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Home My WebLink About20080067 Ver 3_Stormwater Info_20110325WITHERS &- RAVENEL Alston Pond Stormwater Management Plan Fuquay-Varina, North Carolina Prepared For: North Broad Street, LLC 2401 Weston Parkway, Suite 203 Cary, NC 27513 Prepared By: WITHERS & RAVENEL, INC 111 MacKenan Drive Cary, North Carolina 27511 Revised - March 2011 W&R Project No. 02100349 MAR' S Z01 `???`111111/??? V? CA SEAL 9 AL t,?'P.E. • INTRODUCTION . The purpose of this study is to document pre- and post-development peak stormwater discharges for the 1-year and 1o-year design storm events as well as study the Zoo-year water surface elevations in the stormwater BMPs. The goal is to provide adequate stormwater detention devices to safely i maintain a discharge less than or equal to the pre-development peak discharges afterthe site has been developed as well as to provide storage for the post-development volume in excess of the pre- development runoff volume. • Wet detention basins with level spreaders and vegetated filter strips are proposed for this development to meet all town and DWQ criteria for peak attenuation and water quality. BMP's 1 & 3 discharge to existing wetlands outside the buffer and therefore do not require level spreaders. • METHODOLOGY . The stormwater study was conducted using the natural drainage features as depicted by field survey • data and proposed development within the drainage areas. The drainage areas of each pond were entered into the model as a single drainage area based on natural and proposed drainage patterns, to evaluate post development peak discharge rates and runoff volumes. There are four stormwater devices proposed for the site to meet peak attenuation, water quality and storage requirements. Stormwater is collected in catch basins and conveyed via storm sewerto the • wet detention basins. The scope of work included the following analyses: Hydrology ? Estimation of the 1.o" runoff volume and the 1-year 24 hour runoff volume ? Estimation of the time of concentration for the pre- and post-development conditions ? Simulation of the 1-year, to-year and loo-year rainfall events for the Fuquay-Varina area ? Formulation of the 1-year, to-year and loo-year flood hydrographs for the pre- and post- s development drainage areas • Hydraulic ? Routing the 1-year, to-year and loo-year flood hydrographs for post development runoff through the proposed infiltration system. Culvert Sizing • ? There are 3 culvert crossings on site, sized for the 25-year storm and to not overtop the • road in the loo-year storm The results of the hydrology calculations are used in the hydraulic analyses. The hydraulic design • requires the development of stage-storage and stage-discharge functions for the wet ponds. The rainfall/runoff hydrographs, stage-storage and stage-discharge functions have been compiled to create a routing computer simulation model using Bentley PondPack v1o.o software. This PondPack • model was then used to assess the impact of the peak discharges for the design rainfall events. The PondPack modeling results are provided as appendices to this report. SITE DESCRIPTION The proposed residential development is located on a 138 acre parcel, which is anticipated to be approximately 31% impervious. The existing site is generally gently sloping, draining to the northeast. Existing land use is approximately 75% forested and 25% agricultural fields. Wetlands and streams on site are within the Neuse River basin and are tributaries to Basal Creek (stream Index #27-43-15-3, Classification B;NSW), which is on the eastern boundary of the property. HYDROLOGY The SCS Method was used to develop runoff hydrographs for the Type II, 24-hour duration, 1-year storm and NOAA Atlas 14 rainfall data was used for the 1o-year and loo-year storm events for the Fuquay-Varina area. This method requires three basic parameters: a curve number (CN), time of concentration (Q, and drainage area. Curve numbers were based on soil type and land use. Soil types were delineated from the Soil Survey of Wake County, North Carolina. Land use for existing conditions was based on the most recent Wake County aerial photographs. Post development land use is residential based on the proposed site plan. Time of concentration was calculated using methods described in the SCS publication "Urban Hydrology for Small Watersheds, TR-55" and the flow time through the storm sewer, as calculated by our Storm CAD Model for each drainage area, in conjunction with field survey data. Drainage areas were delineated from the proposed grading plans for post development conditions. A summary of data used to formulate hydrographs and peak discharges are included in the appendices of this report. HYDRAULICS Computer simulated reservoir routing of the 1-year, to-year and loo-year design storms utilized stage-storage and stage-discharge functions. Stage-storage functions were derived from the proposed contours for each pond. A non-linear regression relation for surface area versus elevation was derived for each pond. This relation estimates the incremental volume of the basin to the stage or elevation of the basin. Stage-discharge functions were developed to size the outlet structure for each pond. CONCLUSIONS Based on the routing study, the post development peak discharge from the entire site is less than • the pre-development peak for the 1-year, and 1o-year design storms. All BMPs provide at least 12" of freeboard in the loo-year storm. Additionally, the ponds discharge at non-erosive velocities through level spreaders or at least 30' of natural wetlands in place of a constructed vegetated filter strip. The table below summarizes the peak attenuation results. TABLE 1. PRE DEVELOPMENT RUNOFF SUMMARY 1-year Qpeak Outflow 10-year Qpeak Outflow ioo-year Qpeak Outflow Pre Development Runoff 15.61 cfs 117.62 cfs 256.79 cfs TABLE 2. PEAK ATTENUATION SUMMARY FOR THE 1-YEAR DESIGN STORM 1-year Qpeak Inflow 1-year Qpeak Outflow BMP 1 50.63 3.60 BMP 2 62.72 3.43 BMP 3 22.76 1.35 BMP 4 13.06 1.12 Untreated 2.55 Post Development Runoff 10.24 cfs TABLE 3. PEAK ATTENUATION SUMMARY FOR THE 10-YEAR DESIGN STORM io-year Qpeak Inflow 10-year Qpeak Outflow BMP 1 111.20 33.62 BMP 2 137.77 18.83 BMP 3 62.23 31.55 BMP 4 31.11 10.44 Untreated 30.86 i Post Development Runoff 107.70 cfs TABLE 4. WATER SURFACE ELEVATION SUMMARY FOR THE 10-YEAR DESIGN STORM loo-year WSE Berm Elevation for Minimum 1' Freeboard BMP 1 346.19 347.19 BMP 2 371.26 372.26 BMP 3 384.52 385.52 BMP 4 346.37 347.37 Type.... Outlet Input Data Name.... BMP2 Outlets Page 6.08 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\ Pondpak\Al s ton Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = 00 Structure Type = Orifice-Circular ------------------------------------ # of Openings = 1 Invert Elev. = 365.00 ft Diameter = .3333 ft Orifice Coeff. _ .600 Structure ID = TW Structure Type = TW SETUP, DS Channel ------------------------------------ FREE OUTFALL CONDITIONS SPECIFIED CONVERGENCE TOLERANCES... Maximum Iterations= 40 Min. TW tolerance = .01 ft Max. TW tolerance = .01 ft Min. HW tolerance = .01 ft Max. HW tolerance = .01 ft Min. Q tolerance = .00 cfs Max. Q tolerance = .00 cfs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 WET DETENTION POND OUTLET SUMMARY BMP1 • 6'x6' Inlet Box with slab top - Crest = 345.20 (6'x 6' I.D.) • 4" diameter drawdown orifice - Invert @ 342.00 0 3x 4' wide x 6" high peak attenuation orifices a@ 343.80 • 54" dia. RCP outlet barrel - INV UP = 340.33, INV DN = 340.00 • Top of Berm = 347.20, loo-year freeboard =1.o' BMP2 • 6'x6' Inlet Box with slab top - Crest = 370.00 (6'x 6' I.D.) • 4" diameter drawdown orifice - Invert @ 365.00 • 4' wide x 6" high peak attenuation orifice @ 367.4 • 42" dia. RCP outlet barrel - INV UP = 359.00, INV DN = 358.58 • Top of Berm = 372.26, ioo-year freeboard =1.o' • 1o' Level Spreader with Vegetated Filter Strip BMP3 • 5'x5' Inlet Box with slab top - Crest = 384.25 (5'x 5' I.D.) • 2" diameter drawdown orifice - Invert @ 381.oo • 2.5' wide x 12" high peak attenuation orifice @ 382.80 • 36" dia. RCP outlet barrel - INV UP = 376.oo, INV DN = 372.00 • 33' Emergency Spillway @ 383.8o • Top of Berm = 385.52, loo-year freeboard =1.o' BMP 4 • 4'x4' Inlet Box with slab top - Crest = 346.oo W x 4' I.D.) 0 1" diameter drawdown orifice - Invert @ 343.00 • 2.5' wide x 12" high peak attenuation orifice @ 344.5 • 24" dia. RCP outlet barrel - INV UP = 338.oo, INV DN = 337.00 • Top of Berm = 347.50, loo-year freeboard = 1.1' 0 1o' Level Spreader with Vegetated Filter Strip STORMWATER CALCULATIONS Project Name: Alston Pond City/State: Fuquay-Varina Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant Removal Efficiencv in the Piedmont % Impervious Cover Permanent Pool Dept 3.0 4.0 5.0 6.0 h (feet) 7.0 8.0 9.0 10 0.59 0.49 0.43 0.35 0.31 0.29 0.26 20 0.97 0.79 0.70 0.59 0.51 0.46 0.44 30 1.34 1.08 0.97 0.83 0.70 0.64 0.62 40 1.73 1.43 1.25 1.05 0.90 0.82 0.77 50 2.06 1.73 1.50 1.30 1.09 1.00 0.92 60 2.40 2.03 1.71 1.51 1.29 1.18 1.10 70 2.88 2.40 2.07 1.79 1.54 1.35 1.26 80 3.36 2.78 2.38 2.10 1.86 1.60 1.42 90 3.74 3.10 2.66 2.34 2.11 1.83 1.67 Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 10-9, July 2007 STORMWATER BMP 1 - STORMWATER WET POND Land Use Area (ac) % IA Imp. Area (ac) Impervious 15.62 100 15.62 Open Space 16.88 0 0.00 Totals 32.50 15.62 Total % Impervious Surface Area = 48.1 % Surface Area of Permanent Pool: Assumed depth = 3 feet SA/DA ratio = 2.00 % From Table 1.1 Minimum pond surface area (SA) = (DA * SA/DA ratio)/100 SA = 0.649 acres 28258 sq. ft. Normal pool elevation = 342.0 feet Surface area provided = 0.788 acres 34306 sq. ft. 1-Inch Runoff Volume Calculation Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987) Rv = 0.05 + 0.009(1) where, Rv = Runoff coefficient, in./in. I = Percent impervious Rv = 0.48 in./in. Total runoff volume from 1-inch precipitation: Runoff volume, S = (Design rainfall) (Rv) (Drainage Area) S = 1.307 acre-ft 56929 cu. ft. Temporary Pool Elevation = 343.8 Water quality pool elevation= 342.00 feet Storage volume provided = 1.687 acre-ft 73486 cu. ft. Project Name: Alston Pond City/State: Fuquay-Varina STORMWATER BMP 1 - WET POND (25% TN Removal) Orifice Calculator Q =Cd*A*(2gh)^(1/2) Variables WQ Volume Head Draw down time 1.687 Acre-ft 1.80 ft 62 h rs 73485.72 cf 0.6 ft 223200 s Orifice Area = 0.088275 sq. ft Orifice Diameter = 4.023055 in 12.71164 sq. in Constants g= cd = 32.2 ft/s2 0.6 USE 4 INCH DIAMETER ORIFICE • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Average Depth Calculator - BMP 1 * This Calculator will determine the average depth of a pond or wetland." Input Normal Pool Elevation Top of Shelf Bottom of Shelf Output 4 ft 4.5 ft 3.5 ft Normal Pool Surface Area at Top of Shelf Area at Bottom of Shelf Area Bottom of Pond 34306 sf 40369 sf 28441 sf 21265 sf Elevation Depth Area Incr. Volume Acc. Volume 4 0 34306 - - 3 1 27869 31087.5 31087.5 2 2 25612 26740.5 57828 1 3 23440 24526 82354 0 4 21265 22352.5 104706.5 0 4 0 0 104706.5 0 4 0 0 104706.5 0 4 0 0 104706.5 Depth of Pond = ft Average Depth Calculations Option 1 = 3.052133738 ft Option 2 = 3.95 ft Pond Design Average Depth = Average Depth Calculation you should use: 3 ft (minimum 3') Note: Average Depth must be greater than or equal to average depth used to size surface area of pond Forebay 1 A * If you input your Stage-Storage Relationship for your Forebay, this Design tool will help you decide if your Forebay is undersized, sized appropriately or oversized.* Input Elevation Depth 341 0 340 1 339 2 338 3 341 341 341 341 Forebay Volume = Pond Volume = Forebay Precent = Status of Forebay Design: Area 4007 3512 3074 2654 Output Incr. Volume Acc. Volume 3759.5 3759.5 3293 7052.5 2864 9916.5 0 9916.5 0 9916.5 0 9916.5 0 9916.5 9916.5 cf 104706.5 cf 9.47% Note: Forebay volume should be approximately 20% of total Pond Volume ?v(??C.•?q 1.,urtC la rs?y??S - ? ? 6 .S t- l N? •S : - 2126 . I 2t? S ?- • • • • • • • • • • • • • • • • • • • • • • • i • • • • • • • • • • • Forebay 1 B If you input your Stage-Storage Relationship for your Forebay, this Design tool will help you decide if your Forebay is undersized, sized appropriately or oversized.* Input Elevation Depth 341 0 340 1 339 2 338 3 341 341 341 341 Forebay Volume = Pond Volume = Forebay Precent = Status of Forebay Design: Output Area Incr. Volume 4657 - 4096 4376.5 3560 3828 3050 3305 0 0 0 11509.5 cf 104706.5 cf 10.99% Acc. Volume 4376.5 8204.5 11509.5 11509.5 11509.5 11509.5 11509.5 Note: Forebay volume should be approximately 20% of total Pond Volume -SF Project Name: Alston Pond City/State: Fuquay-Varina Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant Removal Efficiencv in the Piedmont % Impervious Cover Permanent Pool Depth (feet) 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 0.59 0.49 0.43 0.35 0.31 0.29 0.26 20 0.97 0.79 0.70 0.59 0.51 0.46 0.44 30 1.34 1.08 0.97 0.83 0.70 0.64 0.62 40 1.73 1.43 1.25 1.05 0.90 0.82 0.77 50 2.06 1.73 1.50 1.30 1.09 1.00 0.92 60 2.40 2.03 1.71 1.51 1.29 1.18 1.10 70 2.88 2.40 2.07 1.79 1.54 1.35 1.26 80 3.36 2.78 2.38 2.10 1.86 1.60 1.42 90 3.74 3.10 2.66 2.34 2.11 1.83 1.67 Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 10-9, July 2007 STORMWATER BMP 2 - STORMWATER WET POND Land Use Area (ac) % IA Imp. Area (ac) Impervious 18.75 100 18.75 Open Space 17.75 0 0.00 Totals 36.50 18.75 Total % Impervious Surface Area = 51.4 % Surface Area of Permanent Pool: Assumed depth = 4 feet SA/DA ratio = 1.77 % From Table 1.1 Minimum pond surface area (SA) = (DA * SA/DA ratio)/100 SA = 0.646 acres 28159 sq. ft. Normal pool elevation = 365.0 feet Surface area provided = 0.649 acres 28282 sq. ft. 1-Inch Runoff Volume Calculation Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987) Rv = 0.05 + 0.009(1) where, Rv = Runoff coefficient, in./in. I = Percent impervious Rv = 0.51 in./in. Total runoff volume from 1-inch precipitation: Runoff volume, S = (Design rainfall) (Rv) (Drainage Area) S = 1.558 acre-ft 67881 cu. ft. Temporary Pool Elevation = 367.4 Water quality pool elevation= 365.00 feet Storage volume provided = 1.936 acre-ft 84332 cu. ft. Project Name: Alston Pond City/State: Fuquay-Varina STORMWATER BMP 2 - WET POND (25% TN Removal) Orifice Calculator Q =Cd*A*(2gh)"(1/2) Variables WQ Volume: Head: Draw down time: 1.936 Acre-ft 1.40 ft 82 hrs 84332.16 cf 0.466667 ft 295200 s Orifice Area = 0.086852 sq. ft Orifice Diameter = 3.990489 in 12.50667 sq. in Constants 9 Cd = 32.2 ft/s2 0.6 USE 4 INCH DIAMETER ORIFICE • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Average Depth Calculator - BMP 2 * This Calculator will determine the average depth of a pond or wetland.* Input Output NNOWMW Normal Pool Elevation 5 ft Top of Shelf 5.5 ft Bottom of Shelf 4.5 ft Normal Pool Surface 28282 sf Area at Top of Shelf 33737 sf Area at Bottom of Shelf 23027 sf Area Bottom of Pond 11660 sf Elevation Depth -Area In cr. Volume Acc. Volume 5 0 28282 - - 4 1 21029 24655.5 24655.5 3 2 19214 20121.5 44777 2 3 17465 18339.5 63116.5 1 4 15679 16572 79688.5 0 5 13943 14811 94499.5 0 5 0 0 94499.5 0 5 0 0 94499.5 Depth of Pond = ? ft Average Depth Calculations Option 1 = 3.341330175 ft Option 2 = 4.22 ft Pond Design Average Depth = 4 Average Depth Calculation you should use Note: Average Depth must be greater than or equal to average depth used to size surface area of pond ft (minimum 3') • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Forebay 2 * If you input your Stage-Storage Relationship for your Forebay, this Design tool will help you decide if your Forebay is undersized, sized appropriately or oversized.* Input Elevation Depth 364 0 363 1 362 2 361 3 360 4 359 5 364 364 Forebay Volume = Pond Volume = Forebay Precent = Status of Forebay Design: Area 6178 5397 4646 3942 3258 2591 Output Incr. Volume Acc. Volume 5787.5 5787.5 5021.5 10809 4294 15103 3600 18703 2924.5 21627.5 465084.5 486712 0 486712 18703 cf 94499.5 cf 19.79% Note: Forebay volume should be approximately 20% of total Pond Volume Project Name: Alston Pond City/State: Fuquay-Varina Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant Removal Efficiencv in the Piedmont % Impervious Cover Permanent Pool Depth (feet) 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 0.59 0.49 0.43 0.35 0.31 0.29 0.26 20 0.97 0.79 0.70 0.59 0.51 0.46 0.44 30 1.34 1.08 0.97 0.83 0.70 0.64 0.62 40 1.73 1.43 1.25 1.05 0.90 0.82 0.77 50 2.06 1.73 1.50 1.30 1.09 1.00 0.92 60 2.40 2.03 1.71 1.51 1.29 1.18 1.10 70 2.88 2.40 2.07 1.79 1.54 1.35 1.26 80 3.36 2.78 2.38 2.10 1.86 1.60 1.42 90 3.74 3.10 2.66 2.34 2.11 1.83 1.67 Source: NCDENP/DWQ Stormwater Best Management Practices, pg. 10-9, July 2007 STORMWATER BMP 3 - STORMWATER WET POND Land Use Area (ac) % IA Imp. Area (ac) Impervious 6.24 100 6.24 Open Space 9.76 0 0.00 Totals 16.00 6.24 Total % Impervious Surface Area = 39.0 % Surface Area of Permanent Pool: Assumed depth = 3 feet SA/DA ratio = 1.69 % From Table 1.1 Minimum pond surface area (SA) = (DA * SA/DA ratio)/100 SA = 0.271 acres 11786 sq. ft. Normal pool elevation = 381.0 feet Surface area provided = 0.285 acres 12414 sq. ft. 1-Inch Runoff Volume Calculation Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987) Rv = 0.05 + 0.009(1) where, Rv = Runoff coefficient, in./in. I = Percent impervious Rv = 0.40 in./in. Total runoff volume from 1-inch precipitation: Runoff volume, S = (Design rainfall) (Rv) (Drainage Area) S = 0.535 acre-ft 23290 cu. ft. Temporary Pool Elevation = 382.8 Water quality pool elevation= 381.00 feet Storage volume provided = 0.638 acre-ft 27791 cu. ft. • a t' Project Name: Alston Pond City/State: Fuquay-Varina STORMWATER BMP 3 - WET POND (25% TN Removal) Orifice Calculator Q =Cd*A*(2gh)"(1/2) Variables WQ Volume: Head: Draw down time: 0.638 Acre-ft 1.80 ft 90 h rs 27791.28 cf 0.6 ft 324000 s Orifice Area = 0.022998 sq. ft Orifice Diameter = 2.053446 in USE 2 INCH DIAMETER ORIFICE 3.31174 sq. in Constants 9 Cd = 32.2 ft/s2 0.6 Average Depth Calculator - BMP 3 * This Calculator will determine the average depth of a pond or wetland.* Input Output Normal Pool Elevation 4 ft Top of Shelf 4.5 ft Bottom of Shelf 3.5 ft Normal Pool Surface 12414 sf Area at Top of Shelf 15292 sf Area at Bottom of Shelf 9710 sf Area Bottom of Pond 5979 sf Elevation 4 3 2 1 0 0 0 0 Depth Area 0 12414 1 8932 2 7940 3 6952 4 5979 4 0 4 0 4 0 Depth of Pond = ' ft Average Depth Calculations Option 1 = 2.65994039 ft Option 2 = 3.68 ft Pond Design Average Depth = Average Depth Calculation you should use: Incr. Volume Acc. Volume 10673 10673 8436 19109 7446 26555 6465.5 33020.5 0 33020.5 0 33020.5 0 33020.5 3 ft (minimum 3') Note: Average Depth must be greater than or equal to average depth used to size surface area of pond Forebay 3 * If you input your Stage-Storage Relationship for your Forebay, this Design tool will help you decide if your Forebay is undersized, sized appropriately or oversized.* Input Output Elevation Depth Area Incr. Volume Acc. Volume 380 0 2842 - - 379 1 2424 2633 2633 378 2 2046 2235 4868 377 3 1688 1867 6735 380 0 6735 380 0 6735 380 0 6735 380 0 6735 Forebay Volume = 6735 cf Pond Volume = 33020.5 cf Forebay Precent = 20.40% Status of Forebay Design: Note: Forebay volume should be approximately 20% of total Pond Volume Project Name: Alston Pond City/State: Fuquay-Varina Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant Removal Effirienev in the Piedmont % Impervious Cover Permanent Pool Depth (feet) 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 0.59 0.49 0.43 0.35 0.31 0.29 0.26 20 0.97 0.79 0.70 0.59 0.51 0.46 0.44 30 1.34 1.08 0.97 0.83 0.70 0.64 0.62 40 1.73 1.43 1.25 1.05 0.90 0.82 0.77 50 2.06 1.73 1.50 1.30 1.09 1.00 0.92 60 2.40 2.03 1.71 1.51 1.29 1.18 1.10 70 2.88 2.40 2.07 1.79 1.54 1.35 1.26 80 3.36 2.78 2.38 2.10 1.86 1.60 1.42 90 3.74 3.10 2.66 2.34 2.11 1.83 1.67 Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 10-9, July 2007 STORMWATER BMP 4 - STORMWATER WET POND Land Use Area (ac) % IA Imp. Area (ac) Impervious 2.6 100 2.60 Open Space 3.4 0 0.00 Totals 6.00 2.60 Total % Impervious Surface Area = 43.3 % Surface Area of Permanent Pool: Assumed depth = 3 feet SA/DA ratio = 1.84 % From Table 1.1 Minimum pond surface area (SA) = (DA * SA/DA ratio)/100 SA = 0.110 acres 4809 sq. ft. Normal pool elevation = 343.0 feet Surface area provided = 0.112 acres 4897 sq. ft. 1-Inch Runoff Volume Calculation Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987) Rv = 0.05 + 0.009(1) where, Rv = Runoff coefficient, in./in. I = Percent impervious Rv = 0.44 in./in. Total runoff volume from 1-inch precipitation: Runoff volume, S = (Design rainfall) (Rv) (Drainage Area) S = 0.220 acre-ft 9583 cu. ft. Temporary Pool Elevation = 344.5 Water quality pool elevation= 343.00 feet Storage volume provided = 0.227 acre-ft 9888 cu. ft. Proiect Name: Alston Pond City/State: Fuquay-Varina STORMWATER BMP 4 - WET POND (25% TN Removal) Orifice Calculator Q =Cd*A*(2gh)"(1/2) Variables WQ Volume Head Draw down time 0.227 Acre-ft 1.50 ft 72 h rs 9888.12 cf 0.5 ft 259200 s Orifice Area = 0.011205 sq. ft Orifice Diameter = 1.433297 in 1.613474 sq. in Constants 9 cd = 32.2 ft/sz 0.6 USE 1 INCH DIAMETER ORIFICE • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Average Depth Calculator - BMP 4 * This Calculator will determine the average depth of a pond or wetland.* Input Output MMEMSM Normal Pool Elevation 4 ft Top of Shelf 4.5 ft Bottom of Shelf 15 ft Normal Pool Surface 4896 sf Area at Top of Shelf 6616 sf Area at Bottom of Shelf 3346 sf Area Bottom of Pond 1418 sf Elevation Depth Area In cr. Volume Acc. Volume 4 0 4896 - - 3 1 2882 3889 3889 2 2 2369 2625.5 6514.5 1 3 1882 2125.5 8640 0 4 1418 1650 10290 0 4 0 0 10290 0 4 0 0 10290 0 4 0 0 10290 Depth of Pond = ft Average Depth Calculations Option 1 = 2.101715686 ft Option 2 = 3.27 ft Pond Design Average Depth = 3 ft (minimum T) Average Depth Calculation you should use: Note: Average Depth must be greater than or equal to average depth used to size surface area of pond Forebay 4 * If you input your Stage-Storage Relationship for your Forebay, this Design tool will help you decide if your Forebay is undersized, sized appropriately or oversized.* Input Elevation Depth 342 0 341 1 340 2 339 3 342 342 342 342 Forebay Volume = Pond Volume = Forebay Precent = Status of Forebay Design: Area 974 736 529 339 Output Incr. Volume Acc. Volume 855 855 632.5 1487.5 434 1921.5 0 1921.5 0 1921.5 0 1921.5 0 1921.5 1921.5 cf 10290 cf 18.67% Note: Forebay volume should be approximately 20% of total Pond Volume ROUTING & SUPPORTING DATA DA 1 DA 2 DA 3 DA 4 n :3 n 0 CL a 0 0 Q o BMP 1 \ BMP ? BM? 3 IP&P 4 0 oI G? m ?p o A Post-Dev _o ?o Untreated J?0 O ?O P Pre-Dev Are, a Q.. 9' 77 0 A Pre-Dev Job File: K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ALSTON POND BMPS.PPW Rain Dir: K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ -------------------------- -------------------------- JOB TITLE Project Date: 12/3/2010 Project Engineer: asmith Project Title: Alston Pond Project Comments: S/N: Bentley Systems, Inc. Bentley PondPack (.10.00.027.00) 10:47 AM 3/24/2011 Table of Contents i Table of Contents ********************** MASTER SUMMARY ********t************* Watershed....... Master Network Summary ............. 1.01 ****************** DESIGN STORMS SUMMARY ******************* RDU NOAA 14 Desi Design. Storms ...................... 2.01 RDU NOAA 14 Desi 10 Design Storms ...................... 2.02 ********************** TC CALCULATIONS ********************* DA 1............ Tc Calcs ........................... 3.01 DA 2............ Tc Calcs ........................... 3.03 DA 3............ Tc Calcs ........................... 3.05 DA 4............ Tc Calcs ........................... 3.07 PRE-DEV AREA.... Tc Calcs ........................... 3.09 UNTR3ATED....... Tc Calcs ........................... 3.11 *«****«*+*********** CN CALCULATIONS **********.***+****** DA 1............ Runoff CN-Area ..................... 4.01 DA 2............ Runoff CN-Area ..................... 4.02 DA 3............ Runoff CN-Area ..................... 4.03 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 • • • • • • • • • • • i • • • • Table of Contents Table of Contents (continued) DA 4............ Runoff CN-Area ..................... 4.04 PRE-DEV AREA.... Runoff CN-Area ..................... 4.05 UNTREATED....... Runoff CN-Area ..................... 4.06 *******tt*+*** POND VOLUMES****+*******trk** BMP 1........... Vol: Elev-Area ..................... 5.01 BMP 2........... Vol: E1ev-Area ..................... 5.02 BMP 3........... Vol: E1ev-Area ..................... 5.03 BMP 4........... Vol: Elev-Area ..................... 5.04 ** x**x***** ****** OUTLET STRUCTURES ** *************** BMPI Outlets.... Outlet Input Data .................. 6.01 BMP2 Outlets.... Outlet Input Data .................. 6.05 BMP3 Outlets.... Outlet Input Data .................. 6.09 BMP4 Outlets.... Outlet Input Data .................. 6.13 **.tr***** POND ROUTING +**+****x ** BMP 1........... Pond E-V-Q Table ................... 7.01 BMP 2........... Pond E-V-Q Table ................... 7.04 BMP 3........... Pond E-V-Q Table ................... 7.08 BMP 4........... Pond E-V-Q Table ................... 7.11 ii S/N: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Master Network Summary Page 1.01 Name.... Watershed File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw MASTER DESIGN STORM SUMMARY Network Storm Collection: RDU NOAA 14 Desi Total Depth Rainfall Return Event ------------ in ------ Type ----- RNF ID 10 4.9800 ----------- Time-Depth Curve ---------------- RDU NOAA 10yr 100 7.3700 Time-Depth Curve RDU NOAA 100yr 1 3.0000 Synthetic Curve TypeII 24hr MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; -Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID ----------- ------ Type ---- Event ------ ac-ft ---- Trun hrs cfs ft ac-ft BMP 1 IN POND 10 ------ 7.541 -- --------- 12.1500 -------- 111.20 -------- ------------ BMP 1 IN POND 100 13.336 12.1500 161.24 BMP 1 IN POND 1 3.219 12.0000 50.63 BM? 1 OUT POND 10 7.456 R 12.4500 33.62 345.25 3.281 BMP 1 OUT POND 100 13.247 R 12.3000 101.53 346.19 4.414 BMP 1 OUT POND 1 3.139 R 13.3000 3.60 343.91 1.790 BMP 2 IN POND 10 8.747 12.1500 137.77 BMP 2 IN POND 100 15.322 12.1500 196.85 BMP 2 IN POND 1 3.802 12.0000 62.72 BMP 2 OUT POND i0 8.680 R 12.6000 18.83 370.11 4.565 BMP 2 OUT POND 100 15.252 R 12.3000 120.93 371.26 5.804 BMP 2 OUT POND 1 3.740 R 13.6500 3.43 367.69 2.190 BMP 3 IN POND 10 3.244 12.1000 62.23 BMP 3 IN POND 100 5.970 12.1000 93.45 BMP 3 IN POND 1 1.281 11.9500 22.76 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 i i s • • • • • • • • • • • • • • • • i i • • • i • Type.... Master Network Summary Page 1.02 Name.... Watershed File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Return HYG Vol Node ID ----------- ------ Type ---- Event ------ ac-ft ---------- Trun -- BMP 3 OUT POND 10 3.198 R BMP 3 OUT POND 100 5.919 R BMP 3 OUT POND 1 1.241 R BMP 4 IN POND 10 1.303 BMP 4 IN POND 100 2.350 BMP 4 IN POND 1 .535 BMP 4 OUT POND 10 1.300 BMP 4 OUT POND 100 2.347 BMP 4 OUT POND 1 .533 DA 1 AREA 10 7.541 DA 1 AREA 100 13.336 DA 1 AREA 1 3.219 DA 2 AREA 10 8.747 DA 2 AREA 100 15.322 DA 2 AREA 1 3.802 DA 3 AREA 10 3.244 DA 3 AREA i00 5.970 DA 3 AREA 1 1.281 DA 4 AREA 10 1.303 DA 4 AREA 100 2.350 DA 4 AREA 1 .535 *POST-DEV JCT 10 24.353 R *POST-DEV JCT 100 45.821 R *POST-DEV JCT 1 9.400 R *PRE-DEV JCT 10 13.314 *PRE-DEV JCT 100 30.634 *PRE-DEV JCT 1 3.149 Max Qpeak Qpeak Max WSEL Pond Storage hrs -------- cfs -------- ft -------- ac-ft ------------ 12.2500 31.55 384.15 1.196 12.1500 82.80 384.52 1.359 13.4500 1.35 382.94 .692 12.1000 24.99 12.1000 36.61 11.9500 9.61 12.2500 10.44 345.73 .462 12.2000 25.09 346.37 .604 12.4500 1.12 344.62 .244 12.1500 111.20 12.1500 161.24 12.0000 50.63 12.1500 137.77 12.1500 196.85 12.0000 62.72 12.1000 62.23 12.1000 93.45 11.9500 22.76 12.1000 24.99 12.1000 36.61 11.9500 9.61 12.3000 107.70 12.3000 354.18 13.3000 10.24 12.4000 117.62 12.3500 256.79 12.3000 15.61 S/N: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Master Network Summary Page 1.03 Name.... Watershed File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Return HYG Vol Qpeak Qpeak Max WSEL Node ID --------------- Type -- ---- Event ------ ac-ft Trun ---------- -- hrs --------- cfs ft PRE-DEV AREA AREA i0 13.314 12.4000 -------- -------- 117.62 PRE-DEV AREA AREA 100 30.634 12.3500 256.79 PRE-DEV AREA AREA 1 3.149 12.3000 15.61 UNTREATED AREA 10 3.715 12.4000 30.86 UNTREATED AREA 100 9.056 12.4000 74.44 UNTREATED AREA 1 .747 12.3500 2.55 Max Pond Storage ac-ft ------------ S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00; 10:47 AM 3/24/2011 Type.... Design Storms Name.... RDU NOAA 14 Desi Page 2.01 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw Title... Project Date: 12/3/2010 Project Engineer: asmith Project Title: Alston Pond Project Comments: DESIGN STORMS SUMMARY Design Storm File,ID = RDU NOAA 14 Desi Storm Tag Name = 10 Data Type, File, ID = Time-Depth Curve RDU NOAA 10yr Storm Frequency = 10 yr Total Rainfall Depth= 4.9800 in Duration Multiplier = 1 Resulting Duration = 23.9904 hrs Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs Storm Tag Name = 100 Data Type, File, ID = Time-Dept, Curve RDU NOAA 100yr Storm Frequency = 100 yr Total Rainfall Depth= 7.3700 in Duration Multiplier = 1 Resulting Duration = 23.9990 hrs Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9990 hrs Storm Tag Name = 1 Data Type, File, ID = Synthetic Storm TypeII 24hr Storm Frequency = 1 yr Total Rainfall Depth= 3.0000 in Duration Multiplier = 1 Resulting Duration. = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Design Storms Page 2.02 Name.... RDU NOAA 14 Desi Event: 10 yr File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw Storm... RDU NOAA 10yr Tag: 10 DESIGN STORMS SUMMARY Design Storm File,ID = RDU NOAA 14 Desi Storm Tag Name = 10 Data Type, File, ID Storm Frequency Total Rainfall Depth Duration Multiplier Resulting Duration Resulting Start Time Time-Depth Curve RDU NOAA 10yr 10 yr 4.9800 in 1 23.9904 hrs .0000 hrs Step= .0833 hrs End= 23.9904 hrs Storm Tag Name = i0C Data Type, File, ID = Time-Depth Curve RD"U NOAA 100yr Storm Frequency = 100 yr Total Rainfall Depth= 7.3700 in Duration Multiplier = 1 Resulting Duration = 23.9990 hrs Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9990 hrs Storm Tag Name = Data Type, File, ID Storm Frequency Total Rainfall Depth Duration Multiplier Resulting Duration Resulting Start Time Synthetic Storm TypeII 24hr 1 yr 3.0000 in 1 24.0000 hrs .00000 hrs Step= .1000 hrs End= 24.0000 hrs SIN: Bentley Systems, Inc. Bentley PondPack ;1C.00.027.00; 10:47 AM 3/24/2011 Type.... Tc Calcs Name.... DA 1 Page 3.01 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ........................................................................ ........................................................................ TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: User Defined Segment #1 Time: .0812 hrs ------------------------------------------------------------------------ Segment #2: Tc: TR-55 Sheet Mannings n Hydraulic Length 2yr, 24hr P Slope Avg velocity .2000 50.00 ft 3.4400 in 025000 ft/ft 13 ft/sec Segment #2 Time: .1041 hrs ------------------------------------------------------------------------ Total Tc: .1853 hrs ------------------------- ------------------------- S/N: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Tc Calcs Name.... DA 1 Page 3.02 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ==== User Defined =-=================-====--=====-=========== ----------- Tc = Value entered by user Where: Tc = Time of concentration __== SLS TR-55 Sheet Flow =================================== --_===--- Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4)) Where: Tc = Time of concentration, hrs n = Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, % SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Tc Calcs Name.... DA 2 Page 3.03 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw TIME OF CONCENTRATION CALCULATOR Segment #1: Tc: TR-55 Sheet Mannings n .2000 Hydraulic Length 50.00 ft 2yr, 24hr P 3.4400 in Slope .025000 ft/ft Avg.Velocity .13 ft/sec Segment #1 Time: .1041 hrs ----------------------------------------------------------------------- Segment #2: Tc: TR-55 Channel Flow Area 1.2300 Wetted Perimeter 3.93 Hydraulic Radius .31 Slope .039000 Mannings n .0130 Hydraulic Length 2073.00 sq.ft ft ft ft/ft ft Avg.Velocity 10.43 ft/sec Segment #2 Time: .0552 hrs ------------------------------------------------------------------------ Total Tc: .1593 hrs SIN: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Tc Calcs Name.... DA 2 Page 3.04 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ==_= SCS TR-55 Sheet Flow ===------===--=======-=====--==-======--=----- Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4)) Where: Tc = Time of concentration, hrs n = Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, _= SCS Channel Flow ________----- =--- R = Aq / Wp V = (1.49 * (R**(2/3)) (Sf**-0.5)) / n Tc - (Lf / V) / (3600sec/hr) Where: R = Hydraulic radius Aq = Flow area, sq.ft. Wp = Wetted perimeter, It V = Velocity, ft/sec Sf = Slope, ft/ft n = Mannings n Tc = Time of concentration, hrs Lf = Flow length, ft S/N: Bentley Systems, Inc. Bentley PondPack 110.00.027.00) 10:47 AM 3/24/2011 • • • • ! • ! i ! i ! • ! ! • • • i • • ! • • Type.... Tc Calcs Name.... DA 3 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ........................................................................ ........................................................................ TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: User Defined Segment #1 Time: .0833 hrs ------------------------------------------------------------------------ Total Tc: .0833 hrs Calculated Tc < Min.Tc: Use Minimum Tc... Use Tc = .0833 hrs Page 3.05 S/N: Bentley PondPack ;10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Tc Calcs Name.... DA 3 Page 3.06 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ==== User Defined ----- _ Tc = Value entered by user Where: Tc = Time of concentration S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 i i • • • s • • • • i • • • • i i • i • i i • • • Type.... Tc Calcs Name.... DA 4 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: User Defined Segment #1 Time: .0833 hrs ------------------------------------------------------------------------ Total Tc: .0833 hrs Calculated Tc < Min.Tc: Use Minimum Tc... Use Tc = .0833 hrs Page 3.07 S/N: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Tc Calcs Name.... DA 4 Page 3.08 File.... K:\10\10-0340\100349-Pre3ton - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw -------------------- Tc Equations used... ------------------------------------------------------------------------ ==== User Defined Tc = Value entered by user Where: Tc = Time of concentration SIN: Bentley Systems, Inc. Bentley PondPack (10.'0.027.00; 10:47 ALM 3/24/2011 Type.... Tc Caics Name.... PRE-DEV AREA Page 3.09 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ........................................................................ ........................................................................ TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: Kirpich (TN) Hydraulic Length 5597.00 ft Slope .019700 ft/ft Multiplier 1.000 (Tc Adjustment) Avg.Velocity 3.43 ft/sec Segment #1 Time: .4534 hrs ------------------------------------------------------------------------ ------------------------- ------------------------- Total Tc: .4534 hrs ------------------------- S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Tc Ca1cs Name.... PRE-DEV AREA Page 3.10 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ==== Kirpich (TN) =========------========-==-===------=================- Tc = 0.00013 * (Lf**0.77) * (Sf**-0.385) * Mt Where: Tc = Time of concentration, hrs Lf = Flow length, ft Sf = Slope, ft/ft Mt = Tc Multiplier (Tc adjustment) SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Tc Calcs Name.... UNTREATED Page 3.11 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ........................................................................ ........................................................................ TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: Kirpich (TN) Hydraulic Length 5597.00 ft Slope .019700 ft/ft Multiplier 1.000 (Tc Adjustment) Avg.Velocity 3.43 ft/sec segment #1 Time: .4534 hrs ------------------------------------------------------------------------ ------------- Total Tc: .4534 hrs ==- SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Tc Calcs Name.... UNTREATED Page 3.12 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ==== Kirpich (TN) ====-=======--=========--====-======================== Tc = 0.00013 * (Lf**0.77) * (Sf**-0.385) * Mt Where: Tc = Time of concentration, hrs Lf = Flow length, ft Sf = Slope, ft/ft Mt = Tc Multiplier (Tc adjustment) SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Runoff CN-Area Name.... DA 1 Page 4.01 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw RUNOFF CURVE NUMBER DATA .......................................................................... .......................................................................... Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C %UC CN -------------------------------- ---- --------- ----- ----- ------ Impervious Areas - Paved parking to 98 15.620 98.00 Open space (Lawns,parks etc.) - Goo 61 16.880 61.00 COMPOSITE AREA & WEIGHTED CN ---> 32.500 78.78 (79) ........................................................................... ........................................................................... S/N: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Runoff CN-Area Name.... DA 2 Page 4.02 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw RUNOFF CURVE NUMBER DATA Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C %UC CN -------------------------------- ---- --------- ----- ----- ------ Impervious 98 18.750 98.00 Open Space 61 17.750 61.00 COMPOSITE AREA & WEIGHTED CN ---> 36.500 80.01 (80) SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Runoff CN-Area Name.... DA 3 Page 4.03 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw RUNOFF CURVE NUMBER DATA .......................................................................... .......................................................................... Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C oUC CN -------------------------------- ---- --------- ----- ----- ------ Impervious 98 6.240 98.00 Open Space 61 9.760 61.00 COMPOSITE AREA & WEIGHTED CN ---> 16.000 75.43 (75) ........................................................................... ........................................................................... S/ N: Bentley PondPack (1C.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Runoff CN-Area Name.... DA 4 Page 4.04 File.... K:\10\10-0340\100349-Preston - Alston Pond \H-H\Pondpak\Alston Pond BMPs.ppw RUNOFF CURVE NUMBER DATA Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C %UC CN -------------------------------- ---- --------- ----- ----- ------ Impervious 98 2.600 98.00 Open Space 61 3.400 61.00 COMPOSITE AREA & WEIGHTED CN ---> 6.000 77.03 (77) SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Runoff CN-Area Name.... PRE-DEV AREA Page 4.05 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw RUNOFF CURVE NUMBER DATA Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C %UC CN -------------------------------- ---- --------- ----- ----- ------ Woods - grass combination - good 58 138.000 58.00 COMPOSITE AREA & WEIGHTED CN ---> 138.000 58.00 (58) ........................................................................... ........................................................................... SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Runoff CN-Area Name.... UNTREATED Page 4.06 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\ Pondpak\Alston Pond BMPs.ppw RUNOFF CURVE NUMBER DATA Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C 'UC CN -------------------------------- ---- --------- ----- ----- ------ Woods - good 55 46.000 55.00 COMPOSITE AREA & WEIGHTED CN ---> 46.000 55.00 (55) SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Vol: Elev-Area Name.... BMP 1 Page 5.01 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum (ft) (sq.in) (sa.ft) --------------- (sq.ft) ----------------- (ac-ft) ---------- (ac-ft) ------------- ------------ 342.00 ------ ----- 34307 0 .000 .000 343.00 ----- 42222 114588 .877 .877 344.00 ----- 45981 132264 1.012 1.889 345.00 ----- 49805 143641 1.099 2.988 346.00 ----- 53691 155208 1.188 4.176 347.00 ----- 57637 166957 1.278 5.453 POND VOLUME EQUATIONS * Incremental volume computed by the Conic Method for Reservoir Volumes. Volume = (1/3) * (EL2-EL1) * (Areal + Areal + sq.rt.(Areal*Area2)) where: EL1, EL2 = Lower and upper elevations of the increment Areal,Area2 = Areas computed for EL1. EL2, respectively Volume = Incremental volume between EL1 and EL2 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Vol: E1ev-Area Name.... BMP 2 Page 5.02 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum (ft) ------------ (sq.in) (sq.ft) --------------------- (sq.ft) --- (ac-ft) (ac-ft) 365.00 ----- 28282 ------------- 0 ---------- .000 ------------ .000 366.00 ----- 35498 95465 .731 .731 367.00 ----- 38109 110387 .845 1.575 368.00 ----- 40561 117986 .903 2.478 369.00 ----- 42917 125200 .958 3.436 370.00 ----- 45270 132265 1.012 4.448 371.00 ----- 47736 139493 1.067 5.516 372.00 ----- 49967 146542 1.121 6.637 POND VOLUME EQUATIONS * Incremental volume computed by the Conic Method for Reservoir Volumes. Volume = (1/3) * (EL2-EL1) * (Areal + Area2 + sq.rt.(Areal*Area2)) where: E171, EL2 = Lower and upper elevations of the increment Areal,Area2 = Areas computed for EL1, EL2, respectively Volume = incremental vol,,:sae between ELl and EL2 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AEI 3/24/2011 Type.... Vol: Elev-Area Name.... BMP 3 Page 5.03 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum (ft) ------------ (sq.in) (sq.ft) --------------------- (sq.ft) ----------------- (ac-ft) --------- (ac-ft) ------- - 381.00 ----- 12414 0 .000 -- --- .000 382.00 ----- 16187 42777 .327 .327 383.00 ----- 17614 50686 .388 .715 384.00 ----- 18753 54542 .417 1.133 385.00 ----- 19919 57999 .444 1.576 386.00 ----- 20043 59943 .459 2.035 POND VOLUME EQUATIONS * Incremental volume computed by the Conic Method for Reservoir Volumes. Volume = (1/3) * (EL2-EL1) * (Area! + Areal + sq.rt.(Areal*Area2)) where: ELI, EL2 = Lower and upper elevations of the increment Areal,Area2 = Areas computed for ELI, EL2, respectively Volume = Incremental volume between ELI and EL2 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Vol: E1ev-Area Page 5.04 Name.... BMP 4 File.... K:\10\10-0340\100349-Preston - Alston. Pond\H-H\Pondpak\Alston Pond BMPs.ppw Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum (ft) (sq.in) ------------------------- (sq.ft) -------- (sq.ft) --- (ac-ft) (ac-ft) 343.00 ----- 4897 ------------- 0 ---------- .000 ------------- .000 344.00 ----- 7179 18005 .138 .138 345.00 ----- 8334 23248 .178 .316 346.00 ----- 9550 26805 .205 .521 347.00 ----- 10822 30538 .234 .754 POND VOLUME EQUATIONS * Incremental volume computed by the Conic Method for Reservoir Volumes. Volume = (1/3) * (EL2-ELI) * (Areal + Areal + sq.rt.(Areal*Area2)) where: EL1, EL2 = Lower and upper elevations of the increment Areal,Area2 = Areas computed for EL1, EL2, respectively Volume = Incremental vol=e between EL1 and EL2 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP1 Outlets Page 6.01 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw REQUESTED POND WS ELEVATIONS: Min. Elev.= 342.00 ft Increment = .10 ft Max. Elev.= 347.00 ft OUTLET CONNECTIVITY ---> Forward Flow Only (UpStream to DnStream) <--- Reverse Flow Only (DnStream to Upstream) <---> Forward and Reverse Both Allowed Structure ----------------- No. ---- Outfall ------- El, ft --------- E2, ft --------- Inlet Box RO ---> CO 345.200 347.000 Orifice-Area Ol ---> CO 343.800 347.000 Culvert-Circular CO ---> TW 340.330 347.000 Orifice-Circular 00 ---> TW 342.000 347.000 TW SETUP, DS Channel SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP1 Outlets Page 6.02 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = RO Structure Type ------------ = Inlet Box ------ # of Openings ------------------ = 1 Invert Elev. = 345.20 ft Orifice Area = 36.0000 sq.ft Orifice Coeff. _ .600 Weir Length = 24.00 ft Weir Coeff. = 3.000 K, Reverse = 1.000 Mannings n = .0000 Kev,Charged Riser = .000 Weir Submergence = No Structure ID = 01 Structure Type = Orifice-Area ------------------------------------ # of Openings = 3 Invert Elev. = 343.80 ft Area = 2.0000 sq.ft Top of Orifice = 344.30 ft Datum Elev. = 344.05 ft Orifice Coeff. _ .600 S/N: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Outlet Input Data Name.... BMPl Outlets Page 6.03 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = CO Structure Type = Culvert-Circular ------------------ No. Barrels ----------- = 1 ------- Barrel Diameter = 4.5000 ft Upstream Invert = 340.33 ft Dnstream Invert = 340.00 ft Horiz. Length = 119.00 ft Barrel Length = 119.00 ft Barrel Slope = .00277 ft/ft OUTLET CONTROL DATA... Mannings n = .0130 Ke = .5000 Kb = .004209 Kr = .5000 HW Convergence = .001 (forward entrance loss) (per ft of full flow) (reverse entrance loss) +/- ft INLET CONTROL DATA... Equation form = 1 Inlet Control K = .0098 inlet Control M = 2.0000 Inlet Control c = .03980 Inlet Control Y = .6700 T1 ratio (HW/D) = 1.159 T2 ratio (HW/D) = 1.305 Slope Factor = -.500 Use unsubmerged inlet control Form 1 equ. below T1 elev. Use submerged inlet control Form 1 equ. above T2 elev. In transition zone between unsubmerged and submerged inlet control, interpolate between flows at T1 & T2... At T1 Elev = 345.54 ft ---> Flow = 118.08 cfs At T2 Elev = 346.20 ft ---> Flow = 134.95 cfs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP1 Outlets Page 6.04 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = 00 Structure Type = Orifice-Circular ------------------------------------ # of Openings = 1 Invert Elev. = 342.00 ft Diameter = .3330 ft Orifice Coeff. _ .600 Structure ID = TW Structure Type = TW SETUP, DS Channel ------------------------------------ FREE OUTFALL CONDITIONS SPECIFIED CONVERGENCE TOLERANCES... Maximum Iterations= 40 Min. TW tolerance = .01 ft Max. TW tolerance = .01 ft Min. HW tolerance = .01 ft Max. HW tolerance = .01 ft Min. Q tolerance = .00 cfs Max. Q tolerance = .00 cfs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP2 Outlets Page 6.05 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw REQUESTED POND WS ELEVATIONS: Min. Elev.= 365.00 ft Increment = .10 ft Max. Elev.= 372.00 ft OUTLET CONNECTIVITY ---> Forward Flow Only (UpStream to DnStream) <--- Reverse Flow Only (DnStream to UpStream) <---> Forward and Reverse Both Allowed Structure ----------------- No. ---- Outfall ------- El, ft --------- E2, ft --------- Inlet Box RO ---> CO 370.000 372.000 Orifice-Area 01 ---> CO 367.400 372.000 Culvert-Circular CO ---> TW 359.000 372.000 Orifice-Circular 00 ---> TW 365.000 372.000 TW SETUP, DS Channel SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 PM 3/24/2011 Type.... Outlet Input Data Name.... BMP2 Outlets Page 6.06 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = RO Structure Type --------- = Inlet Box --------- # of Openings ------------------ = 1 Invert Elev. = 370.00 ft Orifice Area = 36.0000 sq.ft Orifice Coeff. _ .600 Weir LengiLii = 24.00 fr Weir Coeff. = 3.000 K, Reverse = 1.000 Mannings n = .0000 Kev,Cnarged Riser = .000 Weir Submergence = No Structure ID = 01 Structure Type = Orifice-Area ------------------------------------ # of Openings = 1 'Invert Elev. = 367.40 ft Area = 2.0000 sq.ft Top of Orifice = 367.90 ft Datum Elev. = 367.65 ft Orifice Coeff. _ .600 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP2 Outlets Page 6.07 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = CO Structure Type ---- -- = Culvert-Circular ----------- -- - --------- -- No. Barrels - -- -- = 1 Barrel Diameter = 3.5000 ft Upstream Invert = 359.00 ft Dnstream Invert = 358.58 ft Horiz. Length = 63.50 ft Barrel Length = 63.50 ft Barrel Slope = .00661 ft/ft OUTLET CONTROL DATA... Mannings n = .0130 Ke = .5000 Kb = .^005885 Kr = .5000 HW Convergence = .001 (forward entrance loss) (per ft of full flow) (reverse entrance loss) +/- i=t INLET CONTROL DATA... Equation form = 1 Inlet Control K = .0098 Inlet Control M = 2.0000 Inlet Control c = .03980 Inlet Control Y = .6700 T1 ratio (HW/D) = 1.157 T2 ratio (HW/D) = 1.303 Slope Factor = -.500 Use unsubmerged inlet control Form 1 equ. below T1 elev. Use submerged inlet control Form 1 equ. above T2 elev. In transition zone between unsubmerged and submerged inlet control, interpolate between flows at T'1 & T2... At T1 E1ev = 363.05 ft ---> Flow = 63.00 cfs At T2 Elev = 363.56 ft ---> Flow = 72.00 cfs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP3 Outlets Page 6.09 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw REQUESTED POND WS ELEVATIONS: Min. Elev.= 381.00 ft Increment = .10 ft Max. Elev.= 386.00 ft OUTLET CONNECTIVITY ---> Forward Flow Only (Upstream to DnStream) <--- Reverse Flow Only (DnS*_ream to Upstream) <---> Forward and Reverse Both Allowed Structure No. Outfall ------- El, ft --------- E2, ft --------- ----------------- Inlet Box ---- RO ---> CO 384.250 386.000 Orifice-Area 01 ---> CO 382.800 3866.000 Culver*_-Circular CO ---> TW 376.000 386.000 Orifice-Circular 00 ---> TW 391.000 386.000 Weir-Rectangular WO ---> TW 383.800 386.000 TW SETUP, DS Channel SIN: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Outlet Input Data Name.... BMP3 Outlets Page 6.10 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\ Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = RO Structure Type ------------ = Inlet Box ------ # of Openings ------------------ = 1 Invert Elev. = 384.25 ft Orifice Area = 25.0000 sq.ft Orifice Coeff. _ .600 Weir Length = 20.00 ft Weir Coeff. = 3.300 K, Reverse = 1.000 Mannings n = .0000 Kev,Charged Riser = .000 Weir Submergence = No Structure ID = 01 Structure Type = Orifice-Area ------------------------------------ # of Openings = I Invert Elev. = 382.80 ft Area = 2.5000 sq.ft Top of Orifice = 383.80 ft Datum Elev. = 383.30 ft Orifice Coeff. _ .600 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027,00) 10.47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP3 Outlets Page 6.11 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = CO Structure Type - = Culvert-Circular ---------------- ------- ---------- No. Barrels -- = 1 Barrel Diameter = 3.0000 ft Upstream Invert = 376.00 ft Dnstream Invert = 372.00 ft Horiz. Length = 119.00 ft Barrel Length = 119.07 ft Barrel Slope = .03390 ft/ft OUTLET CONTROL DATA... Mannings n = .0130 Ke = .5000 Kb - .007225 Kr = .5000 HW Convergence = .001 (forward entrance loss) (per ft of full flow) (reverse entrance loss) +/- ft INLET CONTROL DATA... Equation fora-, _ Inlet Control K = .0098 Inlet Control M = 2.0000 Inlet Control c = .03980 Inlet Control Y = .6700 Tl ratio (HW/D) = 1.143 T2 ratio (HW/D) = 1.290 Slope Factor = -.500 Use unsubmerged inlet control Form 1 equ. below T1 elev. Use submerged inlet control Form 1 equ. above T2 elev. In transition zone between unsubmerged and submerged inlet control, interpolate between flows at T1 & T2... At Tl Elev = 379.43 ft ---> Flow = 42.85 cfs At T2 Elev = 379.87 fr ---> Flow = 45.97 cfs S/N: Bentley PondPack (10.00.027.00) 10:47 PM Bentley Systems, Inc. 3/24/2011 Type.... Outlet Input Data Name.... BMP3 Outlets Page 6.12 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = 00 Structure Type = Orifice-Circular ------------------------------------ # of Openings = 1 Invert Elev. = 381.00 ft Diameter = .1667 ft Orifice Coeff. _ .600 Structure ID Structure Type -------------- # of Openings Crest Elev. Weir Length Weir Coeff. WO Weir-Rectangular ---------------- 1 383.80 ft 33.00 ft 3.000000 Weir TW effects (Use adjustment equation) Structure ID = TW Structure Type = TW SETUP, DS Channel ------------------------------------ FREE OUTFALL CONDITIONS SPECIFIED CONVERGENCE TOLERANCES ... Maximum Iterations= 40 Min. TW tolerance = .01 ft Max. TW tolerance = .01 ft Min. HW tolerance = .O1 ft Max. HW tolerance = .01 ft Min. Q tolerance = .00 cfs Max. Q tolerance = .00 cfs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP4 Outlets Page 6.13 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw REQUESTED POND WS ELEVATIONS: Min. Elev.= 343.00 ft Increment = .10 ft Max. Elev.= 347.00 ft OUTLET CONNECTIVITY ---> Forward Flow Only (Upstream to DnStream) <--- Reverse Flow Only (DnStream to UpStream) <---> Forward and Reverse Both Allowed Structure ----------------- No. ---- Outfall ------- E1, ft --------- E2, ft --------- Inlet Box RO ---> CO 346.000 347.000 Orifice-Area 01 ---> CO 344.500 347.000 Culvert-Circular CO ---> TW 340.310 347.000 Orifice-Circular 00 ---> TW 343.000 347.000 TW SETUP, DS Channel SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP4 Outlets Page 6.14 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = RO Structure Type ------------ = Inlet Box ------ # of Openings ------------------ = 1 Invert Elev. = 346.00 ft Orifice Area = 16.0000 sq.ft Orifice Coeff. _ .600 Weir Length = 16.00 ft Weir Coeff. = 3.000 K, Reverse = 1.000 Mannings n = .0000 Kev,Charged Riser = .000 Weir Submergence = No Structure ID = 01 Structure Type = Orifice-Area ------------------------------------ # of Openings = 1 Invert Elev. = 344.50 ft Area = 2.5000 sq.ft Top of Orifice = 345.50 ft Datum Elev. = 345.00 ft Orifice Coeff. _ .600 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP4 Outlets Page 6.15 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = CO Structure Type ----------------- = Culvert-Circular ------------------- No. Barrels = 1 Barrel Diameter = 2.0000 ft Upstream Invert = 340.31 ft Dnstream Invert = 340.00 ft Horiz. Length = 66.00 ft Barrel Length = 66.00 ft Barrel Slope = .00470 ft/ft OUTLET CONTROL DATA... Mannings n = .0130 Ke = .5000 Kb = .012411 Kr = .5000 HW Convergence = .001 (forward entrance loss) (per ft of full flow) (reverse entrance loss) +/- ft INLET CONTROL DATA... Equati on form = 1 Inlet Control K = .0099 Inlet Control M = 2.0000 Inlet Control c = .03980 Inlet Control Y = .6700 T1 ratio (HW/D) = 1.138 T2 ratio (HW/D) = 1.304 Slope Factor = -.500 Use unsubmerged inlet control Form 1 equ. below T1 elev. Use submerged inlet control Form 1 equ. above T2 elev. in transition zone between unsubmerged and submerged inlet control, interpolate between flows at T1 & T2... At T1 E1ev = 342.63 ft ---> Flow = 15.55 cfs At T2 Elev = 342.92 ft ---> Flow = 17.77 cfs SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Outlet Input Data Name.... BMP4 Outlets Page 6.16 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw OUTLET STRUCTURE INPUT DATA Structure ID = 00 Structure Type = Orifice-Circular ------------------------------------ # of Openings = 1 Invert Elev. = 343.00 ft Diameter = .1667 ft Orifice Coeff. _ .600 Structure ID = TW Structure Type = TW SETUP, DS Channel ------------------------------------ FREE OUTFALL CONDITIONS SPECIFIED CONVERGENCE TOLERANCES Maximum Iterations= 40 Min. TW tolerance = .01 ft Max. TW tolerance = .01 ft Min. HW tolerance = .01 ft Max. HW tolerance = .01 ft Min. Q tolerance = .00 cfs Max. Q tolerance = .00 cfs SIN: Bentley Systems, Inc. Bentley PordPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.01 Name.... BMP 1 rile.... K:\10\10-0340\100349-Preston. - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work_pad.hyg - BMP 1 IN 10 Outflow HYG file = work pad.hyg - BMP 1 OUT 10 Pond Node Data = BMP 1 Pond Volume Data = BMP 1 Pond Outlet Data = BMPl Outlets No Infiltration INITIAL CONDITIONS Starting WS E1ev = 342.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage Area T_nfilt. Q Total 2S/t + 0 ft ------------- cfs ----------- ac-ft --------- ---- sq.ft -------- cfs ----------- cfs ----- cfs 342.00 .00 .000 34307 .00 ------- .00 ---------- .00 342.10 .02 .080 35062 .00 .02 38.56 342.20 .07 .161 35924 .00 .07 77.99 342.30 .14 .244 36593 .00 .14 118.23 342.40 .20 .329 37374 .00 .20 159.44 342.50 .24 .416 38162 .00 .24 201.45 342.60 .28 .504 38958 .00 .28 244.33 342.70 .31 .595 39761 .00 .31 288.09 342.80 .33 .687 40573 .00 .33 332.74 342.90 .36 .781 41394 of, .36 373.31 343.00 .38 .877 42222 .00 .38 424.78 343.10 .40 .974 42591 .00 .40 471.93 343.20 .43 1.072 42961 .00 .43 519.48 343.30 .45 1.171 43333 .00 .45 567.43 343.40 .47 1.271 43700" .0:, .47 615.81 343.50 .48 1.372 44081 .00 .48 664.60 343.60 .50 1.474 44458 .00 .50 713.81 343.70 .52 1.576 44837 .00 .52 763.44 343.80 .54 1.680 45216 .00 .54 813.47 343.90 3.44 1.784 45598 .00 3.44 866.83 S/N: Bentley Systems, Inc. Bentley PondPack 110.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.02 Name.... BMP 1 Ei-e.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\ Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-2reston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work_pad.hyg - BMP 1 IN 10 Outflow HYG file = work pad.hyg - BMP 1 OUT 10 Pond Node Data = BMP 1 Pond Volume Data = BMP 1 Pond Outlet Data = BMP1 Outlets No Infiltration 1NITIAL CONDITIONS Starting WS Elev = 342.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time incr ement = 0500 hrs Elevation Outflow Storage Area Infilt. Q Total 2S/t + 0 ft ------------- cfs ----------- ac-ft ------ sq.ft cfs cfs cfs 344.00 6.34 ---- 1.839 --- -------- 45981 ----------- .00 ------------ 6.34 ---------- 920.61 344.10 9.25 1.995 46357 .00 9.25 974.82 344.20 12.14 2.102 46734 .00 12.14 1029.43 344.30 15.04 2.210 47112 .00 15.04 1084.45 344.40 17.72 2.318 47492 .00 17.72 1139.69 344.50 20.02 2.428 47874 .00 20.02 1194.98 344.60 22.05 2.538 48257 .00 22.05 1250.42 344.70 23.97 2.649 48642 .00 23.97 1306.17 344.80 25.68 2.761 49028 .00 25.68 1362.13 344.90 27.34 2.874 49416 .0C 27.34 1418.48 345.00 23.85 2.988 498,015 .00 28.85 1475.13 345.10 30.23 3.103 50187 .00 311.28 1532.11 345.20 31.69 3.219 50571 .00 31.69 1589.50 345.30 35.30 3.335 50955 .00 35.30 1649.50 345.40 40.73 3.453 51342 .00 40.73 1711.76 345.50 47.35 3.571 51730 .00 47.35 1775.64 345.60 54.95 3.690 52119 GC 54.95 1840.95 345.70 63.34 3.810 52510 .00 63.34 1907.46 345.80 70.99 3.931 52902 .00 70.99 1973.66 345.90 78.12 4.053 53296 .00 78.12 2039.30 SIN: Bentley Systems, Inc. Bentley PondPack ;10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.03 Name.... BMP 1 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Pre3ton - Alston Pond\H-H\Pondpak\ Inflow HYG file = work pad.hyg - BMP 1 IN. 10 Outflow HYG file = work pad.hyg - BMP 1 OUT 10 Pond Node Data = BMP 1 Pond Volume Data = BMP 1 Pond Outlet Data = BMPi Outlets No Infiltration INITIAL CONDITIONS Starting WS Elev = 342.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow ft ----------- cfs 346.00 ------------ 85.76 346.10 93.81 346.20 102.19 346.30 110.78 346.40 119.48 346.50 128.17 346.60 136.61 346.70 144.04 346.80 149.06 346.90 151.35 347.00 153.40' Storage Area Infilt ac-ft ---------- sq.ft ---------- cfs -------- 4.17'0 53691 .00 4.300 54079 .00 4.424 54469 .00 4.550 54860 .00 4.676 55253 .00 4.803 55647 .00 4.932 56042 .00 5.061 56439 .00 5.191 56837 .00 5.322 57236 .00 5.453 57637 .00 Q Total 2S/t + O cfs ------------- cfs ---------- 85.76 2106.87 93.81 2174.81 102.19 2243.49 110.78 2312.81 119.48 2382.68 128.17 2452.99 136.61 2523.48 144.04 2593.40 149.06 2661.33 151.35 2727.01 153.46 2792.94 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.04 Name.... BMP 2 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work_pad.hyg - BMP 2 IN 10 Outflow HYG file = work pad.hyg - BMP 2 OUT 10 Pond Node Data = BMP 2 Pond Volume Data = BMP 2 Pond Outlet Data = BMP2 Outlets No Infiltration INITIAL CGNDITIONS Starting WS Elev = 365.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time increment = .0500 hrs Elevation Outflow Storage Area Infilt. Q Total 2S/t + 0 ft ------------- cfs ------------ ac-ft --------- --- sq.ft -- cfs cfs cfs 365.00 .00 .000 ------ 28282 ----------- .00 ------------ .00 ---------- .00 365.10 .02 .066 28967 .00 .02 31.82 365.20 .07 .133 29660 .00 .07 64.45 365.30 .14 .202 30361 .00 .14 97.85 365.40 .20 .272 31070 .00 .20 132.05 365.50 .24 .345 31788 .00 .24 167.01 365.60 .28 .418 32513 .00 .28 202.77 365.70 .31 .494 33247 .00 .31 239.33 365.80 .33 .571 33989 .00 .33 276.70 365.90 .36 .650 34740 .00 .366 314.91 366.00 .38 .731 35498 .00 .38 353.96 366.10 .41 .812 35755 .00 .41 393.57 366.20 .43 .895 366013 .00 .43 433.46 366.30 .45 .978 36272 .00 .45 473.63 366.40 .47 1.0661 36531 .00 .47 514.10 366.50 .48 1.145 36792 .00 .48 554.85 3666.60 .50 1.230 370-04 .00 .50 595.90 366.70 .52 1.316 37316 .00 .52 637.24 366.80 .54 1.401 37579 .00 .54 678.85 366.90 .55 1.488 37944 .00 .55 720.77 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.05 Name.... BMP 2 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work pad.hyg - BMP 2 IN 10 Outflow HYG file = work pad.hyg - BMP 2 OUT 10 Pond Node Data = BMP 2 Pond Volume Data = BMP 2 Pond Outlet Data = BMP2 Outlets No Infiltration INITIAL CONDITIONS Starting WS E1ev = 365.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment - .0500 hrs Elevation Outflow Storage Area ft ------------- cfs ----------- ac-ft ---------- sq.ft ---------- 367.00 .57 1.575 38109 367.10 .58 1.663 38351 367.20 .60 1.751 38593 367.30 .61 1.840 38837 367.40 .63 1.930 39081 367.50 1.60 2.020 39325 367.60 2.58 2.110 39571 367.70 3.56 2.201 39817 367.80 4.53 2.293 40064 367.90 5.51 2.385 40312 368.00 6.40 2.478 40561 368.10 7.18 2.571 40794 368.20 7.87 2.665 41027 368.30 8.51 2.760 41261 368.40 9.09 2.855 41495 368.50 9.63 2.950 41731 368.60 10.16 3.046 41967 368.70 10.64 3.143 42203 368.80 11.12 3.240 42440 368.90 11.57 3.338 42678 Infilt. Q Total 2S/t + 0 cfs --------- cfs ------------ cfs ---------- .00 .57 762.99 .00 .58 805.48 .00 .60 848.25 .00 .61 891.27 .00 .63 934.57 .00 1.60 979.11 .00 2.58 1023.92 .00 3.56 1069.00 .00 4.53 1114.35 .00 5.51 1159.98 .00 6.40 1205.80 .00 7.18 1251.78 .00 7.87 1297.93 .00 8.51 1344.28 .00 9.09 1390.83 .00 9.63 1437.62 .00 10.16 1484.64 .00 10.64 1531.89 .00 11.12 1579.38 .00 11.57 1627.12 SIN: Bentley PondPack (10.00.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Pond E-V-Q Table Page 7.06 Name.... BMP 2 File.... K:\10\10-0340\100349-Pre3ton - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work pad.hyg - BMP 2 IN 10 Outflow HYG file = work pad.hyg - BMP 2 OUT 10 Pond Node Data = BMP 2 Pond Volume Data = BMP 2 Pond Outlet Data = BMP2 Outlets No Infiltration INITIAL CONDITIONS Starting WS E1ev = 365.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage Area lnfilt. Q Total 2S/t + 0 ft ------------- cfs ------------ ac-ft - 6q.Lf- cfs cfs cfs 3'09.00 12.01 -------- 3.436 ----------- 42917 ----------- .00 ------------ 12.01 ---------- 1675.12 369.10 12.43 3.535 43149 .00 12.43 1723.36 369.20 12.82 3.634 43383 .00 12.82 1771.83 369.30 13.23 3.734 43616 .00 13.23 1820.55 369.40 13.60 3.835 43851 .00 13.60 19669.52 369.50 13.97 3.935 44086 .00 13.97 1918.75 369.60 14.33 4.037 44321 .00 14.33 1968.22 3669.70 14.68 4.139 44558 .00 14.68 2017.95 369.80 15.02 4.242 44794 .00 15.02 2067.92 369.90 15.35 4.345 45032 .00 15.35 2118.16 370.00 15.67 4.448 45270 .00 15.67 21668.65 370.10 18.28 4.553 45514 .0C 18.28 2221.69 370.20 22.75 4.657 45758 . 22.75 2276.87 370.31, 28.45 4.763 46003 .00 28.45 2333.54 370.40 35.15 4.868 466249 .00 35.15 2391.49 370.50 42.68 4.975 46495 .00 42.68 2450.55 370.60 50.97 5.082 46742 .OC 50.97 2510.65 370.70 59.97 5.190 46989 .00 59.97 2571.72 370.80 69.58 5.298 47238 .00 69.58 2633.667 370.90 79.83 5.406 47486 .00 79.83 2696.54 S/N: Bentley Systems, Inc. Bentley Por_dPack (10.00.027.00) 10:47 AM 3/24/2011 i • • • • Type.... Pond E-V-Q Table Page 7.07 Name.... BMP 2 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work _pad.hyg - BMP 2 IN 10 Outflow HYG file = work pad.hyg - BMP 2 OUT 10 Pond Node Data = BMP 2 Pond Volume Data = BMP 2 Pond Outlet Data = BMP2 Outlets No Infiltration INITIAL CONDITIONS Starting WS Elev = 365.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage Area Infiit. Q Total 2S/t + O ft ------------- cfs ------------ ac-ft ---- sq.ft cfs cfs cfs 371.00 90.64 ---- 5.516 ---- -------- 47736 ----------- .00 ------------ 90.64 ---------- 2760.25 371.10 101.97 5.626 47957 .00 101.97 2824.75 371.20 113.82 5.736 48178 .00 113.82 2890.01 371.30 125.38 5.847 48400 .00 125.38 2955.21 371.40 135.11 5.958 48622 .00 135.11 3018.85 371.50 144.47 6.070 48845 .00 144.47 3082.36 371.60 152.71 6.182 49,069 .00 152.71 3145.00 371.70 156.36 6.295 49292 .00 156.30' 3203.29 371.80 157.10 6.409 49517 .00 157.10 3258.92 371.90 157.85 6.523 497,42 .00 157.85 3314.82 372.00 158.60 6.637 499667 .00 158.60 3370.96 S/N: Bentley PondPack !10.00.027.00; 10:47 AM Bentley Systems, Inc. 3/24/2011 Type.... Pond E-V-Q Table Page 7.08 Name.... BMP 3 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work_pad.hyg - BMP 3 IN 10 Outflow HYG file = work pad.hyg - BMP 3 OUT 10 Pond Node Data = BMP 3 Pond Volume Data = BMP 3 Pond Outlet Data = BMP3 Outlets No Infiltration INITIAL CONDITIONS Starting WS E1ev = 391.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage Area Infilt. Q Total 2S/t + 0 ft ------------- cfs ----------- ac-ft ---------- sq.ft ----- cfs cfs cfs 381.00 .00 .000 ------ 12414 ----------- .00 ------------ .00 ---------- .00 381.10 .01 .029 12769 .00 .01 14.00 381.20 .04 .059 13129 .00 .04 28.41 381.30 .05 .089 13493 .00 .05 43.21 381.40 .06 .121 13863 .00 .066 58.42 381.50 .07 .153 14238 .00 .07 74.04 381.60 .08 .166 14618 .00 .08 90.08 381.70 .08 .220 15003 .00 .08 106.55 381.80 .09 .255 15392 .00 C9 123.43 381.90 .09 .291 15787 .00 .09 140.76 382.00 .10 .327 16187 .00 .10 158.53 32.10 11 .365 166327 .00 .11 176.660 32.20 .11 .402 16468 .00 .11 194.83 382.30 .12 .440 16609 .00 .12 213.20 382.40 .12 .479 16751 .0C .12 231.74 382.50 .12 .517 16893 .00 .12 250.44 382.60 .13 .556 17036 .00 .13 269.29 382.70 .13 .595 17180 .00 .13 288.31 382.80 .14 .635 17324 .00 .14 307.48 382.90 .99 .675 17469 .00 .99 327.66 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.09 Name.... BMP 3 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work_pad.hyg - BMP 3 IN 10 Outflow HYG file = work pad.hyg - BMP 3 OUT 10 Pond Node Data = BMP 3 Pond Volume Data = BMP 3 Pond Outlet Data = BMP3 Outlets No Infiltration INITIAL CONDITIONS Starting WS E1ev = 381.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time increment = .0500 hrs Elevation Outflow Storage Area Infilt. ft ------------ cfs ------------ ac-ft --------- ---- sq.ft -------- cfs --------- 383.00 1.85 .715 17614 .00 383.10 2.70 .756 17726 .00 383.20 3.56 .797 17839 .CO 383.30 4.41 .838 179,52 .00 383.40 5.27 .879 18065 .00 383.50 6.12 .921 18179 .00 383.60 6.98 .962 18293 .00 383.70 7.83 1.005 18408 .00 383.80 6.68 1.047 18522 .00 383.90 12.63 1.090 18637 .,,,. 384.CC 19.11 1.133 18753 .00 384.10 27.21 1.176 18868 .00 384.20 36.64 1.219 18983 .00 384.25 41.79 1.241 19041 .00 384.30 47.97 1.263 191,93 .CC 384.40 62.67 1.307 19215 .00 384.50 79.60 1.351 19332 .00 384.60 93.42 1.396 19448 .00 384.70 118.90 1.440 19566 .00 384.80 140.86 1.485 196683 .00 Q Total 2S/t - 0 cfs ----------- cfs -------- 1.85 -- 348.01 2.70 369.49 3.56 389.11 4.41 409.84 5.27 430.71 6.12 451.70 6.98 472.82 7.83 494.07 8.68 515.42 12.63 540.02 19.11 567.28 27.21 596.28 36.64 626.74 41.79 642.45 47.97 659.22 62.63 695.20 79.60 733.55 98.42 773.92 118.90 816.07 140.86 859.83 SIN Bentley PondPack (10.00.027.00) 10:47 ALM Bentley Systems, Inc. 3/24/2011 Type.... Pond E-V-Q Table Page 7.10 Name.... BMP 3 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work _pad.hyg - BMP 3 IN 10 Outflow HYG file = work pad.hyg - BMP 3 OUT 10 Pond Node Data = BMP 3 Pond Volume Data = BMP 3 Pond Outlet Data = BMP3 Outlets No Infiltration INITIAL CONDITIONS Starting WS Elev = 381.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time increment = .0500 hrs Elevation Outflow Storaae Area Infilt. Q Total 2S/t + 0 ft ------------- cfs ----------- ac-ft ---------- - sq.ft cfs cfs cfs 384.90 164.24 1.531 -- -------- 19801 ----------- .00 ------------ 164.24 ---------- 905.15 385.00 188.90 1.576 19919 .00 188.90 951.88 385.10 214.82 1.622 19931 .00 214.82 999.94 385.20 241.91 1.668 19944 .00 241.91 1049.18 385.30 267.83 1.714 19956 .00 267.83 1097.26 385.40 292.28 1.760 19969 .00 292.28 1143.89 385.50 316.15 1.805 19981 .00 316.15 1189.96 385.'00 337.25 1.851 19993 .00 337.25 1233.27 385.70 358.08 1.897 20006 .00 358.08 1276.33 385.80 379.46 1.943 200118 .00 379.46 1319.93 385.90 401.30' 1.989 20031 .00 401.36 1364.08 386.00 423.75 2.035 20043 .00 423.75 1408.74 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.11 Name.... BMP 4 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work pad.hyg - BMP 4 IN 10 Outflow HYG file = work pad.hyg - BMP 4 OUT 10 Pond Node Data = BMP 4 Pond Volume Data = BMP 4 Pond Outlet Data = BMP4 Outlets No Infiltration INITIAL CONDITIONS Starting WS Elev = 343.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow ft ----------- cfs --------- 343.00 .00 343.10 .01 343.20 .04 343.30 .05 343.40 .06 343.50 .07 343.60 .08 343.70 .08 343.60 .09 343.90 .09 344.00 .10 344.10 .11 344.20 .11 344.30 .12 344.40 .12 344.50 .13 344.'00 .98 344.70 1.84 344.80 2.70 344.90 3.54 Storage Area Infilt. Q Total 2S/t + O ac-ft ------------ sq.ft ------ cfs cfs cfs .000 ---- 4897 ----------- .00 ------------ .00 ---------- .00 .Oil 5106 .00 .01 5.57 .023 5319 .00 .04 11.38 .036 5536 .00 .05 17.43 .049 5758 .00 .06 23.71 .062 5984 .00 .07 30.24 .076 6214 .00 .08 37.03 .091 6449 .00 .08 44.07 .106 6688 .00 .09 51.37 .122 6931 .00 .09 58.94 .138 7179 .00 .10 66.79 .154 7291 .00 1i 74.83 .171 7403 .00 .11 83.00 .188 7516 .00 .12 91.29 .206 7631 on, .12 99.71 .223 7746 .00 .13 108.26 .241 7862 .00 .98 117.79 .260 7978 .00 1.84 127.44 .278 8096 .00 2.70 137.23 .297 8215 .00 3.54 147.14 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 Type.... Pond E-V-Q Table Page 7.12 Name.... BMP 4 File.... K:\10\10-0340\100349-Preston - Alston Pond\H-H\ Pondpak\Als ton Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work_pad.hyg - BMP 4 IN 10 Outflow HYG file = work pad.hyg - BMP 4 OUT 10 Pond Node Data = BMP 4 Pond Volume Data = BMP 4 Pond Outlet Data = BMP4 Outlets No Infiltration INITIAL CONDITIONS Starting WS Elev = 343.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time increment = .0500 hrs E'_evation Outflow Storage Area Infilt. Q Total 2S/t + O ft ------------- cfs ----------- ac-ft ---------- sq.ft ----------- cfs -- - cfs cfs 345.00 4.40 .316 8334 - ------- .00 ------------ 4.40 ---------- 157.19 345.10 5.26 .335 8452 .00 5.26 167.37 345.20 6.10 .354 8571 .00 6.10 177.68 345.30 6.96 .374 8690 .00 6.966 188.12 345.40 7.82 .394 8810 .00 7.82 198.70 345.50 8.67 .415 8932 .00 8.67 209.41 345.60 9.49 .435 9054 .00 9.49 220.22 345.70 10.23 .4566 9177 .00 10.23 231.09 345.80 10.94 .478 9300 .00 10.94 242.06 345.90 11.58 .499 9425 .00 11.58 253.11 346.00 12.22 .521 9550 .00 12.22 264.29 3466.11, 14.32 .543 96674 .00 14.32 277.0-7 346.20 17.66 .565 9798 .00 17.666 291.22 346.30 21.79 .588 9923 .00 21.79 306.31 346.4. 26.J7 .611 10049 .001 26..77 322.19 346.50 30.31 .6634 10176 .00 30.31 337.166 346.60 32.63 .658 10304 .00 32.63 350.87 346.70 34.62 .6681 10432 .00 34.62 364.37 3466.80 35.91 .705 10561 .00 35.91 377.32 34006.90 36.30 .730 10691 .00 306.30 389.52 S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Type.... Pond E-V-Q Table Page 7.13 Name.... BMP 4 File.... 1<.:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\Alston Pond BMPs.ppw LEVEL POOL ROUTING DATA HYG Dir = K:\10\10-0340\100349-Preston - Alston Pond\H-H\Pondpak\ Inflow HYG file = work pad.hyg - BMP 4 IN 10 Outflow HYG file = work pad.hyg - BMP 4 OUT 10 Pond Node Data = BMP 4 Pond Volume Data = BMP 4 Pond Outlet Data = BMP4 Outlets No Infiltration INITIAL CONDITIONS Starting WS Elev = 343.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage ft ----------- cfs ------------ ac-ft ------ 347.00 36.65 --- .754 Area Infilt sq.ft ------------ cfs -------- 10822 .00 Q Total 2S/t + 0 cfs cfs ----------------------- 36.65 401.82 SIN: Bentley PondPack (10.000.027.00) 10:47 AM Bentley Systems, Inc. 3/24/2011 Appendix A Index of Starting Page Numbers for ID Names ----- B ----- BMP 1... 5.01, 7.01 BMP 2... 5.02, 7.04 BMP 3... 5.03, 7.08 BMP 4... 5.04, 7.11 BMP1 Outlets... 6.01 BMP2 Outlets... 6.05 BMP3 Outlets... 6.09 BMP4 Outlets... 6.13 ----- D ----- DA 1... 3.01, 4.01 DA 2... 3.03, 4.02 DA 3... 3.05, 4.03 DA 4... 3.07, 4.04 ----- P ----- PRE-DEV AREA... 3.09, 4.05 ----- R ----- RDU NOAA 14 Desi... 2.01, 2.02 ----- U ----- UNTREATED... 3.11, 4.06 ----- w ----- Watershed... 1.01 A-1 SIN: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:47 AM 3/24/2011 • • • • • • • • • • • • • • • • • • • • • • • • S• • • • • r • • • • • • • • • • • DWQ SUPPLEMENTS Permit (to be provided by DWQ) . of W A TF9 , o? OG NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part Ill) must be printed, filled out and submitted along with all of the required information. Project name Alston Pond Contact person Alwyn V. Smith III, P.E. Phone number 919) 469-3340 Date 24-Mar-11 Drainage area number 1 Site Characteristics Drainage area 1,415,700 fe Impervious area, post-development 680,407 fe % impervious 48.06 % Design rainfall depth 1.0 in Storage Volume: Non-SA Waters Minimum volume required 56,930 ft3 OK Volume provided 73,486 ft3 OK, volume provided is equal to or in excess of volume required. Storage Volume: SA Waters 1.5" runoff volume ft3 Pre-development 1-yr, 24-hr runoff ft3 Post-development 1-yr, 24-hr runoff ft3 Minimum volume required ft3 Volume provided ft3 Peak Flow Calculations Is the pre/post control of the lyr 24hr storm peak flow required? y (Y or N) 1-yr, 24-hr rainfall depth 3.0 in Rational C, pre-development (unitless) Rational C, post-development (unitless) Rainfall intensity: )-yr, 24-hr storm in/hr Pre-development 1-yr, 24-hr peak flow 50.63 ft3/sec Post-development 1-yr, 24-hr peak flow 3.60 ft3/sec Pre/Post 1-yr, 24-hr peak flow control -47.03 ft3/sec Elevations Temporary pool elevation 343.80 fmsl Permanent pool elevation 342.00 fmsl SHWT elevation (approx. at the perm. pool elevation) fmsl Top of 1 Oft vegetated shelf elevation 342.50 fmsl Bottom of 1 Oft vegetated shelf elevation 341.50 fmsl Sediment cleanout, top elevation (bottom of pond) 338.00 fmsl Sediment cleanout, bottom elevation 337.00 fmsl Sediment storage provided 1.00 ft Is there additional volume stored above the state-required temp. pool? n (Y or N) Elevation of the top of the additional volume fmsl Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts I. & II. Design Summary, Page 1 of 2 • • • • • • • • • • • • • Permit No (to be provided by DWQ) Surface Areas Area, temporary pool 45,229 ftz Area REQUIRED, permanent pool 28,314 112 SA/DA ratio 2.00 (unitless) Area PROVIDED, permanent pool, Ap,--,,d 34,306 fe OK Area, bottom of 1 Oft vegetated shelf, Abot a df 28,442 e Area, sediment cleanout, top elevation (bottom of pond), Abot-pand 21,265 ft` Volumes Volume, temporary pool Volume, permanent pool, Vmmj)c Volume, forebay (sum of forebays if more than one forebay) Forebay % of permanent pool volume SAIDA Table Data Design TSS removal Coastal SA/DA Table Used? Mountain/Piedmont SAIDA Table Used? SAIDA ratio Average depth (used in SAIDA table): Calculation option 1 used? (See Figure 10-2b) Volume, permanent pool, Vpe, ;-, Area provided, permanent pool, Ap--" Average depth calculated Average depth used in SA/DA, d.„ (Round to nearest 0.5ft) Calculation option 2 used? (See Figure 10-2b) Area provided, permanent pool, Aao ,X).' Area, bottom of 1 Oft vegetated shelf, Abot_5h?j1 Area, sediment cleanout, top elevation (bottom of pond), Abot-P d "Depth" (distance b/w bottom of 1011 shelf and top of sediment) Average depth calculated Average depth used in SA/DA, d.„ (Round to nearest 0.511) Drawdown Calculations Drawdown through orifice? Diameter of orifice (if circular) Area of orifice (if-non-circular) Coefficient of discharge (CO) Driving head (Ho) Drawdown through weir? Weir type Coefficient of discharge (C.) Length of weir (L) Driving head (H) Pre-development 1-yr, 24-hr peak flow Post-development 1-yr, 24-hr peak flow Storage volume discharge rate (through discharge orifice or weir) Storage volume drawdown time Additional Information Vegetated side slopes Vegetated shelf slope Vegetated shelf width Length of flowpath to width ratio Length to width ratio Trash rack for overflow & orifice? Freeboard provided Vegetated filter provided? Recorded drainage easement provided? Capures all runoff at ultimate build-out? Drain mechanism for maintenance or emergencies is: Forth SW401-Wet Detention Basin-Rev.8-9/17/09 73,486 ft3 OK 104,707 ft3 21,426 ft3 20.5% % OK 85 % n (Y or N) y (Y or N) 2.00 (unitless) n (Y or N) 104,707 ft3 34,306 ft` ft Need 3 ft min. ft y (Y or N) 34,306 ft` 28,442 ft? 21,265 fe 3.50 It 3.95 ft OK 4.0 ft OK y (Y or N) 4.00 in in' 0.60 (unitless) 0.60 ft n (Y or N) 0.3 (unifless) 0.6 (unibess) ft ft 50.63 ft3/sec 3.60 ft3/sec 0.54 ft3/sec 2.60 days OK, draws down in 2-5 days. 3 :1 OK 10 :1 OK 10.0 ft OK 4 :1 OK 4.0 :1 OK y (Y or N) OK 1.0 ft OK y (Y or N) OK y (Y or N) OK y (Y or N) OK Pump required Parts 1. & II. Design Summary, Page 2 of 2 Permit (to be provided by DWQ) (!L. REQUIRENTEMS CHECKLIST Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay finial review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Initials -k< t 'i S w„N1 rat 1, ? 7 -- ? Plans (1" - 50' or larger) of the entire site showing: - Design at ultimate build-out, - Off-site drainage (if applicable), - Delineated drainage basins (include Rational C coefficient per basin), - Basin dimensions, - Pretreatment system, - High flow bypass system, - Maintenance access, - Proposed drainage easement and public right of way (ROW), - Overflow device, and - Boundaries of drainage easement. Pagel Plan Sheet No. I -- U0 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, - Forebay and main pond with hardened emergency spillway, - Basin cross-section, - Vegetation specification for planting shelf, and - Filter strip. -7 - 9 3. Section view of the wet detention basin (1" = 20' or larger) showing: - Side slopes, 3:1 or lower, - Pretreatment and treatment areas, and - Inlet and outlet structures. 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified on the plans prior to use as a wet detention basin. 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. 7. The supporting calculations. 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. 9. A copy of the deed restrictions (if required). t S t R0`u 6? 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County soil maps are not an acceptable source of soils information. Form SW401-Wet Detention Basin-Rev.8-9/17/09 Part III. Required Items Checklist, Page 1 of 1 Permit NCDENR Project name Contact person Phone number Date Drainage area number (to be provided by DWQ) O?oF W ATE9OG 7 ti a?< Alwyn V. Smith III, P.E. 919) 469-3340 24-Mar-11 2 Site Characteristics Drainage area 1,589,940 fe Impervious area, post-development 816,750 ff % impervious 51.37 % Design rainfall depth 1.0 in Storage Volume: Non-SA Waters Minimum volume required Volume provided Storage Volume: SA Waters 1.5" runoff volume Pre-development 1-yr, 24-hr runoff Post-development 1-yr, 24-hr runoff Minimum volume required Volume provided Peak Flow Calculations Is the pre/post control of the lyr 24hr storm peak flow required? 1-yr, 24-hr rainfall depth Rational C, pre-development Rational C, post-development Rainfall intensity: 1-yr, 24-hr storm Pre-development 1-yr, 24-hr peak flow Post-development 1-yr, 24-hr peak flow Pre/Post 1-yr, 24-hr peak flow control Elevations Temporary pool elevation Permanent pool elevation SHWT elevation (approx. at the pens. pool elevation) Top of 1 Oft vegetated shelf elevation Bottom of 1 Oft vegetated shelf elevation Sediment cleanout, top elevation (bottom of pond) Sediment cleanout, bottom elevation Sediment storage provided Is there additional volume stored above the state-required temp. pool? Elevation of the top of the additional volume Form SW401-Wet Detention Basin-Rev.8-9/17/09 STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information. Alston Pond 67,881 ft3 OK 84,332 ft3 OK, volume provided is equal to or in excess of volume required. ft3 ft3 ft3 ft3 ft3 y (Y or N) 3.0 in (unitless) (unitless) in/hr 62.72 ft3/sec 3.43 ft3/sec -59.29 ft3/sec 367.40 fmsl 365.00 fmsl fmsl 365.50 fmsl 364.50 fmsl 360.00 fmsl 359.00 fmsl 1.00 It n (Y or N) fmsl Parts I. & II. Design Summary, Page 1 of 2 Permit (to be provided by DWQ) Surface Areas Area, temporary pool 39,090 ft' Area REQUIRED, permanent pool 28,142 ft' SA/DA ratio 1.77 (unitless) Area PROVIDED, permanent pool, Ap,,,,_pw 28,282 ft2 OK Area, bottom of 1 Oft vegetated shelf, kt s1eif 23,027 ff Area, sediment cleanout, top elevation (bottom of pond), Abot wd 13,943 ft2 Volumes Volume, temporary pool 84,332 ft3 OK Volume, permanent pool, Vpen -pW 94,500 ft3 Volume, forebay (sum of forebays if more than one forebay) 18,703 ft3 Forebay % of permanent pool volume 19.8% % OK SA/DA Table Data Design TSS removal 85 % Coastal SA/DA Table Used? n (Y or N) Mountain/Piedmont SA/DA Table Used? y (Y or N) SA/DA ratio 1.77 (unitless) Average depth (used in SA/DA table): Calculation option 1 used? (See Figure 10-2b) n (Y or N) Volume, permanent pool, Vpem,yoo, 94,500 ft' Area provided, permanent pool, Apem,-Pcd 28,282 ff Average depth calculated It Need 3 ft min. Average depth used in SA/DA, day, (Round to nearest 0.5ft) ft Calculation option 2 used? (See Figure 10-2b) y (Y or N) Area provided, permanent pool, Apermyod 28,282 ff Area, bottom of 1Oft vegetated shelf, Abut ?,e,f 23,027 ff Area, sediment cleanout, top elevation (bottom of pond), Abot-pond 13,943 ft2 "Depth" (distance b/w bottom of 1Oft shelf and top of sediment) 4.50 ft Average depth calculated 4.22 ft OK Average depth used in SA/DA, day, (Round to nearest 0.5ft) 4.0 ft OK Drawdown Calculations Drawdown through orifice? y (Y or N) Diameter of orifice (if circular) 4.00 in Area of orifice (if-non-circular) in2 Coefficient of discharge (Cc) 0.60 (unitless) Driving head (Ho) 0.47 ft Drawdown through weir9 n (Y or N) Weir type (unitless) Coefficient of discharge (CW) (unitless) Length of weir (L) It Driving head (H) It Pre-development 1-yr, 24-hr peak flow 62.72 ft3/sec Post-development 1-yr, 24-hr peak flow 3.43 ft3/sec Storage volume discharge rate (through discharge orifice or weir) 0.63 ft3/sec Storage volume drawdown time 3.40 days OK, draws down in 2-5 days. Additional Information Vegetated side slopes 3 :1 OK Vegetated shelf slope 10 :1 OK Vegetated shelf width 10.0 It OK Length of flowpath to width ratio 3 :1 OK Length to width ratio 3.0 :1 OK Trash rack for overflow & orifice? y (Y or N) OK Freeboard provided 1.0 ft OK Vegetated filter provided? y (Y or N) OK Recorded drainage easement provided? y (Y or N) OK Capures all runoff at ultimate build-out? y (Y or N) OK Drain mechanism for maintenance or emergencies is: Gate valve Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts L & H. Design Summary, Page 2 of 2 Permit No (to be provided by DWQ) 11111-REQUIRED ITEMS CHECKLIST Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Page/ Plan Initials Sheet No. M(,-, -7-5 1. Plans (1" - 50' or larger) of the entire site showing: - Design at ultimate build-out, - Off-site drainage (if applicable), - Delineated drainage basins (include Rational C coefficient per basin), - Basin dimensions, - Pretreatment system, - High flow bypass system, - Maintenance access, - Proposed drainage easement and public right of way (ROM, - Overflow device, and - Boundaries of drainage easement. 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, - Forebay and main pond with hardened emergency spillway, - Basin cross-section, - Vegetation specification for planting shelf, and - Filter strip. - 3. Section view of the wet detention basin (1" = 20' or larger) showing: - Side slopes, 3:1 or lower, - Pretreatment and treatment areas, and c, - Inlet and outlet structures. r? G 4 - 1 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified S J „? on the plans prior to use as a wet detention basin. t/ fRE ?T 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. ^l K - 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. 1? "J C6 I< ;KC PoKT 7. The supporting calculations. i2 la ? kcv,Q ? 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. 9. A copy of the deed restrictions (if required). h! t 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County soil maps are not an acceptable source of soils information. Form SW401-Wet Detention Basin-Rev.8-9/17/09 Part III. Required Items Checklist, Page 1 of 1 Permit ??1 NCDENR Project name Contact person Phone number Date Drainage area number (to be provided by DWQ) O?pF W ATFRQG Alwyn V. Smith III, P.E. 919) 469-3340 22-Mar-11 3 tea„ _ x. 1 - f V 4 5'. r 'Y U.: I =14^hi Gtif Site Characteristics Drainage area 696,960 fe Impervious area, post-development 271,814 fe % impervious 39.00 % Design rainfall depth 1.0 in Storage Volume: Non-SA Waters Minimum volume required Volume provided Storage Volume: SA Waters 1.5" runoff volume Pre-development 1-yr, 24-hr runoff Post-development 1-yr, 24-hr runoff Minimum volume required Volume provided Peak Flow Calculations Is the pre/post control of the lyr 24hr storm peak flow required? 1-yr, 24-hr rainfall depth Rational C, pre-development Rational C, post-development Rainfall intensity: 1-yr, 24-hr storm Pre-development 1-yr, 24-hr peak flow Post-development 1-yr, 24-hr peak flow Pre/Post 1-yr, 24-hr peak flow control Elevations Temporary pool elevation Permanent pool elevation SHWT elevation (approx. at the perm. pool elevation) Top of 1 Oft vegetated shelf elevation Bottom of 1 Oft vegetated shelf elevation Sediment cleanout, top elevation (bottom of pond) Sediment cleanout, bottom elevation Sediment storage provided Is there additional volume stored above the state-required temp. pool? Elevation of the top of the additional volume STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part Ill) must be printed, filled out and submitted along with all of the required information. Alston Pond 23,290 ft3 OK 27,791 ft3 OK, volume provided is equal to or in excess of volume required. ft3 ft3 ft3 ft3 ft3 y (Y or N) 3.0 in (unifless) (unitless) in/hr 22.76 ft3/sec 1.35 ft3/sec -21.41 ft3/sec 382.80 fmsl 381.00 fmsl fmsl 381.50 fmsl 380.50 fmsl 377.00 fmsl 376.00 fmsl 1.00 it n (Y or N) fmsl Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts I. & II. Design Summary, Page 1 of 2 Permit (to be provided by DWQ) "6'y'? fir; ,'. Surface Areas Area, temporary,pool 17,329 ftz Area REQUIRED, permanent pool 11,779 It' SAIDA ratio 1.69 (unitless) Area PROVIDED, permanent pool, Ape,,,, 12,414 fC OK Area, bottom of 1Oft vegetated shelf, Abot shelf 9,710 ft` Area, sediment cleanout, top elevation (bottom of pond), Abot-pond 5,979 If Volumes Volume, temporary pool 27,791 ft3 OK Volume, permanent pool, Vpe._pw 33,021 ft3 Volume, forebay (sum of forebays if more than one forebay) 6,735 ft3 Forebay % of permanent pool volume 20.4% % OK SAIDA Table Data Design TSS removal 85 % Coastal SAIDA Table Used? n (Y or N) Mountain/Piedmont SAIDA Table Used? y (Y or N) SAIDA ratio 1.69 (unitless) Average depth (used in SAIDA table): Calculation option 1 used? (See Figure 10-2b) n (Y or N) Volume, permanent pool, Vpe--" 33,021 ft' Area provided, permanent pool, Ape._,,d 12,414 ft` Average depth calculated ft Need 3 ft min. Average depth used in SAIDA, d.„ (Round to nearest 0.5ft) It Calculation option 2 used? (See Figure 10-2b) y (Y or N) Area provided, permanent pool, Ape,,,,-" 12,414 fe Area, bottom of 1Oft vegetated shelf, Amt she# 9,710 ft` Area, sediment cleanout, top elevation (bottom of pond), Aeotpwd 5,979 ft2 "Depth" (distance b/w bottom of 1Oft shelf and top of sediment) 3.50 It Average depth calculated 3.68 ft OK Average depth used in SAIDA, d.„ (Round to nearest 0.5ft) 3.1 it Insufficient. Check calculation. Drawdown Calculations Drawdown through orifice? y (Y or N) Diameter of orifice (if circular) 2.00 in Area of orifice (if-non-circular) in' Coefficient of discharge (Cc) 0.60 (unitless) Driving head (Ho) 0.60 it Drawdown through weir? n (Y or N) Weir type (unitless) Coefficient of discharge (C,,,) (unifless) Length of weir (L) ft Driving head (H) ft Pre-development 1-yr, 24-hr peak flow 22.76 ft3/sec Post-development 1-yr, 24-hr peak flow 1.35 ft3/sec Storage volume discharge rate (through discharge orifice or weir) 0.14 ft3/sec Storage volume drawdown time 3.75 days OK, draws down in 2-5 days. Additional Information Vegetated side slopes 3 :1 OK Vegetated shelf slope 10 :1 OK Vegetated shelf width 10.0 ft OK Length of flowpath to width ratio 4 :1 OK Length to width ratio 5.0 :1 OK Trash rack for overflow & orifice? y (Y or N) OK Freeboard provided 1.0 ft OK Vegetated filter provided? y (Y or N) OK Recorded drainage easement provided? y (Y or N) OK Capures all runoff at ultimate build-out? y (Y or N) OK Drain mechanism for maintenance or emergencies is: gate valve Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts I. & II. Design Summary, Page 2 of 2 Permit No. (to be provided by DWQ) III. REQUIRED ITEMS CHECKLIST Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Page/ Plan Initials Sheet No. tt 1 -U ' Ce? Plans (1" - 50' or larger) of the entire site showing: - Design at ultimate build-out, - Off-site drainage (if applicable), - Delineated drainage basins (include Rational C coefficient per basin), - Basin dimensions, - Pretreatment system, - High flow bypass system, - Maintenance access, - Proposed drainage easement and public right of way (ROIL, - Overflow device, and - Boundaries of drainage easement. 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, - Forebay and main pond with hardened emergency spillway, - Basin cross-section, - Vegetation specification for planting shelf, and - Filter strip. ? 3. Section view of the wet detention basin (1" = 20' or larger) showing: - Side slopes, 3:1 or lower, - Pretreatment and treatment areas, and - Inlet and outlet structures. ' - 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified on the plans prior to use as a wet detention basin. 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. iv K -7 - ?t 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. tj w >r 1 l? i eP0R"'r 7. The supporting calculations. 'T1L.? <cv o) 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. f71 t <' 9. A copy of the deed restrictions (if required). 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County soil maps are not an acceptable source of soils information. Form SW401-Wet Detention Basin-Rev.8-9/17/09 Part lll. Required Items Checklist, Page 1 of 1 Permit No. (to be provided by DWQ) 015% OF W ATF9 A E1 O? QG NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part Ill) must be printed, filled out and submitted along with all of the required information. f Project name Alston Pond Contact person Alwyn V. Smith III, P.E. Phone number 919) 469-3340 Date 24-Mar-11 Drainage area number 4 Site Characteristics Drainage area 261,360 fe Impervious area, post-development 113,256 ft % impervious 43.33 % Design rainfall depth TO in Storage Volume: Non-SA Waters Minimum volume required 9,584 ft3 OK Volume provided 9,888 ft3 OK, volume provided is equal to or in excess of volume required. Storage Volume: SA Waters 1.5" runoff volume ft3 Pre-development 1-yr, 24-hr runoff ft3 Post-development 1-yr, 24-hr runoff ft3 Minimum volume required ft3 Volume provided ft3 Peak Flow Calculations Is the pre/post control of the 1 yr 24hr storm peak flow required? y (Y or N) 1-yr, 24-hr rainfall depth 3.0 in Rational C, pre-development (unitless) Rational C, post-development (unitless) Rainfall intensity: 1-yr, 24-hr storm in/hr Pre-development 1-yr, 24-hr peak flow 10.44 ft3/sec Post-development 1-yr, 24-hr peak flow 1.12 ft3/sec Pre/Post 1-yr, 24-hr peak flow control -9.32 ft3/sec Elevations Temporary pool elevation 344.50 fmsl Permanent pool elevation 343.00 fmsl SHWT elevation (approx. at the perm. pool elevation) fmsl Top of 1 Oft vegetated shelf elevation 343.50 fmsl Bottom of 1 Oft vegetated shelf elevation 342.50 fmsl Sediment cleanout, top elevation (bottom of pond) 339.00 fmsl Sediment cleanout, bottom elevation 338.00 fmsl Sediment storage provided 1.00 It Is there additional volume stored above the state-required temp. pool? n (Y or N) Elevation of the top of the additional volume fmsl Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts 1.8 II. Design Summary, Page 1 of 2 Permit (to be provided by DWQ) 47 - Surface Areas Area, temporary pool 7,756 ftz Area REQUIRED, permanent pool 4,809 ft SAIDA ratio 1.84 (unitless) Area PROVIDED, permanent pool, APL--" 4,897 ft` OK Area, bottom of 1 Oft vegetated shelf, Abot she 3,346 ft' Area, sediment cleanout, top elevation (bottom of pond), kt?o,d 1,418 ff Volumes Volume, temporary pool Volume, permanent pool, Vim,,,,,., Volume, forebay (sum of forebays if more than one forebay) Forebay % of permanent pool volume SAIDA Table Data Design TSS removal Coastal SAIDA Table Used? Mountain/Piedmont SAIDA Table Used? SAIDA ratio Average depth (used in SAIDA table): Calculation option 1 used? (See Figure 10-2b) Volume, permanent pool, Vp._P. Area provided, permanent pool, Aper,„-pod Average depth calculated Average depth used in SAIDA, d.„ (Round to nearest 0.5ft) Calculation option 2 used? (See Figure 10-2b) Area provided, permanent pool, AL ,,Ocg Area, bottom of 1 Oft vegetated shelf, AW shelf Area, sediment cleanout, top elevation (bottom of pond), Amt-d "Depth" (distance b/w bottom of 1Oft shelf and top of sediment) Average depth calculated Average depth used in SAIDA, d., (Round to nearest 0.5ft) Drawdown Calculations Drawdown through orifice? Diameter of orifice (if circular) Area of orifice (if-non-circular) Coefficient of discharge (CD) Driving head (Ho) Drawdown through weir? Weir type Coefficient of discharge (C„,) Length of weir (L) Driving head (H) Pre-development 1-yr, 24-hr peak flow Post-development 1-yr, 24-hr peak flow Storage volume discharge rate (through discharge orifice or weir) Storage volume drawdown time Additional Information Vegetated side slopes Vegetated shelf slope Vegetated shelf width Length of flowpath to width ratio Length to width ratio Trash rack for overflow & orifice? Freeboard provided Vegetated filter provided? Recorded drainage easement provided? Capures all runoff at ultimate build-out? Drain mechanism for maintenance or emergencies is: 9,888 ft3 OK 10,290 ft3 1,922 ft3 18.7% % OK 85 % n (Y or N) y (Y or N) 1.84 (unitless) n (Y or N) 10,290 ff3 4,897 ff It Need 3 It min. It y (Y or N) 4,897 ff 3,346 ff 1,418 ft 3.50 ft 3.27 ft OK 3.0 ft Insufficient. Check calculation. y (Y or N) 2.00 in inz 0.60 (unitless) 0.50 ft n (Y or N) (unitless) (unitless) It It 10.44 ft3/sec 1.12 ft3/sec 0.13 ft3/sec 2.00 days OK, draws down in 2-5 days. 3 :1 OK 10 :1 OK 10.0 ft OK 3 :1 OK 3.0 :1 OK y (Y or N) OK 1.0 It OK y (Y or N) OK y (Y or N) OK y (Y or N) OK pump required Form SW401-Wet Detention Basin-Rev.8-9117!09 Parts I. & II. Design Summary, Page 2 of 2 Permit No. (to be provided by DWQ) Ill. REQUIRED 1TEMS'CHECKLIST Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Page/ Plan Initials Sheet No. -#A t,< I - Co (s -?-5 Plans (1" - 50' or larger) of the entire site showing: - Design at ultimate build-out, - Off-site drainage (if applicable), - Delineated drainage basins (include Rational C coefficient per basin), - Basin dimensions, - Pretreatment system, - High flow bypass system, - Maintenance access, - Proposed drainage easement and public right of way (ROW), - Overflow device, and - Boundaries of drainage easement. 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, - Forebay and main pond with hardened emergency spillway, - Basin cross-section, - Vegetation specification for planting shelf, and - Filter strip. ^f! 1 3. Section view of the wet detention basin (1" = 20' or larger) showing: - Side slopes, 3:1 or lower, - Pretreatment and treatment areas, and c, - Inlet and outlet structures. v _ 1 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified S w v? on the plans prior to use as a wet detention basin. t/ j'\co 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. C? 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. 5 w +'" ?r11?? 1? `?"r 7. The supporting calculations. 12LC ?Pc j IQ 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. N ? 9. A copy of the deed restrictions (if required). e L xeo' aD 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County soil maps are not an acceptable source of soils information. Form SW401-Wet Detention Basin-Rev.8-9/17/09 Part III. Required Items Checklist, Page 1 of 1 ARA NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM LEVEL SPREADER - VEGETATED FILTER STRIP (LS-VFS) SUPPLEMENT This form must be completely filled out, printed, initialed, and submitted. o?oF warEROc o ? Project name Contact name Phone number Date Drainage area number Alston Pond Alwyn V. Smith III, P.E. 919469-3340 March 24, 2011 BMP #2 The purpose of the LS-VFS Buffer Rule: Diffuse Flow Stormwater enters LS-VFS from A BMP Type of VFS Engineered filter strip (graded & sodded, slope < 8%) Explanation of any "Other" responses above If Stormwater Enters the LS-VFS from the Drainage Area Drainage area ft2 Do not complete this section of the form. Impervious surface area fe Do not complete this section of the form. Percent impervious % Do not complete this section of the form. Rational C coefficient Do not complete this section of the form. Peak flow from the 1 in/hr storm cfs Do not complete this section of the form. Time of concentration min Do not complete this section of the form. Rainfall intensity, 10-yr storm in/hr Do not complete this section of the form. Peak flow from the 10-yr storm cfs Do not complete this section of the form. Design storm Pick one: Maximum amount of flow directed to the LS-VFS cfs Do not complete this section of the form. Is a flow bypass system going to be used? (Y or N) Do not complete this section of the form. Explanation of any "Other" responses above If Stormwater Enters the LS-VFS from a BMP Type of BMP Wet detention pond Peak discharge from the BMP during the design storm 0.63 cfs Peak discharge from the BMP during the 10-year storm cfs Maximum capacity of a 100-foot long LS-VFS 10 cfs Peak flow directed to the LS-VFS 0.63 cfs Is a flow bypass system going to be used? y (Y or N) Explanation of any "Other" responses above LS-VFS Design Forebay surface area sq ft Depth of forebay at stormwater entry point in Depth of forebay at stormwater exit point 6 in Depth is appropriate. Feet of level lip needed per cfs 10 ft/cfs Computed minimum length of the level lip needed 6 ft Ten feet is the minimum level spreader length. Length of level lip provided 10 ft Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 1 of 3 Width of VFS Elevation at downslope base of level lip Elevation at the end of the VFS that is farthest from the LS Slope (from level lip to the end of the VFS) Are any draws present in the VFS? Is there a collector swale at the end of the VFS? Bypass System Design (if applicable) Is a bypass system provided? Is there an engineered flow splitting device? Dimensions of the channel (see diagram below): M B W y (flow depth for 10-year storm) freeboard (during the 10-year storm) Peak velocity in the channel during the 10-yr storm Channel lining material Does the bypass discharge through a wetland? Does the channel enter the stream at an angle? Explanation of any "Other" responses above 30 ft 360.40 fmsl 358.90 fmsl 5.00 % N (Y or N) OK N (Y or N) Y (Y or N) Y (Y or N) Please provide plan details of flow splitter & supporting calcs. 2.00 ft 4.00 ft 12.00 ft 0.85 ft 1.15 ft 3.84 fUsec Pick one: ' Y Q N (Y or N) Y (Y or N) Rip Rap Lined !\ 0100" ", aw Ooftfty EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Requried Item: 1. Plans (1" - 50' or larger) of the entire site showing: - Design at ultimate build-out, Off-site drainage (if applicable), Delineated drainage basins (include Rational C coefficient per basin), Forebay (if applicable), High flow bypass system, Maintenance access, Proposed drainage easement and public right of way (ROW), and Boundaries of drainage easement. le or plan sheet number and any notes: Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 2 of 3 2. Plan details (1" = 30' or larger) for the level spreader showing: - Forebay (if applicable), High flow bypass system, One foot topo lines between the level lip and top of stream bank, Proposed drainage easement, and Design at ultimate build-out. 3. Section view of the level spreader (1" = 20' or larger) showing: - Underdrain system (if applicable), Level lip, Upslope channel, and Downslope filter fabric. 4. Plan details of the flow splitting device and supporting calculations (if applicable). 5. A construction sequence that shows how the level spreader will be protected from y sediment until the entire drainage area is stabilized. 6. If a non-engineered VFS is being used, then provide a photograph of the VFS showing that no draws are present. 7. The supporting calculations. UJ 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. A15 Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 3 of 3 A? YS NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM LEVEL SPREADER - VEGETATED FILTER STRIP (LS-VFS) SUPPLEMENT This form must be completely filled out, printed, initialed, and submitted. Project name Contact name Phone number Date Drainage area number The purpose of the LS-VFS Stormwater enters LS-VFS from Type of VFS Explanation of any "Other" responses above If Stormwater Enters the LS-VFS from the Drainage Area Drainage area Impervious surface area Percent impervious Rational C coefficient Peak flow from the 1 in/hr storm Time of concentration Rainfall intensity, 10-yr storm Peak flow from the 10-yr storm Design storm Maximum amount of flow directed to the LS-VFS Is a flow bypass system going to be used? Explanation of any "Other" responses above If Stormwater Enters the LS-VFS from a BMP Type of BMP Peak discharge from the BMP during the design storm Peak discharge from the BMP during the 10-year storm Maximum capacity of a 100-foot long LS-VFS Peak flow directed to the LS-VFS Is a flow bypass system going to be used? Explanation of any "Other" responses above LS-VFS Design Forebay surface area Depth of forebay at stormwater entry point Depth of forebay at stormwater exit point Feet of level lip needed per cfs Computed minimum length of the level lip needed Length of level lip provided o?0 W A?r 9??c O liii? < Alston Pond Alwyn V. Smith III, P.E. 919-469-3340 January 25, 2011 BMP #4 Buffer Rule: Diffuse Flow A BMP Engineered filter strip (graded & sodded, slope < 8%) ft ft2 % cfs min in/hr cfs Pick one: Do not complete this section of the form. Do not complete this section of the form. Do not complete this section of the form. Do not complete this section of the form. Do not complete this section of the form, Do not complete this section of the form. Do not complete this section of the form. Do not complete this section of the form. cfs (Y or N) Do not complete this section of the form. Do not complete this section of the form. Wet detention pond 0.13 cfs cfs 10 cfs 0.13 cfs y (Y or N) sq ft in 6 in Depth is appropriate. 10 ft/cfs 1 ft Ten feet is the minimum level spreader length. 10 ft Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 1 of 3 Width of VFS Elevation at downslope base of level lip Elevation at the end of the VFS that is farthest from the LS Slope (from level lip to the end of the VFS) Are any draws present in the VFS? Is there a collector swale at the end of the VFS? Bypass System Design (if applicable) Is a bypass system provided? Is there an engineered flow splitting device? Dimensions of the channel (see diagram below): M B W y (flow depth for 10-year storm) freeboard (during the 10-year storm) Peak velocity in the channel during the 10-yr storm Channel lining material Does the bypass discharge through a wetland? Does the channel enter the stream at an angle? Explanation of any "Other" responses above 30 ft 341.50 fmsl 340.00 fmsl 5.00 % N (Y or N) OK N (Y or N) Y (Y or N) Y (Y or N) Please provide plan details of flow splitter & supporting calcs. ft ft ft ft ft Pick one: .'?c /j% X %";, Y (Y r N) edesign channel to discharge to a dissipator pad adjacent to tl (Y or N) Channel is rirp rap lined. Channel enters along wetland edge as stated in the above cell E EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Requried Item: 1. Plans (1" - 50' or larger) of the entire site showing: Design at ultimate build-out, Off-site drainage (if applicable), Delineated drainage basins (include Rational C coefficient per basin), Forebay (if applicable), High flow bypass system, Maintenance access, Proposed drainage easement and public right of way (ROW), and Boundaries of drainage easement. Initials Page or plan sheet number and any notes: G Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 2 of 3 2. Plan details (1" = 30' or larger) for the level spreader showing: - Forebay (if applicable), High flow bypass system, One foot topo lines between the level lip and top of stream bank, Proposed drainage easement, and Design at ultimate build-out. 3. Section view of the level spreader (1 ° = 20' or larger) showing: - Underdrain system (if applicable), Level lip, Upslope channel, and Downslope filter fabric. 4. Plan details of the flow splitting device and supporting calculations (if applicable). 5. A construction sequence that shows how the level spreader will be protected from sediment until the entire drainage area is stabilized. 6. If a non-engineered VFS is being used, then provide a photograph of the VFS showing that no draws are present. 7. The supporting calculations. 8. A copy of the signed and notarized operation and maintenance (OW) agreement. Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 3 of 3 • • • • • • • • • • a • • • • • s • • • • • • i • • • • • • • • • • • s • CULVERT CALCULATIONS • • • • • • • • Culvert Analysis Report Crossing 1 - (HW1) Analysis Component Storm Event Check Discharge 90.49 cfs Peak Discharge Method: Rational Design Return Period 25 year Check Return Period 100 year Design Peak Discharge 73.43 cfs Check Peak Discharge 90.49 cfs Total Area 85.50 acres Time of Concentration 60.00 min Rational Coefficient 0.30 Intensity 3.50 in/hr Area Subwatershed (acres) C 1 85.50 0.30 Tailwater Conditions: Constant Tailwater Tailwater Elevation N/A ft Name Description Discharge HW Elev. Velocity Culvert-1 1-72 inch Circular 90.50 cfs 363.71 ft 16.14 ft/s Weir Roadway (Constant Elevation) 0.00 cfs 363.71 ft N/A Total --------- 90.50 cfs 363.71 ft N/A Title: Alston Pond Project Engineer: asmith k:\...\h-h\culvert master\alston pond culverts.cvm Withers & Ravenel Engineering CulvertMaster v3.1 [03.01.010.00] 03/24/11 12:17:31 PM c Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Page 1 Culvert Analysis Report Crossing 1 - (HW1) Component:Weir Hydraulic Component(s): Roadway (Constant Elevation) Discharge 0.00 cfs Allowable HW Elevation 363.71 ft Roadway Width 80.00 ft Overtopping Coefficient 2.90 US Length 100.00 It Crest Elevation 385.00 ft Headwater Elevation N/A ft Discharge Coefficient (Cr) 2.90 Submergence Factor (Kt) 1.00 Sta (ft) Elev. (ft) 0.00 385.00 100.00 385.00 Title: Alston Pond Project Engineer: asmith k:\...\h-h\culvert master\alston pond culverts.cvm Withers & Ravenel Engineering CulvertMaster v3.1 [03.01.010.00] 03/24/11 12:17:31 PM c Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Page 3 • • Culvert Analysis Report • Crossing 2 (HW3) • • Component:Culvert-1 • Culvert Summary Computed Headwater Elevation 391.61 ft Discharge 24.44 cfs Inlet Control HW Elev. 391.40 ft Tailwater Elevation N/A ft • Outlet Control HW Elev. 391.61 ft Control Type Entrance Control Headwater Depth/Height 0.53 • Grades • Upstream Invert 389.50 ft Downstream Invert 386.50 ft Length 50.00 ft Constructed Slope 0.060000 ft/ft • Hydraulic Profile Profile S2 Depth, Downstream 0.79 ft Slope Type Steep Normal Depth 0.71 ft Flow Regime Supercritical Critical Depth 1.46 ft • Velocity Downstream 13.86 ft/s Critical Slope 0.003575 ft/ft • Section • Section Shape Circular Mannings Coefficient 0.013 Section Material Concrete Span 4.00 ft Section Size 48 inch Rise 4.00 ft Number Sections 1 • • Outlet Control Properties • Outlet Control HW Elev. 391.61 ft Upstream Velocity Head 0.54 ft Ke 0.20 Entrance Loss 0.11 ft • • Inlet Control Properties • Inlet Control HW Elev. 391.40 ft Flow Control Unsubmerged • Inlet Type Groove end projecting Area Full 12.6 ft2 K 0.00450 HDS 5 Chart 1 M 2.00000 HDS 5 Scale 3 C 0.03170 Equation Form 1 . Y 0.69000 M1 • • s • • • • • • Title: Alston Pond Project Engineer: asmith k:\...\h-h\culvert master\alston pond culverts.cvm Withers & Ravenel Engineering CulvertMaster v3.1 [03.01.010.00] • 03/24/11 12:17:31 PM c Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Page 5 • • • • • • • • nalysis Component Storm Event Peak Discharge Method: Rational Culvert Analysis Report Crossing 3 - (FES601) Design Discharge 4.19 cfs • Design Return Period 25 year Check Return Period 25 year Design Peak Discharge 14.19 cfs Check Peak Discharge 14.19 cfs • Total Area 6.60 acres Time of Concentration 10.00 min Rational Coefficient 0.30 Intensity 7.11 in/hr Area • Subwatershed (acres) C 1 6.60 0.30 • • Tailwater Conditions: Constant Tailwater • Tailwater Elevation N/A ft • Name Description Discharge HW Elev. Velocity • Culvert-1 1-18 inch Circular 7.05 cfs 386.08 ft 11.19 ft/s • Weir Roadway (Constant Elevation) 7.19 cfs 386.08 ft N/A Total ---------- 14.24 cfs 386.08 ft N/A • • • • • • • • • • • • • • • • • • • • • • Title: Alston Pond k \ \h Project Engineer: asmith : ... -h\culvert master\alston pond culverts.cvm Withers & Ravenel Engineering CulvertMaster v3.1 [03.01.010.00] • 03/24/11 12:17:31 PM c Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Page 7 Culvert Analysis Report Crossing 3 - (FES601) Component: Weir Hydraulic Component(s): Roadway (Constant Elevation) Discharge 7.19 cfs Allowable HW Elevation 386.08 ft Roadway Width 40.00 ft Overtopping Coefficient 2.93 US Length 100.00 ft Crest Elevation 386.00 ft Headwater Elevation 386.08 ft Discharge Coefficient (Cr) 2.93 Submergence Factor (Kt) 1.00 Sta (ft) Elev. (ft) 0.00 386.00 100.00 386.00 Title: Alston Pond Project Engineer asmith k:\...\h-h\culvert master\alston pond culverts.cvm Withers & Ravenel Engineering CulvertMaster v3.1 (03.01.010.00] 03/24/11 12:17:31 PM c Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Page 9 � � Z 61 4W ~ - 719 76 59 64 74 82- 56 70 54 87 31 89 264 50 FT. lio BUFFER 102 NEUSE 132 20 fuu 41 201 376 377 r 75 150 300 inch 150 ft. Designer Scale Drawn By Date zzz Checked By W&R I Job No. M J&A — AW �ffl` I W I "low Emu E: R 8 OR AV NE Orh'qm E L ENGINEERS I PLANNERS I SURVEYORS 111 MacKenan Drive Cary, North Carolina 27511 tel: 919-469-3340 www.withersravenel.com License No. C-0832 Revision Designer Scale Drawn By Date zzz Checked By W&R I Job No. M J&A — AW �ffl` I W I "low Emu E: R 8 OR AV NE Orh'qm E L ENGINEERS I PLANNERS I SURVEYORS 111 MacKenan Drive Cary, North Carolina 27511 tel: 919-469-3340 www.withersravenel.com License No. C-0832