Indigo Land Design, LLC 860.388.9343 Phone 40 Elm Street, 2 nd Floor 860.391.8854 Fax Old Saybrook, CT 06475 [email protected]E-mail www.Indigo-Land.com August 24, 2020 Re: Muir Office & Warehouse Building 92 Spencer Plain Road – Map 46 Lot 16 Old Saybrook, CT 06475 DRAINAGE REPORT This project involves the construction of a 12,000 s.f. office and warehouse building with a paved driveway and parking lot, installation of low impact development (LID) measures as shown on the site plan, and other associated improvements. The subject property was previously developed and there are remains of an old foundation near the northwest corner of the property. There is an existing gravel driveway that runs east-west along the southern portion of the property that provides access to the adjacent properties to the east. The majority or the site is wooded with some grassed areas along the perimeter of the property. The proposed building will be located on the northern side of the property along Buck Hill Road. The topography generally slopes away from the building and toward the proposed stormwater management basin. The underlying soils within the watershed consist of Agawam fine sandy loam, Canton & Charlton fine sandy loam and Canton-Chatfield Complex (all of which are NRCS hydrologic soil group 'B'). The wetlands area on the property was identified as Agawam fine sandy loam based on NRCS soil mapping, however, NRCS hydrologic soil group ‘D’ was used for design due to its saturated condition. The proposed project includes several BMP and LID techniques and measures to mitigate impacts of stormwater runoff and reduce the pollutant content of stormwater discharge. The proposed methods include, but are not limited to: breaking up areas of impervious surfaces and avoid concentrated point discharges, encouraging overland flow by using open swales and curbless driveway and parking areas, inhibiting erosion by using pre-formed scour holes at pipe outfalls, minimizing the removal of existing trees and introducing new landscaping and wetland plantings, maintaining existing topography and flow paths and promoting infiltration and groundwater recharge by utilizing stone aprons along the downgradient edges of the parking lot. The NRCS TR-55 methodology was utilized to evaluate existing and proposed stormwater runoff conditions with the AutoCAD embedded HydraFlow Hydrographs computer program. The times of concentration were computed using the TR-55 methodology as recommended by the ConnDOT Drainage Manual. The Town of Old Saybrook recommends using the 24-hour NRCS Type III rainfall distribution up to the 25-year storm for designing the drainage system. All rainfall amounts used in this analysis were taken from the Hydrometeorological Design Studies Center of the National Oceanic and Atmospheric Administration (NOAA) National Weather Service and published in NOAA Atlas 14 Volume 10: Precipitation-Frequency Atlas of the United States, Northeastern States, last revised on September 30, 2015. Refer to the plan entitled “Drainage Area Map” (Revised 8/24/2020) enclosed within this report for all watershed information.
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Indigo Land Design, LLC 860.388.9343 Phone 40 Elm Street, 2nd Floor 860.391.8854 Fax Old Saybrook, CT 06475 [email protected] E-mail www.Indigo-Land.com
August 24, 2020 Re: Muir Office & Warehouse Building
92 Spencer Plain Road – Map 46 Lot 16 Old Saybrook, CT 06475
DRAINAGE REPORT
This project involves the construction of a 12,000 s.f. office and warehouse building with a paved driveway and parking lot, installation of low impact development (LID) measures as shown on the site plan, and other associated improvements. The subject property was previously developed and there are remains of an old foundation near the northwest corner of the property. There is an existing gravel driveway that runs east-west along the southern portion of the property that provides access to the adjacent properties to the east. The majority or the site is wooded with some grassed areas along the perimeter of the property. The proposed building will be located on the northern side of the property along Buck Hill Road. The topography generally slopes away from the building and toward the proposed stormwater management basin. The underlying soils within the watershed consist of Agawam fine sandy loam, Canton & Charlton fine sandy loam and Canton-Chatfield Complex (all of which are NRCS hydrologic soil group 'B'). The wetlands area on the property was identified as Agawam fine sandy loam based on NRCS soil mapping, however, NRCS hydrologic soil group ‘D’ was used for design due to its saturated condition. The proposed project includes several BMP and LID techniques and measures to mitigate impacts of stormwater runoff and reduce the pollutant content of stormwater discharge. The proposed methods include, but are not limited to: breaking up areas of impervious surfaces and avoid concentrated point discharges, encouraging overland flow by using open swales and curbless driveway and parking areas, inhibiting erosion by using pre-formed scour holes at pipe outfalls, minimizing the removal of existing trees and introducing new landscaping and wetland plantings, maintaining existing topography and flow paths and promoting infiltration and groundwater recharge by utilizing stone aprons along the downgradient edges of the parking lot. The NRCS TR-55 methodology was utilized to evaluate existing and proposed stormwater runoff conditions with the AutoCAD embedded HydraFlow Hydrographs computer program. The times of concentration were computed using the TR-55 methodology as recommended by the ConnDOT Drainage Manual. The Town of Old Saybrook recommends using the 24-hour NRCS Type III rainfall distribution up to the 25-year storm for designing the drainage system. All rainfall amounts used in this analysis were taken from the Hydrometeorological Design Studies Center of the National Oceanic and Atmospheric Administration (NOAA) National Weather Service and published in NOAA Atlas 14 Volume 10: Precipitation-Frequency Atlas of the United States, Northeastern States, last revised on September 30, 2015. Refer to the plan entitled “Drainage Area Map” (Revised 8/24/2020) enclosed within this report for all watershed information.
Page 2 of 2 Included with this report are HydraFlow supporting computations and hydrographs for the existing conditions and proposed conditions. Detailed summaries of the computational results for the 2, 10, 25, 50 and 100-year storms are also included. The design point used was the inlet end of the existing culvert under Spencer Plain Road. The results indicate that the peak rate of runoff will remain constant for the 2-year storm, will slightly decrease for the 10-year through 50-year storms and will slightly increase for the 100-year storm. The volume of runoff will increase for the 2-year through 100-year storms. Due to shallow groundwater on site, all excess stormwater volume cannot be feasibly dissipated on site however we have included LID measures to offset and mitigate increased volumes such as promoting overland flow, use of grassed swales, a stone underdrain and pavement edge aprons, and minimizing use of curbing, pipe, and drainage structures. Also, the drainage computational model conservatively assumes that there will be no exfiltration from the stormwater management basin.
The Water Quality Volume (WQV) provided for the overall site exceeds the minimum WQV required for the watershed area. The WQV provided in the forebay of the stormwater management basin equals the WQV required for the developed sub-watershed area that will drain to the stormwater management basin. The stormwater management basin is proposed to capture, attenuate and enhance the runoff generated from the proposed site improvements. The outlet control structure will meter the rate of runoff to equal to or less than the existing conditions for the 2-year through 50-year storms. The basin will have approximately 13 inches of freeboard during the 100-year storm. Additionally, assuming the orifices in the outlet control structure are clogged, a minimum of 12 inches of freeboard is still provided. Refer to the attached summary tables for tabulated results for peak rates of runoff, volume, WQV, and water surface elevations for the pre- and post-development conditions. Based on the specific site parameters and soil conditions of the subject site i.e. shallow groundwater, ledge, topography, etc., it is not feasible to fully mitigate increases in runoff volume, however, with the implementation of multiple LID measures and matching or decreasing the peak rates of runoff for up to the 50-year storm, it is our opinion that the proposed site drainage is well balanced. Additionally, several measures have been implemented to enhance stormwater quality as well such as pavement edge aprons, swales, catch basin sump, pre-formed scour holes, stormwater management basin planted with herbaceous wetland plants, etc.
DRAINAGE SUMMARY
DATE:
JULY 15, 2020
SHEET NO.:
1
DS-1
of 2
SCALE:
N/A
DRAWN BY:
RG
CHKD BY:
JW
DWG. NO.:
PLAN PREPARED BY:
INDIGO LAND DESIGN, LLC
JOSEPH WREN, P.E.
CT REG. NO. 21090
40 ELM STREET, 2ND FLOOR
OLD SAYBROOK, CT 06475
PHONE: (860) 388-9343
FAX: (860) 391-8854
PREPARED FOR JOHN MUIR
92 SPENCER PLAIN ROAD -- MAP 46 LOT 16
OLD SAYBROOK, CONNECTICUT
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VOLUME OF RUNOFF
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STORM
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VOLUME OF RUNOFF (CF)
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EXISTING
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PROPOSED
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2-YEAR
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14,324
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22,362
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10-YEAR
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38,576
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50,648
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25-YEAR
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56,775
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70,825
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50-YEAR
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71,323
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86,634
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100-YEAR
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87,706
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104,209
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PEAK RATE OF RUNOFF
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STORM
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PEAK RATE OF RUNOFF (CFS)
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EXISTING
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PROPOSED
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2-YEAR
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1.9
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1.9
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10-YEAR
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6.3
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6.0
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25-YEAR
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9.7
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9.5
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50-YEAR
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12.3
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12.0
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100-YEAR
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15.3
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16.3
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WATER SURFACE ELEVATION IN PROPOSED BASINS
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STORM
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ELEVATION (NORMAL CONDITION - ORIFICES NOT CLOGGED)
NOTE: : 1. FOR DESIGN, THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE FOR DESIGN, THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE DESIGN, THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE DESIGN, THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE BOTTOM OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE OF THE BASIN WAS ASSUMED TO BE EQUAL TO THE THE BASIN WAS ASSUMED TO BE EQUAL TO THE THE BASIN WAS ASSUMED TO BE EQUAL TO THE BASIN WAS ASSUMED TO BE EQUAL TO THE BASIN WAS ASSUMED TO BE EQUAL TO THE WAS ASSUMED TO BE EQUAL TO THE WAS ASSUMED TO BE EQUAL TO THE ASSUMED TO BE EQUAL TO THE ASSUMED TO BE EQUAL TO THE TO BE EQUAL TO THE TO BE EQUAL TO THE BE EQUAL TO THE BE EQUAL TO THE EQUAL TO THE EQUAL TO THE TO THE TO THE THE THE INVERT ELEVATION OF THE 1" DIAMETER ORIFICE (ELEV. 21.20).
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DESCRIPTION
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DATE
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#
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BY
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REVISION'S PER TOWN ENGINEER'S COMMENTS
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6/17/2020
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1
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RG
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GENERAL REVISIONS
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8/24/2020
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2
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RG
WATER QUALITY VOLUME CALCULATIONS
DATE:
JULY 15, 2020
SHEET NO.:
2
WQV-1
of 2
SCALE:
N/A
DRAWN BY:
RG
CHKD BY:
JW
DWG. NO.:
PLAN PREPARED BY:
INDIGO LAND DESIGN, LLC
JOSEPH WREN, P.E.
CT REG. NO. 21090
40 ELM STREET, 2ND FLOOR
OLD SAYBROOK, CT 06475
PHONE: (860) 388-9343
FAX: (860) 391-8854
PREPARED FOR JOHN MUIR
92 SPENCER PLAIN ROAD -- MAP 46 LOT 16
OLD SAYBROOK, CONNECTICUT
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REFERENCE: "SECTION 7.4.1: WATER QUALITY VOLUME (WQV)" OF THE 2004 CONNECTICUT STORMWATER QUALITY MANUAL BY THE CONNECTICUT DEPARTMENT OF ENVIRONMENTAL PROTECTION FIRST INCH OF RAINFALL WQV = (1")(R)(A) / 12 WHERE: R = 0.05 + 0.009 x % IMPERVIOUS R = 0.05 + 0.009 x % IMPERVIOUS A = DRAINAGE AREA IN ACRES
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WATER QUALITY VOLUME (WQV) DATA
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SUB- WATERSHED
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AREA (AC.)
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I (%)
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R (IN.)
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WQV (AC.-FT.)
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WQV (CU. FT.)
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A
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1.280
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65.1
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0.636
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0.068
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2,953
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WQV REQUIRED (MIN.) =
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2,953
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WQV PROVIDED (WITHIN BASIN FOREBAY) =
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3,000±
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NOTE: THE WQV PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE : THE WQV PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE THE WQV PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE THE WQV PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE WQV PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE WQV PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE PROVIDED WITHIN THE BASIN FOREBAY EXCEEDS THE WITHIN THE BASIN FOREBAY EXCEEDS THE WITHIN THE BASIN FOREBAY EXCEEDS THE THE BASIN FOREBAY EXCEEDS THE THE BASIN FOREBAY EXCEEDS THE BASIN FOREBAY EXCEEDS THE BASIN FOREBAY EXCEEDS THE FOREBAY EXCEEDS THE FOREBAY EXCEEDS THE EXCEEDS THE EXCEEDS THE THE THE MINIMUM WQV REQUIRED.
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DESCRIPTION
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DATE
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#
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BY
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REVISION'S PER TOWN ENGINEER'S COMMENTS
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6/17/2020
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1
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RG
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GENERAL REVISIONS
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8/24/2020
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2
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RG
PLAN PREPARED BY:
INDIGO LAND DESIGN, LLC
JOSEPH WREN, P.E.
CT REG. NO. 21090
40 ELM STREET, 2ND FLOOR
OLD SAYBROOK, CT 06475
PHONE: (860) 388-9343
FAX: (860) 391-8854
EXISTING DRAINAGE
COMPUTATIONS
7-15-2020
PREPARED FOR JOHN MUIR
92 SPENCER PLAIN ROAD
MAP 46 LOT 16
OLD SAYBROOK, CONNECTICUT
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DESCRIPTION
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DATE
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#
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BY
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REVISION'S PER TOWN ENGINEER'S COMMENTS
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6/17/2020
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1
AutoCAD SHX Text
RG
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GENERAL REVISIONS
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8/24/2020
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2
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RG
Hydraflow Table of Contents Existing (FINAL).gpw
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020
Watershed Model Schematic...................................................................................... 1
Hydrograph Return Period Recap............................................................................. 2
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Storage / Discharge TableStage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Totalft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
0.00 0 21.20 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.08 177 21.28 0.01 ic 0.01 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0050.16 354 21.36 0.01 ic 0.01 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0090.24 531 21.44 0.01 ic 0.01 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0120.32 709 21.52 0.01 ic 0.01 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0140.40 886 21.60 0.02 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0150.48 1,063 21.68 0.02 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0170.56 1,240 21.76 0.02 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0190.64 1,417 21.84 0.02 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0200.72 1,594 21.92 0.02 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0210.80 1,772 22.00 0.02 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0230.90 2,149 22.10 0.03 ic 0.02 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0241.00 2,527 22.20 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0251.10 2,905 22.30 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0271.20 3,283 22.40 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0281.30 3,660 22.50 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0291.40 4,038 22.60 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0301.50 4,416 22.70 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0311.60 4,794 22.80 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0321.70 5,171 22.90 0.03 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0331.80 5,549 23.00 0.04 ic 0.03 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0341.90 6,121 23.10 0.04 ic 0.04 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0352.00 6,692 23.20 0.04 ic 0.04 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0362.10 7,264 23.30 0.04 ic 0.04 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0372.20 7,836 23.40 0.04 ic 0.04 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.0382.30 8,407 23.50 0.15 ic 0.04 ic 0.11 ic --- 0.00 0.00 --- --- --- --- 0.1462.40 8,979 23.60 0.35 ic 0.04 ic 0.30 ic --- 0.00 0.00 --- --- --- --- 0.3432.50 9,550 23.70 0.61 ic 0.04 ic 0.56 ic --- 0.00 0.00 --- --- --- --- 0.5982.60 10,122 23.80 0.83 ic 0.04 ic 0.78 ic --- 0.00 0.00 --- --- --- --- 0.8142.70 10,694 23.90 0.97 ic 0.04 ic 0.93 ic --- 0.00 0.00 --- --- --- --- 0.9662.80 11,265 24.00 1.10 ic 0.04 ic 1.06 ic --- 0.00 0.00 --- --- --- --- 1.0962.90 11,965 24.10 1.21 ic 0.04 ic 1.17 ic --- 0.00 0.00 --- --- --- --- 1.2133.00 12,665 24.20 1.33 oc 0.04 ic 1.28 ic --- 0.00 0.00 --- --- --- --- 1.3183.10 13,365 24.30 1.80 oc 0.04 ic 1.37 ic --- 0.35 0.00 --- --- --- --- 1.7643.20 14,065 24.40 3.31 oc 0.04 ic 1.47 ic --- 1.81 0.00 --- --- --- --- 3.3143.30 14,765 24.50 5.48 oc 0.03 ic 1.55 ic --- 3.90 0.00 --- --- --- --- 5.4843.40 15,465 24.60 8.03 ic 0.03 ic 1.55 ic --- 6.46 0.00 --- --- --- --- 8.031
Continues on next page...
9
Basin
Stage / Storage / Discharge TableStage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Totalft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
3.50 16,165 24.70 9.49 ic 0.01 ic 0.87 ic --- 8.61 s 0.00 --- --- --- --- 9.4943.60 16,866 24.80 9.89 ic 0.01 ic 0.67 ic --- 9.21 s 0.00 --- --- --- --- 9.8883.70 17,566 24.90 10.17 ic 0.01 ic 0.54 ic --- 9.61 s 0.00 --- --- --- --- 10.163.80 18,266 25.00 10.39 ic 0.01 ic 0.46 ic --- 9.93 s 0.00 --- --- --- --- 10.393.85 18,701 25.05 10.50 ic 0.01 ic 0.42 ic --- 10.07 s 0.29 --- --- --- --- 10.793.90 19,137 25.10 10.59 ic 0.01 ic 0.39 ic --- 10.19 s 0.82 --- --- --- --- 11.413.95 19,573 25.15 10.69 ic 0.01 ic 0.37 ic --- 10.32 s 1.51 --- --- --- --- 12.204.00 20,008 25.20 10.78 ic 0.01 ic 0.34 ic --- 10.42 s 2.33 --- --- --- --- 13.104.05 20,444 25.25 10.87 ic 0.01 ic 0.32 ic --- 10.54 s 3.25 --- --- --- --- 14.124.10 20,880 25.30 10.96 ic 0.00 ic 0.30 ic --- 10.64 s 4.27 --- --- --- --- 15.224.15 21,316 25.35 11.04 ic 0.00 ic 0.29 ic --- 10.75 s 5.38 --- --- --- --- 16.424.20 21,751 25.40 11.13 ic 0.00 ic 0.27 ic --- 10.84 s 6.58 --- --- --- --- 17.694.25 22,187 25.45 11.21 ic 0.00 ic 0.26 ic --- 10.94 s 7.85 --- --- --- --- 19.054.30 22,623 25.50 11.29 ic 0.00 ic 0.25 ic --- 11.04 s 9.19 --- --- --- --- 20.48
...End
Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020
Hyd. No. 4
Combined
Hydrograph type = Combine Peak discharge = 1.938 cfsStorm frequency = 2 yrs Time to peak = 750 minTime interval = 3 min Hyd. volume = 22,362 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Storage / Discharge TableStage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Totalft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
Stage / Storage / Discharge TableStage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Totalft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
3.50 16,165 24.70 9.29 ic 0.00 0.00 --- 9.29 s 0.00 --- --- --- --- 9.2913.60 16,866 24.80 9.83 ic 0.00 0.00 --- 9.83 s 0.00 --- --- --- --- 9.8253.70 17,566 24.90 10.14 ic 0.00 0.00 --- 10.13 s 0.00 --- --- --- --- 10.133.80 18,266 25.00 10.38 ic 0.00 0.00 --- 10.37 s 0.00 --- --- --- --- 10.373.85 18,701 25.05 10.48 ic 0.00 0.00 --- 10.48 s 0.29 --- --- --- --- 10.773.90 19,137 25.10 10.58 ic 0.00 0.00 --- 10.58 s 0.82 --- --- --- --- 11.403.95 19,573 25.15 10.68 ic 0.00 0.00 --- 10.68 s 1.51 --- --- --- --- 12.194.00 20,008 25.20 10.77 ic 0.00 0.00 --- 10.77 s 2.33 --- --- --- --- 13.104.05 20,444 25.25 10.86 ic 0.00 0.00 --- 10.86 s 3.25 --- --- --- --- 14.114.10 20,880 25.30 10.95 ic 0.00 0.00 --- 10.95 s 4.27 --- --- --- --- 15.224.15 21,316 25.35 11.04 ic 0.00 0.00 --- 11.04 s 5.38 --- --- --- --- 16.424.20 21,751 25.40 11.12 ic 0.00 0.00 --- 11.12 s 6.58 --- --- --- --- 17.704.25 22,187 25.45 11.21 ic 0.00 0.00 --- 11.19 s 7.85 --- --- --- --- 19.044.30 22,623 25.50 11.29 ic 0.00 0.00 --- 11.28 s 9.19 --- --- --- --- 20.47
...End
Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020
Hyd. No. 4
Combined
Hydrograph type = Combine Peak discharge = 1.906 cfsStorm frequency = 2 yrs Time to peak = 750 minTime interval = 3 min Hyd. volume = 13,230 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac
10
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CombinedHyd. No. 4 -- 2 Year
Hyd No. 4 Hyd No. 2 Hyd No. 3
Hydrograph Summary Report11
Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph
No. type flow interval Peak volume hyd(s) elevation strge used Description