SW3161201_5 - SWM Calculations REV02-13-20_3/2/2020

Stormwater Management
Calculations
for
The Conservancy
at Waxhaw Creek Phase 2
in
Union County, NC
Stormwater Permit No. SW3161201
Prepared for:
True Homes, LLC
November 28, 2016
REVISED 02-13-20
Richard L. Modlin, P.E.
Civil Engineer
7215 Terrace Drive, Charlotte, NC 28211
Phone: [phone]
ri chardmodlin& att.net

REVISED 02-13-20
Contents
Modification to Stormwater Permit
Background Information
Overview
Existing Site & Drainage Characteristics
Soils
Development Plan for Site
Project Data
USGS Map
BMP Design
Overview
BMP-1 Calculations and Pond Data
BMP-2 Calculations and Pond Data
Time of Concentration Worksheets
BMP-1 Pre -Development
BMP-1 Post -Development
BMP-2 Pre -Development
BMP-2 Post -Development
HydroCAD Reports
BMP-1: 1-yr, 10-yr, 25-yr and 50-yr
BMP-2 1-yr, 10-yr, 25-yr and 50-yr
Outlet Stabilization

Modification to Stormwater Permit No. SW3161201
The Conservancy at Waxhaw Creek Phase 2
Union County, NC
February 13, 2020
These calculations have been revised to reflect modifications to the two wet -pond
designs.
Based on as -built field surveys of the two sediment basins, the proposed final basin
contours were modified to reduce the amount of earthwork required for conversion of
the basins to permanent ponds. Based on the original inflow hydrograph, the modified
storage was input for each design, modelled and the outlet controls adjusted
accordingly.

Background Information
Overview
The project is located off the north side of Steele Road (SR 1177), approximately 4,400 feet west
of its intersection with Lancaster Highway (NC 200) in Union County, NC. The entire property
comprises approximately 127.6 acres named The Conservancy at Waxhaw Creek and is being
developed for single-family homes in three separate phases.
The "Project Site" as noted herein, refers to a 53.85-acre tract, Phase 2 of the development.
Phase 1, with some 38 lots, has been developed and adjoins the proposed Phase 2 to the south.
The future Phase 3 will develop the remaining area north of Phase 2.
Phase 2 will ultimately construct approximately 3,500 feet of roadway to serve approximately 40
new single-family lots. Phase 2 will connect to the existing 800-foot roadway Hawk View Road
(constructed in Phase 1) that extends to Steele Road (SR 1177).
The property is bounded to both the southwest and the northeast by jurisdictional streams within
the conservation area owned by the Catawba Lands Conservancy. A FEMA floodplain lies west of
the property. There are no impacts to jurisdictional streams or wetlands for the proposed work
depicted in this plans.
Existing Site & Drainage Characteristics
The existing site is undeveloped and heavily wooded. Existing ground slopes within the project
area range from 2 to 15 percent. The site drains generally southeast to northwest. The
developed portions of the site will drain to each of two proposed wet detention basins:
■ to the northwest property corner, (Area 1) and
■ to a point roughly 1400 feet southeast of the northwest property corner (Area 2).
On -Site BMP Drainage Areas
Area 1 is approximately 17.3 acres and drains from a high point elevation 585 to elevation 520
over a hydraulic length of approximately 1,700 linear feet.
Area 2 drains from a high point (400 feet off -site) elevation 655 to elevation 542 over a hydraulic
length of approximately 1,600 linear feet. The 22.6-acre drainage area includes runoff from two
off -site areas:
➢ 3.2 acres from adjacent undeveloped property (Area 4A)
➢ 3.5 acres from Phase 1 of Conservancy at Waxhaw Creek (Area 48)
Runoff from both of these areas has been included in the storm drainage design and is accounted
for in the post -construction storm water management plan.

On -Site Undisturbed Undetained Drainage Areas
The 53.85-acre project area includes a significant amount of undisturbed land:
➢ 10.6 acres along the north side of the property (Area 3A)
➢ 9.2 acres along the south side of the property (Area 38)
➢ 0.86 acre at the southeast corner of the property (Area 3C)
Runoff from these areas will not be detained.
Soils
The soils in the project area consist of:
■ Cecil gravelly sandy clay loams of both CeB2 (2 to 8-percent slopes) and CeC2 (8 to 15-
percent slopes). Cecil clay loams are well -drained and are classified as Hydrologic Soil
Group B. These soils comprise roughly 96 percent of the disturbed area.
■ Helena fine sandy loam (HeB, 2 to 8 percent slopes). Helena sandy loams are moderately
well -drained and are classified as Hydrologic Soil Group D. These soils comprise less than
one percent of the disturbed area.
■ Tarrus gravelly silt loam TaD, 15 to 35 percent slopes) Tarrus silt loams are well -drained
and are classified as Hydrologic Soil Group B. These soils comprise less than one percent
of the disturbed area. These soils comprise roughly 3 percent of the disturbed area.

Project Data
Project Name:
Owner/Developer
Parcel ID:
Project Location:
County:
Proposed Development:
Scope of Work:
Denuded Area:
River Basin:
Soils:
The Conservancy at Waxhaw Creek Phase 2
True Homes
05099004A
north side of Steele Road (SR 1177), approximately 4400 feet
west of its intersection with Lancaster Highway (NC 200) in Union
County
Latitude 34.859066 Longitude-80.726398
Union
Construction of 36 single-family lots
Roadway, drainage, home construction
25.1 Ac
Catawba
TaD, HeB, CeB2, CeC2

BMP Design
Based on the Site Specific Water Quality Management Plan for the Goose Creek Watershed (NC
15A NCAC 2B .0600-.0609) the project is required to control and treat the difference in the
stormwater runoff from the predevelopment and post -development conditions for the one-year,
24-hour storm.
Surface Area
SA/DA Charts for the Mountains and Piedmont Region (10-2 and 10-3) were used for
determination of the minimum permanent pool surface areas. Average depth used was 3 feet.
Impervious area for the total 53.85-acre project is 8.01 percent.
Minimum Treatment Volume - based on the Simplified Method using assumed 10-percent
impervious area.
Runoff Calculations
Pre and Post -Development peak runoff values were determined based on the time of
concentration
Rainfall data for the Waxhaw area were downloaded from NOAA website: Atlas 14, Volume 2,
Version 3, "Pont Precipitation Frequency Estimates."
Runoff coefficients were determined for each of the two drainage areas. Assumed buildout of
off -site areas were included in the composite runoff coefficient calculation.
Time of concentration for each of the two drainage areas was determined based on hydraulic
path and land use characteristics.
Routing calculations were performed using HydroCAD software utilizing the Rational Method.
Outlet Structure
Outlet structure will be a 5-foot concrete riser that will house the water quality orifice, weirs,
drawdown drain/valve and outflow barrel.
Drawdown
Maintenance for each of the wet -ponds will be facilitated by 8-inch ductile iron pipe drawdown
drain and handwheel -operated valve located in the riser structure.

CNRRL0T7F 71 AI7-
Scale 1:250,000
i 0 5 10 15 2C Statute Miles
5 0 5 10 15 20 25 30 Kilometers
5 0 5 10 Nautical Miles
CONTOUR INTERVAL 100 FEET WITH
SUPPLEMENTARY CONTOURS AT 50 FOOT INTERVALS
TRANSVERSE MERCATOR PROJECTION
BLACK NUMBERED LINES INDICATE THE 10,000 METER UNIVERSAL TRANSVERSE MERCATOR GRID, ZONE 17
]Re5 MAGNETIC DECLINATION FROM TRUE NORTH VARIES FROM ]- (20 MILS) WESTERLY FOR THE
CENTER OF THE WEST EDGE TO 21hs (40 MILS) WESTERLY FOR THE CENTER OF THE EAST EDGE
FOR SALE BY U. S. GEOLOGICAL SURVEY
DENVER, COLORADO 80225, OR RESTON. VIRGINIA 22092
LOCATION DIAGRAM
USGS Map
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REVISED 02-13-20
BMP-1
Runoff Coefficient
Rational Method
Description
Area
Runoff
c x A
coeff, c
On -site undist area 1
106,436 sf 2.443
ac
Total undisturbed areas
2.443
ac
0.15
0.37
Impervious areas
Roadway
0.750
ac
0.95
0.71
Buildings & driveways
1.520
ac
0.98
1.49
Pond area
30,624 sf 0.703
ac
0.27
0.19
Lawns (heavy soils)
11.844
ac
0.27
3.20
Total acreage 17.260
ac
Subtotal =
5.96
Composite c =
0.35
TOTAL ON -SITE IMPERVIOUS AREA =
98,881
sf
TOTAL IMPERVIOUS AREA =
98,881
sf
BMP-1 Peak Runoff Rate - Pre-Dev
Q=cxIxA
c =
0.15
Tc =
49.00 m i n
i =
1.66 in/hr (1-year, 24-hr storm for Waxhaw)
A =
17.26 ac
Q =
4.30 cfs (for 1-year, 24-hr storm)
BMP-1 Peak Runoff Rate - Post-Dev
Q=cxIxA
c =
0.35
Tc =
19.00 min
i =
2.96 in/hr (1-year, 24-hr storm for Waxhaw)
A =
17.26 ac
Q =
17.63 cfs (for 1-year, 24-hr storm)

REVISED 02-13-20
BMP-1 Runoff Volume (Simple Method)
Drainage area 17.26 ac
Post Development
I = 10.00% (assumed)
Runoff coefficient, Rv
Rv = 0.05+0.009(I) = 0.140 ac-ft
Ro = 2.95 in
Vol = 3630 x Ro x Rv x A = 25,876 cf
Pre -Development
I = 0.00%
Rv = 0.05+0.009(I) = 0.05 ac-ft
Ro = 2.95 in
Vol = 3630 x Ro x Rv x A = 9,241 cf
Volume to control 16,635 cf
Drainage area = 17.26 ac
From Table 10-3 , SA/DA = 0.009
for average depth of 3.Oft and 10016 impervious cover
Min. perm pool surface area = 17.26 x 43,560 x 0.0059
= 6,767 sf
Actual perm pool surface area = 16,158 sf
Average depth calculation
Area (sf) Elevation
Area bot shelf =
14,518 521.50
Area perm pool =
16,158 522.00
Area bot pond =
9,002 518.00
Depth =
4.0
Average depth =
3.71 ft
(Equation 3)
11,123
12,198
7,463
3395
3960
1539
14,518
16,158
9,002

REVISED 02-13-20
B M P-2
Runoff Coefficient/Curve Number
Rational Method
Description
Area
Runoff
c x A
coeff, c
Off -site
Off -site undev area
144,060 sf
F 3.31
ac
0.47 *
1.55
*assume fully developed: 2591 impervious, remaining
area lawn
Impervious area =
0.83 ac
Phase 1 area draining to site
3.54
ac
Impervious area
566 LF rdwy x 9' =
5,094 sf
3 lots @ 4177 sf ea =
12,531 sf
17,625 sf
0.40
ac
0.98
0.40
Remaining pervious area
3.14 ac
Assume 30% undisturbed wooded
0.94 ac
F 0.94
ac
0.15
0.14
70% lawns
2.20 ac
F 2.20
ac
0.20
0.44
On -Site
On -site undist area 1
146,053 sf
3.35
ac
On -site undist area 2
34,494 sf
0.79
ac
Total on -site undisturbed areas
4.14
ac
0.15
0.62
Impervious area (on -site)
2.04
ac
Roadway
0.74
ac
0.98
0.73
Homes & driveways
1.30
ac
0.98
1.27
Pond area
30,624 sf
0.70
ac
0.20
0.14
Lawns (heavy soils)
8.84
ac
60% 5-7 percent slopes
5.31
ac
0.30
1.59
40% 2-5 percent slopes
3.54
ac
0.20
0.71
Total acreage
22.58
ac
Subtotal = 7.59
Composite c = 0.34
TOTAL ON -SITE IMPERVIOUS AREA = 88,862 sf
TOTAL IMPERVIOUS AREA = 142,533 sf

REVISED 02-13-20
BMP-2 Peak Runoff Rate - Pre-Dev
Q=cxIxA
c =
0.15
Tc =
35.00 min
I =
2.09 in/hr (1-year, 24-hr storm for Waxhaw)
A =
22.58 ac
Q =
7.08 cfs
BMP-2 Peak Runoff Rate - Post-Dev
Q=cxIxA
c =
0.34
Tc =
22.00 min
I =
2.74 in/hr (1-year, 24-hr storm for Waxhaw)
A =
22.58 ac
Q =
21.04 cfs
BMP-2 Runoff Volume (Simple Method)
Drainage area (on -site only) 15.73
Drainage area (total) 22.58 ac
Impervious area (on -site) 2.04 ac
Impervious area (total) 3.11 ac
Post Development
1=
Runoff coefficient, Rv
10.00% (assumed)
Rv = 0.05+0.009(I) = 0.140 ac-ft
Ro = 2.95 in
Vol = 3630 x Ro x Rv x A = 33,852 cf
Pre -Development
I = 0.00%
Rv = 0.05+0.009(I) = 0.05 ac-ft
Ro = 2.95 in
Vol = 3630 x Ro x Rv x A = 12,090 cf
Volume to control 21,762 cf

REVISED 02-13-20
Drainage area (on -site) =
15.73 ac
Off -site drainage area =
6.85 ac
Total drainage area =
22.58 ac
From Table 10-1, SA/DA =
0.0059
for average depth of 3.0 ft and 10% impervious cover
Min. perm pool surface area =
22.58 x 43,560 x 0.0059
=
5,803 sf
Actual perm pool surface area =
9,228 sf
Average depth calculation
Area (sf) Elevation
Area bot shelf = 7,903 547.00
Area perm pool = 9,228 546.50
Area bot pond = 3,378 542.00
Depth = 5.0 ft
Average depth = 4.03 ft (Equation 3)

PROJECT: Conservancy at Waxhaw Creek Phase 2 BY
PROJECT. NO.: 16079
DATE: 09/09/16
TIME OF CONCENTRATION: BMP-1 (PRE -DEVELOPMENT)
SHEET FLOW
Surface Description = unpaved
Manning's Roughness (n) = 0.40
Flow Length (ft) = 300 585.0
P2 (in.) = 3.56 575.8
Slope (%) = 3.06 9.2
T(t) (min.) = 41.36
SHALLOW CONCENTRATED FLOW
Surface Description unpaved
Flow Length (ft) = 357 575.8
Water Course Slope (ft/ft) = 0.027 566.1
Average Velocity (fps) = 2.66 9.7
T(t) (min.) = 2.24
SHALLOW CONCENTRATED FLOW
Surface Description unpaved
Flow Length (ft) = 1055 566.1
Water Course Slope (ft/ft) = 0.044 519.4
Average Velocity (fps) = 3.40 46.8
T(t) (min.) = 5.17
SUM OF TRAVEL TIMES = 48.8 minutes
USE TIME OF CONCENTRATION OF 49.0 minutes
0.817 hours
Flow Length 1,712
Fall 65.7
RLM
0.0306
0.0271
0.0444

PROJECT: Conservancy at Waxhaw Creek Phase 2 BY: RLM
PROJECT. NO.: 16079
DATE: 09/09/16
TIME OF CONCENTRATION: BMP-1 (POST DEVELOPMENT)
SHEET FLOW
Surface Description = unpaved
Manning's Roughness (n) = 0.40
Flow Length (ft) = 100 585.0
P2 (in.) = 3.56 580.5 0.0454
Slope (%) = 4.54 4.5
T(t) (min.) = 14.67
SHALLOW CONCENTRATED FLOW
Surface Description
unpaved
Flow Length (ft) =
354
580.5
Water Course Slope (ft/ft) =
0.06
558.8 0.0612
Average Velocity (fps) =
3.99
21.7
T(t) (min.) =
1.48
PIPE FLOW:
Pipe Size (in.) =
18
558.8
Pipe Area (sq.ft.) =
1.77
555.5
Hydraulic Radius =
0.375
3.3
Pipe Slope (%) =
6.9
Manning's Coefficient (n) =
0.012
Velocity (fps) =
16.93
Flow Length (ft) =
48
T(t) (min.) =
0.05
PIPE FLOW:
Pipe Size (in.) =
18
555.5
Pipe Area (sq.ft.) =
1.77
554.0
Hydraulic Radius =
0.375
1.5
Pipe Slope (%) =
0.8
Manning's Coefficient (n) =
0.012
Velocity (fps) =
5.71
Flow Length (ft) =
192
T(t) (min.) =
0.56
SHALLOW CONCENTRATED FLOW
Surface Description unpaved
Flow Length (ft) = 226 554.0
Water Course Slope (ft/ft) = 0.052 542.2 0.0522
Average Velocity (fps) = 3.69 11.8
T(t) (min.) = 1.02

CHANNEL FLOW:
Channel Area (sf) =
4.00
Hydraulic Radius =
0.618
Channel Slope (%) =
5.143
Manning's Coefficient (n) =
0.03
Velocity (fps) =
8.17
Flow Length (ft) =
140
T(t) (min.) =
0.29
PIPE FLOW:
Pipe Size (in.) =
30
Pipe Area (sq.ft.) =
4.91
Hydraulic Radius =
0.625
Pipe Slope (%) =
5.2
Manning's Coefficient (n) =
0.012
Velocity (fps) =
20.62
Flow Length (ft) =
184
T(t) (min.) =
0.15
PIPE FLOW:
Pipe Size (in.) =
30
Pipe Area (sq.ft.) =
4.91
Hydraulic Radius =
0.63
Pipe Slope (%) =
0.5
Manning's Coefficient (n) =
0.012
Velocity (fps) =
6.60
Flow Length (ft) =
42
T(t) (min.) =
0.11
PIPE FLOW:
Pipe Size (in.) =
30
Pipe Area (sq.ft.) =
4.91
Hydraulic Radius =
0.63
Pipe Slope (%) =
0.8
Manning's Coefficient (n) =
0.012
Velocity (fps) =
8.01
Flow Length (ft) =
166
T(t) (min.) =
0.35
Bottom Width (ft) = 2 542.2
Side Slope (ft) = 2 535.0
Depth (ft) = 1 7.2
SUM OF TRAVEL TIMES = 18.66 minutes
USE TIME OF CONCENTRATION OF 19.0 minutes
1452 ft
535.0
525.5
9.5
525.5
525.3
0.2
525.3
524.0
1.3

PROJECT: Conservancy at Waxhaw Creek Phase 2 BY: RLM
PROJECT. NO.: 16079
DATE: 09/09/16
TIME OF CONCENTRATION: BMP-2 (PRE -DEVELOPMENT)
SHEET FLOW
Surface Description =
unpaved
Manning's Roughness (n) =
0.40
Flow Length (ft) =
300 655.0
P2 (in.) =
3.56 633.8 0.0706667
Slope (%) =
7.07 21.2
T(t) (min.) =
29.6
SHALLOW CONCENTRATED FLOW
Surface Description
unpaved
Flow Length (ft) =
545
633.8
Water Course Slope (ft/ft) =
0.066
598.0 0.0656881
Average Velocity (fps) =
4.14
35.8
T(t) (min.) =
2.2
CHANNEL FLOW:
Channel Area (sf) =
2.63
Bottom Width (ft) = 0 598.00
Hydraulic Radius =
0.249
Side Slope (ft) = 10.5 566.04
Channel Slope (%) =
12.533
Depth (ft) = 0.5
Manning's Coefficient (n) =
0.035
Velocity (fps) =
5.96
Flow Length (ft) =
255
T(t) (min.) =
0.7
CHANNEL FLOW
Channel Area (sf) =
8.25
Bottom Width (ft) = 10 566.0
Hydraulic Radius =
0.358
Side Slope (ft) = 13 552.0
Channel Slope (%) =
4.961
Depth (ft) = 0.5
Manning's Coefficient (n) =
0.035
Velocity (fps) =
4.78
Flow Length (ft) =
284
T(t) (min.) =
1.0
SHALLOW CONCENTRATED FLOW:
Surface Description
unpaved
Flow Length (ft) =
210
552.0
Water Course Slope (ft/ft) =
0.049
541.7 0.0488095
Average Velocity (fps) =
3.56
10.3
T(t) (min.) =
1.0
SUM OF TRAVEL TIMES = 34.5 minutes
USE TIME OF CONCENTRATION OF 35.0 minutes
15.7
39.4

PROJECT: Conservancy at Waxhaw Creek Phase 2 BY: RLM
PROJECT. NO.: 16079
DATE: 09/09/16
TIME OF CONCENTRATION: BMP-2 (POST DEVELOPED)
SHEET FLOW
Surface Description =
Manning's Roughness (n) _
Flow Length (ft) _
P2 (in.) _
Slope (%) _
T(t) (min.) _
SHALLOW CONCENTRATED FLOW:
Surface Description
Flow Length (ft) =
Water Course Slope (ft/ft) _
Average Velocity (fps) _
T(t) (min.) =
CHANNEL FLOW:
Channel Area (sf) _
Hydraulic Radius =
Channel Slope (%) _
Manning's Coefficient (n) _
Velocity (fps) =
Flow Length (ft) _
T(t) (min.) =
PIPE FLOW:
Pipe Size (in.) _
Pipe Area (sq.ft.) =
Hydraulic Radius =
Pipe Slope (%) =
Manning's Coefficient (n) _
Velocity (fps) =
Flow Length (ft) _
T(t) (min.) =
CHANNEL FLOW:
Channel Area (sf) _
Hydraulic Radius =
Channel Slope (%) _
Manning's Coefficient (n) _
Velocity (fps) =
Flow Length (ft) _
T(t) (min.) =
unpaved
0.400
100
3.56
2.79
17.8
unpaved
305
0.08
4.64
1.1
2.00
0.447
6.143
0.03
7.20
477
1.1
24
3.14
0.5
1.0
0.012
7.82
80
0.2
3.00
0.474
5.889
0.03
7.33
569
1.3
ASSUMED FULL DEV
655.0
652.2
2.8
652.2
627.0
25.2
Bottom Width (ft) _
Side Slope (ft) _
Depth (ft) =
Bottom Width (ft) _
Side Slope (ft) _
Depth (ft) =
0
2
1
0
3
1
0.0279
0.0827
627.0
597.7
597.7
596.7
1.0
596.7
563.2

PIPE FLOW:
Pipe Size (in.) _
Pipe Area (sq.ft.) _
Hydraulic Radius =
Pipe Slope (%) _
Manning's Coefficient (n) _
Velocity (fps) _
Flow Length (ft) _
T(t) (min.) _
SHALLOW CONCENTRATED FLOW:
Surface Description
Flow Length (ft) _
Water Course Slope (ft/ft) _
Average Velocity (fps) _
T(t) (min.) _
SUM OF TRAVEL TIMES =
36 563.2
7.07 559.72
0.75 3.5
3.5
0.012
19.09
88
0.1
unpaved
90 559.7
0.019 558.0 0.0191
2.23 1.7
0.7
22.2 minutes
USE TIME OF CONCENTRATION OF 22.0 minutes
1709 ft

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 1-yr Duration=19 min, Inten=2.96 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 1
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 17.260 ac, 13.15% Impervious, Inflow Depth = 0.33" for 1-yr event
Inflow = 18.06 cfs @ 0.31 hrs, Volume= 0.472 of
Outflow = 0.11 cfs @ 0.63 hrs, Volume= 0.472 af, Atten= 99%, Lag= 19.0 min
Primary = 0.11 cfs @ 0.63 hrs, Volume= 0.472 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 522.00' Surf.Area= 14,523 sf Storage= 47,497 cf
Peak Elev= 523.18' @ 0.63 hrs Surf.Area= 19,378 sf Storage= 67,896 cf (20,399 cf above start)
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= 1,973.0 min ( 1,991.8 - 18.8 )
Volume Invert
#1 518.00'
Avail.
e Description
106,826 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
518.00
9,002
0 0
520.00
11,986
20,988 20,988
522.00
14,523
26,509 47,497
523.00
18,897
16,710 64,207
524.00
21,531
20,214 84,421
525.00
23,278
22,405 106,826
Device Routing
Invert
Outlet Devices
#1 Primary
520.00'
18.0" Round Culvert L= 40.0' Ke= 0.500
Inlet / Outlet Invert= 520.00' / 519.75' S= 0.0063 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
522.00'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
524.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
523.90'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
523.40'
12.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 1-yr Duration=19 min, Inten=2.96 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 2
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=0.11 cfs @ 0.63 hrs HW=523.18' (Free Discharge)
L1=Culvert (Passes 0.11 cfs of 13.27 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.11 cfs @ 5.24 fps)
4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
=Broad -Crested Rectangular Weir( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=522.00' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 1-yr Duration=19 min, Inten=2.96 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 3
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
47,497
522.00
0.00
0.00
0.00
5.00
0.00
66,133
523.10
0.11
0.11
0.00
10.00
0.00
64,199
523.00
0.11
0.11
0.00
15.00
0.00
62,362
522.89
0.10
0.10
0.00
20.00
0.00
60,632
522.79
0.09
0.09
0.00
25.00
0.00
59,010
522.69
0.09
0.09
0.00
30.00
0.00
57,494
522.60
0.08
0.08
0.00
35.00
0.00
56,085
522.51
0.08
0.08
0.00
40.00
0.00
54,784
522.44
0.07
0.07
0.00
45.00
0.00
53,590
522.36
0.06
0.06
0.00
50.00
0.00
52,502
522.30
0.06
0.06
0.00
55.00
0.00
51,522
522.24
0.05
0.05
0.00
60.00
0.00
50,649
522.19
0.05
0.05
0.00
65.00
0.00
49,885
522.14
0.04
0.04
0.00
70.00
0.00
49,229
522.10
0.03
0.03
0.00
75.00
0.00
48,688
522.07
0.03
0.03
0.00
80.00
0.00
48,262
522.05
0.02
0.02
0.00
85.00
0.00
47,984
522.03
0.01
0.01
0.00
90.00
0.00
47,807
522.02
0.01
0.01
0.00
95.00
0.00
47,694
522.01
0.00
0.00
0.00
100.00
0.00
47,622
522.01
0.00
0.00
0.00
105.00
0.00
47,577
522.00
0.00
0.00
0.00
110.00
0.00
47,548
522.00
0.00
0.00
0.00
115.00
0.00
47,529
522.00
0.00
0.00
0.00
120.00
0.00
47,518
522.00
0.00
0.00
0.00
125.00
0.00
47,510
522.00
0.00
0.00
0.00
130.00
0.00
47,505
522.00
0.00
0.00
0.00
135.00
0.00
47,502
522.00
0.00
0.00
0.00
140.00
0.00
47,500
522.00
0.00
0.00
0.00
145.00
0.00
47,499
522.00
0.00
0.00
0.00
150.00
0.00
47,498
522.00
0.00
0.00
0.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 10-yr Duration=19 min, Inten=4.62 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 4
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 17.260 ac, 13.15% Impervious, Inflow Depth = 0.51" for 10-yr event
Inflow = 28.20 cfs @ 0.31 hrs, Volume= 0.737 of
Outflow = 4.42 cfs @ 0.58 hrs, Volume= 0.737 af, Atten= 84%, Lag= 15.9 min
Primary = 4.42 cfs @ 0.58 hrs, Volume= 0.737 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 522.00' Surf.Area= 14,523 sf Storage= 47,497 cf
Peak Elev= 523.66' @ 0.58 hrs Surf.Area= 20,633 sf Storage= 77,526 cf (30,029 cf above start)
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= 1,785.2 min ( 1,804.0 - 18.8 )
Volume Invert
#1 518.00'
Avail.
e Description
106,826 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
518.00
9,002
0 0
520.00
11,986
20,988 20,988
522.00
14,523
26,509 47,497
523.00
18,897
16,710 64,207
524.00
21,531
20,214 84,421
525.00
23,278
22,405 106,826
Device Routing
Invert
Outlet Devices
#1 Primary
520.00'
18.0" Round Culvert L= 40.0' Ke= 0.500
Inlet / Outlet Invert= 520.00' / 519.75' S= 0.0063 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
522.00'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
524.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
523.90'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
523.40'
12.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 10-yr Duration=19 min, Inten=4.62 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 5
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=4.40 cfs @ 0.58 hrs HW=523.66' (Free Discharge)
L1=Culvert (Passes 4.40 cfs of 14.51 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.14 cfs @ 6.20 fps)
4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
=Broad -Crested Rectangular Weir (Weir Controls 4.26 cfs @ 1.37 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=522.00' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 10-yr Duration=19 min, Inten=4.62 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 6
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
47,497
522.00
0.00
0.00
0.00
5.00
0.00
71,123
523.34
0.12
0.12
0.00
10.00
0.00
68,977
523.24
0.12
0.12
0.00
15.00
0.00
66,919
523.13
0.11
0.11
0.00
20.00
0.00
64,950
523.04
0.11
0.11
0.00
25.00
0.00
63,073
522.93
0.10
0.10
0.00
30.00
0.00
61,301
522.83
0.10
0.10
0.00
35.00
0.00
59,636
522.73
0.09
0.09
0.00
40.00
0.00
58,078
522.63
0.08
0.08
0.00
45.00
0.00
56,627
522.55
0.08
0.08
0.00
50.00
0.00
55,284
522.47
0.07
0.07
0.00
55.00
0.00
54,047
522.39
0.07
0.07
0.00
60.00
0.00
52,918
522.32
0.06
0.06
0.00
65.00
0.00
51,895
522.26
0.05
0.05
0.00
70.00
0.00
50,981
522.21
0.05
0.05
0.00
75.00
0.00
50,173
522.16
0.04
0.04
0.00
80.00
0.00
49,473
522.12
0.04
0.04
0.00
85.00
0.00
48,889
522.08
0.03
0.03
0.00
90.00
0.00
48,410
522.05
0.02
0.02
0.00
95.00
0.00
48,078
522.03
0.01
0.01
0.00
100.00
0.00
47,867
522.02
0.01
0.01
0.00
105.00
0.00
47,733
522.01
0.01
0.01
0.00
110.00
0.00
47,647
522.01
0.00
0.00
0.00
115.00
0.00
47,592
522.01
0.00
0.00
0.00
120.00
0.00
47,558
522.00
0.00
0.00
0.00
125.00
0.00
47,536
522.00
0.00
0.00
0.00
130.00
0.00
47,522
522.00
0.00
0.00
0.00
135.00
0.00
47,513
522.00
0.00
0.00
0.00
140.00
0.00
47,507
522.00
0.00
0.00
0.00
145.00
0.00
47,503
522.00
0.00
0.00
0.00
150.00
0.00
47,501
522.00
0.00
0.00
0.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 25-yr Duration=19 min, Inten=5.13 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 7
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 17.260 ac, 13.15% Impervious, Inflow Depth = 0.57" for 25-yr event
Inflow = 31.31 cfs @ 0.31 hrs, Volume= 0.818 of
Outflow = 7.03 cfs @ 0.56 hrs, Volume= 0.818 af, Atten= 78%, Lag= 14.7 min
Primary = 7.03 cfs @ 0.56 hrs, Volume= 0.818 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 522.00' Surf.Area= 14,523 sf Storage= 47,497 cf
Peak Elev= 523.75' @ 0.56 hrs Surf.Area= 20,884 sf Storage= 79,458 cf (31,961 cf above start)
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= 1,614.0 min ( 1,632.8 - 18.8 )
Volume Invert
#1 518.00'
Avail.
e Description
106,826 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
518.00
9,002
0 0
520.00
11,986
20,988 20,988
522.00
14,523
26,509 47,497
523.00
18,897
16,710 64,207
524.00
21,531
20,214 84,421
525.00
23,278
22,405 106,826
Device Routing
Invert
Outlet Devices
#1 Primary
520.00'
18.0" Round Culvert L= 40.0' Ke= 0.500
Inlet / Outlet Invert= 520.00' / 519.75' S= 0.0063 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
522.00'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
524.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
523.90'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
523.40'
12.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 25-yr Duration=19 min, Inten=5.13 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 8
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=7.00 cfs @ 0.56 hrs HW=523.75' (Free Discharge)
L1=Culvert (Passes 7.00 cfs of 14.75 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.14 cfs @ 6.38 fps)
4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
=Broad -Crested Rectangular Weir (Weir Controls 6.87 cfs @ 1.61 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=522.00' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 25-yr Duration=19 min, Inten=5.13 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 9
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
47,497
522.00
0.00
0.00
0.00
5.00
0.00
71,161
523.34
0.12
0.12
0.00
10.00
0.00
69,013
523.24
0.12
0.12
0.00
15.00
0.00
66,954
523.14
0.11
0.11
0.00
20.00
0.00
64,983
523.04
0.11
0.11
0.00
25.00
0.00
63,104
522.93
0.10
0.10
0.00
30.00
0.00
61,330
522.83
0.10
0.10
0.00
35.00
0.00
59,664
522.73
0.09
0.09
0.00
40.00
0.00
58,104
522.63
0.08
0.08
0.00
45.00
0.00
56,652
522.55
0.08
0.08
0.00
50.00
0.00
55,306
522.47
0.07
0.07
0.00
55.00
0.00
54,068
522.39
0.07
0.07
0.00
60.00
0.00
52,936
522.33
0.06
0.06
0.00
65.00
0.00
51,912
522.26
0.05
0.05
0.00
70.00
0.00
50,995
522.21
0.05
0.05
0.00
75.00
0.00
50,186
522.16
0.04
0.04
0.00
80.00
0.00
49,484
522.12
0.04
0.04
0.00
85.00
0.00
48,898
522.08
0.03
0.03
0.00
90.00
0.00
48,418
522.06
0.02
0.02
0.00
95.00
0.00
48,083
522.04
0.01
0.01
0.00
100.00
0.00
47,870
522.02
0.01
0.01
0.00
105.00
0.00
47,734
522.01
0.01
0.01
0.00
110.00
0.00
47,648
522.01
0.00
0.00
0.00
115.00
0.00
47,593
522.01
0.00
0.00
0.00
120.00
0.00
47,558
522.00
0.00
0.00
0.00
125.00
0.00
47,536
522.00
0.00
0.00
0.00
130.00
0.00
47,522
522.00
0.00
0.00
0.00
135.00
0.00
47,513
522.00
0.00
0.00
0.00
140.00
0.00
47,507
522.00
0.00
0.00
0.00
145.00
0.00
47,503
522.00
0.00
0.00
0.00
150.00
0.00
47,501
522.00
0.00
0.00
0.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 50-yr Duration=19 min, Inten=5.51 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 10
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 17.260 ac, 13.15% Impervious, Inflow Depth = 0.61" for 50-yr event
Inflow = 33.62 cfs @ 0.31 hrs, Volume= 0.879 of
Outflow = 9.01 cfs @ 0.54 hrs, Volume= 0.879 af, Atten= 73%, Lag= 13.9 min
Primary = 9.01 cfs @ 0.54 hrs, Volume= 0.879 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-150.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 522.00' Surf.Area= 14,523 sf Storage= 47,497 cf
Peak Elev= 523.82' @ 0.54 hrs Surf.Area= 21,054 sf Storage= 80,758 cf (33,261 cf above start)
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= 1,505.9 min ( 1,524.7 - 18.8 )
Volume Invert
#1 518.00'
Avail.
e Description
106,826 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
518.00
9,002
0 0
520.00
11,986
20,988 20,988
522.00
14,523
26,509 47,497
523.00
18,897
16,710 64,207
524.00
21,531
20,214 84,421
525.00
23,278
22,405 106,826
Device Routing
Invert
Outlet Devices
#1 Primary
520.00'
18.0" Round Culvert L= 40.0' Ke= 0.500
Inlet / Outlet Invert= 520.00' / 519.75' S= 0.0063 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
522.00'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
524.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
523.90'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
523.40'
12.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 50-yr Duration=19 min, Inten=5.51 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 11
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=8.99 cfs @ 0.54 hrs HW=523.82' (Free Discharge)
L1=Culvert (Passes 8.99 cfs of 14.91 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.14 cfs @ 6.49 fps)
4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
=Broad -Crested Rectangular Weir (Weir Controls 8.85 cfs @ 1.76 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=522.00' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
MOD Conservancy Ph 2 BMP-1 REV Waxhaw 50-yr Duration=19 min, Inten=5.51 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 12
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
47,497
522.00
0.00
0.00
0.00
5.00
0.00
71,178
523.34
0.12
0.12
0.00
10.00
0.00
69,030
523.24
0.12
0.12
0.00
15.00
0.00
66,970
523.14
0.11
0.11
0.00
20.00
0.00
64,998
523.04
0.11
0.11
0.00
25.00
0.00
63,118
522.93
0.10
0.10
0.00
30.00
0.00
61,344
522.83
0.10
0.10
0.00
35.00
0.00
59,676
522.73
0.09
0.09
0.00
40.00
0.00
58,116
522.64
0.08
0.08
0.00
45.00
0.00
56,663
522.55
0.08
0.08
0.00
50.00
0.00
55,316
522.47
0.07
0.07
0.00
55.00
0.00
54,077
522.39
0.07
0.07
0.00
60.00
0.00
52,945
522.33
0.06
0.06
0.00
65.00
0.00
51,920
522.26
0.05
0.05
0.00
70.00
0.00
51,002
522.21
0.05
0.05
0.00
75.00
0.00
50,192
522.16
0.04
0.04
0.00
80.00
0.00
49,489
522.12
0.04
0.04
0.00
85.00
0.00
48,902
522.08
0.03
0.03
0.00
90.00
0.00
48,421
522.06
0.02
0.02
0.00
95.00
0.00
48,085
522.04
0.01
0.01
0.00
100.00
0.00
47,871
522.02
0.01
0.01
0.00
105.00
0.00
47,735
522.01
0.01
0.01
0.00
110.00
0.00
47,649
522.01
0.00
0.00
0.00
115.00
0.00
47,594
522.01
0.00
0.00
0.00
120.00
0.00
47,558
522.00
0.00
0.00
0.00
125.00
0.00
47,536
522.00
0.00
0.00
0.00
130.00
0.00
47,522
522.00
0.00
0.00
0.00
135.00
0.00
47,513
522.00
0.00
0.00
0.00
140.00
0.00
47,507
522.00
0.00
0.00
0.00
145.00
0.00
47,503
522.00
0.00
0.00
0.00
150.00
0.00
47,501
522.00
0.00
0.00
0.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 1-yr Duration=22 min, Inten=2.74 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 1
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 22.580 ac, 11.73% Impervious, Inflow Depth = 0.34" for 1-yr event
Inflow = 21.03 cfs @ 0.37 hrs, Volume= 0.642 of
Outflow = 0.16 cfs @ 0.73 hrs, Volume= 0.642 af, Atten= 99%, Lag= 21.9 min
Primary = 0.16 cfs @ 0.73 hrs, Volume= 0.642 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 546.50' Surf.Area= 9,135 sf Storage= 27,109 cf
Peak Elev= 548.84' @ 0.73 hrs Surf.Area= 14,311 sf Storage= 54,809 cf (27,700 cf above start)
Plug -Flow detention time= 4,864.0 min calculated for 0.020 of (3% of inflow)
Center -of -Mass det. time= 1,838.8 min ( 1,860.8 - 22.0 )
Volume Invert
#1 542.00'
Avail.
e Description
88,785 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
542.00
3,378
0 0
546.00
7,893
22,542 22,542
547.00
10,376
9,135 31,677
548.00
12,770
11,573 43,250
549.00
14,594
13,682 56,932
550.00
15,834
15,214 72,146
551.00
17,445
16,640 88,785
Device Routing
Invert
Outlet Devices
#1 Primary
542.00'
18.0" Round Culvert L= 48.0' Ke= 0.500
Inlet / Outlet Invert= 542.00' / 541.00' S= 0.0208 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
546.50'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
550.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
549.20'
8.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
549.70'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 1-yr Duration=22 min, Inten=2.74 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 2
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=0.16 cfs @ 0.73 hrs HW=548.84' (Free Discharge)
L1=Culvert (Passes 0.16 cfs of 21.01 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.16 cfs @ 7.37 fps)
4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
=Broad -Crested Rectangular Weir( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=546.50' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 1-yr Duration=22 min, Inten=2.74 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 3
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
27,109
546.50
0.00
0.00
0.00
5.00
0.00
52,387
548.67
0.15
0.15
0.00
10.00
0.00
49,668
548.47
0.15
0.15
0.00
15.00
0.00
47,080
548.28
0.14
0.14
0.00
20.00
0.00
44,623
548.10
0.13
0.13
0.00
25.00
0.00
42,298
547.92
0.13
0.13
0.00
30.00
0.00
40,124
547.73
0.12
0.12
0.00
35.00
0.00
38,105
547.56
0.11
0.11
0.00
40.00
0.00
36,240
547.39
0.10
0.10
0.00
45.00
0.00
34,529
547.25
0.09
0.09
0.00
50.00
0.00
32,973
547.11
0.08
0.08
0.00
55.00
0.00
31,572
546.99
0.07
0.07
0.00
60.00
0.00
30,349
546.85
0.06
0.06
0.00
65.00
0.00
29,323
546.74
0.05
0.05
0.00
70.00
0.00
28,493
546.65
0.04
0.04
0.00
75.00
0.00
27,862
546.58
0.03
0.03
0.00
80.00
0.00
27,487
546.54
0.01
0.01
0.00
85.00
0.00
27,299
546.52
0.01
0.01
0.00
90.00
0.00
27,204
546.51
0.00
0.00
0.00
95.00
0.00
27,157
546.51
0.00
0.00
0.00
100.00
0.00
27,133
546.50
0.00
0.00
0.00
105.00
0.00
27,121
546.50
0.00
0.00
0.00
110.00
0.00
27,115
546.50
0.00
0.00
0.00
115.00
0.00
27,112
546.50
0.00
0.00
0.00
120.00
0.00
27,111
546.50
0.00
0.00
0.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 10-yr Duration=22 min, Inten=4.32 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 4
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 22.580 ac, 11.73% Impervious, Inflow Depth = 0.54" for 10-yr event
Inflow = 33.17 cfs @ 0.37 hrs, Volume= 1.013 of
Outflow = 7.23 cfs @ 0.65 hrs, Volume= 1.013 af, Atten= 78%, Lag= 17.2 min
Primary = 7.23 cfs @ 0.65 hrs, Volume= 1.013 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 546.50' Surf.Area= 9,135 sf Storage= 27,109 cf
Peak Elev= 549.67' @ 0.65 hrs Surf.Area= 15,425 sf Storage= 67,126 cf (40,017 cf above start)
Plug -Flow detention time= 3,256.6 min calculated for 0.391 of (39% of inflow)
Center -of -Mass det. time= 1,599.2 min ( 1,621.2 - 22.0 )
Volume Invert
#1 542.00'
Avail.
e Description
88,785 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
542.00
3,378
0 0
546.00
7,893
22,542 22,542
547.00
10,376
9,135 31,677
548.00
12,770
11,573 43,250
549.00
14,594
13,682 56,932
550.00
15,834
15,214 72,146
551.00
17,445
16,640 88,785
Device Routing
Invert
Outlet Devices
#1 Primary
542.00'
18.0" Round Culvert L= 48.0' Ke= 0.500
Inlet / Outlet Invert= 542.00' / 541.00' S= 0.0208 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
546.50'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
550.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
549.20'
8.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
549.70'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 10-yr Duration=22 min, Inten=4.32 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 5
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=7.22 cfs @ 0.65 hrs HW=549.67' (Free Discharge)
L1=Culvert (Passes 7.22 cfs of 22.38 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.19 cfs @ 8.57 fps)
4=Broad-Crested Rectangular Weir (Weir Controls 7.03 cfs @ 1.87 fps)
=Broad -Crested Rectangular Weir( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=546.50' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 10-yr Duration=22 min, Inten=4.32 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 6
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
27,109
546.50
0.00
0.00
0.00
5.00
0.00
58,314
549.09
0.17
0.17
0.00
10.00
0.00
55,331
548.88
0.16
0.16
0.00
15.00
0.00
52,478
548.67
0.15
0.15
0.00
20.00
0.00
49,755
548.48
0.15
0.15
0.00
25.00
0.00
47,163
548.29
0.14
0.14
0.00
30.00
0.00
44,701
548.11
0.13
0.13
0.00
35.00
0.00
42,372
547.92
0.13
0.13
0.00
40.00
0.00
40,193
547.74
0.12
0.12
0.00
45.00
0.00
38,168
547.56
0.11
0.11
0.00
50.00
0.00
36,298
547.40
0.10
0.10
0.00
55.00
0.00
34,583
547.25
0.09
0.09
0.00
60.00
0.00
33,022
547.12
0.08
0.08
0.00
65.00
0.00
31,615
546.99
0.07
0.07
0.00
70.00
0.00
30,386
546.86
0.06
0.06
0.00
75.00
0.00
29,353
546.75
0.05
0.05
0.00
80.00
0.00
28,517
546.65
0.04
0.04
0.00
85.00
0.00
27,879
546.58
0.03
0.03
0.00
90.00
0.00
27,495
546.54
0.01
0.01
0.00
95.00
0.00
27,303
546.52
0.01
0.01
0.00
100.00
0.00
27,206
546.51
0.00
0.00
0.00
105.00
0.00
27,158
546.51
0.00
0.00
0.00
110.00
0.00
27,134
546.50
0.00
0.00
0.00
115.00
0.00
27,122
546.50
0.00
0.00
0.00
120.00
0.00
27,115
546.50
0.00
0.00
0.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 25-yr Duration=22 min, Inten=4.82 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 7
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 22.580 ac, 11.73% Impervious, Inflow Depth = 0.60" for 25-yr event
Inflow = 37.02 cfs @ 0.37 hrs, Volume= 1.131 of
Outflow = 12.10 cfs @ 0.61 hrs, Volume= 1.130 af, Atten= 67%, Lag= 14.8 min
Primary = 12.10 cfs @ 0.61 hrs, Volume= 1.130 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 546.50' Surf.Area= 9,135 sf Storage= 27,109 cf
Peak Elev= 549.80' @ 0.61 hrs Surf.Area= 15,591 sf Storage= 69,161 cf (42,051 cf above start)
Plug -Flow detention time= 2,862.9 min calculated for 0.508 of (45% of inflow)
Center -of -Mass det. time= 1,436.8 min ( 1,458.8 - 22.0 )
Volume Invert
#1 542.00'
Avail.
e Description
88,785 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
542.00
3,378
0 0
546.00
7,893
22,542 22,542
547.00
10,376
9,135 31,677
548.00
12,770
11,573 43,250
549.00
14,594
13,682 56,932
550.00
15,834
15,214 72,146
551.00
17,445
16,640 88,785
Device Routing
Invert
Outlet Devices
#1 Primary
542.00'
18.0" Round Culvert L= 48.0' Ke= 0.500
Inlet / Outlet Invert= 542.00' / 541.00' S= 0.0208 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
546.50'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
550.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
549.20'
8.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
549.70'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 25-yr Duration=22 min, Inten=4.82 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 8
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=11.94 cfs @ 0.61 hrs HW=549.80' (Free Discharge)
L1=Culvert (Passes 11.94 cfs of 22.60 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.19 cfs @ 8.75 fps)
4=Broad-Crested Rectangular Weir (Weir Controls 10.32 cfs @ 2.14 fps)
=Broad -Crested Rectangular Weir (Weir Controls 1.43 cfs @ 0.87 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=546.50' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 25-yr Duration=22 min, Inten=4.82 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 9
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
27,109
546.50
0.00
0.00
0.00
5.00
0.00
58,342
549.09
0.17
0.17
0.00
10.00
0.00
55,358
548.89
0.16
0.16
0.00
15.00
0.00
52,504
548.68
0.15
0.15
0.00
20.00
0.00
49,780
548.48
0.15
0.15
0.00
25.00
0.00
47,186
548.29
0.14
0.14
0.00
30.00
0.00
44,724
548.11
0.13
0.13
0.00
35.00
0.00
42,393
547.93
0.13
0.13
0.00
40.00
0.00
40,213
547.74
0.12
0.12
0.00
45.00
0.00
38,187
547.56
0.11
0.11
0.00
50.00
0.00
36,315
547.40
0.10
0.10
0.00
55.00
0.00
34,598
547.25
0.09
0.09
0.00
60.00
0.00
33,036
547.12
0.08
0.08
0.00
65.00
0.00
31,628
546.99
0.07
0.07
0.00
70.00
0.00
30,397
546.86
0.06
0.06
0.00
75.00
0.00
29,362
546.75
0.05
0.05
0.00
80.00
0.00
28,524
546.65
0.04
0.04
0.00
85.00
0.00
27,884
546.58
0.03
0.03
0.00
90.00
0.00
27,498
546.54
0.01
0.01
0.00
95.00
0.00
27,304
546.52
0.01
0.01
0.00
100.00
0.00
27,207
546.51
0.00
0.00
0.00
105.00
0.00
27,158
546.51
0.00
0.00
0.00
110.00
0.00
27,134
546.50
0.00
0.00
0.00
115.00
0.00
27,122
546.50
0.00
0.00
0.00
120.00
0.00
27,115
546.50
0.00
0.00
0.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 50-yr Duration=22 min, Inten=5.19 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 10
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Summary for Pond 2P: P1
Inflow Area = 22.580 ac, 11.73% Impervious, Inflow Depth = 0.65" for 50-yr event
Inflow = 39.83 cfs @ 0.37 hrs, Volume= 1.217 of
Outflow = 15.90 cfs @ 0.59 hrs, Volume= 1.216 af, Atten= 60%, Lag= 13.2 min
Primary = 15.90 cfs @ 0.59 hrs, Volume= 1.216 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 546.50' Surf.Area= 9,135 sf Storage= 27,109 cf
Peak Elev= 549.88' @ 0.59 hrs Surf.Area= 15,681 sf Storage= 70,266 cf (43,157 cf above start)
Plug -Flow detention time= 2,599.1 min calculated for 0.594 of (49% of inflow)
Center -of -Mass det. time= 1,336.8 min ( 1,358.8 - 22.0 )
Volume Invert
#1 542.00'
Avail.
e Description
88,785 cf Custom Stage Data (Prismatic)Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
542.00
3,378
0 0
546.00
7,893
22,542 22,542
547.00
10,376
9,135 31,677
548.00
12,770
11,573 43,250
549.00
14,594
13,682 56,932
550.00
15,834
15,214 72,146
551.00
17,445
16,640 88,785
Device Routing
Invert
Outlet Devices
#1 Primary
542.00'
18.0" Round Culvert L= 48.0' Ke= 0.500
Inlet / Outlet Invert= 542.00' / 541.00' S= 0.0208 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Device 1
546.50'
2.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#3 Secondary
550.00'
20.0' long x 8.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
#4 Device 1
549.20'
8.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
#5 Device 1
549.70'
16.0' long x 1.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 50-yr Duration=22 min, Inten=5.19 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 11
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
2.50 3.00
Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31
3.30 3.31 3.32
Primary OutFlow Max=15.78 cfs @ 0.59 hrs HW=549.88' (Free Discharge)
L1=Culvert (Passes 15.78 cfs of 22.71 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.19 cfs @ 8.85 fps)
4=Broad-Crested Rectangular Weir (Weir Controls 12.40 cfs @ 2.29 fps)
=Broad -Crested Rectangular Weir (Weir Controls 3.19 cfs @ 1.13 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=546.50' (Free Discharge)
L3= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

REVISED 02-13-20
Conservancy Ph 2 BMP-2 REV Waxhaw 50-yr Duration=22 min, Inten=5.19 in/hr
Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 2/13/2020
HydroCAD®10.10-3a Sampler s/n S16802 ©2020 HydroCAD Software Solutions LLC Page 12
This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and
educational use ONLY. For actual design or modeling applications you MUST use a full version of
HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete
technical support,training materials, and additional features which are essential for actual design work.
Hydrograph for Pond 2P: P1
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
27,109
546.50
0.00
0.00
0.00
5.00
0.00
58,350
549.09
0.17
0.17
0.00
10.00
0.00
55,366
548.89
0.16
0.16
0.00
15.00
0.00
52,511
548.68
0.15
0.15
0.00
20.00
0.00
49,787
548.48
0.15
0.15
0.00
25.00
0.00
47,193
548.29
0.14
0.14
0.00
30.00
0.00
44,730
548.11
0.13
0.13
0.00
35.00
0.00
42,399
547.93
0.13
0.13
0.00
40.00
0.00
40,218
547.74
0.12
0.12
0.00
45.00
0.00
38,192
547.56
0.11
0.11
0.00
50.00
0.00
36,320
547.40
0.10
0.10
0.00
55.00
0.00
34,603
547.25
0.09
0.09
0.00
60.00
0.00
33,040
547.12
0.08
0.08
0.00
65.00
0.00
31,631
547.00
0.07
0.07
0.00
70.00
0.00
30,400
546.86
0.06
0.06
0.00
75.00
0.00
29,364
546.75
0.05
0.05
0.00
80.00
0.00
28,526
546.66
0.04
0.04
0.00
85.00
0.00
27,885
546.58
0.03
0.03
0.00
90.00
0.00
27,499
546.54
0.01
0.01
0.00
95.00
0.00
27,305
546.52
0.01
0.01
0.00
100.00
0.00
27,207
546.51
0.00
0.00
0.00
105.00
0.00
27,158
546.51
0.00
0.00
0.00
110.00
0.00
27,134
546.50
0.00
0.00
0.00
115.00
0.00
27,122
546.50
0.00
0.00
0.00
120.00
0.00
27,115
546.50
0.00
0.00
0.00

REVISED 02-13-20
3
II
I
Outlet K op + La 90
Pipe :
diameter (Do)
80
i rater < 0.500
�Ctl 70 - e
r ,
`rotPt
6n -
s- A n
011"
i
q _ ,� y
-r..
tiA
to
10
ip
La 10'
CL
cc
--�v = ZU
Is
v to a
dso = 0.33'
10 20 so 100 zoo SOD 1000
Q10 4.4
Discharge (0/sec)
= cfs
D=18"
Figure 8.06a Design of outlet protection from a round pipe flowing full, minimum tailwater condition (Tw < 0.5 diameter)
Riprap Apron Design
BMP-1 Outfall

REVISED 02-13-20
3
�I
Outlet W Do + La 90
Pipe :.
diameter IDur
so .
i rater < 0.500 i
�Ctl 70 - e
r ,
"rot 6n -
s- A n
i
q.................. _ y
30
20
» 3
10.. :. }(
4
La = 10,
- -. � _
Oe
{c, a
3t
vr° _
1 i
i5 dso = 0.33'
v x 10 A
v-
10 20 50 100 200 500 1000
Q10 = 7.2 CfS Discharge (0/sec)
D=18"
Figure 8.06a Design of outlet protection from a round pipe flowing full, minimum tailwater condition (Tw < 0.5 diameter)
Riprap Apron Design
BMP-2 Outfall

REVISED 02-13-20
RIPRAP APRON SUMMARY
Do
Q10
d50
La
W1
W2
dmax
T
Pipe No.
(in)
(cfs)
(in)
(ft)
(ft)
(ft)
(in)
(in)
BMP-1
18
4.4
4
10
5
12
6
12
BMP-2
18
7.2
4
10
5
12
6
12