Indigo Land Design, LLC 860.388.9343 Phone 40 Elm Street, 2nd Floor 860.391.8854 Fax Old Saybrook, CT 06475 jwren@Indigo-Land.com 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.

Drainage Report 92 Spencer Plain Road

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

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

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

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

2 - YearSummary Report......................................................................................................................... 3Hydrograph Reports................................................................................................................... 4

Hydrograph No. 1, SCS Runoff, Watershed A.......................................................................... 4TR-55 Tc Worksheet............................................................................................................ 5

10 - YearSummary Report......................................................................................................................... 6Hydrograph Reports................................................................................................................... 7

Hydrograph No. 1, SCS Runoff, Watershed A.......................................................................... 7

25 - YearSummary Report......................................................................................................................... 8Hydrograph Reports................................................................................................................... 9

Hydrograph No. 1, SCS Runoff, Watershed A.......................................................................... 9

50 - YearSummary Report....................................................................................................................... 10Hydrograph Reports................................................................................................................. 11

Hydrograph No. 1, SCS Runoff, Watershed A........................................................................ 11

100 - YearSummary Report....................................................................................................................... 12Hydrograph Reports................................................................................................................. 13

Hydrograph No. 1, SCS Runoff, Watershed A........................................................................ 13

IDF Report.................................................................................................................. 14

Watershed A

1

Watershed Model SchematicHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Project: Existing (FINAL).gpw Wednesday, 07 / 15 / 2020

Hyd. Origin Description

Legend

1 SCS Runoff Watershed A

Hydrograph Return Period Recap2

Hyd. Hydrograph Inflow Peak Outflow (cfs) Hydrograph

No. type hyd(s) Description

(origin) 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

1 SCS Runoff ------ ------- 1.942 ------- ------- 6.341 9.651 12.32 15.30 Watershed A

Proj. file: Existing (FINAL).gpw Wednesday, 07 / 15 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph Summary Report3

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 1.942 3 753 14,324 ------ ------ ------ Watershed A

Existing (FINAL).gpw Return Period: 2 Year Wednesday, 07 / 15 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020

Hyd. No. 1

Watershed A

Hydrograph type = SCS Runoff Peak discharge = 1.942 cfsStorm frequency = 2 yrs Time to peak = 753 minTime interval = 3 min Hyd. volume = 14,324 cuftDrainage area = 6.546 ac Curve number = 62Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 3.45 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

4

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0.00 0.00

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Watershed AHyd. No. 1 -- 2 Year

Hyd No. 1

TR55 Tc Worksheet5

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hyd. No. 1

Watershed A

Description A B C Totals

Sheet FlowManning's n-value = 0.600 0.600 0.240Flow length (ft) = 58.0 56.0 36.0Two-year 24-hr precip. (in) = 3.45 3.45 3.45Land slope (%) = 4.00 16.60 1.90

Travel Time (min) = 14.02 + 7.72 + 6.20 = 27.93

Shallow Concentrated FlowFlow length (ft) = 468.00 0.00 0.00Watercourse slope (%) = 6.20 0.00 0.00Surface description = Unpaved Unpaved PavedAverage velocity (ft/s) =4.02 0.00 0.00

Travel Time (min) = 1.94 + 0.00 + 0.00 = 1.94

Channel FlowX sectional flow area (sqft) = 110.00 0.00 0.00Wetted perimeter (ft) = 112.00 0.00 0.00Channel slope (%) = 0.40 0.00 0.00Manning's n-value = 0.120 0.015 0.015Velocity (ft/s) =0.78

0.000.00

Flow length (ft) ({0})226.0 0.0 0.0

Travel Time (min) = 4.85 + 0.00 + 0.00 = 4.85

Total Travel Time, Tc .............................................................................. 34.70 min

Hydrograph Summary Report6

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 6.341 3 747 38,576 ------ ------ ------ Watershed A

Existing (FINAL).gpw Return Period: 10 Year Wednesday, 07 / 15 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020

Hyd. No. 1

Watershed A

Hydrograph type = SCS Runoff Peak discharge = 6.341 cfsStorm frequency = 10 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 38,576 cuftDrainage area = 6.546 ac Curve number = 62Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 5.25 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

7

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Watershed AHyd. No. 1 -- 10 Year

Hyd No. 1

Hydrograph Summary Report8

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 9.651 3 744 56,775 ------ ------ ------ Watershed A

Existing (FINAL).gpw Return Period: 25 Year Wednesday, 07 / 15 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020

Hyd. No. 1

Watershed A

Hydrograph type = SCS Runoff Peak discharge = 9.651 cfsStorm frequency = 25 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 56,775 cuftDrainage area = 6.546 ac Curve number = 62Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 6.37 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

9

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Watershed AHyd. No. 1 -- 25 Year

Hyd No. 1

Hydrograph Summary Report10

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 12.32 3 744 71,323 ------ ------ ------ Watershed A

Existing (FINAL).gpw Return Period: 50 Year Wednesday, 07 / 15 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020

Hyd. No. 1

Watershed A

Hydrograph type = SCS Runoff Peak discharge = 12.32 cfsStorm frequency = 50 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 71,323 cuftDrainage area = 6.546 ac Curve number = 62Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 7.20 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

11

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0.00 0.00

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6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

14.00 14.00

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Watershed AHyd. No. 1 -- 50 Year

Hyd No. 1

Hydrograph Summary Report12

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 15.30 3 744 87,706 ------ ------ ------ Watershed A

Existing (FINAL).gpw Return Period: 100 Year Wednesday, 07 / 15 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020

Hyd. No. 1

Watershed A

Hydrograph type = SCS Runoff Peak discharge = 15.30 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 87,706 cuftDrainage area = 6.546 ac Curve number = 62Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 8.09 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

13

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3.00 3.00

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Time (min)

Watershed AHyd. No. 1 -- 100 Year

Hyd No. 1

Hydraflow Rainfall Report14

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Wednesday, 07 / 15 / 2020

Return Intensity-Duration-Frequency Equation Coefficients (FHA)Period

(Yrs) B D E (N/A)

1 0.0000 0.0000 0.0000 --------

2 30.1225 6.6000 0.7676 --------

3 0.0000 0.0000 0.0000 --------

5 52.3308 9.8000 0.8367 --------

10 54.7383 10.8000 0.8016 --------

25 101.9813 15.8000 0.8971 --------

50 98.1551 15.7000 0.8577 --------

100 106.5909 17.0000 0.8462 --------

File name: Connecticut 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 4.59 3.49 2.85 2.43 2.13 1.90 1.72 1.58 1.46 1.36 1.27 1.20

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 5.49 4.30 3.57 3.06 2.69 2.40 2.17 1.99 1.84 1.71 1.60 1.50

10 5.99 4.81 4.04 3.51 3.11 2.80 2.55 2.35 2.18 2.03 1.91 1.80

25 6.70 5.52 4.71 4.12 3.66 3.30 3.01 2.76 2.56 2.38 2.23 2.10

50 7.30 6.06 5.20 4.57 4.09 3.70 3.38 3.12 2.90 2.71 2.54 2.40

100 7.79 6.55 5.68 5.02 4.51 4.10 3.76 3.48 3.24 3.04 2.86 2.70

Tc = time in minutes. Values may exceed 60.

Rainfall Precipitation Table (in)

s\rgladstone\Desktop\Projects\2020\2020-590 John Muir - 92 Spencer Plain Rd - OS\Drainage\92 SPR Precip Data.pcp

StormDistribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

SCS 24-hour 2.85 3.45 0.00 4.43 5.25 6.37 7.20 8.09

SCS 6-Hr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

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

PROPOSED DRAINAGE

COMPUTATIONS

7-15-2020

NORMAL CONDITION -

ORIFICES NOT CLOGGED

Hydraflow Table of Contents Proposed (REV2 - UNCLOGGED).gpw

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Watershed Model Schematic...................................................................................... 1

Hydrograph Return Period Recap............................................................................. 2

2 - YearSummary Report......................................................................................................................... 3Hydrograph Reports................................................................................................................... 4

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................... 4Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................... 5

TR-55 Tc Worksheet............................................................................................................ 6Hydrograph No. 3, Reservoir, Basins....................................................................................... 7

Pond Report - Basin............................................................................................................ 8Hydrograph No. 4, Combine, Combined................................................................................ 10

10 - YearSummary Report....................................................................................................................... 11Hydrograph Reports................................................................................................................. 12

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 12Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 13Hydrograph No. 3, Reservoir, Basins..................................................................................... 14Hydrograph No. 4, Combine, Combined................................................................................ 15

25 - YearSummary Report....................................................................................................................... 16Hydrograph Reports................................................................................................................. 17

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 17Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 18Hydrograph No. 3, Reservoir, Basins..................................................................................... 19Hydrograph No. 4, Combine, Combined................................................................................ 20

50 - YearSummary Report....................................................................................................................... 21Hydrograph Reports................................................................................................................. 22

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 22Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 23Hydrograph No. 3, Reservoir, Basins..................................................................................... 24Hydrograph No. 4, Combine, Combined................................................................................ 25

100 - YearSummary Report....................................................................................................................... 26Hydrograph Reports................................................................................................................. 27

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 27Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 28Hydrograph No. 3, Reservoir, Basins..................................................................................... 29Hydrograph No. 4, Combine, Combined................................................................................ 30

IDF Report.................................................................................................................. 31

Subwatershed A Subwatershed B

Basins

Combined

1

Watershed Model SchematicHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Project: Proposed (REV2 - UNCLOGGED).gpw Monday, 08 / 24 / 2020

Hyd. Origin Description

Legend

1 SCS Runoff Subwatershed A

2 SCS Runoff Subwatershed B

3 Reservoir Basins

4 Combine Combined

Hydrograph Return Period Recap2

Hyd. Hydrograph Inflow Peak Outflow (cfs) Hydrograph

No. type hyd(s) Description

(origin) 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

1 SCS Runoff ------ ------- 2.331 ------- ------- 4.206 5.384 6.256 7.188 Subwatershed A

2 SCS Runoff ------ ------- 1.906 ------- ------- 5.678 8.469 10.68 13.14 Subwatershed B

3 Reservoir 1 ------- 0.038 ------- ------- 0.588 1.134 1.605 3.182 Basins

4 Combine 2, 3 ------- 1.938 ------- ------- 5.967 9.497 12.04 16.32 Combined

Proj. file: Proposed (REV2 - UNCLOGGED).gpw Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph Summary Report3

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 2.331 3 729 9,167 ------ ------ ------ Subwatershed A

2 SCS Runoff 1.906 3 750 13,230 ------ ------ ------ Subwatershed B

3 Reservoir 0.038 3 1383 9,133 1 23.34 7,494 Basins

4 Combine 1.938 3 750 22,362 2, 3 ------ ------ Combined

Proposed (REV2 - UNCLOGGED).gpw Return Period: 2 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 2.331 cfsStorm frequency = 2 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 9,167 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 3.45 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

4

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Subwatershed AHyd. No. 1 -- 2 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 1.906 cfsStorm frequency = 2 yrs Time to peak = 750 minTime interval = 3 min Hyd. volume = 13,230 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 3.45 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

5

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Subwatershed BHyd. No. 2 -- 2 Year

Hyd No. 2

TR55 Tc Worksheet6

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hyd. No. 2

Subwatershed B

Description A B C Totals

Sheet FlowManning's n-value = 0.600 0.600 0.240Flow length (ft) = 58.0 56.0 36.0Two-year 24-hr precip. (in) = 3.45 3.45 3.45Land slope (%) = 4.00 16.60 1.90

Travel Time (min) = 14.02 + 7.72 + 6.20 = 27.93

Shallow Concentrated FlowFlow length (ft) = 468.00 0.00 0.00Watercourse slope (%) = 6.20 0.00 0.00Surface description = Unpaved Unpaved UnpavedAverage velocity (ft/s) =4.02 0.00 0.00

Travel Time (min) = 1.94 + 0.00 + 0.00 = 1.94

Channel FlowX sectional flow area (sqft) = 110.00 0.00 0.00Wetted perimeter (ft) = 112.00 0.00 0.00Channel slope (%) = 0.40 0.00 0.00Manning's n-value = 0.120 0.015 0.015Velocity (ft/s) =0.78

0.000.00

Flow length (ft) ({0})226.0 0.0 0.0

Travel Time (min) = 4.85 + 0.00 + 0.00 = 4.85

Total Travel Time, Tc .............................................................................. 34.70 min

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 0.038 cfsStorm frequency = 2 yrs Time to peak = 1383 minTime interval = 3 min Hyd. volume = 9,133 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 23.34 ftReservoir name = Basin Max. Storage = 7,494 cuft

Storage Indication method used.

7

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Time (min)

BasinsHyd. No. 3 -- 2 Year

Hyd No. 3 Hyd No. 1 Total storage used = 7,494 cuft

Pond Report 8

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Pond No. 1 - Basin

Pond DataContours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 21.20 ft

Stage / Storage TableStage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)

0.00 21.20 1,961 0 00.80 22.00 2,468 1,772 1,7721.80 23.00 5,087 3,778 5,5492.80 24.00 6,345 5,716 11,2653.80 25.00 7,656 7,001 18,2664.30 25.50 9,772 4,357 22,623

Culvert / Orifice Structures Weir Structures

[A] [B] [C] [PrfRsr] [A] [B] [C] [D]

Rise (in) = 15.00 1.00 4.00 Inactive

Span (in) = 15.00 1.00 12.00 0.00

No. Barrels = 1 1 1 0

Invert El. (ft) = 21.20 21.20 23.40 0.00

Length (ft) = 21.00 1.00 1.00 0.00

Slope (%) = 0.95 0.10 0.10 n/a

N-Value = .013 .013 .013 n/a

Orifice Coeff. = 0.60 0.60 0.60 0.60

Multi-Stage = n/a Yes Yes No

Crest Len (ft) = 12.00 10.00 Inactive Inactive

Crest El. (ft) = 24.25 25.00 0.00 0.00

Weir Coeff. = 2.60 2.60 3.33 3.33

Weir Type = Broad Broad --- ---

Multi-Stage = Yes No No No

Exfil.(in/hr) = 0.000 (by Contour)

TW Elev. (ft) = 0.00

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

10

0 540 1080 1620 2160 2700 3240 3780 4320 4860 5400

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)

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

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 4.206 3 729 16,726 ------ ------ ------ Subwatershed A

2 SCS Runoff 5.678 3 747 33,956 ------ ------ ------ Subwatershed B

3 Reservoir 0.588 3 774 16,692 1 23.70 9,529 Basins

4 Combine 5.967 3 750 50,648 2, 3 ------ ------ Combined

Proposed (REV2 - UNCLOGGED).gpw Return Period: 10 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 4.206 cfsStorm frequency = 10 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 16,726 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 5.25 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

12

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Q (cfs)

0.00 0.00

1.00 1.00

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3.00 3.00

4.00 4.00

5.00 5.00

Q (cfs)

Time (min)

Subwatershed AHyd. No. 1 -- 10 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 5.678 cfsStorm frequency = 10 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 33,956 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 5.25 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

13

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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)

Subwatershed BHyd. No. 2 -- 10 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 0.588 cfsStorm frequency = 10 yrs Time to peak = 774 minTime interval = 3 min Hyd. volume = 16,692 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 23.70 ftReservoir name = Basin Max. Storage = 9,529 cuft

Storage Indication method used.

14

0 720 1440 2160 2880 3600 4320 5040 5760 6480 7200

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

Q (cfs)

Time (min)

BasinsHyd. No. 3 -- 10 Year

Hyd No. 3 Hyd No. 1 Total storage used = 9,529 cuft

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 = 5.967 cfsStorm frequency = 10 yrs Time to peak = 750 minTime interval = 3 min Hyd. volume = 50,648 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

15

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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)

CombinedHyd. No. 4 -- 10 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydrograph Summary Report16

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 5.384 3 729 21,618 ------ ------ ------ Subwatershed A

2 SCS Runoff 8.469 3 744 49,242 ------ ------ ------ Subwatershed B

3 Reservoir 1.134 3 759 21,584 1 24.03 11,494 Basins

4 Combine 9.497 3 747 70,825 2, 3 ------ ------ Combined

Proposed (REV2 - UNCLOGGED).gpw Return Period: 25 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 5.384 cfsStorm frequency = 25 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 21,618 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 6.37 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

17

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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)

Subwatershed AHyd. No. 1 -- 25 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 8.469 cfsStorm frequency = 25 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 49,242 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 6.37 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

18

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Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

Q (cfs)

Time (min)

Subwatershed BHyd. No. 2 -- 25 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 1.134 cfsStorm frequency = 25 yrs Time to peak = 759 minTime interval = 3 min Hyd. volume = 21,584 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.03 ftReservoir name = Basin Max. Storage = 11,494 cuft

Storage Indication method used.

19

0 540 1080 1620 2160 2700 3240 3780 4320 4860 5400 5940 6480

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)

BasinsHyd. No. 3 -- 25 Year

Hyd No. 3 Hyd No. 1 Total storage used = 11,494 cuft

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 = 9.497 cfsStorm frequency = 25 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 70,825 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

20

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8.00 8.00

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Q (cfs)

Time (min)

CombinedHyd. No. 4 -- 25 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydrograph Summary Report21

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 6.256 3 729 25,295 ------ ------ ------ Subwatershed A

2 SCS Runoff 10.68 3 744 61,373 ------ ------ ------ Subwatershed B

3 Reservoir 1.605 3 756 25,261 1 24.26 13,115 Basins

4 Combine 12.04 3 747 86,634 2, 3 ------ ------ Combined

Proposed (REV2 - UNCLOGGED).gpw Return Period: 50 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 6.256 cfsStorm frequency = 50 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 25,295 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 7.20 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

22

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Q (cfs)

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3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)

Subwatershed AHyd. No. 1 -- 50 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 10.68 cfsStorm frequency = 50 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 61,373 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 7.20 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

23

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Q (cfs)

0.00 0.00

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8.00 8.00

10.00 10.00

12.00 12.00

Q (cfs)

Time (min)

Subwatershed BHyd. No. 2 -- 50 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 1.605 cfsStorm frequency = 50 yrs Time to peak = 756 minTime interval = 3 min Hyd. volume = 25,261 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.26 ftReservoir name = Basin Max. Storage = 13,115 cuft

Storage Indication method used.

24

0 540 1080 1620 2160 2700 3240 3780 4320 4860 5400 5940

Q (cfs)

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2.00 2.00

3.00 3.00

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5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)

BasinsHyd. No. 3 -- 50 Year

Hyd No. 3 Hyd No. 1 Total storage used = 13,115 cuft

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 = 12.04 cfsStorm frequency = 50 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 86,634 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

25

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Q (cfs)

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8.00 8.00

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12.00 12.00

14.00 14.00

Q (cfs)

Time (min)

CombinedHyd. No. 4 -- 50 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydrograph Summary Report26

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 7.188 3 729 29,273 ------ ------ ------ Subwatershed A

2 SCS Runoff 13.14 3 744 74,971 ------ ------ ------ Subwatershed B

3 Reservoir 3.182 3 744 29,239 1 24.39 14,005 Basins

4 Combine 16.32 3 744 104,209 2, 3 ------ ------ Combined

Proposed (REV2 - UNCLOGGED).gpw Return Period: 100 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 7.188 cfsStorm frequency = 100 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 29,273 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 8.09 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

27

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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)

Subwatershed AHyd. No. 1 -- 100 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 13.14 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 74,971 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 8.09 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

28

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Q (cfs)

0.00 0.00

2.00 2.00

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6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

14.00 14.00

Q (cfs)

Time (min)

Subwatershed BHyd. No. 2 -- 100 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 3.182 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 29,239 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.39 ftReservoir name = Basin Max. Storage = 14,005 cuft

Storage Indication method used.

29

0 360 720 1080 1440 1800 2160 2520 2880 3240

Q (cfs)

0.00 0.00

2.00 2.00

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6.00 6.00

8.00 8.00

Q (cfs)

Time (min)

BasinsHyd. No. 3 -- 100 Year

Hyd No. 3 Hyd No. 1 Total storage used = 14,005 cuft

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 = 16.32 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 104,209 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

30

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Q (cfs)

0.00 0.00

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12.00 12.00

15.00 15.00

18.00 18.00

Q (cfs)

Time (min)

CombinedHyd. No. 4 -- 100 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydraflow Rainfall Report31

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Return Intensity-Duration-Frequency Equation Coefficients (FHA)Period

(Yrs) B D E (N/A)

1 0.0000 0.0000 0.0000 --------

2 30.1225 6.6000 0.7676 --------

3 0.0000 0.0000 0.0000 --------

5 52.3308 9.8000 0.8367 --------

10 54.7383 10.8000 0.8016 --------

25 101.9813 15.8000 0.8971 --------

50 98.1551 15.7000 0.8577 --------

100 106.5909 17.0000 0.8462 --------

File name: Connecticut 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 4.59 3.49 2.85 2.43 2.13 1.90 1.72 1.58 1.46 1.36 1.27 1.20

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 5.49 4.30 3.57 3.06 2.69 2.40 2.17 1.99 1.84 1.71 1.60 1.50

10 5.99 4.81 4.04 3.51 3.11 2.80 2.55 2.35 2.18 2.03 1.91 1.80

25 6.70 5.52 4.71 4.12 3.66 3.30 3.01 2.76 2.56 2.38 2.23 2.10

50 7.30 6.06 5.20 4.57 4.09 3.70 3.38 3.12 2.90 2.71 2.54 2.40

100 7.79 6.55 5.68 5.02 4.51 4.10 3.76 3.48 3.24 3.04 2.86 2.70

Tc = time in minutes. Values may exceed 60.

Rainfall Precipitation Table (in)

s\rgladstone\Desktop\Projects\2020\2020-590 John Muir - 92 Spencer Plain Rd - OS\Drainage\92 SPR Precip Data.pcp

StormDistribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

SCS 24-hour 2.85 3.45 0.00 4.43 5.25 6.37 7.20 8.09

SCS 6-Hr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

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

PROPOSED DRAINAGE

COMPUTATIONS

7-15-2020

ASSUMING ORIFICES

ARE CLOGGED

Hydraflow Table of Contents Proposed (REV2 - CLOGGED).gpw

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Watershed Model Schematic...................................................................................... 1

Hydrograph Return Period Recap............................................................................. 2

2 - YearSummary Report......................................................................................................................... 3Hydrograph Reports................................................................................................................... 4

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................... 4Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................... 5

TR-55 Tc Worksheet............................................................................................................ 6Hydrograph No. 3, Reservoir, Basins....................................................................................... 7

Pond Report - Basin............................................................................................................ 8Hydrograph No. 4, Combine, Combined................................................................................ 10

10 - YearSummary Report....................................................................................................................... 11Hydrograph Reports................................................................................................................. 12

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 12Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 13Hydrograph No. 3, Reservoir, Basins..................................................................................... 14Hydrograph No. 4, Combine, Combined................................................................................ 15

25 - YearSummary Report....................................................................................................................... 16Hydrograph Reports................................................................................................................. 17

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 17Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 18Hydrograph No. 3, Reservoir, Basins..................................................................................... 19Hydrograph No. 4, Combine, Combined................................................................................ 20

50 - YearSummary Report....................................................................................................................... 21Hydrograph Reports................................................................................................................. 22

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 22Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 23Hydrograph No. 3, Reservoir, Basins..................................................................................... 24Hydrograph No. 4, Combine, Combined................................................................................ 25

100 - YearSummary Report....................................................................................................................... 26Hydrograph Reports................................................................................................................. 27

Hydrograph No. 1, SCS Runoff, Subwatershed A.................................................................. 27Hydrograph No. 2, SCS Runoff, Subwatershed B.................................................................. 28Hydrograph No. 3, Reservoir, Basins..................................................................................... 29Hydrograph No. 4, Combine, Combined................................................................................ 30

IDF Report.................................................................................................................. 31

Subwatershed A Subwatershed B

Basins

Combined

1

Watershed Model SchematicHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Project: Proposed (REV2 - CLOGGED).gpw Monday, 08 / 24 / 2020

Hyd. Origin Description

Legend

1 SCS Runoff Subwatershed A

2 SCS Runoff Subwatershed B

3 Reservoir Basins

4 Combine Combined

Hydrograph Return Period Recap2

Hyd. Hydrograph Inflow Peak Outflow (cfs) Hydrograph

No. type hyd(s) Description

(origin) 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

1 SCS Runoff ------ ------- 2.331 ------- ------- 4.206 5.384 6.256 7.188 Subwatershed A

2 SCS Runoff ------ ------- 1.906 ------- ------- 5.678 8.469 10.68 13.14 Subwatershed B

3 Reservoir 1 ------- 0.000 ------- ------- 0.207 0.703 1.984 3.653 Basins

4 Combine 2, 3 ------- 1.906 ------- ------- 5.678 8.469 12.30 16.80 Combined

Proj. file: Proposed (REV2 - CLOGGED).gpw Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph Summary Report3

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 2.331 3 729 9,167 ------ ------ ------ Subwatershed A

2 SCS Runoff 1.906 3 750 13,230 ------ ------ ------ Subwatershed B

3 Reservoir 0.000 3 n/a 0 1 23.63 9,167 Basins

4 Combine 1.906 3 750 13,230 2, 3 ------ ------ Combined

Proposed (REV2 - CLOGGED).gpw Return Period: 2 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 2.331 cfsStorm frequency = 2 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 9,167 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 3.45 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

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Subwatershed AHyd. No. 1 -- 2 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 1.906 cfsStorm frequency = 2 yrs Time to peak = 750 minTime interval = 3 min Hyd. volume = 13,230 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 3.45 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

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Subwatershed BHyd. No. 2 -- 2 Year

Hyd No. 2

TR55 Tc Worksheet6

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hyd. No. 2

Subwatershed B

Description A B C Totals

Sheet FlowManning's n-value = 0.600 0.600 0.240Flow length (ft) = 58.0 56.0 36.0Two-year 24-hr precip. (in) = 3.45 3.45 3.45Land slope (%) = 4.00 16.60 1.90

Travel Time (min) = 14.02 + 7.72 + 6.20 = 27.93

Shallow Concentrated FlowFlow length (ft) = 468.00 0.00 0.00Watercourse slope (%) = 6.20 0.00 0.00Surface description = Unpaved Unpaved UnpavedAverage velocity (ft/s) =4.02 0.00 0.00

Travel Time (min) = 1.94 + 0.00 + 0.00 = 1.94

Channel FlowX sectional flow area (sqft) = 110.00 0.00 0.00Wetted perimeter (ft) = 112.00 0.00 0.00Channel slope (%) = 0.40 0.00 0.00Manning's n-value = 0.120 0.015 0.015Velocity (ft/s) =0.78

0.000.00

Flow length (ft) ({0})226.0 0.0 0.0

Travel Time (min) = 4.85 + 0.00 + 0.00 = 4.85

Total Travel Time, Tc .............................................................................. 34.70 min

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 0.000 cfsStorm frequency = 2 yrs Time to peak = n/aTime interval = 3 min Hyd. volume = 0 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 23.63 ftReservoir name = Basin Max. Storage = 9,167 cuft

Storage Indication method used.

7

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BasinsHyd. No. 3 -- 2 Year

Hyd No. 3 Hyd No. 1 Total storage used = 9,167 cuft

Pond Report 8

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Pond No. 1 - Basin

Pond DataContours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 21.20 ft

Stage / Storage TableStage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)

0.00 21.20 1,961 0 00.80 22.00 2,468 1,772 1,7721.80 23.00 5,087 3,778 5,5492.80 24.00 6,345 5,716 11,2653.80 25.00 7,656 7,001 18,2664.30 25.50 9,772 4,357 22,623

Culvert / Orifice Structures Weir Structures

[A] [B] [C] [PrfRsr] [A] [B] [C] [D]

Rise (in) = 15.00 Inactive Inactive Inactive

Span (in) = 15.00 1.00 12.00 0.00

No. Barrels = 1 1 1 0

Invert El. (ft) = 21.20 21.20 23.40 0.00

Length (ft) = 21.00 1.00 1.00 0.00

Slope (%) = 0.95 0.10 0.10 n/a

N-Value = .013 .013 .013 n/a

Orifice Coeff. = 0.60 0.60 0.60 0.60

Multi-Stage = n/a Yes Yes No

Crest Len (ft) = 12.00 10.00 Inactive Inactive

Crest El. (ft) = 24.25 25.00 0.00 0.00

Weir Coeff. = 2.60 2.60 3.33 3.33

Weir Type = Broad Broad --- ---

Multi-Stage = Yes No No No

Exfil.(in/hr) = 0.000 (by Contour)

TW Elev. (ft) = 0.00

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 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.16 354 21.36 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.24 531 21.44 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.32 709 21.52 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.40 886 21.60 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.48 1,063 21.68 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.56 1,240 21.76 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.64 1,417 21.84 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.72 1,594 21.92 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.80 1,772 22.00 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0000.90 2,149 22.10 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.00 2,527 22.20 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.10 2,905 22.30 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.20 3,283 22.40 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.30 3,660 22.50 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.40 4,038 22.60 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.50 4,416 22.70 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.60 4,794 22.80 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.70 5,171 22.90 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.80 5,549 23.00 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0001.90 6,121 23.10 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.00 6,692 23.20 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.10 7,264 23.30 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.20 7,836 23.40 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.30 8,407 23.50 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.40 8,979 23.60 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.50 9,550 23.70 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.60 10,122 23.80 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.70 10,694 23.90 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.80 11,265 24.00 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0002.90 11,965 24.10 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0003.00 12,665 24.20 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.0003.10 13,365 24.30 0.35 ic 0.00 0.00 --- 0.35 0.00 --- --- --- --- 0.3493.20 14,065 24.40 1.83 oc 0.00 0.00 --- 1.81 0.00 --- --- --- --- 1.8133.30 14,765 24.50 3.90 oc 0.00 0.00 --- 3.90 0.00 --- --- --- --- 3.9003.40 15,465 24.60 6.46 oc 0.00 0.00 --- 6.46 0.00 --- --- --- --- 6.460

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 9.29 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

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 4.206 3 729 16,726 ------ ------ ------ Subwatershed A

2 SCS Runoff 5.678 3 747 33,956 ------ ------ ------ Subwatershed B

3 Reservoir 0.207 3 930 4,059 1 24.26 13,080 Basins

4 Combine 5.678 3 747 38,015 2, 3 ------ ------ Combined

Proposed (REV2 - CLOGGED).gpw Return Period: 10 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 4.206 cfsStorm frequency = 10 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 16,726 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 5.25 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

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Subwatershed AHyd. No. 1 -- 10 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 5.678 cfsStorm frequency = 10 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 33,956 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 5.25 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

13

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Subwatershed BHyd. No. 2 -- 10 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 0.207 cfsStorm frequency = 10 yrs Time to peak = 930 minTime interval = 3 min Hyd. volume = 4,059 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.26 ftReservoir name = Basin Max. Storage = 13,080 cuft

Storage Indication method used.

14

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BasinsHyd. No. 3 -- 10 Year

Hyd No. 3 Hyd No. 1 Total storage used = 13,080 cuft

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 = 5.678 cfsStorm frequency = 10 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 38,015 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

15

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CombinedHyd. No. 4 -- 10 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydrograph Summary Report16

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 5.384 3 729 21,618 ------ ------ ------ Subwatershed A

2 SCS Runoff 8.469 3 744 49,242 ------ ------ ------ Subwatershed B

3 Reservoir 0.703 3 777 8,950 1 24.32 13,534 Basins

4 Combine 8.469 3 744 58,192 2, 3 ------ ------ Combined

Proposed (REV2 - CLOGGED).gpw Return Period: 25 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 5.384 cfsStorm frequency = 25 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 21,618 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 6.37 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

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Subwatershed AHyd. No. 1 -- 25 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 8.469 cfsStorm frequency = 25 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 49,242 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 6.37 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

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Subwatershed BHyd. No. 2 -- 25 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 0.703 cfsStorm frequency = 25 yrs Time to peak = 777 minTime interval = 3 min Hyd. volume = 8,950 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.32 ftReservoir name = Basin Max. Storage = 13,534 cuft

Storage Indication method used.

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BasinsHyd. No. 3 -- 25 Year

Hyd No. 3 Hyd No. 1 Total storage used = 13,534 cuft

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 = 8.469 cfsStorm frequency = 25 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 58,192 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

20

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CombinedHyd. No. 4 -- 25 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydrograph Summary Report21

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 6.256 3 729 25,295 ------ ------ ------ Subwatershed A

2 SCS Runoff 10.68 3 744 61,373 ------ ------ ------ Subwatershed B

3 Reservoir 1.984 3 753 12,628 1 24.41 14,123 Basins

4 Combine 12.30 3 747 74,001 2, 3 ------ ------ Combined

Proposed (REV2 - CLOGGED).gpw Return Period: 50 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 6.256 cfsStorm frequency = 50 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 25,295 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 7.20 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

22

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Q (cfs)

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5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)

Subwatershed AHyd. No. 1 -- 50 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 10.68 cfsStorm frequency = 50 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 61,373 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 7.20 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

23

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Q (cfs)

0.00 0.00

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Q (cfs)

Time (min)

Subwatershed BHyd. No. 2 -- 50 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 1.984 cfsStorm frequency = 50 yrs Time to peak = 753 minTime interval = 3 min Hyd. volume = 12,628 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.41 ftReservoir name = Basin Max. Storage = 14,123 cuft

Storage Indication method used.

24

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Q (cfs)

0.00 0.00

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7.00 7.00

Q (cfs)

Time (min)

BasinsHyd. No. 3 -- 50 Year

Hyd No. 3 Hyd No. 1 Total storage used = 14,123 cuft

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 = 12.30 cfsStorm frequency = 50 yrs Time to peak = 747 minTime interval = 3 min Hyd. volume = 74,001 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

25

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Q (cfs)

Time (min)

CombinedHyd. No. 4 -- 50 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydrograph Summary Report26

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph

No. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 7.188 3 729 29,273 ------ ------ ------ Subwatershed A

2 SCS Runoff 13.14 3 744 74,971 ------ ------ ------ Subwatershed B

3 Reservoir 3.653 3 744 16,606 1 24.49 14,683 Basins

4 Combine 16.80 3 744 91,576 2, 3 ------ ------ Combined

Proposed (REV2 - CLOGGED).gpw Return Period: 100 Year Monday, 08 / 24 / 2020

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 1

Subwatershed A

Hydrograph type = SCS Runoff Peak discharge = 7.188 cfsStorm frequency = 100 yrs Time to peak = 729 minTime interval = 3 min Hyd. volume = 29,273 cuftDrainage area = 1.280 ac Curve number = 85Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 10.00 minTotal precip. = 8.09 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

27

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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)

Subwatershed AHyd. No. 1 -- 100 Year

Hyd No. 1

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 2

Subwatershed B

Hydrograph type = SCS Runoff Peak discharge = 13.14 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 74,971 cuftDrainage area = 5.266 ac Curve number = 64Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 34.70 minTotal precip. = 8.09 in Distribution = Type IIIStorm duration = 24 hrs Shape factor = 484

28

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Q (cfs)

0.00 0.00

2.00 2.00

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8.00 8.00

10.00 10.00

12.00 12.00

14.00 14.00

Q (cfs)

Time (min)

Subwatershed BHyd. No. 2 -- 100 Year

Hyd No. 2

Hydrograph ReportHydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Hyd. No. 3

Basins

Hydrograph type = Reservoir Peak discharge = 3.653 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 16,606 cuftInflow hyd. No. = 1 - Subwatershed A Max. Elevation = 24.49 ftReservoir name = Basin Max. Storage = 14,683 cuft

Storage Indication method used.

29

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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)

BasinsHyd. No. 3 -- 100 Year

Hyd No. 3 Hyd No. 1 Total storage used = 14,683 cuft

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 = 16.80 cfsStorm frequency = 100 yrs Time to peak = 744 minTime interval = 3 min Hyd. volume = 91,576 cuftInflow hyds. = 2, 3 Contrib. drain. area = 5.266 ac

30

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Q (cfs)

Time (min)

CombinedHyd. No. 4 -- 100 Year

Hyd No. 4 Hyd No. 2 Hyd No. 3

Hydraflow Rainfall Report31

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Monday, 08 / 24 / 2020

Return Intensity-Duration-Frequency Equation Coefficients (FHA)Period

(Yrs) B D E (N/A)

1 0.0000 0.0000 0.0000 --------

2 30.1225 6.6000 0.7676 --------

3 0.0000 0.0000 0.0000 --------

5 52.3308 9.8000 0.8367 --------

10 54.7383 10.8000 0.8016 --------

25 101.9813 15.8000 0.8971 --------

50 98.1551 15.7000 0.8577 --------

100 106.5909 17.0000 0.8462 --------

File name: Connecticut 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 4.59 3.49 2.85 2.43 2.13 1.90 1.72 1.58 1.46 1.36 1.27 1.20

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 5.49 4.30 3.57 3.06 2.69 2.40 2.17 1.99 1.84 1.71 1.60 1.50

10 5.99 4.81 4.04 3.51 3.11 2.80 2.55 2.35 2.18 2.03 1.91 1.80

25 6.70 5.52 4.71 4.12 3.66 3.30 3.01 2.76 2.56 2.38 2.23 2.10

50 7.30 6.06 5.20 4.57 4.09 3.70 3.38 3.12 2.90 2.71 2.54 2.40

100 7.79 6.55 5.68 5.02 4.51 4.10 3.76 3.48 3.24 3.04 2.86 2.70

Tc = time in minutes. Values may exceed 60.

Rainfall Precipitation Table (in)

s\rgladstone\Desktop\Projects\2020\2020-590 John Muir - 92 Spencer Plain Rd - OS\Drainage\92 SPR Precip Data.pcp

StormDistribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

SCS 24-hour 2.85 3.45 0.00 4.43 5.25 6.37 7.20 8.09

SCS 6-Hr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00