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HomeMy WebLinkAboutStormDrainageReport STORM WATER DESIGN REPORT FOR NWX APARTMENTS (INCLUSIVE OF MASTER SITE PLAN, PHASE 1 AND PHASE 2) BOZEMAN, MONTANA Prepared By: Morrison-Maierle, Inc. 2880 Technology Blvd. West P.O. Box 1113 Bozeman, Montana 59771-1113 Engineer: Kevin D. Jacobsen, P.E. Date: September 16, 2021, Updated June 2, 2022 File: 5305.008 __________________________________________________________________________________ NWX APARTMENTS - STORM WATER DESIGN REPORT 2 NWX APARTMENTS STORM WATER DESIGN REPORT TABLE OF CONTENTS 1.0 Introduction ..................................................................................................... Page 3 2.0 Drainage Patterns ............................................................................................ Page 3 3.0 Hydrological Methodology and Calculations (On-Site Basin) ....................... Page 3 4.0 Retention Area Calculations and Storm Water Treatment (On-Site Basin) ... Page 5 5.0 Storm Drain Pipe Calculations (On-Site Basin) ............................................. Page 6 6.0 Storm Water Maintenance Plan ...................................................................... Page 7 7.0 Summary ......................................................................................................... Page 7 LIST OF APPENDICES Appendix A. Overall Storm Exhibit B. City of Bozeman Intensity-Duration-Frequency Curve (IDF) C. Basin Hydrology and Calculations __________________________________________________________________________________ NWX APARTMENTS - STORM WATER DESIGN REPORT 3 NWX APARTMENTS STORM WATER DESIGN REPORT 1.0 Introduction A multi-family development is being proposed north of West Oak Street, west of Cottonwood Road, east of Rosa Way, and south of Harvest Parkway. The site plan is in the Northwest Crossing Subdivision that is nearing the final stages of final plat. Eighteen buildings are spread over 15 acres with approximately 338 residential units, a clubhouse and maintenance building. Improvements include driveway approaches off adjacent streets, parking drive aisles and associated parking infrastructure, utility infrastructure including storm drainage, water, sanitary sewer and dry utilities. Park and open spaces are included throughout this development as well. Existing infrastructure surrounding the development is being installed as part of the approved subdivision. 2.0 Drainage Patterns This project is being separated into three areas as it relates to drainage. Each area is essentially a block that will collect its own runoff. Please refer to the attached “STORM” exhibit for a depiction of each drainage basin (SW, NW, and NE). The subdivision will handle all the post-development runoff from the right of way areas and pre-development flows from the site. Each individual drainage basin will attenuate the post-development flows. The NW drainage basin includes two small drainage areas on the south end of the basin that will handle storm water separately from the overall NW drainage basin. These basins include the roof drainage and surrounding ground for buildings 13 and 14. The existing land generally flows from the south to the north at approximately 1.25%. Baxter ditch flows along the west side of Rosa Way. Proposed grading will provide for appropriate vehicular and pedestrian access while routing runoff to the northern edges of each basin. Sheet and pipe flow will be the predominant means of conveyance on this site. 3.0 Hydrological Methodology and Calculations (On-Site Basin) Below is a table that lists each drainage basin, along with the corresponding values necessary for utilizing the Rational Method. The resultant runoff rates and storage area sizing can be seen in table as well. The City of Bozeman IDF curves were utilized for the calculations. __________________________________________________________________________________ NWX APARTMENTS - STORM WATER DESIGN REPORT 4 The C-values used were 0.20 for the pre-development rate which is reasonable for the open land that currently exists. The post-development C-value was generated utilizing a composite calculation based on the percentage of impervious and pervious land. Areas of pervious were given a C-value of 0.20 and impervious areas a value of 0.85. In general, this dense multi-family development has approximately 75% impervious area and we feel that the calculated composite C-value of 0.70 used is appropriate, if not conservative. Condition Area (ac) Composite C-Value Tc (min) Q10 (cfs) Q25 (cfs) Detention Size (cu.ft.) First ½” (cu.ft.) Retention Size (cu.ft.) Basin SW Pre-Dev. 6.74 0.20 35 1.22 Basin SW Post-Dev. 6.74 0.70 20 6.17 7.43 5,940 9,800 13,930 Basin NW Pre-Dev. 4.38 0.20 32 0.84 Basin NW Post-Dev. 4.38 0.70 13 5.30 6.36 3,480 6,620 9,050 Basin NW-SUB Pre-Dev. 0.28 0.20 17 0.08 Basin NW-SUB Post-Dev. 0.28 0.70 9 0.43 0.51 190 585 580 Basin NE Pre-Dev. 2.47 0.20 36 0.44 Basin NE Post-Dev. 2.47 0.70 16 2.61 3.14 2,090 3,370 5,100 __________________________________________________________________________________ NWX APARTMENTS - STORM WATER DESIGN REPORT 5 4.0 Storage Area Calculations and Storm Water Treatment The calculations shown above in the table depict the storage volumes for both detention and retention areas, as well as the volume associated with the first 0.5-inch of rain. This site is being designed to provide retention for all drainage basins and storage areas. All areas will be underground within parking areas and grassed areas around the site. Each retention area is sized (see above) based on a 10-year, 2-hour storm intensity per City of Bozeman requirements. The formula for calculating the retention volume is listed below. V = 7200(C)(I)(A) C = 0.70 I = 0.41 in/hr A = varies per basin The City’s design standards also require Low Impact Development (LID) practices that infiltrate, evapotranspire or capture runoff, to the extent feasible, for a specified design runoff event as noted above with the first 0.5-inch of rainfall. The proposed underground systems will combine both runoff capture and infiltration. Underground systems are widely accepted LID systems found to remove 80 percent of total suspended solids from municipal storm runoff, and in the case of retention there will be no discharge from the site for the 10-year storm event. It meets LEED criteria for storm water treatment (SS6.2 water quality credit). The facilities proposed for this project provide for infiltration. Runoff from the first 0.5-inch of rainfall will percolate through a gravel filter layer before infiltrating into the native soil beneath. The native soil underneath the gravel filter layer is a well-draining gravel, cobble and sand mix (based on geotechnical report). This sandy gravel layer exists at various elevations and (~3-feet to 5-feet below existing grade) throughout the site. The bottom of the chambers will be set to ensure that groundwater does not impact the storage volume. Groundwater monitoring has occurred on the site to measure the high groundwater and a groundwater lowering system is being installed to lower the groundwater approximately two feet below the high groundwater level. The system will be installed above the high groundwater and will ensure connection to the underlying gravel strata. __________________________________________________________________________________ NWX APARTMENTS - STORM WATER DESIGN REPORT 6 Volume of first ½” of rainfall to be infiltrated on the site is conservatively based on the total area of impervious surface (includes building and parking area). V = (0.5 inches x A impervious)/12 Basin Impervious Area (sq.ft.) ½” Volume (cu.ft.) SW 235,000 9,800 NW 158,800 6,620 NW-SUB 14,000 585 NE 80,800 3,370 In order to provide pretreatment for the underground systems in the parking areas, isolator rows will reduce the amount of debris and sediment that enters the infiltration media. The isolator rows can be periodically cleaned when necessary. The grassed infiltration areas will slope to a sump where debris and sediment can be removed as part of maintenance activities. Both infiltration systems can be jetted out as necessary. The underground systems located in the parking areas, as described above, along with the gravel strata below the chambers, will provide for runoff capture, TSS removal and infiltration necessary to not only meet, but exceed, the City’s current design standards. The small infiltration basins in the southern portion of the NW basin will also contain gravel media that will be tied to the gravel strata. Infiltration rates were not used in the sizing of these retention areas to be conservative. 5.0 Storm Drain Pipe Calculations Piping will be utilized only where required for collection and convenance, as the majority of runoff will be via surface flow. The piping, in accordance with City Standards shall be designed to accommodate the 25-year storm event. The SW basin includes most of the piping due the size and complexity of the basin. This basin also includes the clubhouse and pool, which will require area drains in coordination with the pool consultant. The overflow for this SW basin, during events larger than 10 years, will surcharge the inlet at the far northwest corner of the site and flow to Wellspring Drive. We have separated the basin in three areas in regard to pipe sizing. Storm drain Manhole 1-5 is the location where the piping changes from 15” to 18.” The pool area also has a separate calculation to illustrate a 12” pipe size. See table below and the Appendix for calculations. __________________________________________________________________________________ NWX APARTMENTS - STORM WATER DESIGN REPORT 7 The NW and NE basins have nearby storm drain infrastructure within the adjacent roadways and will therefore have connections for storm events exceeding 10 years. Piping in the NE basin will be 15” throughout. The NW basin will be 18” piping other thean the small infiltration basins that are 12” pipe. The locations of the outlet pipes and overflows is such that a very large storm event has a route to flow away from structures. Runoff will flow to adjacent roadways and flow down the streets, ultimately making its way to Baxter Ditch. See piping chart below. Basin Interior Pipe (in.) SW (Beyond SD 1-5) 18” @ 0.5% SW (Up To SD 1-5) ---12” OK for Beginning Inlets--- 15” @ 0.5% SW (Pool Area) ---Smaller Sizes OK for Area Drains--- 12” @ 0.3% NW 18” @ 0.5% NW-SUB 12” @ 0.5% NE 15” @ 0.5% 6.0 Storm Water Maintenance Plan The maintenance of on-site storm water collection, retention, and overflow facilities will be integrated as part of the maintenance of the site per the Storm Water Management System Operation and Maintenance Manual submitted with the site plan. Duties shall include routine inspection to ensure that sediment, debris, yard waste, and seasonal ice does not impede operation of the storm drain facilities. It is recommended that these inspections occur after major runoff events and monthly throughout the year, with flushing and sediment removal as necessary. Maintenance of the manufactured underground systems shall be per their recommendations. 7.0 Summary The storm water analysis for the proposed site was completed using applicable state and local regulations/standards as well as sound engineering practices. The result is a storm water plan that provides for the conveyance, storage and treatment of storm water runoff while protecting private property and promoting public safety. APPENDIX A S78°41'34"W 227.20'L31L30L29 L28N78°41'34"E 447.36' N78°41'34"E 547.89'S16°12'27"E66.15'C59 118.01'S0°59'41"W 2627.49'S89°30'03"W 2649.87'151.00'D DSDSDSD DDSDSDSDSDD SD SD D D SDSDSDD 4745.67 D D D SDSDSDSDSDSDDD D D D D D D SD SDSD II ESD 26+0027+0028+0029+0030+0031+0032+0033+0034+0035+0036+0037+0038+0039+0040+0041+00MAIL BLDG 1 BLDG 2 BLDG 3 BLDG 4 BLDG 7 BLDG 8 BLDG 9 BLDG 13 BLDG 14 BLDG 15 BLDG 17 BLDG 18 BLDG 12 BLDG 11 BLDG 10 BLDG 5 BLDG 6 BLDG 16 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>8W8S8S8W8W8W 8S8W8W 8W D D D SDSDD DD D D D SDSDD D D D D DD D D D D D P P P P P PP P P P P P P P P E E EEEEEEEEEEEE E EEEEEEE EEEEEE E G GGGGGG G G G GGGGGGG G GGGGGGGGGG 188.44'DSD EGFIGURE NUMBER © PROJECT NO.DRAWN BY: DSGN. BY: APPR. BY: DATE: COPYRIGHT MORRISON-MAIERLE, INC.,2022 N:\5305\008 - NW Crossing Multi Family\ACAD\Exhibits\Storm Drainage Exhibit.dwg Plotted by kevin d. jacobsen on Jun/2/2022 engineers surveyors planners scientists MorrisonMaierle 2880 Technology Blvd West Bozeman, MT 59718 406.587.0721 www.m-m.net 5305.008 STORM KDJ BOZEMAN MONTANA STORM DRAINAGE PLAN KDJ NWX APARTMENTS 06/2022 W. OAK STREET HARVEST P A R K W A Y ROSA WAYWELLSPRING DRIVE DAYSPRING AVENUE COTTONWOOD ROAD80 1600 SCALE IN FEET TWIN LAKES AVEPHASE 1 BOUNDARY: BUILDINGS 1-12 PHASE 2 BOUNDARY: BUILDINGS 13-18 NOTES: 1. STORAGE AND INFILTRATION SYSTEMS WILL INCLUDE A COMBINATION OF UNDERGROUND CHAMBERS (I.E. STORMTECH) AS WELL SLOTTED UNDERGROUND PIPING WRAPPED IN POROUS MEDIA AND GEOTEXTILE FILTER FABRIC. 2. RUNOFF CONVEYANCE IS PRIMARILY VIA SURFACE RUNOFF ALTHOUGH PIPING IS UTILIZED IN SPECIFIC AREAS THROUGHOUT THE SITE AS NECESSARY. POOL AREA DRAIN PIPING LAYOUT AND SIZING WILL BE FINALIZED IN COORDINATION WITH THE POOL CONSULTANT. 3. ALL STORAGE VOLUMES ARE SIZED FOR RETENTION. THE NW AND NE QUADRANTS HAVE OUTLET PIPING TO ACCOMMODATE LARGER STORM EVENTS. THE SW QUADRANT IS DESIGNED TO OVERFLOW TO WELLSPRING DRIVE DURING LARGER EVENTS. NW NE SW NE DRAINAGE BASIN DESCRIPTOR STORM PIPING STORAGE / INFILTRATION FACILITY UNDERGROUND INFILTRATION CHAMBER RETENTION V=5,100 CU.FT. LINEAR SLOTTED COLLECTION DRAIN 15" OUTLET PIPEUNDERGROUND MANUFACTURED INFILTRATION CHAMBER RETENTION V=9,050 CU.FT. 18" OUTLET PIPE INLET DRAIN CURB/SIDEWALK CHASES UNDERGROUND INFILTRATION SYSTEM RETENTION V=585 CU.FT.UNDERGROUND INFILTRATION SYSTEM RETENTION V=585 CU.FT. UNDERGROUND MANUFACTURED INFILTRATION CHAMBER RETENTION V=13,930 CU.FT. INLET DRAIN CURB INLET DRAIN 18" PIPES TO NORTH, 15" PIPES TO SOUTH BAXTER DITCHCURB/SIDEWALK CHASES 12" POOL AREA PIPING (AREAS DRAINS CAN BE SMALLER PER PLUMBING CONSULTATION) APPENDIX B 0 5 10 15 20 25 30 35 40 45 50 55 60 Int. (in/hr) 0.00 0.00 2.00 2.00 4.00 4.00 6.00 6.00 8.00 8.00 10.00 10.00 12.00 12.00 14.00 14.00 Time (min) 100-Yr 50-Yr 25-Yr 10-Yr 5-Yr 2-Yr IDF file: COB IDF.IDF Express Hydraflow IDF Curves Hydraflow IDF Report Page 1 of 1 Return Equation Coefficients (FHA) Period (Yrs) B D E (N/A) 1 0.0000 0.0000 0.0000 -------- 2 4.1995 0.0000 0.6000 -------- 3 0.0000 0.0000 0.0000 -------- 5 7.1453 0.0000 0.6400 -------- 10 9.1617 0.0000 0.6500 -------- 25 10.7179 0.0000 0.6400 -------- 50 13.7204 0.0000 0.6600 -------- 100 15.6922 0.0000 0.6700 -------- N:\2605\027\Design Docs\Reports\Storm Drainage\COB IDF.IDF Intensity = B / (Tc + D)^E Return Intensity Values (in/hr) Period (Yrs) 5 min 10 15 20 25 30 35 40 45 50 55 60 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 1.60 1.05 0.83 0.70 0.61 0.55 0.50 0.46 0.43 0.40 0.38 0.36 3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 2.55 1.64 1.26 1.05 0.91 0.81 0.73 0.67 0.63 0.58 0.55 0.52 10 3.22 2.05 1.58 1.31 1.13 1.00 0.91 0.83 0.77 0.72 0.68 0.64 25 3.83 2.46 1.89 1.58 1.37 1.22 1.10 1.01 0.94 0.88 0.82 0.78 50 4.74 3.00 2.30 1.90 1.64 1.45 1.31 1.20 1.11 1.04 0.97 0.92 100 5.34 3.35 2.56 2.11 1.82 1.61 1.45 1.33 1.22 1.14 1.07 1.01 Tc = time in minutes. Min Tc = 0 APPENDIX C Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 Pre Basin Hydrology (10-yr) Basin SW Hydrograph type = Rational Peak discharge (cfs) = 1.225 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 6.740 Runoff coeff. (C) = 0.2 Rainfall Inten (in/hr) = 0.909 Tc by FAA (min) = 35 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 2,572 (cuft); 0.059 (acft) 0 10 20 30 40 50 60 70 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 1.22 (cfs) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Pre Basin Hydrology (10-yr) Basin SW Description Flow length (ft) = 610.00 Watercourse slope (%) = 1.56 Runoff coefficient (C) = 0.20 Time of Conc. (min) = 35 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 Post Basin Hydrology (10-yr) Basin SW Hydrograph type = Rational Peak discharge (cfs) = 6.167 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 6.740 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.307 Tc by FAA (min) = 20 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 7,400 (cuft); 0.170 (acft) 0 5 10 15 20 25 30 35 40 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 7.00 7.00 Q (cfs) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 6.17 (cfs)Outflow Hyd *Req. Stor = 5,935 (cuft) * * Estimated FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (10-yr) Basin SW Description Flow length (ft) = 860.00 Watercourse slope (%) = 1.15 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 20 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 Post Basin Hydrology (25-yr) Basin SW Hydrograph type = Rational Peak discharge (cfs) = 7.434 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 6.740 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.576 Tc by FAA (min) = 20 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 8,921 (cuft); 0.205 (acft) 0 5 10 15 20 25 30 35 40 Q (cfs) 0.00 0.00 2.00 2.00 4.00 4.00 6.00 6.00 8.00 8.00 Q (cfs) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 7.43 (cfs) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Basin SW Description Flow length (ft) = 860.00 Watercourse slope (%) = 1.15 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 20 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 SW Pipe Flow (25-yr Storm) Beyond SD 1-5 Circular Diameter (ft) = 1.50 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 7.43 Highlighted Depth (ft) = 1.23 Q (cfs) = 7.430 Area (sqft) = 1.55 Velocity (ft/s) = 4.78 Wetted Perim (ft) = 3.41 Crit Depth, Yc (ft) = 1.06 Top Width (ft) = 1.15 EGL (ft) = 1.59 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (25-yr) Basin SW-Up to SD 1-5 Hydrograph type = Rational Peak discharge (cfs) = 3.846 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 3.260 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.686 Tc by FAA (min) = 18 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 4,154 (cuft); 0.095 (acft) 0 5 10 15 20 25 30 35 40 Q (cfs) 0.00 0 1.00 25 2.00 50 3.00 75 4.00 100 Vol (%) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 3.85 (cfs)Hyd Volume = 4,154 (cuft) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Basin SW-Up to SD 1-5 Description Flow length (ft) = 600.00 Watercourse slope (%) = 0.91 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 18 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 SW Pipe Flow (25-yr Storm) UP TO SD 1-5 Circular Diameter (ft) = 1.25 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 3.85 Highlighted Depth (ft) = 0.88 Q (cfs) = 3.850 Area (sqft) = 0.93 Velocity (ft/s) = 4.16 Wetted Perim (ft) = 2.49 Crit Depth, Yc (ft) = 0.80 Top Width (ft) = 1.14 EGL (ft) = 1.15 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (25-yr) Basin SW-Pool Area Hydrograph type = Rational Peak discharge (cfs) = 1.815 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 1.310 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.980 Tc by FAA (min) = 14 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 1,525 (cuft); 0.035 (acft) 0 5 10 15 20 25 30 Q (cfs) 0.00 0 1.00 50 2.00 100 Vol (%) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 1.82 (cfs)Hyd Volume = 1,525 (cuft) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Basin SW-Pool Area Description Flow length (ft) = 300.00 Watercourse slope (%) = 0.75 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 14 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 SW Pipe Flow (25-yr Storm) POOL AREA Circular Diameter (ft) = 1.00 Invert Elev (ft) = 100.00 Slope (%) = 0.30 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 1.82 Highlighted Depth (ft) = 0.77 Q (cfs) = 1.820 Area (sqft) = 0.65 Velocity (ft/s) = 2.80 Wetted Perim (ft) = 2.15 Crit Depth, Yc (ft) = 0.58 Top Width (ft) = 0.84 EGL (ft) = 0.89 0 1 2 3 Elev (ft)Depth (ft)Section 99.50 -0.50 100.00 0.00 100.50 0.50 101.00 1.00 101.50 1.50 102.00 2.00 Reach (ft) Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Pre Basin Hydrology (10-yr) Basin NW Hydrograph type = Rational Peak discharge (cfs) = 0.844 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 4.380 Runoff coeff. (C) = 0.2 Rainfall Inten (in/hr) = 0.963 Tc by FAA (min) = 32 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 1,620 (cuft); 0.037 (acft) 0 10 20 30 40 50 60 70 Q (cfs) 0.00 0.00 0.10 0.10 0.20 0.20 0.30 0.30 0.40 0.40 0.50 0.50 0.60 0.60 0.70 0.70 0.80 0.80 0.90 0.90 1.00 1.00 Q (cfs) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 0.84 (cfs) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Pre Basin Hydrology (10-yr) Basin NW Description Flow length (ft) = 490.00 Watercourse slope (%) = 1.43 Runoff coefficient (C) = 0.20 Time of Conc. (min) = 32 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (10-yr) Basin NW Hydrograph type = Rational Peak discharge (cfs) = 5.303 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 4.380 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.729 Tc by FAA (min) = 13 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 4,136 (cuft); 0.095 (acft) 0 5 10 15 20 25 30 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 Q (cfs) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 5.30 (cfs)Outflow Hyd *Req. Stor = 3,483 (cuft) * * Estimated FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (10-yr) Basin NW Description Flow length (ft) = 520.00 Watercourse slope (%) = 1.85 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 13 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (25-yr) Basin NW Hydrograph type = Rational Peak discharge (cfs) = 6.364 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 4.380 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 2.076 Tc by FAA (min) = 13 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 4,964 (cuft); 0.114 (acft) 0 5 10 15 20 25 30 Q (cfs) 0.00 0 1.00 14 2.00 29 3.00 43 4.00 57 5.00 71 6.00 86 7.00 100 Vol (%) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 6.36 (cfs)Hyd Volume = 4,964 (cuft) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Basin NW Description Flow length (ft) = 520.00 Watercourse slope (%) = 1.85 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 13 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 NW Pipe Flow (25-yr Storm) Circular Diameter (ft) = 1.50 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 6.36 Highlighted Depth (ft) = 1.07 Q (cfs) = 6.360 Area (sqft) = 1.35 Velocity (ft/s) = 4.71 Wetted Perim (ft) = 3.02 Crit Depth, Yc (ft) = 0.98 Top Width (ft) = 1.35 EGL (ft) = 1.41 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Pre Basin Hydrology (10-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Hydrograph type = Rational Peak discharge (cfs) = 0.081 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 0.280 Runoff coeff. (C) = 0.2 Rainfall Inten (in/hr) = 1.453 Tc by FAA (min) = 17 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 83 (cuft); 0.002 (acft) 0 5 10 15 20 25 30 35 Q (cfs) 0.00 0 0.01 10 0.02 20 0.03 30 0.04 40 0.05 50 0.06 60 0.07 70 0.08 80 0.09 90 0.10 100 Vol (%) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 0.08 (cfs)Hyd Volume = 82.98 (cuft) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Pre Basin Hydrology (10-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Description Flow length (ft) = 80.00 Watercourse slope (%) = 0.58 Runoff coefficient (C) = 0.20 Time of Conc. (min) = 17 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (10-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Hydrograph type = Rational Peak discharge (cfs) = 0.431 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 0.280 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 2.196 Tc by FAA (min) = 9 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 232 (cuft); 0.005 (acft) 0 5 10 15 20 Q (cfs) 0.00 0 0.05 10 0.10 20 0.15 30 0.20 40 0.25 50 0.30 60 0.35 70 0.40 80 0.45 90 0.50 100 Vol (%) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 0.43 (cfs)Outflow Hyd *Req. Stor = 189 (cuft) * * Estimated FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (10-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Description Flow length (ft) = 235.00 Watercourse slope (%) = 1.71 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 9 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (25-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Hydrograph type = Rational Peak discharge (cfs) = 0.515 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 0.280 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 2.627 Tc by FAA (min) = 9 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 278 (cuft); 0.006 (acft) 0 5 10 15 20 Q (cfs) 0.00 0 0.10 10 0.20 20 0.30 30 0.40 40 0.50 50 0.60 60 0.70 70 0.80 80 0.90 90 1.00 100 Vol (%) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 0.51 (cfs)Hyd Volume = 278.00 (cuft) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Description Flow length (ft) = 235.00 Watercourse slope (%) = 1.71 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 9 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Pipe Flow-Post Basin (25-yr) Basin NW-SUB (2 BASINS EACH-SAME SIZE) Circular Diameter (ft) = 1.00 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 0.51 Highlighted Depth (ft) = 0.31 Q (cfs) = 0.510 Area (sqft) = 0.21 Velocity (ft/s) = 2.44 Wetted Perim (ft) = 1.18 Crit Depth, Yc (ft) = 0.30 Top Width (ft) = 0.93 EGL (ft) = 0.40 0 1 2 3 Elev (ft)Depth (ft)Section 99.50 -0.50 100.00 0.00 100.50 0.50 101.00 1.00 101.50 1.50 102.00 2.00 Reach (ft) Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 Pre Basin Hydrology (10-yr) Basin NE Hydrograph type = Rational Peak discharge (cfs) = 0.441 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 2.470 Runoff coeff. (C) = 0.2 Rainfall Inten (in/hr) = 0.892 Tc by FAA (min) = 36 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 952 (cuft); 0.022 (acft) 0 10 20 30 40 50 60 70 80 Q (cfs) 0.00 0.00 0.05 0.05 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 0.30 0.30 0.35 0.35 0.40 0.40 0.45 0.45 0.50 0.50 Q (cfs) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 0.44 (cfs) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Pre Basin Hydrology (10-yr) Basin NE Description Flow length (ft) = 520.00 Watercourse slope (%) = 1.06 Runoff coefficient (C) = 0.20 Time of Conc. (min) = 36 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 Post Basin Hydrology (10-yr) Basin NE Hydrograph type = Rational Peak discharge (cfs) = 2.613 Storm frequency (yrs) = 10 Time interval (min) = 1 Drainage area (ac) = 2.470 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.511 Tc by FAA (min) = 16 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 2,508 (cuft); 0.058 (acft) 0 5 10 15 20 25 30 35 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) Runoff Hydrograph 10-yr frequency Runoff Hyd - Qp = 2.61 (cfs)Outflow Hyd *Req. Stor = 2,083 (cuft) * * Estimated FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (10-yr) Basin NE Description Flow length (ft) = 630.00 Watercourse slope (%) = 1.35 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 16 Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 Post Basin Hydrology (25-yr) Basin NE Hydrograph type = Rational Peak discharge (cfs) = 3.142 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 2.470 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 1.817 Tc by FAA (min) = 16 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 3,017 (cuft); 0.069 (acft) 0 5 10 15 20 25 30 35 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 3.14 (cfs) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Basin NE Description Flow length (ft) = 630.00 Watercourse slope (%) = 1.35 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 16 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Sep 15 2021 NE Pipe Flow (25-yr Storm) Circular Diameter (ft) = 1.25 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 3.14 Highlighted Depth (ft) = 0.77 Q (cfs) = 3.140 Area (sqft) = 0.79 Velocity (ft/s) = 3.96 Wetted Perim (ft) = 2.26 Crit Depth, Yc (ft) = 0.72 Top Width (ft) = 1.22 EGL (ft) = 1.01 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) Hydrology Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Post Basin Hydrology (25-yr) Worst Case Sidewalk Chase Hydrograph type = Rational Peak discharge (cfs) = 0.687 Storm frequency (yrs) = 25 Time interval (min) = 1 Drainage area (ac) = 0.400 Runoff coeff. (C) = 0.7 Rainfall Inten (in/hr) = 2.455 Tc by FAA (min) = 10 IDF Curve = COB IDF.IDF Rec limb factor = 1.00 Hydrograph Volume = 412 (cuft); 0.009 (acft) 0 5 10 15 20 Q (cfs) 0.00 0 0.10 10 0.20 20 0.30 30 0.40 40 0.50 50 0.60 60 0.70 70 0.80 80 0.90 90 1.00 100 Vol (%) Time (min) Runoff Hydrograph 25-yr frequency Runoff Hyd - Qp = 0.69 (cfs)Hyd Volume = 412.50 (cuft) FAA Formula Tc Worksheet Tc = 1.8(1.1 - C) x Flow length^0.5 / Watercourse slope^0.333 Hydraflow Express by Intelisolve Rational Post Basin Hydrology (25-yr) Worst Case Sidewalk Chase Description Flow length (ft) = 275.00 Watercourse slope (%) = 1.93 Runoff coefficient (C) = 0.70 Time of Conc. (min) = 10 Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Jun 2 2022 Sidewalk Chase (25-yr Storm) Worst Case Rectangular Bottom Width (ft) = 1.00 Total Depth (ft) = 0.38 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 0.69 Highlighted Depth (ft) = 0.28 Q (cfs) = 0.690 Area (sqft) = 0.28 Velocity (ft/s) = 2.46 Wetted Perim (ft) = 1.56 Crit Depth, Yc (ft) = 0.25 Top Width (ft) = 1.00 EGL (ft) = 0.37 0 .25 .5 .75 1 1.25 1.5 Elev (ft)Depth (ft)Section 99.75 -0.25 100.00 0.00 100.25 0.25 100.50 0.50 100.75 0.75 101.00 1.00 Reach (ft)