SW3200501_The Grove at Chestnut Park Storm & EC Report 4-24-20_5/5/2020

EROSION CONTROL, STORM DRAINAGE &
BMP CALCULATION PACKAGE

THE GROVE AT CHESTNUT PARK

Prepared for:
Mattamy Homes
2127 Ayrsley Town Blvd. Suite 202
Charlotte, NC 28273
[phone]

Prepared by:
ESP Associates, Inc.
3475 Lakemont Blvd
Fort Mill, SC 29708
[phone]

Project Number HT35.400

Original: April 24, 2020

04/01/202004/02/202004/17/202004/23/202004/24/2020

Table of Contents

1. Project Narrative & Summary
2. Location & USGS Map
3. Soils Map & Information
4. FEMA Flood Insurance Map
5. Erosion Control Calculations
A. Temporary Sediment Basin SB-A
B. Sediment Basin SB-1
C. Ditch Calculations
D. Ditch Matting Calculations
E. Temporary HDPE Slope Drain Calculations
6. Storm Drainage Calculations
A. Storm A Tabulation Report
B. Storm B Tabulation Report
C. Storm C Tabulation Report
D. Inlet Capacity Chart / Spread Calculations

7. Rip Rap Calculations
8. Wet Pond
A. Pre-Development
B. Wet Pond Post-Development
C. Pond Calculations
D. Post-Development Bypass Area
E. Total Post Development Flows
F. Watershed Schematic
9. Drainage Area Maps
10. Post Construction Controls Worksheet

11. Appendix
A. Runoff Coefficients
B. Rainfall Data
C. Faircloth Skimmer Design
1.
Project Narrative & Summary

PROJECT NARRATIVE

The project “The Grove at Chestnut Park” is a proposed multi-family townhouse
development located at the intersection of Matthews Indian Trail Road and
Chestnut Parkway in the Town of Indian Trail, Union County, North Carolina.
The existing site is 7.87 acres and being developed as a multi-family community
with public streets and utilities consisting of 90 3-story townhome units.

The project site is located in Zone X per FEMA FIRM Map for Town of Indian
Trail, North Carolina –Map Number 3710540900J and 3710540800J, both with
an effective date of October, 16, 2008. The existing site mostly consists of trees
to the southeast with an open gravel lot in the north east portion of the site and a
group of single-family lots in the southwest corner. The existing area drains to
drop inlets located on each side of the site in the southeast and southwest
corners. Approximately 6.8 acres of the post development runoff will first be
conveyed to a proposed wet detention pond, to control the peak flow for the 10
and 25-year 6-hour storm events and provide water quality treatment for TSS
and TP removal.

On site erosion control measures will be provided throughout the construction
phases. The erosion control plan will have two (2) phases. In Erosion Control
Phase 1, one (1) sediment basin SB-A – designed to meet the NC Erosion and
Sediment Control Planning and Design Manual – shall be installed to treat the
runoff from the disturbed area. Temporary diversion ditches shall be installed to
convey the runoff to the sediment basin. In Erosion Control Phase 2, once the
on-site storm drainage system is installed, inlet protection shall be installed in
applicable storm structures. Sediment basin SB-1 is proposed to be graded per
the final permanent BMP. The temporary sediment basin SB-A can be removed
upon inspector approval. The Erosion Control Phase 2 sediment basin SB-1 has
been sized to treat the flow from The Grove at Chestnut Park. The site will be
mass graded and disturb approximately 8.22 acres.

CONCLUSION

The proposed sediment basins, associated Faircloth skimmers, and outfall pipes
have been designed to meet the erosion and sedimentation control requirements
for a 10-year storm event. The Faircloth Skimmers have been adequately sized
to control site runoff and release the site’s storm water runoff over a minimum 2-
day period and a maximum 5-day period.

One (1) permanent wet pond, has been designed for the site to control the storm
drainage runoff peak flow for the 10, and 25-year storms for the entire
contributing drainage area. The proposed wet pond has been designed to
reduce the runoff to below pre-development conditions.

In conclusion, due to existing site conditions and proposed runoff control
measures, the proposed project is not anticipated to have negative impacts on
downstream or adjacent properties.

2.
Location & USGS Map
Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, EsriChina (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c) OpenStreetMap contributors, and theGIS User C ommunity
SITE
I
LOCATION MAPTHE GROVE AT CHESTNUT PARKINDIAN TRAIL, NC
1 " = 1,000 '
Copyright:© 2013 National Geographic Society, i-cubed
SITE
I
USGS MAPTHE GROVE AT CHESTNUT PARKINDIAN TRAIL, NC
1 " = 1,000 '
3.
Soils Map & Information
4.
FEMA Flood Insurance Maps
USGS The National Map: Orthoimagery. Data refreshed April, 2019.
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250Feet
Ü80°40'18.45"W 35°5'18.94"N 80°39'41.00"W 35°4'49.50"N
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOODHAZARD AR EAS
Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR
Regulator y Floodway
0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X
Future Conditions 1% AnnualChance Flood Hazard Zone XArea with Reduced Flood Risk due toLevee. See Notes.Zone X
Area with Flood Risk due to Levee Zone D
NO SCREE N Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood Hazard Zone D
Channel, Culver t, or Storm SewerLevee, Dike, or Floodwall
Cross Sections with 1% Annual Chance17.5 Water Surface ElevationCoastal Transect
Coastal Transect BaselineProfile BaselineHydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of StudyJurisdiction Boundar y
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards
The flood hazard information is derived directly from theauthoritative NFHL web ser vices provided by FEMA. This mapwas exported on 4/27/2020 at 10:36:25 AM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.
This map image is void if the one or more of the following mapelements do not appear: basemap imagery, flood zone labels,legend, scale bar, map creation date, community identifiers,FIRM panel number, and FIRM effective date. Map images forunmapped and unmodernized areas cannot be used forregulatory purposes.
Legend
OTHER AREAS OFFLOOD HAZARD
OTHER AREAS
GENERALSTRUCTURES
OTHERFEATURES
MAP PANELS
8
1:6,000
B 20.2
The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative proper ty location.
5.
Erosion Control Calculations
5A.
Temporary Sediment Basin SB-A
ESP Associates, Inc.
3475 Lakemont Blvd. Fort Mill, SC 29708 Phone [phone] Fax [phone]
Time of Concentration (Tc) or Travel Time (Tt)
Project By Date
Location Checked Date
Circle One: Present Developed
1. SHEET FLOW
1. Surface description (table 3-1)
2. Manning's roughness coefficient, n (table 3-1)..
3. Flow length, L (total L ≤ 300 ft)....ft
4. Two-year 24-hour rainfall, P .....in
5. Land slope, s .....ft/ft
6. Tt = 0.007 (nL)^0.8 ......hr 0.25
2. SHALLOW CONCENTRATED FLOW
7. Surface description (paved or unpaved)....
8. Flow length, L ................ft
9. Watercourse slope, s ............ft/ft
10. Average velocity, V (figure 3-1).
11. Tt = L .....hr 0.02
3. CHANNEL FLOW
12. Channel type (Pipe or Open Channel)
13. Cross sectional flow area, a ................ft²
14. Wetted perimeter, pw ........ft
15. Hydraulic radius r = a/pw ..ft
16. Channel slope, s .......ft/ft
17. Manning's roughness coefficient, n ...............
18. V = [1.49 r^(2/3) s^(1/2)] / n Compute V ..ft/s
19. Flow length, L ...ft
20. Tt = L ......hr 0.00
21. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19)Hr = 0.27
Min = 16.2
Reference:Urban Hydrology for Small Watersheds Rainfall, P, taken from
Technical Release 55, Soil Conservation Service
U.S. Department of Agriculture, June 1986
NOAA Rainfall Data, April 2020
Compute r 0.50 0.50
0.005
Compute Tt 0.25 +0.00
Woods-Light Woods-Light
0.4 0.4
100 21
3.54 3.54
0.0447 0.0654
Unpaved
3600 V
0.005
0.012 0.012
5.53 5.53
558 1733
Compute Tt 0.00 +0.00
Unpaved
3600 V
SEGMENT ID
4/24/2020
4/24/2020
SEGMENT ID A
RHJ
MRR
THE GROVE AT CHESTNUT PARK
INDIAN TRAIL, NC
SB-A EC PH1
P2^0.5 s^0.4
SEGMENT ID B
262.74 50
0.0601 0.0200
3.955 2.28
Compute Tt 0.02 +0.00
6.28 6.28
Pipe Pipe
3.14 3.14
ESP Associates, Inc.
Po Box 7030
Charlotte NC 28241
SB-A EC PH1
SB-A EC PH 1 TOC CALCS
4/27/2020
Project:
County/City:Designed By:RHJ Date:4/24/2020
State:Checked By:MRR Date:4/24/2020
Basin:1
Total Drainage Area to Basin:5.98 Acres
Potential Max. Disturbed Area to Basin:5.44 Acres
Area C Value Area (Acres)Composite C
Denuded 0.60 5.44 0.55
Woods 0.25 0.54 0.02
Grass 0.30 0.00 0.00
Open Space 0.40 0.00 0.00
Impervious 0.95 0.00 0.00
TOTAL:-5.98 0.57
Minimum Volume Requirement:
Minimum Volume = 1800 ft3/disturbed acre
Minimum Volume = 9,796 ft3 OK
Volume Provided = 38,586 ft3
Peak Inflows:
16.2 min.
3.86 in/hr
4.98 in/hr
5.49 in/hr
0.57
Q2 =13.24 cfs (Calculated by Rational Method)
Q10 =17.07 cfs (Calculated by Rational Method)
Minimum Basin Surface Area:
Minimum Surface Area =435 sf/cfs (10-year, 24 hour storm peak inflow)
Minimum Surface Area =7,424 sf OK
Surface Area Provided =15,010 sf
Elevation
(FT)Area (SF)Incremental
Volume(CF)
Cumulative
Volume(CF)
692.00 10,747 0 0
693.00 12,143 11,445 11,445
694.00 13,564 12,854 24,299
695.00 15,010 14,287 38,586
696.00 16,482 15,746 54,332
697.00 17,978 17,230 71,562
2-Year rainfall intensity =
10-Year rainfall intensity =
25-Year rainfall intensity =
Runoff Coefficient (C) =
THE GROVE AT CHESTNUT PARK
INDIAN TRAIL
NC
SB-A Erosion Control Phase
Time of Concentration =
ESP Assocates, Inc.
PoBox 7030
Charlotte NC 28241
SB-A EC PH 1
SB-A EC PH 1 DESIGN

Principal Spillway - Riser:
695.00
4.00-ft
12.57-ft
3.33
1.00-ft (Must be 1' Minimum)
Q2 IN = 13.24 cfs (Calculated by Rational Method)
Q2 OUT = 41.85 cfs
0.60
12.57-sf
32.20 ft/sec2
1.00-ft
Q2 IN = 13.24 cfs (Calculated by Rational Method)
Q2 OUT = 60.51 cfs
Pipe Flow Check:
2.00-ft
692.00
691.47
3.14-sf
32.20 ft/sec2
2.53-ft (Measured at Outfall)
1.0
102.00-ft
0.0165 (Taken from Table 8.07a, n=0.015)
Q2 IN = 13.24 cfs (Routed in Hydraflow using Rational Method)
Q2 OUT = 20.90 cfs
Emergency Spillway Design:
12.57-ft
695.00
3.32
Q10 Less Q2 = 3.83 cfs (Calculated by Rational Method)
1.20 ft (Based on Weir Equation)
12.20 % (from Table 8.07c)
697.00
Freeboard = 0.80 ft OK
Skimmer Design - Volume Required:
Volume Required = 9,796 ft3
2.69 days (From NCDENR)OK
1.0
2.0
2.0
C = 0.59 (From Faircloth Skimmer Packet)
A = 3.14 in2 (From Faircloth Skimmer Packet)
g = 32.2 ft/sec
H =2.00 in (From Faircloth Skimmer Packet)
Qout = 0.04
Orifice Size (diameter) = inches (From Faircloth Skimmer Packet)
Spillway length :
Spillway elevation :
Weir Coef. (c):
Spillway stage (H):
Maximum slope:
Top of berm elevation:
Km:
Barrel Length (L):
Drawdown Time =
Number of Skimmers =
Skimmer Size = inches (From Faircloth Skimmer Packet)
Cross Sectional Area (A):
Accel. Of Gravity (g):
Head (H):
Barrel Diameter:
Invert In:
Kp:
Invert Out:
Cross Sectional Area (A):
Accel. Of Gravity (g):
Head (H):
Riser Diameter:
Spillway Length (L):
Weir Coef. (C):
Head (H):
Orifice Flow Check
Orifice Coef. (C):
Weir Flow Check
Spillway Elevation:
.=
2 .=
A*
.
=
2 .=
=
ESP Assocates, Inc.
PoBox 7030
Charlotte NC 28241
SB-A EC PH 1
SB-A EC PH 1 DESIGN
5B.
Sediment Basin SB-1
ESP Associates, Inc.
3475 Lakemont Blvd. Fort Mill, SC 29708 Phone [phone] Fax [phone]
Time of Concentration (Tc) or Travel Time (Tt)
Project By Date
Location Checked Date
Circle One: Present Developed
1. SHEET FLOW
1. Surface description (table 3-1)
2. Manning's roughness coefficient, n (table 3-1)..
3. Flow length, L (total L ≤ 300 ft)....ft
4. Two-year 24-hour rainfall, P .....in
5. Land slope, s .....ft/ft
6. Tt = 0.007 (nL)^0.8 ......hr 0.07
2. SHALLOW CONCENTRATED FLOW
7. Surface description (paved or unpaved)....
8. Flow length, L ................ft
9. Watercourse slope, s ............ft/ft
10. Average velocity, V (figure 3-1).
11. Tt = L .....hr 0.02
3. CHANNEL FLOW
12. Channel type (Pipe or Open Channel)
13. Cross sectional flow area, a ................ft²
14. Wetted perimeter, pw ........ft
15. Hydraulic radius r = a/pw ..ft
16. Channel slope, s .......ft/ft
17. Manning's roughness coefficient, n ...............
18. V = [1.49 r^(2/3) s^(1/2)] / n Compute V ..ft/s
19. Flow length, L ...ft
20. Tt = L ......hr 0.05
21. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19)Hr = 0.14
Min = 8.4
Reference:Urban Hydrology for Small Watersheds Rainfall, P, taken from
Technical Release 55, Soil Conservation Service
U.S. Department of Agriculture, June 1986
NOAA Rainfall Data, April 2020
Compute r 0.38 0.50
0.005
Compute Tt 0.07 +0.00
Grass-Short Woods-Light
0.15 0.4
53 21
3.54 3.54
0.0400 0.0654
Unpaved
3600 V
0.005
0.012 0.012
4.57 5.53
521 302
Compute Tt 0.03 +0.02
Unpaved
3600 V
SEGMENT ID
4/24/2020
4/24/2020
SEGMENT ID A
RCT
MRR
The Grove at Chestnut Park
Indian Trail, Union County, NC
Post-Dev TOC
P2^0.5 s^0.4
SEGMENT ID B
190 50
0.0252 0.0200
2.561 2.28
Compute Tt 0.02 +0.00
4.71 6.28
Pipe Pipe
1.77 3.14
C D
ESP Associates, Inc.
Po Box 7030
Charlotte NC 28241
Post-Dev TOC
SB-1 EC PH 2 TOC CALCS
4/27/2020
Project:
County/City:Designed By:RHJ Date:4/24/2020
State:Checked By:MRR Date:4/24/2020
Basin:2
Total Drainage Area to Basin:6.69 Acres
Potential Max. Disturbed Area to Basin:4.73 Acres
Area C Value Area (Acres)Composite C
Denuded 0.60 4.73 0.42
Woods 0.25 0.55 0.02
Grass 0.30 0.00 0.00
Open Space 0.40 0.00 0.00
Impervious 0.95 1.41 0.20
TOTAL:-6.69 0.64
Minimum Volume Requirement:
Minimum Volume = 1800 ft3/disturbed acre
Minimum Volume = 8,516 ft3 OK
Volume Provided = 79,898 ft3
Peak Inflows:
8.4 min.
5.10 in/hr
6.52 in/hr
7.18 in/hr
0.64
Q2 =22.17 cfs (Calculated by Rational Method)
Q10 =28.36 cfs (Calculated by Rational Method)
Minimum Basin Surface Area:
Minimum Surface Area =435 sf/cfs (10-year, 24 hour storm peak inflow)
Minimum Surface Area =12,338 sf OK
Surface Area Provided =12,511 sf
Elevation
(FT)Area (SF)Incremental
Volume(CF)
Cumulative
Volume(CF)
672.00 0 0 0
673.00 117 59 59
674.00 435 276 335
675.00 787 611 946
676.00 1,174 981 1,926
677.00 1,599 1,387 3,313
678.00 2,061 1,830 5,143
679.00 2,565 2,313 7,456
680.00 3,117 2,841 10,297
681.00 3,708 3,413 13,709
682.00 4,331 4,020 17,729
683.00 4,988 4,660 22,388
684.00 5,677 5,333 27,721
685.00 6,398 6,038 33,758
686.00 12,085 9,242 43,000
687.00 12,229 12,157 55,157
688.00 12,371 12,300 67,457
689.00 12,511 12,441 79,898
690.00 12,651 12,581 92,479
691.00 12,791 12,721 105,200
692.00 12,931 12,861 118,061
2-Year rainfall intensity =
10-Year rainfall intensity =
25-Year rainfall intensity =
Runoff Coefficient (C) =
THE GROVE AT CHESTNUT PARK
INDIAN TRAIL
NC
SB-1 Erosion Control Phase
Time of Concentration =
ESP Assocates, Inc.
PoBox 7030
Charlotte NC 28241
SB-A EC PH 1
SB-1 EC PH 2 DESIGN

Principal Spillway - Riser:
689.25
5.00-ft
20.00-ft
3.33
1.00-ft (Must be 1' Minimum)
Q2 IN = 22.17 cfs (Calculated by Rational Method)
Q2 OUT = 66.60 cfs
0.60
25.00-sf
32.20 ft/sec2
1.00-ft
Q2 IN = 22.17 cfs (Calculated by Rational Method)
Q2 OUT = 120.37 cfs
Pipe Flow Check:
2.00-ft
681.28
681.50
3.14-sf
32.20 ft/sec2
6.75-ft (Measured at Outfall)
1.0
19.00-ft
0.0165 (Taken from Table 8.07a, n=0.015)
Q2 IN = 22.17 cfs (Routed in Hydraflow using Rational Method)
Q2 OUT = 43.06 cfs
Emergency Spillway Design:
20.00-ft
689.25
3.32
Q10 Less Q2 = 6.20 cfs (Calculated by Rational Method)
1.21 ft (Based on Weir Equation)
12.20 % (from Table 8.07c)
692.00
Freeboard = 1.54 ft OK
Skimmer Design - Volume Required:
Volume Required = 8,516 ft3
2.34 days (From NCDENR)OK
1.0
2.0
2.0
C = 0.59 (From Faircloth Skimmer Packet)
A = 3.14 in2 (From Faircloth Skimmer Packet)
g = 32.2 ft/sec
H =2.00 in (From Faircloth Skimmer Packet)
Qout = 0.04
Orifice Size (diameter) = inches (From Faircloth Skimmer Packet)
Spillway length :
Spillway elevation :
Weir Coef. (c):
Spillway stage (H):
Maximum slope:
Top of berm elevation:
Km:
Barrel Length (L):
Drawdown Time =
Number of Skimmers =
Skimmer Size = inches (From Faircloth Skimmer Packet)
Cross Sectional Area (A):
Accel. Of Gravity (g):
Head (H):
Barrel Diameter:
Invert In:
Kp:
Invert Out:
Cross Sectional Area (A):
Accel. Of Gravity (g):
Head (H):
Riser Diameter:
Spillway Length (L):
Weir Coef. (C):
Head (H):
Orifice Flow Check
Orifice Coef. (C):
Weir Flow Check
Spillway Elevation:
.=
2 .=
A*
.
=
2 .=
=
ESP Assocates, Inc.
PoBox 7030
Charlotte NC 28241
SB-A EC PH 1
SB-1 EC PH 2 DESIGN
5C.
Ditch Calculations
ESP Associates, Inc.
3475 Lakemont Blvd. Fort Mill, SC 29708 Phone [phone] Fax [phone]
Time of Concentration (Tc) or Travel Time (Tt)
Project By Date
Location Checked Date
Circle One: Present Developed
1. SHEET FLOW
1. Surface description (table 3-1)
2. Manning's roughness coefficient, n (table 3-1)..
3. Flow length, L (total L ≤ 300 ft)....ft
4. Two-year 24-hour rainfall, P .....in
5. Land slope, s .....ft/ft
6. Tt = 0.007 (nL)^0.8 ......hr 0.37
2. SHALLOW CONCENTRATED FLOW
7. Surface description (paved or unpaved)....
8. Flow length, L ................ft
9. Watercourse slope, s ............ft/ft
10. Average velocity, V (figure 3-1).
11. Tt = L .....hr 0.01
3. CHANNEL FLOW
12. Channel type (Pipe or Open Channel)
13. Cross sectional flow area, a ................ft²
14. Wetted perimeter, pw ........ft
15. Hydraulic radius r = a/pw ..ft
16. Channel slope, s .......ft/ft
17. Manning's roughness coefficient, n ...............
18. V = [1.49 r^(2/3) s^(1/2)] / n Compute V ..ft/s
19. Flow length, L ...ft
20. Tt = L ......hr 0.03
21. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19)Hr = 0.41
Min = 24.6
Reference:Urban Hydrology for Small Watersheds Rainfall, P, taken from
Technical Release 55, Soil Conservation Service
U.S. Department of Agriculture, June 1986
THE GROVE AT CHESTNUT PARK RHJ 4/24/2020
INDIAN TRAIL, NC MRR 4/24/2020
DITCH 1A
SEGMENT ID A
Woods-Light Fallow
0.4 0.05
100 45
3.54 3.54
0.0158 0.0126
Compute Tt 0.37 +0.00
SEGMENT ID B
Unpaved Unpaved
Compute Tt 0.01 +0.00
P2^0.5 s^0.4
164.68 561
0.0373 0.0587
3.116 3.91
3600 V
0.040 0.040
Open Channel Open Channel
16.00 132.75
14.65 14.65
Compute r 1.09 9.06
0.014 0.002
SEGMENT ID C
3600 V
NOAA Rainfall Data, April 2020
4.71 7.24
461.44 100
Compute Tt 0.03 +0.00
ESP Associates, Inc.
Po Box 7030
Charlotte NC 28241
DITCH 1A
DITCH 1A - TOC CALC
4/27/2020
Hydrology Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Apr 23 2020
DITCH 1A (ECP1)
Hydrograph type = Rational Peak discharge (cfs) = 2.326
Storm frequency (yrs) = 10 Time interval (min) = 1
Drainage area (ac) = 1.140 Runoff coeff. (C) = 0.5
Rainfall Inten (in/hr) = 4.081 Tc by User (min) = 25
IDF Curve = Indian Trail.IDF Rec limb factor = 1.00
Hydrograph Volume = 3,490 (cuft); 0.080 (acft)
0 5 10 15 20 25 30 35 40 45 50
Q (cfs)
0.00 0.00
1.00 1.00
2.00 2.00
3.00 3.00
Q (cfs)
Time (min)
Runoff Hydrograph
10-yr frequency
Runoff Hyd - Qp = 2.33 (cfs)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Apr 27 2020
DITCH 1A (ECP1)
Trapezoidal
Bottom Width (ft) = 2.00
Side Slopes (z:1) = 3.00, 3.00
Total Depth (ft) = 2.00
Invert Elev (ft) = 700.00
Slope (%) = 1.00
N-Value = 0.018
Calculations
Compute by: Known Q
Known Q (cfs) = 2.33
Highlighted
Depth (ft) = 0.29
Q (cfs) = 2.330
Area (sqft) = 0.83
Velocity (ft/s) = 2.80
Wetted Perim (ft) = 3.83
Crit Depth, Yc (ft) = 0.30
Top Width (ft) = 3.74
EGL (ft) = 0.41
0 2 4 6 8 10 12 14 16 18
Elev (ft)Depth (ft)Section
699.50 -0.50
700.00 0.00
700.50 0.50
701.00 1.00
701.50 1.50
702.00 2.00
702.50 2.50
703.00 3.00
Reach (ft)
ESP Associates, Inc.
3475 Lakemont Blvd. Fort Mill, SC 29708 Phone [phone] Fax [phone]
Time of Concentration (Tc) or Travel Time (Tt)
Project By Date
Location Checked Date
Circle One: Present Developed
1. SHEET FLOW
1. Surface description (table 3-1)
2. Manning's roughness coefficient, n (table 3-1)..
3. Flow length, L (total L ≤ 300 ft)....ft
4. Two-year 24-hour rainfall, P .....in
5. Land slope, s .....ft/ft
6. Tt = 0.007 (nL)^0.8 ......hr 0.27
2. SHALLOW CONCENTRATED FLOW
7. Surface description (paved or unpaved)....
8. Flow length, L ................ft
9. Watercourse slope, s ............ft/ft
10. Average velocity, V (figure 3-1).
11. Tt = L .....hr 0.02
3. CHANNEL FLOW
12. Channel type (Pipe or Open Channel)
13. Cross sectional flow area, a ................ft²
14. Wetted perimeter, pw ........ft
15. Hydraulic radius r = a/pw ..ft
16. Channel slope, s .......ft/ft
17. Manning's roughness coefficient, n ...............
18. V = [1.49 r^(2/3) s^(1/2)] / n Compute V ..ft/s
19. Flow length, L ...ft
20. Tt = L ......hr 0.01
21. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19)Hr = 0.30
Min = 18.0
Reference:Urban Hydrology for Small Watersheds Rainfall, P, taken from
Technical Release 55, Soil Conservation Service
U.S. Department of Agriculture, June 1986
THE GROVE AT CHESTNUT PARK RHJ 4/24/2020
INDIAN TRAIL, NC MRR 4/24/2020
DITCH 2A
SEGMENT ID A
Woods-Light Fallow
0.4 0.05
100 45
3.54 3.54
0.0354 0.0126
Compute Tt 0.27 +0.00
SEGMENT ID B
Unpaved Unpaved
Compute Tt 0.02 +0.00
P2^0.5 s^0.4
D
186.46 561
0.0285 0.0587
2.724 3.91
3600 V
0.040 0.040
Open Channel Open Channel
16.00 16.00
14.65 14.65
Compute r 1.09 1.09
0.070 0.015
SEGMENT ID C
3600 V
NOAA Rainfall Data, April 2020
10.45 4.81
130.77 206.14
Compute Tt 0.00 +0.01
ESP Associates, Inc.
Po Box 7030
Charlotte NC 28241
DITCH 2A
DITCH 2A - TOC CALC
4/27/2020
Hydrology Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Apr 27 2020
DITCH 2A (ECP1)
Hydrograph type = Rational Peak discharge (cfs) = 3.326
Storm frequency (yrs) = 10 Time interval (min) = 1
Drainage area (ac) = 1.380 Runoff coeff. (C) = 0.5
Rainfall Inten (in/hr) = 4.820 Tc by User (min) = 18
IDF Curve = Indian Trail.IDF Rec limb factor = 1.00
Hydrograph Volume = 3,592 (cuft); 0.082 (acft)
0 5 10 15 20 25 30 35 40
Q (cfs)
0.00 0.00
1.00 1.00
2.00 2.00
3.00 3.00
4.00 4.00
Q (cfs)
Time (min)
Runoff Hydrograph
10-yr frequency
Runoff Hyd - Qp = 3.33 (cfs)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Apr 27 2020
DITCH 2A (ECP1)
Trapezoidal
Bottom Width (ft) = 2.00
Side Slopes (z:1) = 3.00, 3.00
Total Depth (ft) = 2.00
Invert Elev (ft) = 700.00
Slope (%) = 1.00
N-Value = 0.018
Calculations
Compute by: Known Q
Known Q (cfs) = 3.33
Highlighted
Depth (ft) = 0.34
Q (cfs) = 3.330
Area (sqft) = 1.03
Velocity (ft/s) = 3.24
Wetted Perim (ft) = 4.15
Crit Depth, Yc (ft) = 0.37
Top Width (ft) = 4.04
EGL (ft) = 0.50
0 2 4 6 8 10 12 14 16 18
Elev (ft)Depth (ft)Section
699.50 -0.50
700.00 0.00
700.50 0.50
701.00 1.00
701.50 1.50
702.00 2.00
702.50 2.50
703.00 3.00
Reach (ft)
5D.
Ditch Matting Calculations
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
> > > DITCH 1A
Name DITCH 1A
Discharge 2.33
Peak Flow Period 6
Channel Slope 0.014
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class C 6-12 in
Vegetation Type Mix (Sod and Bunch)
Vegetation Density Good 75-95%
Soil Type Clay Loam (CL)
C125
C125
Unvegetated
Straight 2.33 cfs 2.24 ft/s 0.34 ft 0.031 2.3 lbs/ft2 0.3 lbs/ft2 7.68 STABLE D
Underlying
Substrate
Straight 2.33 cfs 2.24 ft/s 0.34 ft 0.031 2.51 lbs/ft2 0.22 lbs/ft2 11.52 STABLE D
SC150
SC150
Unvegetated
Straight 2.33 cfs 1.58 ft/s 0.44 ft 0.051 1.6 lbs/ft2 0.39 lbs/ft2 4.13 STABLE E
Underlying
Substrate
Straight 2.33 cfs 1.58 ft/s 0.44 ft 0.051 1.74 lbs/ft2 0.27 lbs/ft2 6.49 STABLE E
S150
S150
Unvegetated
Straight 2.33 cfs 1.58 ft/s 0.44 ft 0.051 1.8 lbs/ft2 0.39 lbs/ft2 4.65 STABLE E
Underlying
Substrate
Straight 2.33 cfs 1.58 ft/s 0.44 ft 0.051 1.96 lbs/ft2 0.27 lbs/ft2 7.3 STABLE E
DS150
DS150
Unvegetated
Straight 2.33 cfs 1.58 ft/s 0.44 ft 0.051 1.8 lbs/ft2 0.39 lbs/ft2 4.65 STABLE D
Underlying
Substrate
Straight 2.33 cfs 1.58 ft/s 0.44 ft 0.051 1.96 lbs/ft2 0.27 lbs/ft2 7.3 STABLE D
S75
S75 Unvegetated Straight 2.33 cfs 2 ft/s 0.37 ft 0.036 1.6 lbs/ft2 0.33 lbs/ft2 4.91 STABLE D
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
ECMDS 7.0 https://ecmds.com/project/143839/channel-analysis/182018/show
1 of 2 4/27/2020, 3:33 PM
Underlying
Substrate
Straight 2.33 cfs 2 ft/s 0.37 ft 0.036 1.74 lbs/ft2 0.23 lbs/ft2 7.47 STABLE D
Unreinforced Vegetation
Unreinforced
Vegetation
Straight 2.33 cfs 1.2 ft/s 0.54 ft 0.074 4 lbs/ft2 0.47 lbs/ft2 8.51 STABLE --
Underlying
Substrate
Straight 2.33 cfs 1.2 ft/s 0.54 ft 0.074 12.47 lbs/ft2 0.31 lbs/ft2 39.65 STABLE --
DS75
DS75
Unvegetated
Straight 2.33 cfs 2 ft/s 0.37 ft 0.036 1.6 lbs/ft2 0.33 lbs/ft2 4.91 STABLE D
Underlying
Substrate
Straight 2.33 cfs 2 ft/s 0.37 ft 0.036 1.74 lbs/ft2 0.23 lbs/ft2 7.47 STABLE D
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
ECMDS 7.0 https://ecmds.com/project/143839/channel-analysis/182018/show
2 of 2 4/27/2020, 3:33 PM
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
> > > DITCH 2A (LOWER)
Name DITCH 2A (LOWER)
Discharge 3.33
Peak Flow Period 6
Channel Slope 0.015
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class C 6-12 in
Vegetation Type Mix (Sod and Bunch)
Vegetation Density Good 75-95%
Soil Type Clay Loam (CL)
C125
C125
Unvegetated
Straight 3.33 cfs 2.55 ft/s 0.41 ft 0.031 2.3 lbs/ft2 0.38 lbs/ft2 6.06 STABLE D
Underlying
Substrate
Straight 3.33 cfs 2.55 ft/s 0.41 ft 0.031 2.51 lbs/ft2 0.27 lbs/ft2 9.36 STABLE D
SC150
SC150
Unvegetated
Straight 3.33 cfs 1.85 ft/s 0.51 ft 0.048 1.6 lbs/ft2 0.48 lbs/ft2 3.36 STABLE E
Underlying
Substrate
Straight 3.33 cfs 1.85 ft/s 0.51 ft 0.048 1.74 lbs/ft2 0.32 lbs/ft2 5.41 STABLE E
S150
S150
Unvegetated
Straight 3.33 cfs 1.85 ft/s 0.51 ft 0.048 1.8 lbs/ft2 0.48 lbs/ft2 3.78 STABLE E
Underlying
Substrate
Straight 3.33 cfs 1.85 ft/s 0.51 ft 0.048 1.96 lbs/ft2 0.32 lbs/ft2 6.09 STABLE E
DS150
DS150
Unvegetated
Straight 3.33 cfs 1.85 ft/s 0.51 ft 0.048 1.8 lbs/ft2 0.48 lbs/ft2 3.78 STABLE D
Underlying
Substrate
Straight 3.33 cfs 1.85 ft/s 0.51 ft 0.048 1.96 lbs/ft2 0.32 lbs/ft2 6.09 STABLE D
S75
S75 Unvegetated Straight 3.33 cfs 2.31 ft/s 0.44 ft 0.036 1.6 lbs/ft2 0.41 lbs/ft2 3.92 STABLE D
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
ECMDS 7.0 https://ecmds.com/project/143839/channel-analysis/182023/show#
1 of 2 4/27/2020, 3:43 PM
Underlying
Substrate
Straight 3.33 cfs 2.31 ft/s 0.44 ft 0.036 1.74 lbs/ft2 0.28 lbs/ft2 6.14 STABLE D
Unreinforced Vegetation
Unreinforced
Vegetation
Straight 3.33 cfs 1.42 ft/s 0.61 ft 0.069 4 lbs/ft2 0.57 lbs/ft2 6.99 STABLE --
Underlying
Substrate
Straight 3.33 cfs 1.42 ft/s 0.61 ft 0.069 10.86 lbs/ft2 0.37 lbs/ft2 29.04 STABLE --
DS75
DS75
Unvegetated
Straight 3.33 cfs 2.31 ft/s 0.44 ft 0.036 1.6 lbs/ft2 0.41 lbs/ft2 3.92 STABLE D
Underlying
Substrate
Straight 3.33 cfs 2.31 ft/s 0.44 ft 0.036 1.74 lbs/ft2 0.28 lbs/ft2 6.14 STABLE D
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
ECMDS 7.0 https://ecmds.com/project/143839/channel-analysis/182023/show#
2 of 2 4/27/2020, 3:43 PM
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
> > > DITCH 2A (UPPER)
Name DITCH 2A (UPPER)
Discharge 3.33
Peak Flow Period 6
Channel Slope 0.068
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class C 6-12 in
Vegetation Type Mix (Sod and Bunch)
Vegetation Density Good 75-95%
Soil Type Clay Loam (CL)
C125
C125
Unvegetated
Straight 3.33 cfs 4.35 ft/s 0.27 ft 0.031 2.3 lbs/ft2 1.15 lbs/ft2 2 STABLE D
Underlying
Substrate
Straight 3.33 cfs 4.35 ft/s 0.27 ft 0.031 2.51 lbs/ft2 0.87 lbs/ft2 2.87 STABLE D
SC150
SC150
Unvegetated
Straight 3.33 cfs 3.95 ft/s 0.29 ft 0.036 1.6 lbs/ft2 1.24 lbs/ft2 1.29 STABLE E
Underlying
Substrate
Straight 3.33 cfs 3.95 ft/s 0.29 ft 0.036 1.74 lbs/ft2 0.93 lbs/ft2 1.88 STABLE E
S150
S150
Unvegetated
Straight 3.33 cfs 3.95 ft/s 0.29 ft 0.036 1.8 lbs/ft2 1.24 lbs/ft2 1.45 STABLE E
Underlying
Substrate
Straight 3.33 cfs 3.95 ft/s 0.29 ft 0.036 1.96 lbs/ft2 0.93 lbs/ft2 2.11 STABLE E
DS150
DS150
Unvegetated
Straight 3.33 cfs 3.95 ft/s 0.29 ft 0.036 1.8 lbs/ft2 1.24 lbs/ft2 1.45 STABLE D
Underlying
Substrate
Straight 3.33 cfs 3.95 ft/s 0.29 ft 0.036 1.96 lbs/ft2 0.93 lbs/ft2 2.11 STABLE D
S75
S75 Unvegetated Straight 3.33 cfs 4.39 ft/s 0.27 ft 0.031 1.6 lbs/ft2 1.15 lbs/ft2 1.4 STABLE D
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
ECMDS 7.0 https://ecmds.com/project/143839/channel-analysis/182022/show
1 of 2 4/27/2020, 3:34 PM
Underlying
Substrate
Straight 3.33 cfs 4.39 ft/s 0.27 ft 0.031 1.74 lbs/ft2 0.87 lbs/ft2 2.01 STABLE D
Unreinforced Vegetation
Unreinforced
Vegetation
Straight 3.33 cfs 3.29 ft/s 0.34 ft 0.046 4 lbs/ft2 1.43 lbs/ft2 2.81 STABLE --
Underlying
Substrate
Straight 3.33 cfs 3.29 ft/s 0.34 ft 0.046 4.79 lbs/ft2 1.04 lbs/ft2 4.61 STABLE --
DS75
DS75
Unvegetated
Straight 3.33 cfs 4.39 ft/s 0.27 ft 0.031 1.6 lbs/ft2 1.15 lbs/ft2 1.4 STABLE D
Underlying
Substrate
Straight 3.33 cfs 4.39 ft/s 0.27 ft 0.031 1.74 lbs/ft2 0.87 lbs/ft2 2.01 STABLE D
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
Phase Reach Discharge Velocity
Normal
Depth Mannings N Permissable
Shear Stress
Calculated
Shear Stress
Safety
Factor Remarks Staple
Pattern
ECMDS 7.0 https://ecmds.com/project/143839/channel-analysis/182022/show
2 of 2 4/27/2020, 3:34 PM
5E.
Temporary HDPE Slope Drain
Calculations
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Apr 23 2020
SLOPE DRAIN 1A
Invert Elev Dn (ft) = 692.00
Pipe Length (ft) = 60.00
Slope (%) = 8.33
Invert Elev Up (ft) = 697.00
Rise (in) = 15.0
Shape = Circular
Span (in) = 15.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Square edge w/headwall (C)
Coeff. K,M,c,Y,k = 0.0098, 2, 0.0398, 0.67, 0.5
Embankment
Top Elevation (ft) = 699.00
Top Width (ft) = 8.00
Crest Width (ft) = 20.00
Calculations
Qmin (cfs) = 2.33
Qmax (cfs) = 2.33
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 2.33
Qpipe (cfs) = 2.33
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 2.38
Veloc Up (ft/s) = 3.92
HGL Dn (ft) = 692.93
HGL Up (ft) = 697.61
Hw Elev (ft) = 697.83
Hw/D (ft) = 0.67
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Apr 27 2020
SLOPE DRAIN 2A
Invert Elev Dn (ft) = 692.00
Pipe Length (ft) = 87.00
Slope (%) = 1.15
Invert Elev Up (ft) = 693.00
Rise (in) = 15.0
Shape = Circular
Span (in) = 15.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Square edge w/headwall (C)
Coeff. K,M,c,Y,k = 0.0098, 2, 0.0398, 0.67, 0.5
Embankment
Top Elevation (ft) = 699.00
Top Width (ft) = 8.00
Crest Width (ft) = 20.00
Calculations
Qmin (cfs) = 3.33
Qmax (cfs) = 3.33
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 3.33
Qpipe (cfs) = 3.33
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 3.19
Veloc Up (ft/s) = 4.44
HGL Dn (ft) = 692.99
HGL Up (ft) = 693.73
Hw Elev (ft) = 694.11
Hw/D (ft) = 0.88
Flow Regime = Inlet Control
6.
Storm Drainage Calculations
6A.
Storm A Tabulation Report
6B.
Storm B Tabulation Report
6C.
Storm C Tabulation Report
6D.
Inlet Capacity Chart/ Spread
Calculations
PROJECT:The Grove at Chestnut ParkDESIGNED BY:DJBDATE: 4/24/2020MAXIMUM ALLOWABLE SPREAD FOR:LOCATION:Indian Trail, NCCHECKED BY: MRRDATE:4/24/20202'-6" STANDARD CURB & GUTTER = 8' VALLEY CURB AND GUTTER = 7'RAINFALL INTENSITY 4.00 IN/HR REFERENCE: "Indian Trail Stormwater Ordinance" INLET #SUB. TOTAL LONG. TRANS. K Q CAP SPREAD DEPTHREMARKSCB#A20.19 0.85ON GRADE 0.65 0.82 1.00% 2.08% N/A 0.71 6.54 0.14 CB#A32 0.110CB#A30.08 0.85ON GRADE 0.27 0.34 1.00% 2.08% N/A 0.46 4.68 0.10 CB#A11 0.000CB#A40.11 0.85ON GRADE 0.37 0.51 2.00% 2.08% N/A 0.45 4.81 0.10 CB#A3 0.065CB#A50.23 0.85ON GRADE 0.78 0.91 2.00% 2.08% N/A 0.77 5.96 0.12 CB#A4 0.140CB#A70.15 0.85ON GRADE 0.51 0.57 2.00% 2.08% N/A 0.51 5.01 0.10 CB#A5 0.064CB#A80.16 0.85ON GRADE 0.54 0.56 3.00% 2.08% N/A 0.50 4.60 0.10 CB#A7 0.062CB#A90.03 0.85ON GRADE 0.10 0.10 1.00% 2.08% N/A 0.09 2.99 0.06 CB#A10 0.014CB#A100.23 0.85ON GRADE 0.78 0.80 3.00% 2.08% N/A 0.65 5.25 0.11 CB#B11 0.146CB#A110.12 0.85ON GRADE 0.41 0.41 1.00% 2.08% N/A 0.37 5.03 0.10 CB#C1 0.043CB#A130.07 0.85ON GRADE 0.24 0.24 2.00% 2.08% N/A 0.43 3.61 0.07 CB#C1 0.000CB#A140.13 0.85ON GRADE 0.44 0.44 4.00% 2.08% N/A 0.57 3.99 0.08 CB#A13 0.000CB#A150.13 0.85ON GRADE 0.44 0.50 3.00% 2.08% N/A 0.53 4.42 0.09 CB#A14 0.000CB#A160.09 0.85ON GRADE 0.31 0.45 1.00% 2.08% N/A 0.40 5.20 0.11 CB#A15 0.052CB#A170.15 0.85ON GRADE 0.51 0.58 1.00% 2.08% N/A 0.44 5.74 0.12 CB#A16 0.142CB#A180.15 0.85ON GRADE 0.51 0.51 1.00% 2.08% N/A 0.44 5.47 0.11 CB#A36 0.072CB#A200.01 0.95ON GRADE 0.04 0.08 3.00% 2.08% N/A 0.03 2.22 0.05 CB#A5 0.047CB#A210.12 0.85ON GRADE 0.41 0.42 3.00% 2.08% N/A 0.38 4.14 0.09 CB#A20 0.042CB#A220.08 0.85ON GRADE 0.27 0.28 4.00% 2.08% N/A 0.27 3.36 0.07 CB#A21 0.014CB#A230.08 0.85ON GRADE 0.27 0.27 4.00% 2.08% N/A 0.27 3.33 0.07 CB#A25 0.007CB#A240.03 0.85ON GRADE 0.10 0.10 4.00% 2.08% N/A 0.10 2.30 0.05 CB#A18 0.002CB#A270.22 0.85ON GRADE 0.75 0.88 2.00% 2.08% N/A 0.71 5.89 0.12 CB#A2 0.176CB#A280.15 0.85ON GRADE 0.51 0.58 2.00% 2.08% N/A 0.45 5.04 0.10 CB#A27 0.133CB#A290.16 0.85ON GRADE 0.54 0.55 3.00% 2.08% N/A 0.48 4.58 0.10 CB#A28 0.072CB#A300.06 0.85ON GRADE 0.20 0.20 1.50% 2.08% N/A 0.20 3.59 0.07 CB#B9 0.009CB#A320.04 0.85ON GRADE 0.14 0.25 1.00% 2.08% N/A 0.14 4.16 0.09 CB#C1 0.108CB#A330.04 0.85ON GRADE 0.14 0.34 2.00% 2.08% N/A 0.14 4.10 0.09 CB#C2 0.195CB#A340.18 0.85ON GRADE 0.61 0.74 3.50% 2.08% N/A 0.54 4.96 0.10 CB#A33 0.199CB#A360.20 0.85ON GRADE 0.68 0.70 2.00% 2.08% N/A 0.57 5.39 0.11 CB#A34 0.124CB#A390.13 0.65ON GRADE 0.34 0.34 3.00% 2.08% N/A 0.32 3.81 0.08 CB#A5 0.01610-YR STORM: SPREAD CALCULATIONS / INLET CAPACITY CHARTSURFACE 'Q' SLOPEINLET TYPE INLETDRAINAGE AREAINLET 'C'STORM SYSTEM ABYPASS To Inlet #BYPASS Q
PROJECT:The Grove At Chestnut ParkDESIGNED BY:DJBDATE: 4/24/2020MAXIMUM ALLOWABLE SPREAD FOR:LOCATION:Indian Trail, NCCHECKED BY: MRRDATE:4/24/20202'-6" STANDARD CURB & GUTTER = 8' VALLEY CURB AND GUTTER = 7'RAINFALL INTENSITY4.00 IN/HRREFERENCE: "Indian Trail Stormwater Ordinance" INLET #SUB. TOTAL LONG. TRANS. K Q CAP SPREAD DEPTHREMARKSCB#B90.22 0.85ON GRADE 0.75 0.75 3.00% 2.08% N/A 0.63 5.13 0.11 CB#B10 0.116CB#B100.11 0.85ON GRADE 0.37 0.37 3.00% 2.08% N/A 0.45 3.96 0.08 N/A 0.000CB#B110.12 0.85ON GRADE 0.41 0.41 3.00% 2.08% N/A 0.49 4.09 0.09 N/A 0.000BYPASS Q10-YR STORM: SPREAD CALCULATIONS / INLET CAPACITY CHARTSTORM SYSTEM BDRAINAGE AREAINLET 'C' INLET TYPESURFACE 'Q' SLOPE INLETBYPASS To Inlet #
PROJECT:The Grove at Chestnut ParkDESIGNED BY:DJBDATE: 4/24/2020MAXIMUM ALLOWABLE SPREAD FOR:LOCATION:Indian Trail, NCCHECKED BY: MRRDATE:4/24/20202'-6" STANDARD CURB & GUTTER = 8' VALLEY CURB AND GUTTER = 7'RAINFALL INTENSITY4.00 IN/HRREFERENCE: "Indian Trail Stormwater Ordinance" INLET #SUB. TOTAL LONG. TRANS. K Q CAP SPREAD DEPTHREMARKSCB#C10.13 0.85ON GRADE 0.44 0.44 2.00% 2.08% N/A 0.40 4.55 0.09 N/A 0.046CB#C20.10 0.85ON GRADE 0.34 0.34 2.00% 2.08% N/A 0.32 4.12 0.09 N/A 0.023BYPASS Q10-YR STORM: SPREAD CALCULATIONS / INLET CAPACITY CHARTSTORM SYSTEM BDRAINAGE AREAINLET 'C' INLET TYPESURFACE 'Q' SLOPE INLETBYPASS To Inlet #
7.
Rip Rap Calculations

La= 10’
Q= 2.33
SLOPE DRAIN 1A
FLOW= 2.33 cfs
D50= 0.5’
D0= 15”
3D0 = 3.75’
W=11.25’
RIP RAP MINIMUM MIDRANGE MAXIMUM
CLASS (IN.) (IN.) (IN.)
1 5 10 17
2 9 14 23

#
La= 10’
Q= 3.33
SLOPE DRAIN 2A
FLOW= 3.33 cfs
D50= 0.5’
D0= 15”
3D0 = 3.75’
W=11.25’
RIP RAP MINIMUM MIDRANGE MAXIMUM
CLASS (IN.) (IN.) (IN.)
1 5 10 17
2 9 14 23

#
La= 11’
Q= 17.07
SB-A OUTFALL
FLOW= 17.07 cfs
D50= 0.5’
D0= 24”
3D0 = 6’
W=13’
RIP RAP MINIMUM MIDRANGE MAXIMUM
CLASS (IN.) (IN.) (IN.)
1 5 10 17
2 9 14 23

#
La= 16’
Q= 27.80
STORM A OUTFALL
FLOW= 27.80 cfs
D50= 0.6’
D0= 30”
3D0 = 7.5’
W=18.5’
RIP RAP MINIMUM MIDRANGE MAXIMUM
CLASS (IN.) (IN.) (IN.)
1 5 10 17
2 9 14 23

#
La= 14’
Q= 5.61
STORM B OUTFALL
FLOW= 5.61 cfs
D50= 0.5’
D0= 24”
3D0 = 6’
W=16’
RIP RAP MINIMUM MIDRANGE MAXIMUM
CLASS (IN.) (IN.) (IN.)
1 5 10 17
2 9 14 23

8. Wet Pond No. 1
A.
Pre-Development
ESP Associates, Inc.
3475 Lakemont Blvd. Fort Mill, SC 29708 Phone [phone] Fax [phone]
Time of Concentration (Tc) or Travel Time (Tt)
Project By Date
Location Checked Date
Circle One: Present Developed
1. SHEET FLOW
1. Surface description (table 3-1)……………………………
2. Manning's roughness coefficient, n (table 3-1)……………..
3. Flow length, L (total L ≤ 300 ft)………………………....ft
4. Two-year 24-hour rainfall, P ………...…………………..in
5. Land slope, s …………………....……………………….ft/ft
6. Tt = 0.007 (nL)^0.8 …...………...hr 0.23
2. SHALLOW CONCENTRATED FLOW
7. Surface description (paved or unpaved)……………....…
8. Flow length, L …………….……….…......……...…….....ft
9. Watercourse slope, s …………….……..........……….ft/ft
10. Average velocity, V (figure 3-1)……………………….…
11. Tt = L …...……..hr 0.07
3. CHANNEL FLOW
12. Channel type (Pipe or Open Channel)
13. Cross sectional flow area, a ……………................……ft²
14. Wetted perimeter, pw ……………………..….…...…..ft
15. Hydraulic radius r = a/pw ……………..ft
16. Channel slope, s …………...…………….…………...ft/ft
17. Manning's roughness coefficient, n …...……….....….......
18. V = [1.49 r^(2/3) s^(1/2)] / n Compute V …………..ft/s
19. Flow length, L …………….……………………………..ft
20. Tt = L …...……...hr 0.00
21. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19)Hr = 0.30
Min = 18.0
Reference:Urban Hydrology for Small Watersheds Rainfall, P, taken from
Technical Release 55, Soil Conservation Service
U.S. Department of Agriculture, June 1986
NCDENR BMP Design Manual, July 2007
Compute r 0.38 0.50
0.006
Compute Tt 0.23 +0.00
Woods-Light Fallow
0.4 0.05
100 52
3.54 3.54
0.0550 0.057
Unpaved
3600 V
0.012
0.012 0.012
4.84 8.42
32 67
Compute Tt 0.00 +0.00
Unpaved
3600 V
SEGMENT ID
4/24/2020
4/24/2020
SEGMENT ID A
RCT
MRR
The Grove at Chestnut Park
Indian Trail, Union County, NC
Wet Pond 1 Pre-Dev TOC
P2^0.5 s^0.4
SEGMENT ID B C
284 382.5
0.0422 0.0147
3.314 1.96
Compute Tt 0.02 +0.05
4.71 6.28
Pipe Pipe
1.77 3.14
D E
ESP Associates, Inc.
Po Box 7030
Charlotte NC 28241
Wet Pond 1 Pre-Dev TOC
The Grove at Chestnut Park - Pond 1 - TOC Calcs Pre-Dev
4/27/2020
NCDENR BMP Design Manual, May 2013
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Summary for Subcatchment PRE: Pre-Development
Runoff = 50.79 cfs @ 12.10 hrs, Volume= 3.672 af, Depth= 5.77"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"
Area (ac) CN Description
1.590 96 Gravel surface, HSG C
6.050 79 50-75% Grass cover, Fair, HSG C
7.640 83 Weighted Average
7.640 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
18.0 Direct Entry, Refer to TOC Calcs Pre-Dev Spreadsheet
Type II 24-hr 1-YR 24-HR Rainfall=2.94"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment PRE: Pre-Development
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
1-YR 24-HR Rainfall=2.94"
Runoff Area=7.640 ac
Runoff Volume=0.890 af
Runoff Depth=1.40"
Tc=18.0 min
CN=83
12.58 cfs
Type II 24-hr 2-YR 24-HR Rainfall=3.54"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment PRE: Pre-Development
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
2-YR 24-HR Rainfall=3.54"
Runoff Area=7.640 ac
Runoff Volume=1.205 af
Runoff Depth=1.89"
Tc=18.0 min
CN=83
17.09 cfs
Type II 24-hr 10-YR 24-HR Rainfall=5.17"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment PRE: Pre-Development
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
10-YR 24-HR Rainfall=5.17"
Runoff Area=7.640 ac
Runoff Volume=2.119 af
Runoff Depth=3.33"
Tc=18.0 min
CN=83
29.88 cfs
Type II 24-hr 25-YR 24-HR Rainfall=6.16"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment PRE: Pre-Development
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
25-YR 24-HR Rainfall=6.16"
Runoff Area=7.640 ac
Runoff Volume=2.700 af
Runoff Depth=4.24"
Tc=18.0 min
CN=83
37.79 cfs
Type II 24-hr 50-YR 24-HR Rainfall=6.96"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment PRE: Pre-Development
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
50-YR 24-HR Rainfall=6.96"
Runoff Area=7.640 ac
Runoff Volume=3.177 af
Runoff Depth=4.99"
Tc=18.0 min
CN=83
44.21 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment PRE: Pre-Development
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
100-YR 24-HR Rainfall=7.78"
Runoff Area=7.640 ac
Runoff Volume=3.672 af
Runoff Depth=5.77"
Tc=18.0 min
CN=83
50.79 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Events for Subcatchment PRE: Pre-Development
Event Rainfall
(inches)
Runoff
(cfs)
Volume
(acre-feet)
Depth
(inches)
1-YR 24-HR 2.94 12.58 0.890 1.40
2-YR 24-HR 3.54 17.09 1.205 1.89
10-YR 24-HR 5.17 29.88 2.119 3.33
25-YR 24-HR 6.16 37.79 2.700 4.24
50-YR 24-HR 6.96 44.21 3.177 4.99
100-YR 24-HR 7.78 50.79 3.672 5.77
B.
Post-Development
ESP Associates, Inc.
3475 Lakemont Blvd. Fort Mill, SC 29708 Phone [phone] Fax [phone]
Time of Concentration (Tc) or Travel Time (Tt)
Project By Date
Location Checked Date
Circle One: Present Developed
1. SHEET FLOW
1. Surface description (table 3-1)……………………………
2. Manning's roughness coefficient, n (table 3-1)……………..
3. Flow length, L (total L ≤ 300 ft)………………………....ft
4. Two-year 24-hour rainfall, P ………...…………………..in
5. Land slope, s …………………....……………………….ft/ft
6. Tt = 0.007 (nL)^0.8 …...………...hr 0.07
2. SHALLOW CONCENTRATED FLOW
7. Surface description (paved or unpaved)……………....…
8. Flow length, L …………….……….…......……...…….....ft
9. Watercourse slope, s …………….……..........……….ft/ft
10. Average velocity, V (figure 3-1)……………………….…
11. Tt = L …...……..hr 0.02
3. CHANNEL FLOW
12. Channel type (Pipe or Open Channel)
13. Cross sectional flow area, a ……………................……ft²
14. Wetted perimeter, pw ……………………..….…...…..ft
15. Hydraulic radius r = a/pw ……………..ft
16. Channel slope, s …………...…………….…………...ft/ft
17. Manning's roughness coefficient, n …...……….....….......
18. V = [1.49 r^(2/3) s^(1/2)] / n Compute V …………..ft/s
19. Flow length, L …………….……………………………..ft
20. Tt = L …...……...hr 0.05
21. Watershed or subarea Tc or Tt (add Tt in steps 6, 11, and 19)Hr = 0.14
Min = 8.4
Reference:Urban Hydrology for Small Watersheds Rainfall, P, taken from
Technical Release 55, Soil Conservation Service
U.S. Department of Agriculture, June 1986
Compute Tt 0.02 +0.00
4.71 6.28
Pipe Pipe
1.77 3.14
C D
190 50
0.0252 0.0200
2.561 2.28
P2^0.5 s^0.4
SEGMENT ID B
4/24/2020
4/24/2020
SEGMENT ID A
RCT
MRR
The Grove at Chestnut Park
Indian Trail, Union County, NC
Post-Dev TOC
Unpaved
3600 V
0.005
0.012 0.012
4.57 5.53
521 302
Compute Tt 0.03 +0.02
Unpaved
3600 V
SEGMENT ID
Compute Tt 0.07 +0.00
Grass-Short Woods-Light
0.15 0.4
53 21
3.54 3.54
0.0400 0.0654
NCDENR BMP Design Manual, July 2007
Compute r 0.38 0.50
0.005
ESP Associates, Inc.
Po Box 7030
Charlotte NC 28241
Post-Dev TOC
The Grove at Chestnut Park - Pond 1 - TOC Calcs Post-Dev
4/27/2020
NCDENR BMP Design Manual, May 2013
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Summary for Subcatchment POST: Post-Development
Runoff = 72.57 cfs @ 11.99 hrs, Volume= 4.069 af, Depth= 6.59"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"
Area (ac) CN Description
* 4.960 98 Impervious
2.450 74 >75% Grass cover, Good, HSG C
7.410 90 Weighted Average
2.450 33.06% Pervious Area
4.960 66.94% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
8.4 Direct Entry, Refer to TOC Calcs Post-Dev Spreadsheet
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Summary for Pond WP1: Wet Pond No. 1
Inflow Area = 7.410 ac, 66.94% Impervious, Inflow Depth = 6.59" for 100-YR 24-HR event
Inflow = 72.57 cfs @ 11.99 hrs, Volume= 4.069 af
Outflow = 28.11 cfs @ 12.12 hrs, Volume= 2.853 af, Atten= 61%, Lag= 7.8 min
Primary = 28.11 cfs @ 12.12 hrs, Volume= 2.853 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs
Peak Elev= 689.72' @ 12.12 hrs Surf.Area= 12,612 sf Storage= 98,746 cf
Plug-Flow detention time= 818.2 min calculated for 2.852 af (70% of inflow)
Center-of-Mass det. time= 723.6 min ( 1,499.1 - 775.5 )
Volume Invert Avail.Storage Storage Description
#1 672.00' 127,877 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
672.00 0 0 0
673.00 117 59 59
674.00 435 276 335
675.00 787 611 946
676.00 1,238 1,013 1,958
677.00 1,782 1,510 3,468
678.00 2,396 2,089 5,557
679.00 3,084 2,740 8,297
680.00 3,852 3,468 11,765
681.00 4,691 4,272 16,037
682.00 5,592 5,142 21,178
683.00 6,555 6,074 27,252
684.00 7,580 7,068 34,319
685.00 8,664 8,122 42,441
686.00 12,085 10,375 52,816
687.00 12,229 12,157 64,973
688.00 12,371 12,300 77,273
689.00 12,511 12,441 89,714
690.00 12,651 12,581 102,295
691.00 12,791 12,721 115,016
692.00 12,931 12,861 127,877
Device Routing Invert Outlet Devices
#1 Primary 681.50'24.0" Round outlet pipe
L= 19.0' RCP, sq.cut end projecting, Ke= 0.500
Inlet / Outlet Invert= 681.50' / 681.28' S= 0.0116 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 3.14 sf
#2 Device 1 686.00'2.0" Vert. low flow orifice C= 0.600
#3 Device 1 688.25'30.0" W x 6.0" H Vert. Rectangular Weir C= 0.600
#4 Device 1 689.25'60.0" x 60.0" Horiz. top of riser C= 0.600
Limited to weir flow at low heads
#5 Secondary 691.00'10.0' long x 10.0' breadth Top of Wall
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=27.69 cfs @ 12.12 hrs HW=689.72' (Free Discharge)
1=outlet pipe (Passes 27.69 cfs of 40.64 cfs potential flow)
2=low flow orifice (Orifice Controls 0.20 cfs @ 9.18 fps)
3=Rectangular Weir (Orifice Controls 6.63 cfs @ 5.30 fps)
4=top of riser (Weir Controls 20.86 cfs @ 2.23 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=672.00' (Free Discharge)
5=Top of Wall ( Controls 0.00 cfs)
Type II 24-hr 1-YR 24-HR Rainfall=2.94"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Pond WP1: Wet Pond No. 1
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=7.410 ac
Peak Elev=685.91'
Storage=51,890 cf
22.82 cfs
0.00 cfs
0.00 cfs
0.00 cfs
Type II 24-hr 2-YR 24-HR Rainfall=3.54"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Pond WP1: Wet Pond No. 1
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=7.410 ac
Peak Elev=686.95'
Storage=64,412 cf
29.04 cfs
0.10 cfs
0.10 cfs
0.00 cfs
Type II 24-hr 10-YR 24-HR Rainfall=5.17"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Pond WP1: Wet Pond No. 1
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)50
45
40
35
30
25
20
15
10
5
0
Inflow Area=7.410 ac
Peak Elev=688.49'
Storage=83,329 cf
45.91 cfs
1.15 cfs
1.15 cfs
0.00 cfs
Type II 24-hr 25-YR 24-HR Rainfall=6.16"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Pond WP1: Wet Pond No. 1
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=7.410 ac
Peak Elev=688.85'
Storage=87,851 cf
56.07 cfs
3.62 cfs
3.62 cfs
0.00 cfs
Type II 24-hr 50-YR 24-HR Rainfall=6.96"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Pond WP1: Wet Pond No. 1
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=7.410 ac
Peak Elev=689.37'
Storage=94,375 cf
64.24 cfs
8.84 cfs
8.84 cfs
0.00 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Pond WP1: Wet Pond No. 1
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=7.410 ac
Peak Elev=689.72'
Storage=98,746 cf
72.57 cfs
28.11 cfs
28.11 cfs
0.00 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond WP1: Wet Pond No. 1
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
672.00 0 0
672.20 23 12
672.40 47 23
672.60 70 35
672.80 94 47
673.00 117 59
673.20 181 114
673.40 244 169
673.60 308 224
673.80 371 279
674.00 435 335
674.20 505 457
674.40 576 579
674.60 646 701
674.80 717 823
675.00 787 946
675.20 877 1,148
675.40 967 1,350
675.60 1,058 1,553
675.80 1,148 1,755
676.00 1,238 1,958
676.20 1,347 2,260
676.40 1,456 2,562
676.60 1,564 2,864
676.80 1,673 3,166
677.00 1,782 3,468
677.20 1,905 3,886
677.40 2,028 4,304
677.60 2,150 4,721
677.80 2,273 5,139
678.00 2,396 5,557
678.20 2,534 6,105
678.40 2,671 6,653
678.60 2,809 7,201
678.80 2,946 7,749
679.00 3,084 8,297
679.20 3,238 8,991
679.40 3,391 9,684
679.60 3,545 10,378
679.80 3,698 11,071
680.00 3,852 11,765
680.20 4,020 12,619
680.40 4,188 13,474
680.60 4,355 14,328
680.80 4,523 15,182
681.00 4,691 16,037
681.20 4,871 17,065
681.40 5,051 18,093
681.60 5,232 19,121
681.80 5,412 20,150
682.00 5,592 21,178
682.20 5,785 22,393
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
682.40 5,977 23,607
682.60 6,170 24,822
682.80 6,362 26,037
683.00 6,555 27,252
683.20 6,760 28,665
683.40 6,965 30,078
683.60 7,170 31,492
683.80 7,375 32,905
684.00 7,580 34,319
684.20 7,797 35,943
684.40 8,014 37,568
684.60 8,230 39,192
684.80 8,447 40,817
685.00 8,664 42,441
685.20 9,348 44,516
685.40 10,032 46,591
685.60 10,717 48,666
685.80 11,401 50,741
686.00 12,085 52,816
686.20 12,114 55,247
686.40 12,143 57,678
686.60 12,171 60,110
686.80 12,200 62,541
687.00 12,229 64,973
687.20 12,257 67,433
687.40 12,286 69,892
687.60 12,314 72,353
687.80 12,343 74,812
688.00 12,371 77,273
688.20 12,399 79,761
688.40 12,427 82,249
688.60 12,455 84,737
688.80 12,483 87,225
689.00 12,511 89,714
689.20 12,539 92,230
689.40 12,567 94,746
689.60 12,595 97,262
689.80 12,623 99,778
690.00 12,651 102,295
690.20 12,679 104,839
690.40 12,707 107,383
690.60 12,735 109,927
690.80 12,763 112,471
691.00 12,791 115,016
691.20 12,819 117,588
691.40 12,847 120,160
691.60 12,875 122,732
691.80 12,903 125,304
692.00 12,931 127,877
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Events for Pond WP1: Wet Pond No. 1
Event Inflow
(cfs)
Outflow
(cfs)
Primary
(cfs)
Secondary
(cfs)
Elevation
(feet)
Storage
(cubic-feet)
1-YR 24-HR 22.82 0.00 0.00 0.00 685.91 51,890
2-YR 24-HR 29.04 0.10 0.10 0.00 686.95 64,412
10-YR 24-HR 45.91 1.15 1.15 0.00 688.49 83,329
25-YR 24-HR 56.07 3.62 3.62 0.00 688.85 87,851
50-YR 24-HR 64.24 8.84 8.84 0.00 689.37 94,375
100-YR 24-HR 72.57 28.11 28.11 0.00 689.72 98,746
C.
Pond Calculations
Basin ID:Required Designer Input=Project Name:Project # :Designer:Date: 04/24/20Rev 1:4.96 ac216,057.60 sf2.45 ac106,722.00 sf0.00 ac7.41 ac 322,779.60 sfPerform Water Balance Calcs.66.94%1.00-inI = 66.94%Rv = 0.65V(design) = 0.40-ac-ft17,549.24-cfVmp =42,749.94-cfTotal Impervious Area:Total Pervious Area:Percent BUA:WQv = (1 x 0.43 x 13.33)/12Calculate The Design VolumeDesign Rainfall:Total Area:Determine the Runoff Coefficient (Rv) for the 1-in rainfallRv = 0.05 + 0.9 x (I)WQv = Design Rainfall x Rv x Onsite Drainage Area Rv is 0.43Design Rainfall is 1 InchDrainage Area is 7.41 AcresR. TurnerWet Detention Basin WorksheetWet Pond No. 1The Grove at Chestnut ParkHT35.400Basin Drainage Area SummaryCalculate The Required Main Pool VolumeDetermine the Water Quality Volume (WQv)Total Future Impervious Area:
V(forebay) = 20% of Vmp =8,549.99-cf686.00-ft685.00-ftRequired Permanent Pool Volume:51,299.92-cfForebay Crest Elevation =685.00-ftElev. Forebay Area Main Bay Area Total Area Forebay Incr. Vol. Forebay Accumulated Vol.Main Bay Incr. Vol.Main Bay Accumulated Vol.Total Accumulated Vol.672.00 .00 sf .00 sf .00 sf 0.00-cf 0.00-cf 0.00-cf 0.00-cf0.00-cf673.00 .00 sf 117.00 sf 117.00 sf 0.00-cf 0.00-cf 58.50-cf 58.50-cf58.50-cf674.00 .00 sf 435.00 sf 435.00 sf 0.00-cf 0.00-cf 276.00-cf 334.50-cf334.50-cf675.00 .00 sf 787.00 sf 787.00 sf 0.00-cf 0.00-cf 611.00-cf 945.50-cf945.50-cf676.00 64.00 sf 1,174.00 sf 1,238.00 sf 32.00-cf 32.00-cf 980.50-cf 1,926.00-cf1,958.00-cf677.00 183.00 sf 1,599.00 sf 1,782.00 sf 123.50-cf 155.50-cf 1,386.50-cf 3,312.50-cf3,468.00-cf678.00 335.00 sf 2,061.00 sf 2,396.00 sf 259.00-cf 414.50-cf 1,830.00-cf 5,142.50-cf5,557.00-cf679.00 519.00 sf 2,565.00 sf 3,084.00 sf 427.00-cf 841.50-cf 2,313.00-cf 7,455.50-cf8,297.00-cf680.00 735.00 sf 3,117.00 sf 3,852.00 sf 627.00-cf 1,468.50-cf 2,841.00-cf 10,296.50-cf11,765.00-cf681.00 983.00 sf 3,708.00 sf 4,691.00 sf 859.00-cf 2,327.50-cf 3,412.50-cf 13,709.00-cf16,036.50-cf682.00 1,261.00 sf 4,331.00 sf 5,592.00 sf 1,122.00-cf 3,449.50-cf 4,019.50-cf 17,728.50-cf21,178.00-cf683.00 1,567.00 sf 4,988.00 sf 6,555.00 sf 1,414.00-cf 4,863.50-cf 4,659.50-cf 22,388.00-cf27,251.50-cf684.00 1,903.00 sf 5,677.00 sf 7,580.00 sf 1,735.00-cf 6,598.50-cf 5,332.50-cf 27,720.50-cf34,319.00-cf685.00 2,266.00 sf 6,398.00 sf 8,664.00 sf 2,084.50-cf 8,683.00-cf 6,037.50-cf 33,758.00-cf42,441.00-cf686.00 .00 sf 12,085.00 sf 12,085.00 sf 0.00-cf 8,683.00-cf 9,241.50-cf 42,999.50-cf51,682.50-cf% Forebay =20.19%Required PPE = 685.96-ftProposed PPE =686.00-ftElev.Incr. Vol. Accumul. Vol.686.000.00 cf51,682.50 cf687.0012,157.00 cf63,839.50 cf688.0012,300.00 cf76,139.50 cf689.0012,441.00 cf88,580.50 cf690.0012,581.00 cf101,161.50 cf691.0012,721.00 cf113,882.50 cf692.0012,861.00 cf126,743.50 cf12,651.00 sf12,931.00 sfBasin Permanent Pool Stage/Storage12,229.00 sf12,511.00 sfBasin Detention Stage/Storage Above Permanent Pool ElevationContour Area12,085.00 sf12,371.00 sf12,791.00 sfAssumed Elev. Of Permanent Pool:Elevation at Bottom of Littoral Shelf:Calculate the Permanent Pool Elevation from Proposed Contours with ForebayCalculate The Required Forebay Volume
PPE = 686.00-ftP.P. Perimeter = 490.00-ftVpp = 42,999.50-cfApp = 12,085.00-sfBottom of Shelf Elev = 685.00-ftA(bottom of shelf) = 8,664.00-sfV(shelf) = 2,450.00-cfDavg = 4.68-ftCalculate the Average Depth of the Pond
See Town of Indian Trail Post Construction Storm Water Ordinance - Section 3.303.B1-year, 24-hour Storm Pre-Development Runoff Volume =37,635.84-cf(See Hydraflow Hydrographs)1-year, 24-hour Storm Post-Development Runoff Volume =56,130.00-cf(See Hydraflow Hydrographs)Difference =18,494.16-cfVpp = 51,682.50-cfStorm Water Volume Control Volume = 70,176.66-cfStorm Water Volume Control Elevation = 687.51-ftC = 0.6A = 3.14 in2g = 32.2 ft/secH = 0.76 ftOrifice Diameter = 2.00 inQout = 0.09 cfsDrawdown Time = 2.34 daysOK1" Design Volume =17,549.24-cf1" Design Elevation =687.44-cfC = 0.6A = 3.14 in2g = 32.2 ft/secH = 0.72 ftOrifice Diameter = 2.00 inQout = 0.09 cfsDrawdown Time = 2.28 daysOKDetermine The Orifice Size of the Riser StructureCheck 1" Design Volume:2.
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Summary for Pond WP1: Wet Pond No. 1
Inflow Area = 7.410 ac, 66.94% Impervious, Inflow Depth = 6.59" for 100-YR 24-HR event
Inflow = 72.57 cfs @ 11.99 hrs, Volume= 4.069 af
Outflow = 28.11 cfs @ 12.12 hrs, Volume= 2.853 af, Atten= 61%, Lag= 7.8 min
Primary = 28.11 cfs @ 12.12 hrs, Volume= 2.853 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs
Peak Elev= 689.72' @ 12.12 hrs Surf.Area= 12,612 sf Storage= 98,746 cf
Plug-Flow detention time= 818.2 min calculated for 2.852 af (70% of inflow)
Center-of-Mass det. time= 723.6 min ( 1,499.1 - 775.5 )
Volume Invert Avail.Storage Storage Description
#1 672.00' 127,877 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
672.00 0 0 0
673.00 117 59 59
674.00 435 276 335
675.00 787 611 946
676.00 1,238 1,013 1,958
677.00 1,782 1,510 3,468
678.00 2,396 2,089 5,557
679.00 3,084 2,740 8,297
680.00 3,852 3,468 11,765
681.00 4,691 4,272 16,037
682.00 5,592 5,142 21,178
683.00 6,555 6,074 27,252
684.00 7,580 7,068 34,319
685.00 8,664 8,122 42,441
686.00 12,085 10,375 52,816
687.00 12,229 12,157 64,973
688.00 12,371 12,300 77,273
689.00 12,511 12,441 89,714
690.00 12,651 12,581 102,295
691.00 12,791 12,721 115,016
692.00 12,931 12,861 127,877
Device Routing Invert Outlet Devices
#1 Primary 681.50'24.0" Round outlet pipe
L= 19.0' RCP, sq.cut end projecting, Ke= 0.500
Inlet / Outlet Invert= 681.50' / 681.28' S= 0.0116 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 3.14 sf
#2 Device 1 686.00'2.0" Vert. low flow orifice C= 0.600
#3 Device 1 688.25'30.0" W x 6.0" H Vert. Rectangular Weir C= 0.600
#4 Device 1 689.25'60.0" x 60.0" Horiz. top of riser C= 0.600
Limited to weir flow at low heads
#5 Secondary 691.00'10.0' long x 10.0' breadth Top of Wall
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=27.69 cfs @ 12.12 hrs HW=689.72' (Free Discharge)
1=outlet pipe (Passes 27.69 cfs of 40.64 cfs potential flow)
2=low flow orifice (Orifice Controls 0.20 cfs @ 9.18 fps)
3=Rectangular Weir (Orifice Controls 6.63 cfs @ 5.30 fps)
4=top of riser (Weir Controls 20.86 cfs @ 2.23 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=672.00' (Free Discharge)
5=Top of Wall ( Controls 0.00 cfs)
TOTAL DRAINAGE AREA:7.41AC POND X-SEC AREA AT TOP OF POND:12,931SQ FT 0.30 ACPERMANENT POOL POND X-SEC AREA:12,0850.28 AC BOTTOM OF POND ELEV:672.00 INFILTRATION RATE (Kh):0.10FT/DAY (CLAY LINER) POND X-SEC AREA AT BOTTOM:0SQ FT 0.00 ACHYDRAULIC GRADIENT (Gh): 1 HEAD/DISTANCE RUNOFF RATE:0.65PERM POOL ELEVATION686FT. APPROX. STORAGE VOL. TO PERM. POOL: 1.94 ACRE-FEET TO PERMANENT POOL ELEV.JULYAUGUSTSEPTEMBEROCTOBERNOVEMBERDECEMBERJANUARYFEBRUARYMARCHAPRILMAYJUNEDAYS/MONTH313130313031312931303130PRECIPITATION (IN.)3.963.723.483.363.243.483.723.844.442.643.843.36EVAPORATION (IN.)4.84.53.32.41.51.11.21.52.53.74.44.6RUNOFF (AC-FT)1.381.291.211.171.131.211.291.341.550.921.341.17POND PRECIPITATION (AC-FT)0.0980.0920.0860.0830.0800.0860.0920.0950.1100.0650.0950.083EVAPORATION (AC-FT)0.1190.1110.0820.0590.0370.0270.0300.0370.0620.0920.1090.114INFILTRATION (AC-FT/DAY)0.860.860.830.860.830.860.860.800.860.830.860.83MONTHLY BALANCE (AC-FT):0.500.420.380.330.340.410.500.590.730.060.460.31RUNNING BALANCE OF RETAINED POND VOLUME (AC-FT)0.50 0.91 0.38 0.33 0.34 0.41 0.50 0.59 0.73 0.06 0.46 0.31POND WATER SURFACE ELEVATION (FT.)686.1686.0686.0686.0686.0686.0686.0686.0686.0686.0686.0686.0WATER SURFACE WITH RESPECT TO PERM. POOL ELEVATION (FT.)0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0JANUARYFEBRUARYMARCHAPRILMAYJUNEJULYAUGUSTSEPTEMBEROCTOBERNOVEMBERDECEMBERDAYS/MONTH312931303130313130313031PRECIPITATION (IN.)3.723.844.442.643.843.363.963.723.483.363.243.48EVAPORATION (IN.)1.21.52.53.74.44.64.84.53.32.41.51.1RUNOFF (AC-FT)1.291.341.550.921.341.171.381.291.211.171.131.21POND PRECIPITATION (AC-FT)0.0920.0950.1100.0650.0950.0830.0980.0920.0860.0830.0800.086EVAPORATION (AC-FT)0.0300.0370.0620.0920.1090.1140.1190.1110.0820.0590.0370.027INFILTRATION (AC-FT/DAY)0.860.800.860.830.860.830.860.860.830.860.830.86MONTHLY BALANCE (AC-FT):0.500.590.730.060.460.310.500.420.380.330.340.41RUNNING BALANCE OF RETAINED POND VOLUME (AC-FT)0.00 0.59 1.32 1.38 1.85 1.94 1.94 1.94 1.94 1.94 1.94 1.94POND WATER SURFACE ELEVATION (FT.)686.0686.0686.0686.0686.0686.0686.0686.0686.0686.0686.0686.0WATER SURFACE WITH RESPECT TO PERM. POOL ELEVATION (FT.)0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0THE GROVE AT CHESTNUT PARKTOWN OF INDIAN TRAIL, UNION COUNTY, NCWET POND NO. 1 - WATER BALANCE
THE GROVE AT CHESTNUT PARK
Unit wt. of concrete (pcf) =150 lb/ft3
Unit wt. of H2O =62.4 lb/ft3
TOP OF RISER ELEV. = 689.25 ft
INV. OUT OF RISER ELEV. = 681.50 ft
INT. WIDTH OF RISER = 60 in
INT. LENGTH OF RISER = 60 in
WALL THICK. OF RISER = 6 in
BASE THICK. OF RISER = 6 in
VOL. OF RISER = 297.0 ft3
BUOYANT FORCE =18532.8 lbs Vol. of Riser x Unit wt. of H2O
VOL. CONC. IN RISER =103.25 ft3
SINKING FORCE OF RISER = 9044.7 lbs
Vol. of Conc. x (Unit wt. of Conc. - Unit wt. of H 2O)
CONC. PAD THICKNESS =30 in
CONC. PAD WIDTH/LENGTH =8 ft
VOL. OF CONC. PAD =160.00 ft3 L x W x H / Pad Thickness
SINKING FORCE OF PAD =14016 lbs Vol. of Pad x (Unit wt. of Conc. - Unit wt. of H 2O)
TOTAL SINKING FORCE =23060.7 lbs

F.S. = 1.24 OK F.S. MUST BE GREATER THAN 1.10
CONCRETE ANCHOR BUOYANCY CALCULATIONS
WET POND NO. 1
JB#C3
Factor of safety = SINKING FORCE
BUOYANT FORCE
D.
Post-Development Bypass Area
(CB#C1 and CB#C2)
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Summary for Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff = 2.64 cfs @ 11.96 hrs, Volume= 0.145 af, Depth= 7.54"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"
Area (ac) CN Description
* 0.230 98 CB#C1 and CB#C2
0.230 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Minimum Time of Concentration
Type II 24-hr 1-YR 24-HR Rainfall=2.94"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)1
0
Type II 24-hr
1-YR 24-HR Rainfall=2.94"
Runoff Area=0.230 ac
Runoff Volume=0.052 af
Runoff Depth=2.71"
Tc=5.0 min
CN=98
0.98 cfs
Type II 24-hr 2-YR 24-HR Rainfall=3.54"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)1
0
Type II 24-hr
2-YR 24-HR Rainfall=3.54"
Runoff Area=0.230 ac
Runoff Volume=0.063 af
Runoff Depth=3.31"
Tc=5.0 min
CN=98
1.19 cfs
Type II 24-hr 10-YR 24-HR Rainfall=5.17"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)1
0
Type II 24-hr
10-YR 24-HR Rainfall=5.17"
Runoff Area=0.230 ac
Runoff Volume=0.095 af
Runoff Depth=4.93"
Tc=5.0 min
CN=98
1.75 cfs
Type II 24-hr 25-YR 24-HR Rainfall=6.16"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)2
1
0
Type II 24-hr
25-YR 24-HR Rainfall=6.16"
Runoff Area=0.230 ac
Runoff Volume=0.113 af
Runoff Depth=5.92"
Tc=5.0 min
CN=98
2.08 cfs
Type II 24-hr 50-YR 24-HR Rainfall=6.96"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)2
1
0
Type II 24-hr
50-YR 24-HR Rainfall=6.96"
Runoff Area=0.230 ac
Runoff Volume=0.129 af
Runoff Depth=6.72"
Tc=5.0 min
CN=98
2.36 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Runoff
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)2
1
0
Type II 24-hr
100-YR 24-HR Rainfall=7.78"
Runoff Area=0.230 ac
Runoff Volume=0.145 af
Runoff Depth=7.54"
Tc=5.0 min
CN=98
2.64 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/24/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Events for Subcatchment BYPASS: Post-Dev Bypass (C1 & C2)
Event Rainfall
(inches)
Runoff
(cfs)
Volume
(acre-feet)
Depth
(inches)
1-YR 24-HR 2.94 0.98 0.052 2.71
2-YR 24-HR 3.54 1.19 0.063 3.31
10-YR 24-HR 5.17 1.75 0.095 4.93
25-YR 24-HR 6.16 2.08 0.113 5.92
50-YR 24-HR 6.96 2.36 0.129 6.72
100-YR 24-HR 7.78 2.64 0.145 7.54
E.
Total Post-Development Flows
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Summary for Reach Total: Post-Dev Total
Total Post-Development Discharges
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 7.640 ac, 67.93% Impervious, Inflow Depth = 4.71" for 100-YR 24-HR event
Inflow = 28.55 cfs @ 12.12 hrs, Volume= 2.997 af
Outflow = 28.55 cfs @ 12.12 hrs, Volume= 2.997 af, Atten= 0%, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-YR 24-HR Rainfall=2.94"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Reach Total: Post-Dev Total
Inflow
Outflow
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)1
0
Inflow Area=7.640 ac
0.98 cfs
0.98 cfs
Type II 24-hr 2-YR 24-HR Rainfall=3.54"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Reach Total: Post-Dev Total
Inflow
Outflow
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)1
0
Inflow Area=7.640 ac
1.19 cfs
1.19 cfs
Type II 24-hr 10-YR 24-HR Rainfall=5.17"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Reach Total: Post-Dev Total
Inflow
Outflow
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)1
0
Inflow Area=7.640 ac
1.75 cfs
1.75 cfs
Type II 24-hr 25-YR 24-HR Rainfall=6.16"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Reach Total: Post-Dev Total
Inflow
Outflow
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)4
3
2
1
0
Inflow Area=7.640 ac
3.73 cfs
3.73 cfs
Type II 24-hr 50-YR 24-HR Rainfall=6.96"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Reach Total: Post-Dev Total
Inflow
Outflow
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)10
9
8
7
6
5
4
3
2
1
0
Inflow Area=7.640 ac
9.08 cfs
9.08 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Reach Total: Post-Dev Total
Inflow
Outflow
Hydrograph
Time (hours)
1501401301201101009080706050403020100Flow (cfs)30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=7.640 ac
28.55 cfs
28.55 cfs
Type II 24-hr 100-YR 24-HR Rainfall=7.78"The Grove at Chestnut Park - Wet Pond No. 1
Printed 4/27/2020Prepared by ESP Associates, Inc.
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Events for Reach Total: Post-Dev Total
Event Inflow
(cfs)
Outflow
(cfs)
Elevation
(feet)
Storage
(cubic-feet)
1-YR 24-HR 0.98 0.98 0.00 0
2-YR 24-HR 1.19 1.19 0.00 0
10-YR 24-HR 1.75 1.75 0.00 0
25-YR 24-HR 3.73 3.73 0.00 0
50-YR 24-HR 9.08 9.08 0.00 0
100-YR 24-HR 28.55 28.55 0.00 0
The Grove at Chestnut Park
Prepared by ESP Associates, Inc.
Pre- Wet Bypass Post Pre vs Post
Development Pond Area Development Difference
(cfs) (cfs) (cfs) (cfs) (cfs)
1-yr Storm 12.58 0.00 0.98 0.98 -11.60
2-yr Storm 17.09 0.10 1.19 1.29 -15.80
10-yr Storm 29.88 1.15 1.75 2.90 -26.98
25-yr Storm 37.79 3.62 2.08 5.70 -32.09
50-yr Storm 44.21 8.84 2.36 11.20 -33.01
100-yr Storm 50.79 28.11 2.64 30.75 -20.04
Pre. Vs Post. Development Discharge Summary Table
F.
Watershed Schematic

BYPASS
Post-Dev Bypass (C1 &
C2)
POST
Post-Development
PRE
Pre-Development
Total
Post-Dev Total
WP1
Wet Pond No. 1
Routing Diagram for The Grove at Chestnut Park - Wet Pond No. 1
Prepared by ESP Associates, Inc., Printed 4/27/2020
HydroCAD® 10.00-24 s/n 03281 © 2018 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
11.
Appendix
11A.
Runoff Coefficients
11B.
Rainfall Data

NOAA Atlas 14, Volume 2, Version 3
Location name: Indian Trail, North Carolina, USA*
Latitude: 35.0623°, Longitude: -80.6596°
Elevation: 668.06 ft**
* source: ESRI Maps
** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF_tabular | PF_graphical | Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1
Duration
Average recurrence interval (years)
1 2 5 10 25 50 100 200 500 1000
5-min 0.416
(0.384‑0.452)
0.492
(0.453‑0.535)
0.571
(0.525‑0.621)
0.629
(0.576‑0.682)
0.694
(0.634‑0.752)
0.740
(0.672‑0.801)
0.781
(0.706‑0.846)
0.818
(0.736‑0.886)
0.859
(0.766‑0.933)
0.888
(0.786‑0.966)
10-min 0.665
(0.613‑0.722)
0.787
(0.724‑0.856)
0.914
(0.840‑0.995)
1.01
(0.922‑1.09)
1.11
(1.01‑1.20)
1.18
(1.07‑1.28)
1.24
(1.12‑1.34)
1.30
(1.17‑1.40)
1.36
(1.21‑1.48)
1.40
(1.24‑1.52)
15-min 0.831
(0.766‑0.902)
0.989
(0.910‑1.08)
1.16
(1.06‑1.26)
1.27
(1.17‑1.38)
1.40
(1.28‑1.52)
1.49
(1.36‑1.62)
1.57
(1.42‑1.70)
1.64
(1.47‑1.77)
1.71
(1.53‑1.86)
1.76
(1.55‑1.91)
30-min 1.14
(1.05‑1.24)
1.37
(1.26‑1.49)
1.64
(1.51‑1.79)
1.84
(1.69‑2.00)
2.08
(1.90‑2.25)
2.25
(2.04‑2.43)
2.40
(2.17‑2.60)
2.55
(2.29‑2.76)
2.72
(2.43‑2.96)
2.84
(2.52‑3.09)
60-min 1.42
(1.31‑1.54)
1.71
(1.58‑1.87)
2.11
(1.94‑2.29)
2.40
(2.20‑2.60)
2.77
(2.53‑3.00)
3.04
(2.77‑3.30)
3.31
(2.99‑3.58)
3.57
(3.21‑3.87)
3.91
(3.48‑4.24)
4.15
(3.67‑4.51)
2-hr 1.64
(1.51‑1.80)
1.99
(1.82‑2.18)
2.47
(2.26‑2.70)
2.83
(2.58‑3.09)
3.30
(2.99‑3.59)
3.65
(3.30‑3.98)
4.01
(3.60‑4.36)
4.36
(3.89‑4.75)
4.82
(4.26‑5.26)
5.17
(4.53‑5.65)
3-hr 1.75
(1.60‑1.92)
2.11
(1.93‑2.32)
2.63
(2.40‑2.89)
3.04
(2.77‑3.32)
3.58
(3.24‑3.92)
4.01
(3.61‑4.38)
4.44
(3.98‑4.84)
4.89
(4.34‑5.33)
5.50
(4.82‑6.00)
5.98
(5.18‑6.53)
6-hr 2.10
(1.92‑2.30)
2.53
(2.32‑2.78)
3.16
(2.89‑3.47)
3.66
(3.34‑4.00)
4.33
(3.93‑4.72)
4.86
(4.38‑5.29)
5.41
(4.84‑5.89)
5.97
(5.29‑6.50)
6.76
(5.90‑7.34)
7.37
(6.37‑8.01)
12-hr 2.48
(2.28‑2.72)
3.00
(2.76‑3.30)
3.76
(3.45‑4.13)
4.37
(3.99‑4.79)
5.21
(4.72‑5.69)
5.90
(5.30‑6.42)
6.60
(5.88‑7.18)
7.34
(6.47‑7.98)
8.38
(7.27‑9.10)
9.22
(7.89‑10.0)
24-hr 2.94
(2.72‑3.18)
3.54
(3.28‑3.84)
4.45
(4.11‑4.82)
5.17
(4.77‑5.60)
6.16
(5.66‑6.67)
6.96
(6.38‑7.53)
7.78
(7.11‑8.43)
8.64
(7.86‑9.37)
9.84
(8.90‑10.7)
10.8
(9.72‑11.7)
2-day 3.46
(3.20‑3.74)
4.16
(3.86‑4.51)
5.19
(4.80‑5.63)
6.01
(5.54‑6.51)
7.13
(6.56‑7.72)
8.03
(7.37‑8.70)
8.96
(8.19‑9.71)
9.93
(9.04‑10.8)
11.3
(10.2‑12.3)
12.4
(11.1‑13.5)
3-day 3.66
(3.40‑3.95)
4.40
(4.08‑4.76)
5.46
(5.06‑5.90)
6.30
(5.82‑6.81)
7.46
(6.88‑8.06)
8.39
(7.71‑9.07)
9.35
(8.57‑10.1)
10.4
(9.44‑11.2)
11.7
(10.7‑12.8)
12.9
(11.6‑14.0)
4-day 3.87
(3.60‑4.17)
4.64
(4.31‑5.00)
5.73
(5.32‑6.18)
6.60
(6.11‑7.11)
7.80
(7.19‑8.41)
8.76
(8.06‑9.45)
9.74
(8.94‑10.5)
10.8
(9.85‑11.6)
12.2
(11.1‑13.2)
13.4
(12.1‑14.5)
7-day 4.47
(4.18‑4.80)
5.34
(5.00‑5.72)
6.50
(6.08‑6.97)
7.44
(6.94‑7.97)
8.73
(8.11‑9.35)
9.76
(9.04‑10.5)
10.8
(10.00‑11.6)
11.9
(11.0‑12.8)
13.5
(12.3‑14.5)
14.7
(13.4‑15.9)
10-day 5.13
(4.81‑5.48)
6.10
(5.72‑6.52)
7.35
(6.87‑7.85)
8.32
(7.77‑8.89)
9.65
(8.98‑10.3)
10.7
(9.94‑11.4)
11.7
(10.9‑12.6)
12.8
(11.9‑13.7)
14.3
(13.2‑15.4)
15.5
(14.2‑16.7)
20-day 6.87
(6.47‑7.30)
8.10
(7.64‑8.62)
9.57
(9.01‑10.2)
10.7
(10.1‑11.4)
12.3
(11.5‑13.1)
13.5
(12.7‑14.4)
14.8
(13.8‑15.7)
16.1
(14.9‑17.1)
17.8
(16.5‑19.0)
19.1
(17.7‑20.5)
30-day 8.42
(7.96‑8.92)
9.90
(9.36‑10.5)
11.5
(10.9‑12.2)
12.8
(12.1‑13.5)
14.4
(13.6‑15.3)
15.7
(14.8‑16.7)
17.0
(15.9‑18.0)
18.2
(17.1‑19.4)
19.9
(18.6‑21.2)
21.2
(19.7‑22.6)
45-day 10.6
(10.1‑11.1)
12.4
(11.8‑13.0)
14.2
(13.5‑14.9)
15.6
(14.8‑16.4)
17.4
(16.5‑18.2)
18.7
(17.7‑19.7)
20.1
(18.9‑21.1)
21.4
(20.1‑22.5)
23.1
(21.7‑24.3)
24.3
(22.8‑25.7)
60-day 12.6
(12.1‑13.2)
14.7
(14.1‑15.4)
16.7
(15.9‑17.4)
18.2
(17.3‑19.0)
20.1
(19.1‑21.0)
21.5
(20.5‑22.6)
22.9
(21.8‑24.1)
24.3
(23.0‑25.5)
26.1
(24.6‑27.4)
27.4
(25.8‑28.9)
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for
a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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PF graphical
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Small scale terrain
Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.0623&...
2 of 4 4/7/2020, 11:07 AM
NOAA Atlas 14, Volume 2, Version 3
Location name: Indian Trail, North Carolina, USA*
Latitude: 35.0623°, Longitude: -80.6596°
Elevation: 668.06 ft**
* source: ESRI Maps
** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF_tabular | PF_graphical | Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1
Duration
Average recurrence interval (years)
1 2 5 10 25 50 100 200 500 1000
5-min 4.99
(4.61‑5.42)
5.90
(5.44‑6.42)
6.85
(6.30‑7.45)
7.55
(6.91‑8.18)
8.33
(7.61‑9.02)
8.88
(8.06‑9.61)
9.37
(8.47‑10.2)
9.82
(8.83‑10.6)
10.3
(9.19‑11.2)
10.7
(9.43‑11.6)
10-min 3.99
(3.68‑4.33)
4.72
(4.34‑5.14)
5.48
(5.04‑5.97)
6.04
(5.53‑6.55)
6.64
(6.07‑7.19)
7.07
(6.43‑7.66)
7.45
(6.73‑8.06)
7.78
(7.00‑8.42)
8.15
(7.27‑8.85)
8.39
(7.43‑9.13)
15-min 3.32
(3.06‑3.61)
3.96
(3.64‑4.30)
4.63
(4.25‑5.04)
5.09
(4.66‑5.52)
5.61
(5.12‑6.08)
5.97
(5.42‑6.46)
6.27
(5.68‑6.79)
6.54
(5.88‑7.09)
6.84
(6.10‑7.43)
7.02
(6.22‑7.64)
30-min 2.28
(2.10‑2.47)
2.73
(2.51‑2.97)
3.29
(3.02‑3.58)
3.69
(3.38‑4.00)
4.15
(3.80‑4.50)
4.49
(4.08‑4.87)
4.80
(4.35‑5.20)
5.09
(4.58‑5.52)
5.44
(4.86‑5.91)
5.69
(5.03‑6.19)
60-min 1.42
(1.31‑1.54)
1.71
(1.58‑1.87)
2.11
(1.94‑2.29)
2.40
(2.20‑2.60)
2.77
(2.53‑3.00)
3.04
(2.77‑3.30)
3.31
(2.99‑3.58)
3.57
(3.21‑3.87)
3.91
(3.48‑4.24)
4.15
(3.67‑4.51)
2-hr 0.822
(0.754‑0.898)
0.994
(0.912‑1.09)
1.23
(1.13‑1.35)
1.41
(1.29‑1.54)
1.65
(1.50‑1.80)
1.83
(1.65‑1.99)
2.00
(1.80‑2.18)
2.18
(1.95‑2.37)
2.41
(2.13‑2.63)
2.59
(2.27‑2.82)
3-hr 0.582
(0.532‑0.639)
0.702
(0.643‑0.772)
0.876
(0.801‑0.962)
1.01
(0.921‑1.11)
1.19
(1.08‑1.30)
1.34
(1.20‑1.46)
1.48
(1.32‑1.61)
1.63
(1.45‑1.78)
1.83
(1.60‑2.00)
1.99
(1.73‑2.17)
6-hr 0.351
(0.321‑0.385)
0.423
(0.388‑0.464)
0.528
(0.483‑0.579)
0.611
(0.557‑0.668)
0.723
(0.655‑0.788)
0.812
(0.732‑0.884)
0.903
(0.808‑0.983)
0.998
(0.884‑1.09)
1.13
(0.986‑1.23)
1.23
(1.06‑1.34)
12-hr 0.206
(0.189‑0.226)
0.249
(0.229‑0.274)
0.312
(0.286‑0.342)
0.363
(0.331‑0.397)
0.433
(0.392‑0.472)
0.489
(0.440‑0.533)
0.548
(0.488‑0.596)
0.610
(0.537‑0.663)
0.696
(0.603‑0.755)
0.766
(0.655‑0.832)
24-hr 0.122
(0.113‑0.132)
0.148
(0.137‑0.160)
0.185
(0.171‑0.201)
0.215
(0.199‑0.233)
0.257
(0.236‑0.278)
0.290
(0.266‑0.314)
0.324
(0.296‑0.351)
0.360
(0.328‑0.390)
0.410
(0.371‑0.445)
0.450
(0.405‑0.489)
2-day 0.072
(0.067‑0.078)
0.087
(0.080‑0.094)
0.108
(0.100‑0.117)
0.125
(0.115‑0.135)
0.149
(0.137‑0.161)
0.167
(0.153‑0.181)
0.187
(0.171‑0.202)
0.207
(0.188‑0.225)
0.235
(0.212‑0.256)
0.257
(0.231‑0.281)
3-day 0.051
(0.047‑0.055)
0.061
(0.057‑0.066)
0.076
(0.070‑0.082)
0.088
(0.081‑0.095)
0.104
(0.096‑0.112)
0.117
(0.107‑0.126)
0.130
(0.119‑0.141)
0.144
(0.131‑0.156)
0.163
(0.148‑0.177)
0.179
(0.161‑0.194)
4-day 0.040
(0.037‑0.043)
0.048
(0.045‑0.052)
0.060
(0.055‑0.064)
0.069
(0.064‑0.074)
0.081
(0.075‑0.088)
0.091
(0.084‑0.098)
0.102
(0.093‑0.110)
0.112
(0.103‑0.121)
0.127
(0.116‑0.138)
0.139
(0.126‑0.151)
7-day 0.027
(0.025‑0.029)
0.032
(0.030‑0.034)
0.039
(0.036‑0.041)
0.044
(0.041‑0.047)
0.052
(0.048‑0.056)
0.058
(0.054‑0.062)
0.064
(0.060‑0.069)
0.071
(0.065‑0.076)
0.080
(0.073‑0.086)
0.087
(0.080‑0.094)
10-day 0.021
(0.020‑0.023)
0.025
(0.024‑0.027)
0.031
(0.029‑0.033)
0.035
(0.032‑0.037)
0.040
(0.037‑0.043)
0.045
(0.041‑0.048)
0.049
(0.045‑0.052)
0.053
(0.049‑0.057)
0.060
(0.055‑0.064)
0.065
(0.059‑0.069)
20-day 0.014
(0.013‑0.015)
0.017
(0.016‑0.018)
0.020
(0.019‑0.021)
0.022
(0.021‑0.024)
0.026
(0.024‑0.027)
0.028
(0.026‑0.030)
0.031
(0.029‑0.033)
0.033
(0.031‑0.036)
0.037
(0.034‑0.040)
0.040
(0.037‑0.043)
30-day 0.012
(0.011‑0.012)
0.014
(0.013‑0.015)
0.016
(0.015‑0.017)
0.018
(0.017‑0.019)
0.020
(0.019‑0.021)
0.022
(0.020‑0.023)
0.024
(0.022‑0.025)
0.025
(0.024‑0.027)
0.028
(0.026‑0.029)
0.029
(0.027‑0.031)
45-day 0.010
(0.009‑0.010)
0.012
(0.011‑0.012)
0.013
(0.012‑0.014)
0.014
(0.014‑0.015)
0.016
(0.015‑0.017)
0.017
(0.016‑0.018)
0.019
(0.018‑0.020)
0.020
(0.019‑0.021)
0.021
(0.020‑0.023)
0.023
(0.021‑0.024)
60-day 0.009
(0.008‑0.009)
0.010
(0.010‑0.011)
0.012
(0.011‑0.012)
0.013
(0.012‑0.013)
0.014
(0.013‑0.015)
0.015
(0.014‑0.016)
0.016
(0.015‑0.017)
0.017
(0.016‑0.018)
0.018
(0.017‑0.019)
0.019
(0.018‑0.020)
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for
a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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2mi
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100km
60mi
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100km
60mi
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