Storm Water Management

Calculations

Project:

BATH SENIOR LIFESTYLE CARE FACILITY Township of Bath

Summit County, Ohio

Prepared By:

TGC Engineering 1310 Sharon Copley Road

Sharon Center, Ohio 44274

Christopher M. Schmidt, PE

November 16, 2017

Table of Contents

Project Description ......................................................................................................................................... 3 Stormwater Detention Design Methodology ................................................................................................ 3 Hydrologic Soil Group ................................................................................................................................... 3 Stormwater Management Design .................................................................................................................. 3 Critical Storm Calculation .............................................................................................................................. 4 Appendices ..................................................................................................................................................... 5 Figures ............................................................................................................................................................. 5

Project Description

Bath Senior Lifestyle Care Facility is a commercial project including a paved parking lot, storm sewer, sanitary sewer, water main, & water quality/quantity control basins. Stormwater Detention Design Methodology

Summit County Engineer requirements were used to evaluate the present and developed storm water run-off.

The data was collected via site visits, aerial photos, field surveys, and UDSA soils maps.

The data was processed and analyzed using Hydraflow Hydrographs 2016 computer software. The TR-55 method was used to develop the hydrographs.

Hydrologic Soil Group The site contains the following soil type & hydrologic group classification:

CpA A

CpC A

DkE A

Ho D Stormwater Management Design There is a primary stormwater management pond for on-site detention. When the primary stormwater management pond becomes full the excess will discharge into a secondary dry detention basin located on the west side of the property. There is also a third stormwater management pond available to serve as a drainage collection point for the northwest area of the site. Utilizing all three of these ponds all stormwater management requirements will be met or exceeded.

Critical Storm Calculation The critical storm for the watershed is as follows:

The one-year storm was used for this calculation.

VOLUME

AREA PRE POST % CHANGE

CALCULATED CRITICAL STORM

Critical

8,158

13,700

68%

10

Appendices

Appendix A – 1 YR Pre & Post Hydrographs Appendix B – CN & Tc calculations Figures Hydrology: Pre-Development 1/2 Hydrology: Post-Development 2/2

Appendix A – 1 YR Pre & Post Hydrographs

Hydrograph Report

Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11 Thursday, 11 / 16 / 2017

Hyd. No. 1

PRE

Hydrograph type = SCS Runoff Peak discharge = 1.103 cfsStorm frequency = 1 yrs Time to peak = 732 minTime interval = 1 min Hyd. volume = 8,158 cuftDrainage area = 12.290 ac Curve number = 68Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 23.00 minTotal precip. = 1.97 in Distribution = Type IIStorm duration = 24 hrs Shape factor = 484

1

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)

PRE

Hyd. No. 1 -- 1 Year

Hyd No. 1

Hydrograph Report

Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11 Thursday, 11 / 16 / 2017

Hyd. No. 2

POST

Hydrograph type = SCS Runoff Peak discharge = 2.677 cfsStorm frequency = 1 yrs Time to peak = 731 minTime interval = 1 min Hyd. volume = 13,700 cuftDrainage area = 12.290 ac Curve number = 73Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 25.30 minTotal precip. = 1.97 in Distribution = Type IIStorm duration = 24 hrs Shape factor = 484

3

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

POST

Hyd. No. 2 -- 1 Year

Hyd No. 2

Appendix B – CN & Tc Calculations

Area

98 1.14 111.72

76 0.14 10.64

PASTURE, GRASSLAND, OR RANGE (FAIR) 49 4.35 213.15

WOODS/GRASS COMBINATION (FAIR) 43 0.22 9.46

WOODS (FAIR) 36 0.50 18.00

CREEK 98 0.30 29.40

79 3.47 274.13

77 2.17 167.09

Totals 12.29 833.59

Total Product 833.59

Total Area 12.29

Worksheet 2: Runoff curve number and runoff

Project: BATH SENIOR LIFESTYLE CARE

FACILITY

By: MRD 11/15/2017 PRE

Location: BATH TOWNSHIP, SUMMIT

COUNTY

Checked:

Check one:

1. Runoff curve number

Soil name and hydrologic

group (appendix A)

Cover description CN1/ Product of CN x area(cover type, treatment, and hydrologic condition; percent impervious;

unconnected/connected impervious area ratio)

Ta

ble

2-2

Fig

ure

2-3

Fig

ure

2-4

A IMPERVIOUS

CpA-A GRAVEL DRIVE

CpA-A

CpA-A

Ho-D WOODS (FAIR)

Ho-D BRUSH, BRUSH/WEED/GRASS MIX (FAIR)

DkE-A

Ho-D

Use CN

1/

Use only one CN source per line

CN (weighted)=

= = 68

Present Developed

Acres

mi2

%

Area

98 2.97 291.06

PAVERS 95 0.16 15.20

39 2.72 106.08

36 0.50 18.00

98 0.30 29.40

79 3.47 274.13

77 2.17 167.09

0.00

0.00

Totals 12.29 900.96

Total Product 900.96

Total Area 12.29= = 73 Use CN

Ho-D WOODS (FAIR)

1/

Use only one CN source per line

CN (weighted)=

Ho-D BRUSH, BRUSH, WEED/GRASS MIX (FAIR)

DkE-A WOODS (FAIR)

Ho-D CREEK

A IMPERVIOUS

CpA-A GRASS (GOOD)

CpA-A

Check one:

1. Runoff curve number

Soil name and hydrologic

group (appendix A)

Cover description CN1/ Product of CN x area(cover type, treatment, and hydrologic condition; percent impervious;

unconnected/connected impervious area ratio)

Ta

ble

2-2

Fig

ure

2-3

Fig

ure

2-4

Worksheet 2: Runoff curve number and runoff

Project: BATH SENIOR LIFESTYLE CARE

FACILITY

By: MRD 11/15/2017 POST

Location: BATH TOWNSHIP, SUMMIT

COUNTY

Checked:

Present Developed

Acres

mi2

%

TR55 Tc Worksheet2

Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11

Hyd. No. 1

PRE

Description A B C Totals

Sheet FlowManning's n-value = 0.240 0.011 0.011Flow length (ft) = 200.0 0.0 0.0Two-year 24-hr precip. (in) = 2.36 0.00 0.00Land slope (%) = 5.00 0.00 0.00

Travel Time (min) = 20.05 + 0.00 + 0.00 = 20.05

Shallow Concentrated FlowFlow length (ft) = 200.00 0.00 0.00Watercourse slope (%) = 3.00 0.00 0.00Surface description = Unpaved Paved PavedAverage velocity (ft/s) =2.79 0.00 0.00

Travel Time (min) = 1.19 + 0.00 + 0.00 = 1.19

Channel FlowX sectional flow area (sqft) = 15.00 0.00 0.00Wetted perimeter (ft) = 11.00 0.00 0.00Channel slope (%) = 0.54 0.00 0.00Manning's n-value = 0.015 0.015 0.015Velocity (ft/s) =8.99

0.000.00

Flow length (ft) ({0})950.0 0.0 0.0

Travel Time (min) = 1.76 + 0.00 + 0.00 = 1.76

Total Travel Time, Tc .............................................................................. 23.00 min

TR55 Tc Worksheet4

Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11

Hyd. No. 2

POST

Description A B C Totals

Sheet FlowManning's n-value = 0.240 0.011 0.011Flow length (ft) = 160.0 0.0 0.0Two-year 24-hr precip. (in) = 2.36 0.00 0.00Land slope (%) = 5.00 0.00 0.00

Travel Time (min) = 16.78 + 0.00 + 0.00 = 16.78

Shallow Concentrated FlowFlow length (ft) = 770.00 0.00 0.00Watercourse slope (%) = 1.00 0.00 0.00Surface description = Paved Paved PavedAverage velocity (ft/s) =2.03 0.00 0.00

Travel Time (min) = 6.31 + 0.00 + 0.00 = 6.31

Channel FlowX sectional flow area (sqft) = 15.00 0.00 0.00Wetted perimeter (ft) = 11.00 0.00 0.00Channel slope (%) = 0.54 0.00 0.00Manning's n-value = 0.015 0.015 0.015Velocity (ft/s) =8.99

0.000.00

Flow length (ft) ({0})1200.0 0.0 0.0

Travel Time (min) = 2.23 + 0.00 + 0.00 = 2.23

Total Travel Time, Tc .............................................................................. 25.30 min

Figures