 cfs 5. Summary: Peak Outflow for Post Development is less than Peak Outflow for Pre- Development Condition. CONCORD 2290 Diamond Blvd. Suite 100 Concord, CA 94520-5744 Tel. 928569 PLEASANTON 7041 Koll Parkway, Suite 132 Pleasanton, CA 94566-3128 Tel. 9281.4885 Civil Engineering Land Surveying
Appendix A Pre-Development Calculations CONCORD 2290 Diamond Blvd. Suite 100 Concord, CA 94520-5744 Tel. 928569 PLEASANTON 7041 Koll Parkway, Suite 132 Pleasanton, CA 94566-3128 Tel. 9281.4885 Civil Engineering Land Surveying
Scenario: Pre-Development 100yr-24hr CM-1 O-1 2015-07-15 Canyon Estates.ppc Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
Scenario Calculation Summary Scenario Summary ID Label Notes Active Topology Hydrology Rainfall Runoff Physical Initial Condition Boundary Condition Infiltration and Inflow Output User Data Extensions PondPack Engine Calculation Options 1 Pre-Development 100yr-24hr Pre-Development Active Topology Pre-Development Hydrology 100yr-24hr Pre-Development Physical Pre-Development Initial Condition Pre-Development Boundary Condition Pre-Development Infiltration and Inflow Pre-Development Output Pre-Development User Data Extensions Base Calculation Options Output Summary Output Increment 50 hours Duration 24.000 hours Rainfall Summary Return Event Tag Total 100 6.0 in Rainfall Type Storm Event Time- Curve 100yr-24hr Executive Summary (Nodes) Label Scenario Return Event (years) Truncation Hydrograph Volume Time to Peak (hours) Peak Flow (ft³/s) Maximum Water Surface Elevation (ft) Maximum Pond Storage CM-1 O-1 Pre- Developme nt 100yr- 24hr Pre- Developme nt 100yr- 24hr 100 100 None None 10.578 10.578 8.100 8.100 28.96 28.96 Executive Summary (Links) Label Type Location Hydrograph Volume Peak Time (hours) Peak Flow (ft³/s) End Point Node Flow Direction 2015-07-15 Canyon Estates-Pre- Development.ppc Page 1 of 1
Subsection: Time- Curve Label: Type IA Time- Curve: 100yr-24hr Label Start Time Increment End Time Return Event 100yr-24hr 00 hours 00 hours 24.000 hours 100 years Time (hours) 00 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500 5.000 00 6.000 6.500 7.000 7.500 8.000 8.500 9.000 9.500 100 10.500 11.000 11.500 12.000 12.500 13.000 13.500 14.000 14.500 15.000 100 16.000 16.500 17.000 17.500 CUMULATIVE RAINFALL Output Time Increment = 00 hours Time on left represents time for first value in each row. 2015-07-15 Canyon Estates-Pre- Development.ppc 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.1 1.2 1.4 1.6 1.9 2.6 2.9 3.1 3.3 3.5 3.6 3.7 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.1 1.3 1.5 1.7 2.0 2.6 2.9 3.2 3.3 3.5 3.6 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 0.2 0.2 0.3 0.4 0.5 0.6 0.7 0.9 1.0 1.1 1.3 1.5 1.7 2.1 2.7 3.0 3.2 3.4 3.5 3.7 3.8 3.9 4.0 4.1 4.3 4.4 4.5 4.6 4.7 4.7 4.8 4.9 5.0 5.1 0.2 0.3 0.4 0.5 0.5 0.7 0.8 0.9 1.0 1.2 1.3 1.5 1.7 2.3 2.8 3.0 3.2 3.4 3.5 3.7 3.8 3.9 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.0 5.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.1 1.2 1.4 1.6 1.8 2.4 2.8 3.1 3.3 3.4 3.6 3.7 3.8 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.1 Page 1 of 2
Subsection: Time- Curve Label: Type IA Time (hours) 18.000 18.500 19.000 19.500 200 20.500 21.000 21.500 22.000 22.500 23.000 23.500 24.000 CUMULATIVE RAINFALL Output Time Increment = 00 hours Time on left represents time for first value in each row. 5.2 5.2 5.3 6.0 5.2 5.3 5.3 6.0 5.2 5.3 6.0 5.2 5.3 6.0 5.2 5.3 6.0 2015-07-15 Canyon Estates-Pre- Development.ppc Page 2 of 2
Subsection: Master Network Summary Catchments Summary CM-1 Label Scenario Pre-Development 100yr-24hr Return Event (years) 100 Hydrograph Volume 10.578 Time to Peak (hours) 8.100 Peak Flow (ft³/s) 28.96 Node Summary O-1 Label Scenario Pre-Development 100yr-24hr Return Event (years) 100 Hydrograph Volume 10.578 Time to Peak (hours) 8.100 Peak Flow (ft³/s) 28.96 2015-07-15 Canyon Estates-Pre- Development.ppc Page 1 of 1
Subsection: Unit Hydrograph Summary Label: CM-1 Storm Event Return Event Duration Time of Concentration (Composite) Area (User Defined) 100yr-24hr 100 years 24.000 hours 6.0 in 0.400 hours 34.800 acres Computational Time Increment Time to Peak (Computed) Flow (Peak, Computed) Output Increment Time to Flow (Peak Interpolated Output) Flow (Peak Interpolated Output) 53 hours 8.107 hours 29.01 ft³/s 50 hours 8.100 hours 28.96 ft³/s Drainage Area SCS CN (Composite) Area (User Defined) Maximum Retention (Pervious) Maximum Retention (Pervious, 20 percent) 79.000 34.800 acres 2.7 in 0.5 in Cumulative Runoff Cumulative Runoff (Pervious) Runoff Volume (Pervious) 3.7 in 10.671 ac-ft Hydrograph Volume (Area under Hydrograph curve) Volume 10.578 ac-ft SCS Unit Hydrograph Parameters 2015-07-15 Canyon Estates-Pre- Development.ppc Time of Concentration (Composite) Computational Time Increment Unit Hydrograph Shape Factor K Factor Receding/Rising, Tr/Tp Unit peak, qp Unit peak time, Tp 0.400 hours 53 hours 483.432 0.749 1.670 98.57 ft³/s 0.267 hours Page 1 of 2
Subsection: Unit Hydrograph Summary Label: CM-1 SCS Unit Hydrograph Parameters Unit receding limb, Tr Total unit time, Tb 1.067 hours 1.333 hours 2015-07-15 Canyon Estates-Pre- Development.ppc Page 2 of 2
Appendix B Post-Development Calculations CONCORD 2290 Diamond Blvd. Suite 100 Concord, CA 94520-5744 Tel. 928569 PLEASANTON 7041 Koll Parkway, Suite 132 Pleasanton, CA 94566-3128 Tel. 9281.4885 Civil Engineering Land Surveying
Scenario: Post-Development 100yr-24hr Outlet-1 2015-07-15 Canyon Estates - Post Dev-1..ppc Page 1 of 1
Scenario Calculation Summary Scenario Summary ID Label Notes Active Topology Hydrology Rainfall Runoff Physical Initial Condition Boundary Condition Infiltration and Inflow Output User Data Extensions PondPack Engine Calculation Options 40 Post-Development 100yr-24hr Pre-Development Active Topology Pre-Development Hydrology 100yr-24hr Pre-Development Physical Pre-Development Initial Condition Pre-Development Boundary Condition Pre-Development Infiltration and Inflow Pre-Development Output Pre-Development User Data Extensions Base Calculation Options Output Summary Output Increment 50 hours Duration 24.000 hours Rainfall Summary Return Event Tag Total 100 6.0 in Rainfall Type Storm Event Time- Curve 100yr-24hr Executive Summary (Nodes) Label Scenario Return Event (years) Truncation Hydrograph Volume Time to Peak (hours) Peak Flow (ft³/s) Maximum Water Surface Elevation (ft) Maximum Pond Storage CM-1 CM-2 CM-3 O-3 PO-1 (IN) Post- Developme nt 100yr- 24hr Post- Developme nt 100yr- 24hr Post- Developme nt 100yr- 24hr Post- Developme nt 100yr- 24hr Post- Developme nt 100yr- 24hr 100 100 100 100 100 None None None None None 2.028 6.235 0.236 8.354 8.500 8.050 8.150 7.900 8.400 8.100 0 16.66 0.71 18.09 22.79 Page 1 of 2
Scenario Calculation Summary Executive Summary (Nodes) Label PO-1 (OUT) Scenario Post- Developme nt 100yr- 24hr Return Event (years) 100 Truncation None Hydrograph Volume 8.354 Time to Peak (hours) 8.400 Peak Flow (ft³/s) 18.09 Maximum Water Surface Elevation (ft) 114.97 Maximum Pond Storage 0.578 Executive Summary (Links) Label Outlet-1 Outlet-1 Outlet-1 Outlet-1 Type Pond Outlet Pond Outlet Pond Outlet Pond Outlet Location Upstream Outflow Link Downstream Hydrograph Volume 8.500 8.354 8.354 8.354 Peak Time (hours) 8.100 8.400 8.400 8.400 Peak Flow (ft³/s) 22.79 18.09 18.09 18.09 End Point PO-1 PO-1 O-3 Node Flow Direction Pond Inflow Pond Outflow Message Id Scenario Element Type Element Id Label Time Message Source Messages 15 Post-Development 100yr-24hr Composite Outlet Structure 39 Composite Outlet Structure - 1 Kr (reverse flow entrance loss coefficient) was not specified. Kr was set to same value as Ke= 0.200. Warning Page 2 of 2
Subsection: Time- Curve Label: Time- - 1 Time- Curve: 100yr-24hr Label Start Time Increment End Time Return Event 100yr-24hr 00 hours 00 hours 24.000 hours 100 years Time (hours) 00 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500 5.000 00 6.000 6.500 7.000 7.500 8.000 8.500 9.000 9.500 100 10.500 11.000 11.500 12.000 12.500 13.000 13.500 14.000 14.500 15.000 100 16.000 16.500 17.000 17.500 CUMULATIVE RAINFALL Output Time Increment = 00 hours Time on left represents time for first value in each row. 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.1 1.2 1.4 1.6 1.9 2.6 2.9 3.1 3.3 3.5 3.6 3.7 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.1 1.3 1.5 1.7 2.0 2.6 2.9 3.2 3.3 3.5 3.6 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 0.2 0.2 0.3 0.4 0.5 0.6 0.7 0.9 1.0 1.1 1.3 1.5 1.7 2.1 2.7 3.0 3.2 3.4 3.5 3.7 3.8 3.9 4.0 4.1 4.3 4.4 4.5 4.6 4.7 4.7 4.8 4.9 5.0 5.1 0.2 0.3 0.4 0.5 0.5 0.7 0.8 0.9 1.0 1.2 1.3 1.5 1.7 2.3 2.8 3.0 3.2 3.4 3.5 3.7 3.8 3.9 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.0 5.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.1 1.2 1.4 1.6 1.8 2.4 2.8 3.1 3.3 3.4 3.6 3.7 3.8 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.1 Page 1 of 2
Subsection: Time- Curve Label: Time- - 1 Time (hours) 18.000 18.500 19.000 19.500 200 20.500 21.000 21.500 22.000 22.500 23.000 23.500 24.000 CUMULATIVE RAINFALL Output Time Increment = 00 hours Time on left represents time for first value in each row. 5.2 5.2 5.3 6.0 5.2 5.3 5.3 6.0 5.2 5.3 6.0 5.2 5.3 6.0 5.2 5.3 6.0 Page 2 of 2
Subsection: Unit Hydrograph Summary Label: CM-1 Storm Event Return Event Duration Time of Concentration (Composite) Area (User Defined) 100yr-24hr 100 years 24.000 hours 6.0 in 0.330 hours 90 acres Computational Time Increment Time to Peak (Computed) Flow (Peak, Computed) Output Increment Time to Flow (Peak Interpolated Output) Flow (Peak Interpolated Output) 44 hours 8.052 hours 0 ft³/s 50 hours 8.050 hours 0 ft³/s Drainage Area SCS CN (Composite) Area (User Defined) Maximum Retention (Pervious) Maximum Retention (Pervious, 20 percent) 83.000 90 acres 2.0 in 0.4 in Cumulative Runoff Cumulative Runoff (Pervious) Runoff Volume (Pervious) 4.1 in 2.042 ac-ft Hydrograph Volume (Area under Hydrograph curve) Volume 2.028 ac-ft SCS Unit Hydrograph Parameters Time of Concentration (Composite) Computational Time Increment Unit Hydrograph Shape Factor K Factor Receding/Rising, Tr/Tp Unit peak, qp Unit peak time, Tp 0.330 hours 44 hours 483.432 0.749 1.670 20.57 ft³/s 0.220 hours Page 1 of 2
Subsection: Unit Hydrograph Summary Label: CM-1 SCS Unit Hydrograph Parameters Unit receding limb, Tr Total unit time, Tb 0.880 hours 1.100 hours Page 2 of 2
Subsection: Unit Hydrograph Summary Label: CM-2 Storm Event Return Event Duration Time of Concentration (Composite) Area (User Defined) 100yr-24hr 100 years 24.000 hours 6.0 in 0.500 hours 18.480 acres Computational Time Increment Time to Peak (Computed) Flow (Peak, Computed) Output Increment Time to Flow (Peak Interpolated Output) Flow (Peak Interpolated Output) 67 hours 8.133 hours 16.70 ft³/s 50 hours 8.150 hours 16.66 ft³/s Drainage Area SCS CN (Composite) Area (User Defined) Maximum Retention (Pervious) Maximum Retention (Pervious, 20 percent) 83.000 18.480 acres 2.0 in 0.4 in Cumulative Runoff Cumulative Runoff (Pervious) Runoff Volume (Pervious) 4.1 in 6.301 ac-ft Hydrograph Volume (Area under Hydrograph curve) Volume 6.235 ac-ft SCS Unit Hydrograph Parameters Time of Concentration (Composite) Computational Time Increment Unit Hydrograph Shape Factor K Factor Receding/Rising, Tr/Tp Unit peak, qp Unit peak time, Tp 0.500 hours 67 hours 483.432 0.749 1.670 41.88 ft³/s 0.333 hours Page 1 of 2
Subsection: Unit Hydrograph Summary Label: CM-2 SCS Unit Hydrograph Parameters Unit receding limb, Tr Total unit time, Tb 1.333 hours 1.667 hours Page 2 of 2
Subsection: Unit Hydrograph Summary Label: CM-3 Storm Event Return Event Duration Time of Concentration (Composite) Area (User Defined) 100yr-24hr 100 years 24.000 hours 6.0 in 83 hours 0.770 acres Computational Time Increment Time to Peak (Computed) Flow (Peak, Computed) Output Increment Time to Flow (Peak Interpolated Output) Flow (Peak Interpolated Output) 11 hours 7.922 hours 0.72 ft³/s 50 hours 7.900 hours 0.71 ft³/s Drainage Area SCS CN (Composite) Area (User Defined) Maximum Retention (Pervious) Maximum Retention (Pervious, 20 percent) 79.000 0.770 acres 2.7 in 0.5 in Cumulative Runoff Cumulative Runoff (Pervious) Runoff Volume (Pervious) 3.7 in 0.236 ac-ft Hydrograph Volume (Area under Hydrograph curve) Volume 0.236 ac-ft SCS Unit Hydrograph Parameters Time of Concentration (Composite) Computational Time Increment Unit Hydrograph Shape Factor K Factor Receding/Rising, Tr/Tp Unit peak, qp Unit peak time, Tp 83 hours 11 hours 483.432 0.749 1.670 10.47 ft³/s 56 hours Page 1 of 2
Subsection: Unit Hydrograph Summary Label: CM-3 SCS Unit Hydrograph Parameters Unit receding limb, Tr Total unit time, Tb 0.222 hours 0.278 hours Page 2 of 2
Subsection: Outlet Input Data Label: Composite Outlet Structure - 1 Requested Pond Water Surface Elevations Minimum (Headwater) Increment (Headwater) Maximum (Headwater) 110 ft 0.50 ft 120 ft Outlet Connectivity Structure Type Culvert-Circular Tailwater Settings Outlet ID Culvert - 1 Tailwater Direction Forward TW Outfall E1 (ft) 112.00 E2 (ft) 120 Page 1 of 3
Subsection: Outlet Input Data Label: Composite Outlet Structure - 1 Structure ID: Culvert - 1 Structure Type: Culvert-Circular Number of Barrels Diameter Length Length (Computed Barrel) Slope (Computed) 1 21.0 in 190 ft 197 ft 42 ft/ft Outlet Control Data Manning's n Ke Kb Kr Convergence Tolerance 13 0.200 15 00 0 ft Inlet Control Data Equation Form K M C Y T1 ratio (HW/D) T2 ratio (HW/D) Slope Correction Factor Form 1 045 2.0000 317 0.6900 1.074 1.176-0.500 Use unsubmerged inlet control 0 equation below T1 elevation. Use submerged inlet control 0 equation above T2 elevation In transition zone between unsubmerged and submerged inlet control, interpolate between flows at T1 & T2... T1 Elevation T2 Elevation 113.88 ft 114.06 ft T1 Flow T2 Flow 11.14 ft³/s 12.73 ft³/s Page 2 of 3
Subsection: Outlet Input Data Label: Composite Outlet Structure - 1 Structure ID: TW Structure Type: TW Setup, DS Channel Tailwater Type Free Outfall Convergence Tolerances Maximum Iterations Tailwater Tolerance (Minimum) Tailwater Tolerance (Maximum) Headwater Tolerance (Minimum) Headwater Tolerance (Maximum) Flow Tolerance (Minimum) Flow Tolerance (Maximum) 30 1 ft 0.50 ft 1 ft 0.50 ft 01 ft³/s 100 ft³/s Page 3 of 3
Subsection: Trapezoidal Volume Label: PO-1 Length.--Top---- B ----------. W i.------b2------. d A b1 C t `----Bottom----' h `----------D-----------' Diagram Not to Scale Pond Volume Calculation for Trapezoidal Basin Trapezoid Top Elevation Trapezoid Top Length (A to C) Trapezoid Top Width (B to D) Trapezoid Bottom Elevation Trapezoid Bottom Length Trapezoid Bottom Width Trapezoid Width Offset (B to b2) Trapezoid Length Offset (A to b1) Trapezoid Vertical Increment 120 ft 142.00 ft 116.00 ft 112.00 ft 100 ft 70 ft 0 ft 0 ft 0.20 ft Elevation (ft) 112.00 112.20 112.40 112.60 112.80 113.00 113.20 113.40 113.60 113.80 114.00 114.20 114.40 114.60 114.80 115.00 115.20 110 110 110 Planimeter (ft²) Area (acres) 61 65 69 74 78 83 88 92 97 0.202 0.207 0.212 0.217 0.222 0.227 0.232 0.237 0.242 0.248 0.253 A1+A2+sqr (A1*A2) (acres) 00 0.489 0.502 0.515 0.529 0.542 0.556 0.570 0.584 0.598 0.613 0.628 0.642 0.657 0.673 0.688 0.703 0.719 0.735 0.751 Volume 00 33 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Volume (Total) 00 33 66 00 36 72 0.209 0.247 0.286 0.326 0.367 0.408 0.451 0.495 0.540 0.586 0.633 0.681 0.729 0.780 Page 1 of 2
Subsection: Trapezoidal Volume Label: PO-1 Elevation (ft) 116.00 116.20 116.40 116.60 116.80 117.00 117.20 117.40 117.60 117.80 118.00 118.20 118.40 118.60 118.80 119.00 119.20 119.40 119.60 119.80 120 Planimeter (ft²) Area (acres) 0.258 0.264 0.269 0.275 0.281 0.286 0.292 0.298 0.304 0.310 0.315 0.321 0.328 0.334 0.340 0.346 0.352 0.359 0.365 0.372 0.378 A1+A2+sqr (A1*A2) (acres) 0.767 0.783 0.800 0.816 0.833 0.850 0.867 0.885 0.902 0.920 0.937 0.955 0.974 0.992 1.010 1.029 1.048 1.067 1.086 1.105 1.125 Volume 51 52 53 54 56 57 58 59 60 61 62 64 65 66 67 69 70 71 72 74 75 Volume (Total) 0.831 0.883 0.936 0.991 1.046 1.103 1.161 1.220 1.280 1.341 1.404 1.467 1.532 1.598 1.666 1.734 1.804 1.875 1.948 2.021 2.096 Page 2 of 2
Subsection: Level Pool Pond Routing Summary Label: PO-1 (IN) Infiltration Infiltration Method (Computed) No Infiltration Initial Conditions Elevation (Water Surface, Initial) Volume (Initial) Flow (Initial Outlet) Flow (Initial Infiltration) Flow (Initial, Total) Time Increment 112.00 ft 00 ac-ft 0 ft³/s 0 ft³/s 0 ft³/s 50 hours Inflow/Outflow Hydrograph Summary Flow (Peak In) Flow (Peak Outlet) 22.79 ft³/s 18.09 ft³/s Time to Peak (Flow, In) Time to Peak (Flow, Outlet) 8.100 hours 8.400 hours Elevation (Water Surface, Peak) 114.97 ft Volume (Peak) 0.578 ac-ft Mass Balance Volume (Initial) Volume (Total Inflow) Volume (Total Infiltration) Volume (Total Outlet Outflow) Volume (Retained) Volume (Unrouted) Error (Mass Balance) 00 ac-ft 8.500 ac-ft 00 ac-ft 8.354 ac-ft 34 ac-ft -12 ac-ft % Page 1 of 1