Filetype Excel XLSX | Posted on 17 Aug 2022 | 3 years ago
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207x Filetype XLSX File size 0.17 MB Source: charlottenc.gov
Sheet 1: Basic info
| BMP Sizing Data | ld | |||||||||
| XX.XX | Required user input data | |||||||||
| XX.XX | Calculations | |||||||||
| Post Developed Basin Data | Pre-Developed Basin Data | |||||||||
| Drainage Area = | 1.000 | ac | Drainage Area = | 1.000 | ac | |||||
| Impervious % (I)= | 85.000 | % | Impervious % (I)= | 50.000 | % | |||||
| Impervious acres = | 0.850 | ac | Impervious acres = | 0.500 | ac | |||||
| Curve Number (CN) = | 80.000 | Curve Number (CN) = | 65.000 | |||||||
| Tc = | 7.000 | minutes = | 0.117 | hours | Tc = | 19.000 | minutes = | 0.317 | hours | |
| T lag = | 4.200 | minutes = | 0.070 | hours | T lag = | 11.400 | minutes = | 0.190 | hours | |
| Water Quality Volume Calculations | Channel Protection Volume Calculations | |||||||||
| Rv = 0.05+0.009(I) = | 0.815 | Q = (P-0.2S)^2/(P+0.8S) = | 0.945 | inches | ||||||
| WQv = 1.0RvA/12 = | 0.068 | ac-ft | S = 1000/CN-10 = | 2.500 | ||||||
| WQv = 1.0Rv = | 0.815 | inches | CPv = | 0.079 | acre-ft | |||||
| Modified CN = | 98.260 |
| 4.1.7 Design Procedure Form | |||||||||||||||||||||
| Design Procedure Form: Bioretention | Detention time | Detention time | Media | ||||||||||||||||||
| Days | hours + 3 hrs | Depth | |||||||||||||||||||
| BIORETENTION FEASIBILITY | NOTES: | 1 | Optimal | 1.3 | 34.2 | 4 | |||||||||||||||
| 1. | Is the use of Bioretention appropriate? | 2 | Standard | 1 | 27 | 2 | |||||||||||||||
| 2. | Confirm other design criteria and applicability. | ||||||||||||||||||||
| Pollutant Removal Effectiveness Required | Optimal | Dt | |||||||||||||||||||
| 1.3 | 34.2 | 4 | |||||||||||||||||||
| PRELIMINARY HYDROLOGIC CALCULATIONS | |||||||||||||||||||||
| 3 | Compute site hydrologic input parameters | ||||||||||||||||||||
| Development Conditions | Pre-developed | Post-developed | |||||||||||||||||||
| Area | 1 | acres | 1 | acres | |||||||||||||||||
| CN (SCS curve number) | 65 | 80 | |||||||||||||||||||
| Adjusted CN (curve number adjusted for 1-inch storm) | 98.26 | ||||||||||||||||||||
| Time of concentration | 19 | min | 7 | min | |||||||||||||||||
| 0.32 | hours | 0.12 | hours | ||||||||||||||||||
| 4 | Compute,WQv water quality volume requirements | ||||||||||||||||||||
| Compute Runoff Coefficient, Rv | Rv = | 0.82 | |||||||||||||||||||
| Compute WQv Volume requirements | WQv = | 0.07 | acre-ft | ||||||||||||||||||
| 5 | Compute WQp peak flow using SCS | WQp = | cfs | ||||||||||||||||||
| Compute modified SCS curve number | CN = | 98.26 | |||||||||||||||||||
| 6 | Compute CPv | ||||||||||||||||||||
| Compute S (maximum retention) | S = | 2.50 | |||||||||||||||||||
| Compute 1-yr, 24-hr total rainfall depth | Rainfall Depth = | 2.58 | inches | ||||||||||||||||||
| Compute Qd (runoff volume) | Qd = | 0.94 | inches | ||||||||||||||||||
| Compute CPv (chnnnel protection volume) | CPv = | 0.08 | acre-ft | 3429.00262008734 | |||||||||||||||||
| 7 | Size Flow Diversion Structure | ||||||||||||||||||||
| BIORETENTION AREA DESIGN | |||||||||||||||||||||
| 8 | Pretreatment facility type and design parameters | ||||||||||||||||||||
| Size bioretention ponding area to contain Water Quality Volume | |||||||||||||||||||||
| 9 | Determine Area of bioretention ponding/filter area | Af = | 3690.9 | ft2 | 2958.45 | ft2 | |||||||||||||||
| Size using Darcy's equation using hf=0.5 | |||||||||||||||||||||
| 10 | Set design eleveations and dimensions of facility | Length = | ft | 3690.9 | ft2 | ||||||||||||||||
| Width = | ft | ||||||||||||||||||||
| Top Elevation = | ft | ||||||||||||||||||||
| 11 | Develop stage-discharge and stage storage | ||||||||||||||||||||
| Elevation | Area (ft2) | Volume (ft3) | Acc. Vol (ft3) | Q (cfs) | |||||||||||||||||
| 12 | Route flows through bioretention area. Resize the footprint area, if desired. Step is most effective for facilities with flow diverters. Ensure detention time requirements and maximum ponding depth requirements are met. | ||||||||||||||||||||
| 13 | Design conveyance to facility | ||||||||||||||||||||
| 14 | Size underdrain system | Length = | ft | ||||||||||||||||||
| 15 | Design emergency overflow | Length of Weir (if used) = | ft | ||||||||||||||||||
| 16 | Prepare vegetation and landscaping plan | Notes: | |||||||||||||||||||
| 4.2.7 Design Procedure Form | |||||||||||||||||||||
| Design Procedure Form: Wet pond | Detention time | Detention time | |||||||||||||||||||
| Days | hours + 3 hrs | WQv/PPv | |||||||||||||||||||
| WET POND FEASIBILITY | NOTES: | 1 | Optimal | 4 | 99 | 0.3 | |||||||||||||||
| 1 | Is the use of a wet pond appropriate? | 2 | Standard | 2 | 51 | 0.6 | |||||||||||||||
| 3 | TSS-only | 4 | 99 | 0.4 | |||||||||||||||||
| 2 | Confirm other design criteria and applicability. | ||||||||||||||||||||
| Pollutant Removal Effectiveness Required | Optimal | Dt | WQv/PPv | ||||||||||||||||||
| 99 | 0.3 | ||||||||||||||||||||
| PRELIMINARY HYDROLOGIC CALCULATIONS | |||||||||||||||||||||
| 3 | Compute site hydrologic input parameters | ||||||||||||||||||||
| Development Conditions | Pre-developed | Post-developed | |||||||||||||||||||
| Area | 1 | acres | 1 | acres | |||||||||||||||||
| CN (SCS curve number) | 65 | 80 | |||||||||||||||||||
| Adjusted CN (curve number adjusted for 1-inch storm) | 98.26 | ||||||||||||||||||||
| Time of concentration | 19 | min | 7 | min | |||||||||||||||||
| 0.32 | hours | 0.12 | hours | ||||||||||||||||||
| 4 | Compute,WQv water quality volume requirements | ||||||||||||||||||||
| Compute Runoff Coefficient, Rv | Rv = | 0.82 | |||||||||||||||||||
| Compute WQv Volume requirements | WQv = | 0.068 | acre-ft | ||||||||||||||||||
| 5 | Compute WQp peak flow using SCS | WQp = | cfs | ||||||||||||||||||
| Compute modified SCS curve number | CN = | 98.26 | |||||||||||||||||||
| 6 | Compute CPv | ||||||||||||||||||||
| Compute S (maximum retention) | S = | 2.50 | |||||||||||||||||||
| Compute 1-yr, 24-hr total rainfall depth | Rainfall Depth = | 2.58 | inches | ||||||||||||||||||
| Compute Qd (runoff volume) | Qd = | 0.94 | inches | ||||||||||||||||||
| Compute CPv (chnnnel protection volume) | CPv = | 0.08 | acre-ft | ||||||||||||||||||
| Estimate tc (time of concentration) | tc = | 0.12 | hours | ||||||||||||||||||
| Compute approximate storage volume | Storage volume = | XXXXXX | acre-ft | ||||||||||||||||||
| 7 | Compute release rates | ||||||||||||||||||||
| Compute WQv release rate | Release Rate = | 0.008 | cfs | ||||||||||||||||||
| Compute CPv release rate | Release Rate = | 0.016 | cfs | 60 | hours - time for CPv to be released | ||||||||||||||||
| must be between 60-132 hours | |||||||||||||||||||||
| STORM WATER DETENTION BASIN DESIGN | |||||||||||||||||||||
| 8. | Pretreatment volume | ||||||||||||||||||||
| Volpre = Acres of Impervious Area(0.2”)(1‟/12”) | WQpre = | 0.014 | acre-ft | ||||||||||||||||||
| 9. | Compute Permanent Pool Volume and | ||||||||||||||||||||
| Water Quality Extended Volume | |||||||||||||||||||||
| Compute WQv/PPv | WQv/PPv = | 0.3 | |||||||||||||||||||
| Compute PPv | PPv = | 0.23 | acre-ft | ||||||||||||||||||
| Size extended detention – pool volume is greater | |||||||||||||||||||||
| of WQv or CPv | ED Pool Volume = | 0.08 | acre-ft | ||||||||||||||||||
| 10. Conduction grading and determine storage available | Prepare an elevation-storage table and curve using | ||||||||||||||||||||
| for permanent pool (and WQv-ED volume if applicable) | the average area method for computing volumes. | ||||||||||||||||||||
| Elevation | Area | Average Area | Depth | Incremental Volume | Cumulative Volume | Volume above Permanent Pool | |||||||||||||||
| MSL | (acres) | (acres) | (ft) | (acre-ft) | (acre-ft) | (acre-ft) | |||||||||||||||
| 12. | WQv Orifice Computations | ||||||||||||||||||||
| Average ED release rate | Release Rate = | cfs | |||||||||||||||||||
| Average head, h = (ED elev. – Permanent pool elev.) / 2 | h = | ft | |||||||||||||||||||
| Area of orifice from orifice equation: Q = CA(2gh)0.5 | A = | ft2 | |||||||||||||||||||
| Diameter = | in | ||||||||||||||||||||
| 13. | Compute release rate for CPv control and | ||||||||||||||||||||
| Establish CPv elevation | WSEL = | ft | |||||||||||||||||||
| Release rate | Release Rate = | cfs | |||||||||||||||||||
| Average head h = CPv elev. – Permanent pool elev.) / 2 | h = | ft | |||||||||||||||||||
| Area or orifice from orifice equation: Q = CA(2gh)0.5 | A = | ft2 | |||||||||||||||||||
| Diameter = | in | ||||||||||||||||||||
| 14. | Calculate Qp release rate and water surface elevation | ||||||||||||||||||||
| Set up a stage-storage-discharge relationships. | |||||||||||||||||||||
| Peak stage for (WQv), the 1-inch, 6-hour storm | Peak Stage = | ft | |||||||||||||||||||
| Peak stage for (CPv), the 1-yr, 24-hour storm | Peak State = | ft | |||||||||||||||||||
| Peak Q10 – Undeveloped | Q10-undev = | cfs | |||||||||||||||||||
| Peak Q10 – Developed | Q10-dev = | cfs | |||||||||||||||||||
| Peak Q25 – Undeveloped | Q25-undev = | cfs | |||||||||||||||||||
| Peak Q25 – Developed | Q25-dev = | cfs | |||||||||||||||||||
| Size emergency spillway, calculate 50-year WSEL | WSEL50 = | ft | |||||||||||||||||||
| and set top of embankment elevation | Embankment Elevation = | ft | |||||||||||||||||||
| 15. | Investigate potential wet detention basin hazard | Notes: | |||||||||||||||||||
| classification | |||||||||||||||||||||
| 16. | Assess maintenance access and safety features. | ||||||||||||||||||||
| 17. | Attach landscaping plan | ||||||||||||||||||||
