06-BUC871015D_H&H Report 03-15-2024.pdf

STORM WATER CALCULATIONS

For:

DICK SLOAN WETLAND

BUC871015D

Iowa Department of Agriculture and Land Stewardship

Brandon, Iowa

S-H PROJECT # 2142204320

March 15, 2024

I hereby certify that the portion of this engineering document was prepared by me or under my direct personal supervision. I am a duly licensed Professional Engineer under the laws of the State of Iowa.

Signature: ____________________________________________

Name: Dan Jensen, P.E. .

Date: _________________________

My license renewal date is December 31, 2025.

Pages, sheets, or divisions covered by this certification: ________

_Stormwater Report and Attachments __________________

Prepared by:

4125 Westown Parkway, Suite 100 – West Des Moines, Iowa 50266

(515) 223-8104

03/15/2024

TABLE OF CONTENTS

1. Project Summary

2. Drainage Area Map

3. Soil Map/Land Characteristics

4. Hydrology & Hydraulic Model Output

PROJECT SUMMARY

GENERAL

The proposed work includes construction of a wetland to the north of Brandon, IA. The location can be more specifically described as the SE ¼ of Section 15 and SW ¼ of Section 16, Township 87 North, Range 10 West of the Fifth Principal meridian, Buchanan County, Iowa. A dam and sheet pile weir will be constructed to impound water for the wetland. A drawdown structure on the dam will allow for pool elevation control.

DESIGN STANDARDS, ANALYSIS, AND ASSUMPTIONS

The design procedures and guidelines were obtained from the following resources:

1. “National Engineering Handbook 4 – Hydrology”

2. “NRCS Practice Standard 656, 378, 410” (as applicable)

3. “IDNR Chapter 73 – Approval, Construction, Use, Maintenance, Removal, Inspections, and Safety of Dams”

DESIGN CRITERIA AND GUIDELINES

WATER CONTROL STRUCTURE – Low Flow Spillway The water control structure is a 48” circular CMP riser equipped with stop logs for water elevation control. The stop logs will be maintained approximately 1 inch below the crest of the sheet pile to provide passage of low flow. An 18’’ CMP will enter the structure from the pool area. An 18” CMP discharge pipe will run east and daylight into the proposed plunge pool then into the existing stream to the east.

The maximum embankment height is approximately 7 feet, which is well below the threshold of the 25 feet listed in IDNR Chapter 73. However, the dam has a storage of 66.27 acre-feet at the top of dam, which is greater than the 50 acre-feet threshold spelled out in IDNR Chapter 73. For this reason, Chapter 73 applies. The structure is classified as a low hazard dam according to IDNR Chapter 73 because failure of the dam would result in no probable loss of human life, low economic losses, and low public damages. The area downstream of the embankment is rural and predominately agricultural lands.

PRINCIPAL SPILLWAY

The principal spillway consists of an 80’ wide steel sheet pile structure in the embankment at an elevation of 879.50’. The following standards were used to design the principal spillway: NRCS 378, NRCS 410, NRCS 656, and IDNR Chapter 73. A summary of the design criteria is listed below:

NRCS 378:

• Principal Spillway Capacity - 25-year, 24-hour storm

NRCS 410:

• Principal Spillway Capacity - 10-year, 24-hour storm

NRCS 656:

• Principal Spillway Capacity - 25-year, 24-hour storm without overtopping embankment, refers to NRCS 378 for all other spillway requirements.

IDNR Chapter 73:

• Spillway Design Flood - 10-year, 24-hour storm

Using the more conservative of these standards, the wetland was designed for the principal spillway to pass the 25-year, 24-hour storm, according to NRCS 378. Based on NRCS 378, the spillway design storm shall be the 25-year, 24-hour storm and the design shall be passed without the wetland pool elevation passing the auxiliary spillway. This equates to a storm producing a rainfall depth of 5.60”. The 25-year, 24-hour storm will produce a discharge of 788.3 cfs through the principal spillway and a peak water surface elevation of 881.42’. The auxiliary spillway elevation is set at 881.50’.

FREEBOARD DESIGN

The auxiliary spillway consists of a 150’ wide spillway in the embankment at an elevation of 881.50’.

The following standards were used to design the auxiliary spillway: NRCS 378, NRCS 410, NRCS 656, and IDNR Chapter 73. A summary of the design criteria is listed below:

NRCS 378:

• Auxiliary Spillway Capacity - 50-year, 24-hour storm

NRCS 410:

• Total Capacity - 25-year, 24-hour storm

NRCS 656:

• Refer to NRCS 378 IDNR Chapter 73:

• Freeboard Design Flood - 100-year, 24-hour storm

Using the more conservative of these standards, the wetland was designed for the auxiliary spillway to pass the 100-year, 24-hour storm, according to IDNR Chapter 73. Based on IDNR Chapter 73, the freeboard design storm shall be the 100-year, 24-hour storm and the design shall be passed without the wetland pool elevation overtopping the embankment. This equates to a storm producing a rainfall depth of 7.50”. The 100-year, 24-hour storm will produce a discharge of 1226.0 cfs through the principal spillway and a peak water surface elevation of 881.94’. The top of dam elevation is set at 882.50’.

WATER QUALITY IMPROVEMENT

The wetland drawdown was designed to meet NRCS 656 requirements. Wetland will drawdown and return to design operating levels within 48 hours after a 10-year, 24-hour storm. The 10-year, 24-hour storm produced a 19-hour drawdown frequency. To promote emergent vegetation, 50% of the pool area (51% for this design) shall have depths from 0-24 inches.

SLOPE DESIGN

Side slopes were designed to meet NRCS 656 requirements which reference NRCS 378. Slopes designed with a ratio if three horizontal to one vertical (3:1) or flatter.

EMBANKMENT DESIGN

Per NRCS 378, top width required for dams with total heights less than 15 feet require a minimum of 10 feet top width. A 12-foot top width was chosen for this design. Minimum settlement of 5% of the total height of the dam was accounted for on the final construction elevation of the dam. This equates to a final construction elevation of 882.85’ ([7 feet x 0.05] + 882.50). Per NRSC 656, an additional 1 foot of overfill was added to the embankment design 50 feet on each side of the principal spillway (elevation of 883.50’).

IMPOUNDMENT LIFE

The Impoundment life was calculated using estimated sediment delivery and NRCS standard total erosion rate estimates. The erosion rates are based on the Average Annual Soil Erosion by Water on Cropland and CRP Land, 1982, published by USDA and revised in December 2000. This indicated that the erosion rates for the area ranged from 3 to 5 tons per acre per year. Furthermore, sediment delivery was based on NRCS FOTG “Erosion & Sediment Delivery”, (Chart I: Estimated sediment delivery for landform regions). The chart indicated a sediment delivery percentage of approximately 19% for a 631-acre drainage area located in the Iowan Surface Landform. Finally, the estimated sediment storage is based on 6” below normal pool storage volume which equates to 14.4 ac-ft in the wetland pool and 3.01 ac-ft in the forebays.

Based on the assumed soil erosion rate (4 T/Ac/yr), delivery ratio (19%), a sediment unit weight of 100 PCF, and sediment capture rate of 70% of delivered sediment, approximately 335.7 tons of sediment per year (6,714 CF) is anticipated to be retained in the wetland. With a total sediment capacity of 17.4 ac-ft, this equates to an expected impoundment life of 113 years.

GEOTECHNICAL INVESTIGATION AND EVALUATION

A geotechnical investigation has been completed by Terracon for the proposed wetland. A report compiling the findings and associated recommendations is included in the appendix of this report.

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NORTHERN DRAINAGE AREA

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Hydrologic Soil Group—Buchanan County, Iowa

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

3/12/2024

0582300 582400 582500 582600 582700 582800 582900 583000 583100 583200 583300 583400 583500 583600 583700 583800 583900

582300 582400 582500 582600 582700 582800 582900 583000 583100 583200 583300 583400 583500 583600 583700 583800 583900

42° 21' 5'' N

' 3 '' W

42° 21' 5'' N

8'

9' ' W

42° 20' 29'' N

' 3 '' W

42° 20' 29'' N

8'

9' ' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 15N WGS84 0 350 700 1400 2100

Feet 0 100 200 400 600

Meters Map Scale: 1:7,770 if printed on A landscape (11" x 8.5") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Lines A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Points A

A/D

B

B/D

C

C/D

D

Not rated or not available

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:15,800.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Buchanan County, Iowa Survey Area Data: Version 29, Sep 12, 2023

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Jul 20, 2022—Aug 4, The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Hydrologic Soil Group—Buchanan County, Iowa

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

3/12/2024

Hydrologic Soil Group

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

41 Sparta loamy sand, 0 to 2 percent slopes

A 0.7 0.3%

41B Sparta loamy sand, 2 to 5 percent slopes

A 7.9 3.2%

83B Kenyon loam, 2 to 5 percent slopes

C 52.9 21.2%

83C Kenyon loam, 5 to 9 percent slopes

C 1.4 0.6%

83C2 Kenyon loam, 5 to 9 percent slopes, eroded

C 15.5 6.2%

84 Clyde clay loam, 0 to 3 percent slopes

C/D 56.2 22.5%

175 Dickinson fine sandy loam, 0 to 2 percent slopes

A 0.6 0.3%

198B Floyd loam, 1 to 4 percent slopes

B/D 4.9 1.9%

391B Clyde-Floyd complex, 1 to 4 percent slopes

C/D 70.7 28.3%

399 Readlyn silt loam, 1 to 3 percent slopes

C/D 0.0 0.0%

407B Schley loam, 1 to 4 percent slopes

B/D 10.9 4.4%

408B Olin sandy loam, 2 to 5 percent slopes

C 28.2 11.3%

Totals for Area of Interest 249.9 100.0%

Hydrologic Soil Group—Buchanan County, Iowa

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture.

These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Hydrologic Soil Group—Buchanan County, Iowa

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Scenario: Post-Development 10 year

Northern Drainage Area

Western Drainage Area

Buchanan Wetland

Wetland Outlet

Wetland Outfall

Wetland Outlet Structure

Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-16663/12/2024

PondPack CONNECT Edition [10.02.00.01]Bentley Systems, Inc. Haestad Methods Solution CenterBuchananCo_SloanWetland_Section 3_MSE4.ppc

Northern Drainage Area

Western Drainage Area

Buchanan Wetland

Wetland Outlet

Wetland Outfall

Wetland Outlet Structure

Pondpack Diagram

54Addition Summary, 100 years (Post-Development 100 year)

53Addition Summary, 50 years (Post-Development 50 year)

52Addition Summary, 25 years (Post-Development 25 year)

51Addition Summary, 10 years (Post-Development 10 year)

Wetland Outfall

49Unit Hydrograph Summary, 100 years (Post-Development 100 year)

47Unit Hydrograph Summary, 50 years (Post-Development 50 year)

45Unit Hydrograph Summary, 25 years (Post-Development 25 year)

43Unit Hydrograph Summary, 10 years (Post-Development 10 year)

Western Drainage Area

41Unit Hydrograph Summary, 100 years (Post-Development 100 year)

39Unit Hydrograph Summary, 50 years (Post-Development 50 year)

37Unit Hydrograph Summary, 25 years (Post-Development 25 year)

35Unit Hydrograph Summary, 10 years (Post-Development 10 year)

Northern Drainage Area

32Time of Concentration Calculations, 100 years (Post- Development 100 year)

29Time of Concentration Calculations, 50 years (Post- Development 50 year)

26Time of Concentration Calculations, 25 years (Post- Development 25 year)

23Time of Concentration Calculations, 10 years (Post- Development 10 year)

Western Drainage Area

20Time of Concentration Calculations, 100 years (Post- Development 100 year)

17Time of Concentration Calculations, 50 years (Post- Development 50 year)

14Time of Concentration Calculations, 25 years (Post- Development 25 year)

11Time of Concentration Calculations, 10 years (Post- Development 10 year)

Northern Drainage Area

9Time-Depth Curve, 50 years (Post-Development 50 year)

7Time-Depth Curve, 25 years (Post-Development 25 year)

5Time-Depth Curve, 100 years (Post-Development 100 year)

3Time-Depth Curve, 10 years (Post-Development 10 year)

MSE4

1Master Network Summary

Table of Contents

Table of Contents

105Outlet Input Data, 100 years (Post-Development 100 year)

103Outlet Input Data, 50 years (Post-Development 50 year)

101Outlet Input Data, 25 years (Post-Development 25 year)

99Outlet Input Data, 10 years (Post-Development 10 year)

80' Sheet Pile with Aux

98Elevation-Area Volume Curve, 100 years (Post-Development 100 year)

97Elevation-Area Volume Curve, 50 years (Post-Development 50 year)

96Elevation-Area Volume Curve, 25 years (Post-Development 25 year)

95Elevation-Area Volume Curve, 10 years (Post-Development 10 year)

Buchanan Wetland

90Time vs. Volume, 100 years (Post-Development 100 year)

85Time vs. Volume, 50 years (Post-Development 50 year)

80Time vs. Volume, 25 years (Post-Development 25 year)

75Time vs. Volume, 10 years (Post-Development 10 year)

Buchanan Wetland

70Time vs. Elevation, 100 years (Post-Development 100 year)

65Time vs. Elevation, 50 years (Post-Development 50 year)

60Time vs. Elevation, 25 years (Post-Development 25 year)

55Time vs. Elevation, 10 years (Post-Development 10 year)

Buchanan Wetland (OUT)

BUC871015D_StormwaterReport Subsection: Master Network Summary

Catchments Summary Peak Flow

(ft³/s) Time to Peak

(hours) Hydrograph

Volume (ac-ft)

Return Event

(years)

ScenarioLabel

285.1512.90057.33310Post-Development 10 year

Western Drainage Area

407.0712.90080.94025Post-Development 25 year

Western Drainage Area

514.3912.900101.93550Post-Development 50 year

Western Drainage Area

633.1612.900125.399100Post-Development 100 year

Western Drainage Area

270.1313.10058.03110Post-Development 10 year

Northern Drainage Area

383.9113.10081.92625Post-Development 25 year

Northern Drainage Area

484.5912.950103.17750Post-Development 50 year

Northern Drainage Area

597.1512.950126.928100Post-Development 100 year

Northern Drainage Area

Node Summary Peak Flow

(ft³/s) Time to Peak

(hours) Hydrograph

Volume (ac-ft)

Return Event

(years)

ScenarioLabel

465.4513.400115.36410Post-Development 10 year

Wetland Outfall

675.5913.350162.86625Post-Development 25 year

Wetland Outfall

894.9313.300205.11250Post-Development 50 year

Wetland Outfall

1,123.2613.250252.327100Post-Development 100 year

Wetland Outfall

Pond Summary Maximum

Pond Storage (ac-ft)

Maximum Water

Surface Elevation

(ft)

Peak Flow (ft³/s)

Time to Peak (hours)

Hydrograph Volume (ac-ft)

Return Event

(years)

ScenarioLabel

(N/A)(N/A)552.6813.050115.36410Post- Development 10 year

Buchanan Wetland (IN)

38.809881.01465.4513.400115.36410Post- Development 10 year

Buchanan Wetland

(OUT)

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3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

BuchananCo_SloanWetland_Section 3_MSE4.ppc

Subsection: Master Network Summary

Pond Summary Maximum

Pond Storage (ac-ft)

Maximum Water

Surface Elevation

(ft)

Peak Flow (ft³/s)

Time to Peak (hours)

Hydrograph Volume (ac-ft)

Return Event

(years)

ScenarioLabel

(N/A)(N/A)788.2612.950162.86625Post- Development 25 year

Buchanan Wetland (IN)

45.668881.42675.5913.350162.86625Post- Development 25 year

Buchanan Wetland

(OUT)

(N/A)(N/A)996.0512.950205.11250Post- Development 50 year

Buchanan Wetland (IN)

50.528881.70894.9313.300205.11250Post- Development 50 year

Buchanan Wetland

(OUT)

(N/A)(N/A)1,226.0212.950252.327100Post- Development 100 year

Buchanan Wetland (IN)

55.173881.941,123.2613.250252.327100Post- Development 100 year

Buchanan Wetland

(OUT)

Page 2 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: MSE4

Return Event: 10 yearsSubsection: Time-Depth Curve

Time-Depth Curve: 10 year

10 year Label hours0.000Start Time hours0.100Increment hours24.000End Time years10Return Event

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

0.00.00.00.00.00.000 0.00.00.00.00.00.500 0.00.00.00.00.01.000 0.00.00.00.00.01.500 0.10.10.10.10.12.000 0.10.10.10.10.12.500 0.10.10.10.10.13.000 0.10.10.10.10.13.500 0.20.20.20.20.14.000 0.20.20.20.20.24.500 0.20.20.20.20.25.000 0.30.30.30.20.25.500 0.30.30.30.30.36.000 0.30.30.30.30.36.500 0.40.40.40.40.47.000 0.40.40.40.40.47.500 0.50.50.50.50.48.000 0.50.50.50.50.58.500 0.60.60.60.60.59.000 0.70.70.70.60.69.500 0.80.80.70.70.710.000 0.90.90.90.80.810.500 1.21.11.11.01.011.000 1.71.51.41.31.211.500 3.23.12.92.72.112.000 3.53.43.43.33.312.500 3.73.63.63.63.513.000 3.83.73.73.73.713.500 3.83.83.83.83.814.000 3.93.93.93.93.914.500 4.04.04.03.93.915.000 4.04.04.04.04.015.500 4.14.14.14.04.016.000 4.14.14.14.14.116.500

Page 3 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: MSE4

Return Event: 10 yearsSubsection: Time-Depth Curve

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

4.24.24.14.14.117.000 4.24.24.24.24.217.500 4.24.24.24.24.218.000 4.34.34.34.24.218.500 4.34.34.34.34.319.000 4.34.34.34.34.319.500 4.44.44.34.34.320.000 4.44.44.44.44.420.500 4.44.44.44.44.421.000 4.44.44.44.44.421.500 4.44.44.44.44.422.000 4.54.54.44.44.422.500 4.54.54.54.54.523.000 4.54.54.54.54.523.500

(N/A)(N/A)(N/A)(N/A)4.524.000

Page 4 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Scenario: Post-Development 100 year Storm Event: 100 yearLabel: MSE4

Return Event: 100 yearsSubsection: Time-Depth Curve

Time-Depth Curve: 100 year

100 year Label hours0.000Start Time hours0.100Increment hours24.000End Time years100Return Event

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

0.00.00.00.00.00.000 0.00.00.00.00.00.500 0.10.10.00.00.01.000 0.10.10.10.10.11.500 0.10.10.10.10.12.000 0.20.10.10.10.12.500 0.20.20.20.20.23.000 0.20.20.20.20.23.500 0.30.30.30.30.24.000 0.30.30.30.30.34.500 0.40.40.40.40.35.000 0.40.40.40.40.45.500 0.50.50.50.50.56.000 0.60.60.60.50.56.500 0.60.60.60.60.67.000 0.70.70.70.70.77.500 0.80.80.80.80.78.000 0.90.90.90.80.88.500 1.01.01.00.90.99.000 1.21.11.11.11.09.500 1.31.31.21.21.210.000 1.61.51.41.41.310.500 1.91.81.81.71.611.000 2.92.62.32.22.011.500 5.35.14.94.63.512.000 5.85.75.65.55.412.500 6.16.06.05.95.913.000 6.36.26.26.26.113.500 6.46.46.46.36.314.000 6.56.56.56.56.414.500 6.66.66.66.66.615.000 6.76.76.76.76.715.500 6.86.86.86.86.716.000 6.96.96.86.86.816.500

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PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: MSE4

Return Event: 100 yearsSubsection: Time-Depth Curve

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

6.96.96.96.96.917.000 7.07.07.07.07.017.500 7.17.17.07.07.018.000 7.17.17.17.17.118.500 7.27.27.27.17.119.000 7.27.27.27.27.219.500 7.37.37.37.27.220.000 7.37.37.37.37.320.500 7.47.37.37.37.321.000 7.47.47.47.47.421.500 7.47.47.47.47.422.000 7.47.47.47.47.422.500 7.57.57.57.47.423.000 7.57.57.57.57.523.500

(N/A)(N/A)(N/A)(N/A)7.524.000

Page 6 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Scenario: Post-Development 25 year Storm Event: 25 yearLabel: MSE4

Return Event: 25 yearsSubsection: Time-Depth Curve

Time-Depth Curve: 25 year

25 year Label hours0.000Start Time hours0.100Increment hours24.000End Time years25Return Event

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

0.00.00.00.00.00.000 0.00.00.00.00.00.500 0.00.00.00.00.01.000 0.10.10.10.00.01.500 0.10.10.10.10.12.000 0.10.10.10.10.12.500 0.10.10.10.10.13.000 0.20.20.20.20.13.500 0.20.20.20.20.24.000 0.20.20.20.20.24.500 0.30.30.30.30.35.000 0.30.30.30.30.35.500 0.40.40.40.40.36.000 0.40.40.40.40.46.500 0.50.50.50.50.47.000 0.50.50.50.50.57.500 0.60.60.60.60.68.000 0.70.60.60.60.68.500 0.80.70.70.70.79.000 0.90.80.80.80.89.500 1.00.90.90.90.910.000 1.21.11.11.01.010.500 1.41.41.31.31.211.000 2.21.91.71.61.511.500 4.03.83.73.42.612.000 4.34.24.24.14.112.500 4.54.54.54.44.413.000 4.74.64.64.64.613.500 4.84.74.74.74.714.000 4.94.84.84.84.814.500 4.94.94.94.94.915.000 5.05.05.05.04.915.500 5.15.05.05.05.016.000 5.15.15.15.15.116.500

Page 7 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: MSE4

Return Event: 25 yearsSubsection: Time-Depth Curve

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

5.25.25.15.15.117.000 5.25.25.25.25.217.500 5.35.25.25.25.218.000 5.35.35.35.35.318.500 5.35.35.35.35.319.000 5.45.45.45.45.319.500 5.45.45.45.45.420.000 5.45.45.45.45.420.500 5.55.55.55.45.421.000 5.55.55.55.55.521.500 5.55.55.55.55.522.000 5.55.55.55.55.522.500 5.55.55.55.55.523.000 5.65.65.65.65.523.500

(N/A)(N/A)(N/A)(N/A)5.624.000

Page 8 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Scenario: Post-Development 50 year Storm Event: 50 yearLabel: MSE4

Return Event: 50 yearsSubsection: Time-Depth Curve

Time-Depth Curve: 50 year

50 year Label hours0.000Start Time hours0.100Increment hours24.000End Time years50Return Event

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

0.00.00.00.00.00.000 0.00.00.00.00.00.500 0.00.00.00.00.01.000 0.10.10.10.10.11.500 0.10.10.10.10.12.000 0.10.10.10.10.12.500 0.20.20.20.10.13.000 0.20.20.20.20.23.500 0.20.20.20.20.24.000 0.30.30.30.30.34.500 0.30.30.30.30.35.000 0.40.40.40.40.35.500 0.40.40.40.40.46.000 0.50.50.50.50.56.500 0.60.60.50.50.57.000 0.60.60.60.60.67.500 0.70.70.70.70.68.000 0.80.80.70.70.78.500 0.90.90.80.80.89.000 1.01.01.00.90.99.500 1.11.11.11.11.010.000 1.31.31.21.21.210.500 1.71.61.51.51.411.000 2.52.22.01.91.811.500 4.64.54.34.03.012.000 5.04.94.94.84.712.500 5.35.25.25.15.113.000 5.45.45.45.35.313.500 5.65.55.55.55.514.000 5.75.65.65.65.614.500 5.85.75.75.75.715.000 5.85.85.85.85.815.500 5.95.95.95.95.816.000 6.05.95.95.95.916.500

Page 9 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: MSE4

Return Event: 50 yearsSubsection: Time-Depth Curve

CUMULATIVE RAINFALL (in) Output Time Increment = 0.100 hours

Time on left represents time for first value in each row.

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Depth (in)

Time (hours)

6.06.06.06.06.017.000 6.16.16.06.06.017.500 6.16.16.16.16.118.000 6.26.26.26.16.118.500 6.26.26.26.26.219.000 6.36.36.26.26.219.500 6.36.36.36.36.320.000 6.36.36.36.36.320.500 6.46.46.46.36.321.000 6.46.46.46.46.421.500 6.46.46.46.46.422.000 6.46.46.46.46.422.500 6.56.56.56.56.423.000 6.56.56.56.56.523.500

(N/A)(N/A)(N/A)(N/A)6.524.000

Page 10 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Northern Drainage Area

Return Event: 10 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft8,148.00Hydraulic Length

77.000CN

ft/ft0.041Slope ft/s1.47Average Velocity hours1.538Segment Time of Concentration

Time of Concentration (Composite) hours1.538Time of Concentration (Composite)

Page 11 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Northern Drainage Area

Return Event: 10 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 13 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Northern Drainage Area

Return Event: 25 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft8,148.00Hydraulic Length

77.000CN

ft/ft0.041Slope ft/s1.47Average Velocity hours1.538Segment Time of Concentration

Time of Concentration (Composite) hours1.538Time of Concentration (Composite)

Page 14 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Northern Drainage Area

Return Event: 25 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 16 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Northern Drainage Area

Return Event: 50 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft8,148.00Hydraulic Length

77.000CN

ft/ft0.041Slope ft/s1.47Average Velocity hours1.538Segment Time of Concentration

Time of Concentration (Composite) hours1.538Time of Concentration (Composite)

Page 17 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Northern Drainage Area

Return Event: 50 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 19 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Northern Drainage Area

Return Event: 100 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft8,148.00Hydraulic Length

77.000CN

ft/ft0.041Slope ft/s1.47Average Velocity hours1.538Segment Time of Concentration

Time of Concentration (Composite) hours1.538Time of Concentration (Composite)

Page 20 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Northern Drainage Area

Return Event: 100 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 22 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Western Drainage Area

Return Event: 10 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft7,139.00Hydraulic Length

77.000CN

ft/ft0.040Slope ft/s1.42Average Velocity hours1.401Segment Time of Concentration

Time of Concentration (Composite) hours1.401Time of Concentration (Composite)

Page 23 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Western Drainage Area

Return Event: 10 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 25 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Western Drainage Area

Return Event: 25 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft7,139.00Hydraulic Length

77.000CN

ft/ft0.040Slope ft/s1.42Average Velocity hours1.401Segment Time of Concentration

Time of Concentration (Composite) hours1.401Time of Concentration (Composite)

Page 26 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Western Drainage Area

Return Event: 25 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 28 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Western Drainage Area

Return Event: 50 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft7,139.00Hydraulic Length

77.000CN

ft/ft0.040Slope ft/s1.42Average Velocity hours1.401Segment Time of Concentration

Time of Concentration (Composite) hours1.401Time of Concentration (Composite)

Page 29 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Western Drainage Area

Return Event: 50 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 31 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Western Drainage Area

Return Event: 100 yearsSubsection: Time of Concentration Calculations

Time of Concentration Results Segment #1: SCS Lag ft7,139.00Hydraulic Length

77.000CN

ft/ft0.040Slope ft/s1.42Average Velocity hours1.401Segment Time of Concentration

Time of Concentration (Composite) hours1.401Time of Concentration (Composite)

Page 32 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Western Drainage Area

Return Event: 100 yearsSubsection: Time of Concentration Calculations

==== SCS Lag

0.000877 * (Lf**0.8) * ((1000/CN)-9)**0.7) * (Sf**-0.5)Tc = Tc= Time of concentration, hours Lf= Flow length, feet CN= SCS Curve Number Sf= Slope, ft/ft

Where:

Page 34 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Northern Drainage Area

Return Event: 10 yearsSubsection: Unit Hydrograph Summary

10 yearStorm Event years10Return Event hours48.000Duration in4.5Depth hours1.538Time of Concentration (Composite) ft²13,825,072.80Area (User Defined) hours0.205Computational Time Increment hours13.124Time to Peak (Computed) ft³/s270.53Flow (Peak, Computed) hours0.050Output Increment hours13.100Time to Flow (Peak Interpolated Output) ft³/s270.13Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,825,072.80Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in2.2Cumulative Runoff Depth (Pervious) ac-ft58.038Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft58.031Volume

SCS Unit Hydrograph Parameters hours1.538Time of Concentration (Composite) hours0.205Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 35 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Northern Drainage Area

Return Event: 10 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s233.81Unit peak, qp hours1.025Unit peak time, Tp hours4.101Unit receding limb, Tr hours5.127Total unit time, Tb

Page 36 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Northern Drainage Area

Return Event: 25 yearsSubsection: Unit Hydrograph Summary

25 yearStorm Event years25Return Event hours48.000Duration in5.6Depth hours1.538Time of Concentration (Composite) ft²13,825,072.80Area (User Defined) hours0.205Computational Time Increment hours13.124Time to Peak (Computed) ft³/s384.07Flow (Peak, Computed) hours0.050Output Increment hours13.100Time to Flow (Peak Interpolated Output) ft³/s383.91Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,825,072.80Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in3.1Cumulative Runoff Depth (Pervious) ac-ft81.935Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft81.926Volume

SCS Unit Hydrograph Parameters hours1.538Time of Concentration (Composite) hours0.205Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 37 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Northern Drainage Area

Return Event: 25 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s233.81Unit peak, qp hours1.025Unit peak time, Tp hours4.101Unit receding limb, Tr hours5.127Total unit time, Tb

Page 38 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Northern Drainage Area

Return Event: 50 yearsSubsection: Unit Hydrograph Summary

50 yearStorm Event years50Return Event hours48.000Duration in6.5Depth hours1.538Time of Concentration (Composite) ft²13,825,072.80Area (User Defined) hours0.205Computational Time Increment hours12.919Time to Peak (Computed) ft³/s484.73Flow (Peak, Computed) hours0.050Output Increment hours12.950Time to Flow (Peak Interpolated Output) ft³/s484.59Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,825,072.80Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in3.9Cumulative Runoff Depth (Pervious) ac-ft103.189Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft103.177Volume

SCS Unit Hydrograph Parameters hours1.538Time of Concentration (Composite) hours0.205Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 39 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Northern Drainage Area

Return Event: 50 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s233.81Unit peak, qp hours1.025Unit peak time, Tp hours4.101Unit receding limb, Tr hours5.127Total unit time, Tb

Page 40 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Northern Drainage Area

Return Event: 100 yearsSubsection: Unit Hydrograph Summary

100 yearStorm Event years100Return Event hours48.000Duration in7.5Depth hours1.538Time of Concentration (Composite) ft²13,825,072.80Area (User Defined) hours0.205Computational Time Increment hours12.919Time to Peak (Computed) ft³/s597.71Flow (Peak, Computed) hours0.050Output Increment hours12.950Time to Flow (Peak Interpolated Output) ft³/s597.15Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,825,072.80Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in4.8Cumulative Runoff Depth (Pervious) ac-ft126.941Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft126.928Volume

SCS Unit Hydrograph Parameters hours1.538Time of Concentration (Composite) hours0.205Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 41 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Northern Drainage Area

Return Event: 100 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s233.81Unit peak, qp hours1.025Unit peak time, Tp hours4.101Unit receding limb, Tr hours5.127Total unit time, Tb

Page 42 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Western Drainage Area

Return Event: 10 yearsSubsection: Unit Hydrograph Summary

10 yearStorm Event years10Return Event hours48.000Duration in4.5Depth hours1.401Time of Concentration (Composite) ft²13,656,931.20Area (User Defined) hours0.187Computational Time Increment hours12.889Time to Peak (Computed) ft³/s285.28Flow (Peak, Computed) hours0.050Output Increment hours12.900Time to Flow (Peak Interpolated Output) ft³/s285.15Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,656,931.20Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in2.2Cumulative Runoff Depth (Pervious) ac-ft57.332Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft57.333Volume

SCS Unit Hydrograph Parameters hours1.401Time of Concentration (Composite) hours0.187Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 43 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Western Drainage Area

Return Event: 10 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s253.57Unit peak, qp hours0.934Unit peak time, Tp hours3.736Unit receding limb, Tr hours4.670Total unit time, Tb

Page 44 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Western Drainage Area

Return Event: 25 yearsSubsection: Unit Hydrograph Summary

25 yearStorm Event years25Return Event hours48.000Duration in5.6Depth hours1.401Time of Concentration (Composite) ft²13,656,931.20Area (User Defined) hours0.187Computational Time Increment hours12.889Time to Peak (Computed) ft³/s407.47Flow (Peak, Computed) hours0.050Output Increment hours12.900Time to Flow (Peak Interpolated Output) ft³/s407.07Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,656,931.20Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in3.1Cumulative Runoff Depth (Pervious) ac-ft80.939Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft80.940Volume

SCS Unit Hydrograph Parameters hours1.401Time of Concentration (Composite) hours0.187Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 45 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Western Drainage Area

Return Event: 25 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s253.57Unit peak, qp hours0.934Unit peak time, Tp hours3.736Unit receding limb, Tr hours4.670Total unit time, Tb

Page 46 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Western Drainage Area

Return Event: 50 yearsSubsection: Unit Hydrograph Summary

50 yearStorm Event years50Return Event hours48.000Duration in6.5Depth hours1.401Time of Concentration (Composite) ft²13,656,931.20Area (User Defined) hours0.187Computational Time Increment hours12.889Time to Peak (Computed) ft³/s515.06Flow (Peak, Computed) hours0.050Output Increment hours12.900Time to Flow (Peak Interpolated Output) ft³/s514.39Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,656,931.20Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in3.9Cumulative Runoff Depth (Pervious) ac-ft101.934Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft101.935Volume

SCS Unit Hydrograph Parameters hours1.401Time of Concentration (Composite) hours0.187Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 47 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 50 yearLabel: Western Drainage Area

Return Event: 50 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s253.57Unit peak, qp hours0.934Unit peak time, Tp hours3.736Unit receding limb, Tr hours4.670Total unit time, Tb

Page 48 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Western Drainage Area

Return Event: 100 yearsSubsection: Unit Hydrograph Summary

100 yearStorm Event years100Return Event hours48.000Duration in7.5Depth hours1.401Time of Concentration (Composite) ft²13,656,931.20Area (User Defined) hours0.187Computational Time Increment hours12.889Time to Peak (Computed) ft³/s634.13Flow (Peak, Computed) hours0.050Output Increment hours12.900Time to Flow (Peak Interpolated Output) ft³/s633.16Flow (Peak Interpolated Output)

Drainage Area

77.000SCS CN (Composite) ft²13,656,931.20Area (User Defined) in3.0Maximum Retention (Pervious) in0.6Maximum Retention (Pervious, 20 percent)

Cumulative Runoff in4.8Cumulative Runoff Depth (Pervious) ac-ft125.397Runoff Volume (Pervious)

Hydrograph Volume (Area under Hydrograph curve) ac-ft125.399Volume

SCS Unit Hydrograph Parameters hours1.401Time of Concentration (Composite) hours0.187Computational Time Increment

483.432Unit Hydrograph Shape Factor

0.749K Factor 1.670Receding/Rising, Tr/Tp

Page 49 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 100 yearLabel: Western Drainage Area

Return Event: 100 yearsSubsection: Unit Hydrograph Summary

SCS Unit Hydrograph Parameters ft³/s253.57Unit peak, qp hours0.934Unit peak time, Tp hours3.736Unit receding limb, Tr hours4.670Total unit time, Tb

Page 50 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 10 yearLabel: Wetland Outfall

Return Event: 10 yearsSubsection: Addition Summary

Summary for Hydrograph Addition at 'Wetland Outfall'

Upstream NodeUpstream Link Buchanan WetlandWetland Outlet

Node Inflows

Flow (Peak) (ft³/s)

Time to Peak (hours)

Volume (ac-ft)

ElementInflow Type

465.4513.400115.364Wetland OutletFlow (From) 465.4513.400115.364Wetland

Outfall Flow (In)

Page 51 of 10827 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/12/2024

PondPack CONNECT Edition [10.02.00.01]

Bentley Systems, Inc. Haestad Methods Solution Center

Storm Event: 25 yearLabel: Wetland Outfall

Return Event: 25 yearsSubsection: Addition Summary

Summary for Hydrograph Addition at 'Wetland Outfall'

Upstream NodeUpstream Link Buchanan WetlandWetland Outlet

Node Inflows

Flow (Peak) (ft³/s)

Time to Peak (hours)

Volume (ac-ft)

ElementInflow Type

675.5913.350162.866Wetla…