20191641 Ver 1_2019-1012 Preliminary SW report_20191127

301 McCullough Drive, Suite 109 Charlotte, North
Carolina 28262
p. 704.548.0333
[e-mail]
Job Number: 2019-1012
LUMLEY ROAD HONDA
Preliminary Stormwater Management Plan (SWMP)
Prepared For: Hendrick Automotive Group
November 14, 2019

PROJECT SUMMARY

Project Name: Lumley Road Honda
Location: City of Raleigh, Wake County, North Carolina
Type: Stormwater Management Plan
Reviewing Agency: City of Raleigh, North Carolina DEQ

HYDROLOGIC SUMMARY

Rainfall Data: City of Raleigh Stormwater Manual

1-yr 3.00”
2-yr 3.60”
5-yr 4.56”
10-yr 5.28”
25-yr 6.48”
50-yr 7.20”
100-yr 8.00”

Rainfall Distribution: NRCS Type II 24 hour
Detention Policy: City of Raleigh
Water Quality: City of Raleigh, North Carolina DEQ
Hydrology Modeling Program: HydroCAD 10.0

DESIGN SUMMARY

Detention: Underground Sand Filters
Water Quality: Underground Sand Filters
Receiving Water Body: Unnamed Tributary of Sycamore Creek

REVISIONS

TABLE OF CONTENTS

1.0 Introduction ............................................................................................................................................ 1
2.0 Hydrologic Analysis ............................................................................................................................. 1
3.0 Existing Conditions Analysis ................................................................................................................ 1
4.0 Post-Developed Analysis .................................................................................................................... 3
5.0 Water Quality ...................................................................................................................................... 5
6.0 Nutrient Management ......................................................................................................................... 5
7.0 Conclusion .............................................................................................................................................. 5

TABLES

Table 1 - Existing Subarea Characteristics ........................................................................................... 2
Table 2 - Exisitng Peak Flow Rates ........................................................................................................ 2
Table 3 - Post-developed Subarea Characteristics ............................................................................ 3
Table 4 - Allowable and Proposed Release Rates for Outfall 01 (Sand Filter 01) .................... 4
Table 5 - Allowable and Proposed Release Rates for Outfall 02 (Sand Filter 02) .................... 4
Table 6 - Offsite Watershed Peak Flow Rates ................................................................................... 4
Table 7 - Water Quality Calculations ................................................................................................... 5

APPENDICES

Appendix A: USDA Soils Report
Appendix B: Water Quality Calculations
Appendix C: HydroCAD Output
Appendix D: Exhibits

Lumley Road Honda emht.com | 1
1.0 INTRODUCTION

The following report provides a preliminary analysis and design of the Stormwater Management
Plan for Lumley Road Honda. The proposed site is located on the northeast corner of the Mt. Heman
Road and Lumley Road intersection in Raleigh, North Carolina. The Proposed project area involves
the redevelopment of existing parking lot area and development of wooded area into a
commercial building and associated parking lots. The Stormwater Management Plan was prepared
in accordance with the requirements of both the City of Raleigh and the North Carolina DEQ. The
runoff from this site will be routed through a series of sand filters for water quality, nutrient
management, and quantity control before discharging to an unnamed tributary of Sycamore Creek.

Figure 1 – Site Location Map

2.0 HYDROLOGIC ANALYSIS

Hydrologic parameters such as Runoff Curve Number (RCN) and Time of Concentration were
determined using standard Natural Resources Conservation Service (NRCS) methodology. The 2-,
10-, 25-, 50-, and 100-year storm event discharge amounts were calculated using the NRCS TR-
55 method. This analysis reflects the NRCS Type II distribution, 24-hr storm duration. Rainfall depths
were obtained from the City of Raleigh Stormwater Manual. The peak flow rates were computed
using the HydroCAD 10.0 computer program.

3.0 EXISTING CONDITIONS ANALYSIS

The existing condition, as seen on Exhibit 1 in Appendix D, consists of parking lots and wooded
area in good condition in Type “B and C” soils (Chewacla and Creedmoor-Green level complex).
SITE

Lumley Road Honda emht.com | 2
Existing 01 and Existing 03 naturally drain to the stream in the center of the site, the unnamed
tributary of Sycamore Creek or Outfall 01. Existing 02 and Existing 04 naturally drain to the
southeast into the storm sewers along Lumley Road, Outfall 02. The storm sewer eventually
discharges into the same unnamed tributary of Sycamore Creek that Outfall 01 releases to.

Existing 05 and Existing 06 are tributary to Sycamore Creek at a point further downstream than
where the rest of the area discharge. These areas will not be useable as parking lot in the future
when Lumley Road is relocated.

All pre-developed subarea characteristics are summarized in Table 1. Existing peak flow rates are
provided in Table 2 of each outfall. All time of concentration calculations can be found in the
HydroCAD output in Appendix C.

Table 1 - Existing Subarea Characteristics
Subarea
Identifier
Tributary
Area
(acres) Land Usage
Runoff
Curve
Number
%
Impervious
(%)
Time of
Concentration
(min)
Existing 01 2.00
Existing Parking
Lot 97 97% 5.0
Existing 02 1.87
Existing Parking
Lot 97 98% 5.0
Existing 03 4.17 Wooded Area 65 0% 23.5
Existing 04 2.41 Wooded Area 70 0% 19.1
Existing 05 0.51
Existing Parking
Lot 97 95% 5.0
Existing 06 0.88
Existing Parking
Lot 98 99% 5.0

Table 2 - Exisitng Peak Flow Rates
Storm Event
(year)
Existing Outfall
01
Peak Flow Rates
(cfs)
Existing Outfall
02
Peak Flow Rates
(cfs)
Existing 05
Peak Flow
Rates
(cfs)
Existing 06
Peak Flow
Rates
(cfs)
1 8.75 8.65 2.20 3.86
2 10.97 10.88 2.66 4.64
5 14.89 14.61 3.39 5.90
10 17.98 17.49 3.94 6.84
25 23.33 22.42 4.85 8.41
50 26.63 25.42 5.39 9.35
100 30.37 28.80 6.00 10.40

Exhibit 02 displays the existing watershed to the unnamed tributary of Sycamore Creek. This
watershed will be modified in the proposed condition, but the HydroCAD for this area has been
developed to ensure there are no negative impacts on the peak flow rates within the stream.
HydroCAD output has been provided in Appendix C with these flow rates.

Lumley Road Honda emht.com | 3
4.0 POST-DEVELOPED ANALYSIS

Exhibit 3, provided within Appendix D, shows the post-developed condition. The Lumley Road
Honda project will utilize two underground sand filters to provide water quality, nutrient
management, and quantity control for the proposed development.

Post 01 will drain to Sand Filter 01 which discharges to Outfall 01. Undetained 01 will flow to
Outfall 01 without being treated. Post 02 will drain to Sand Filter 02 which discharges to Outfall
02. Undetained 02 will drain to Outfall 02 without being treated.

Post 03 and Post 04 will remain parking lot for the preliminary design, but could potentially be
demolished and replaced with pervious surface to build credit for those outfalls.

The Offsite Watershed area will be bypassed through the site by storm sewers. The flow rates
listed in Table 6 will be used to design the bypass system. The post-developed subarea
characteristics are summarized in Table 3.

Table 3 - Post-developed Subarea Characteristics
Subarea
Identifier
Tributary
Area
(acres) Land Usage
Runoff
Curve
Number
%
Impervious
(%)
Time of
Concentration
(min)
Post 01 3.53
Proposed Building
and Lots 93 82% 5.0
Post 02 5.37
Proposed Building
and Lots 93 78% 5.0
Post 03 0.51
Existing Parking
Lot 97 95% 5.0
Post 04 0.88
Existing Parking
Lot 98 99% 5.0
Undetained 01 1.69
Existing/Proposed
Parking Lot 96 92% 5.0
Undetained 02 0.17
Proposed
Driveways 98 100% 5.0
Offsite
Watershed 30.88 Mixed Use 81 40% 19.7

The City of Raleigh requires the 2-, 10-, 25-, 50-, and 100-year storms be detained to the pre-
developed or existing rates. The post-developed allowable release rates and proposed release
rates can be found in Tables 4 and 5 for Outfall 01 and Outfall 02, respectively. HydroCAD output
has been provided in Appendix C.

Lumley Road Honda emht.com | 4
Table 4 - Allowable and Proposed Release Rates for Outfall 01 (Sand Filter 01)
Storm
Event
(yr.)
Existing Outfall
01
Peak Flow Rates
(cfs)
Allowable
Release Rates
(cfs.)
Total
Proposed to
Outfall 01
(cfs.)
Sand Filter
01 Proposed
Release Rates
(cfs.)
Maximum
W.S.E., T.O.S.
= 370.00
(feet)
Storage
Volume
Utilized
(ac-ft)
1 8.75 - 7.14 0.81 365.98 0.416
2 10.97 10.97 9.12 1.11 366.62 0.518
5 14.89 - 12.02 5.87 367.29 0.624
10 17.98 17.98 17.50 6.80 367.89 0.719
25 23.33 23.33 22.62 8.20 368.96 0.885
50 26.63 26.63 25.07 8.90 369.57 0.981
100 30.37 30.37 27.61 9.35 369.98 1.062

Storage Utilized (100-yr event): 1.062 ac-ft
Storage Provided (Top of Storage = 370.00 ft.): 1.068 ac-ft

Table 5 - Allowable and Proposed Release Rates for Outfall 02 (Sand Filter 02)
Storm
Event
(yr.)
Existing Outfall
02
Peak Flow Rates
(cfs)
Allowable
Release Rates
(cfs.)
Total
Proposed to
Outfall 02
(cfs.)
Sand Filter
02 Proposed
Release Rates
(cfs.)
Maximum
W.S.E., T.O.B.
= 378.00
(feet)
Storage
Volume
Utilized
(ac-ft)
1 8.65 - 2.92 2.83 373.96 0.583
2 10.88 10.88 5.81 5.65 374.49 0.703
5 14.61 - 8.83 8.57 375.37 0.901
10 17.49 17.49 10.92 10.58 376.02 1.046
25 22.42 22.42 13.62 13.15 377.05 1.277
50 25.42 25.42 14.93 14.36 377.61 1.402
100 28.80 28.80 16.12 15.11 377.98 1.507

Storage Utilized (100-yr event): 1.507 ac-ft
Storage Provided (Top of Storage = 378.00 ft.): 1.514 ac-ft

Table 6 - Offsite Watershed Peak Flow Rates
Storm
Event
(yr.)
Peak Flow Rates
to Bypass System
(cfs)
1 45.04
2 61.88
5 90.07
10 111.81
25 148.60
50 170.90
100 195.66

Lumley Road Honda emht.com | 5
5.0 WATER QUALITY

The North Carolina DEQ requires that the first flush (or first 1” of rainfall) gets treated for water
quality. Water quality will be provided by the sand filters in each basin.

Table 7 - Water Quality Calculations
Basin Identifier
Tributary
area
(acres)
Percent
Impervious
(%)
Water Quality
Volume
(ac-ft)
Water Quality
Elevation
(feet)
Required Sand
Area
(sf.)
Provided
Sand Area
(sf.)
Sand Filter 01 3.53 82% 0.232 369.40 1046 1624
Sand Filter 02 5.37 78% 0.337 377.46 1515 2088

6.0 NUTRIENT MANAGEMENT

The proposed underground sand filters will provide nutrient management for the majority of the
new impervious area created by the development. Undetained 01 is exempt from nutrient
management as it exists onsite today. Nutrient calculations are summarized in Table XX below and
included in Appendix B. The calculations result in a TN export of 9.34 lbs/acre/year for the 11.23
acres of onsite area. The nutrient requirement is 9.34 – 3.6 lbs/acre/year for 30 years over the
11.23 acres of development area for a mitigation burden of 1934.25 lbs of nitrogen.

Type of Land Cover
Site
Area
(acres)
TN Export
Coefficient
(lbs/ac/yr)
TN Export
Coeff. With
Sand Filter
35% reduction
(lbs/ac/yr)
TN Export
by Land Use
(lbs/yr)
TN Export
from Site
(lbs/ac/yr)
Impervious surfaces -
Undetained Driveways 0.17 21.2 21.2 3.56
Permanently preserved
undisturbed open space 0.60 0.6 0.6 0.36
Permanently preserved
managed open space 1.56 1.2 1.2 1.88
BMP - Permanently
preserved undisturbed
open space 0.22 0.6 0.39 0.09
BMP - Permanently
preserved managed
open space 1.58 1.2 0.78 1.23
BMP - Impervious
surfaces 7.10 21.2 13.78 97.78
Total 11.23 104.90
Average for site 9.34

7.0 CONCLUSION

The preliminary proposed stormwater management plan for Lumley Road Honda meets all
requirements for detention and water quality as set forth by the City of Raleigh and the North
Carolina DEQ.

APPENDIX A:

USDA Soils Report

Hydrologic Soil Group—Wake County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
10/23/2019
Page 1 of 4397490039750003975100397520039753003975400397500039751003975200397530039754003975500700900701000701100701200701300701400701500701600701700
700900 701000 701100 701200 701300 701400 701500 701600 701700
35° 54' 11'' N 78° 46' 27'' W35° 54' 11'' N78° 45' 50'' W35° 53' 51'' N
78° 46' 27'' W35° 53' 51'' N
78° 45' 50'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,260 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Wake County, North Carolina
Survey Area Data: Version 18, Sep 16, 2019
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Apr 27, 2014—May
6, 2014
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Hydrologic Soil Group—Wake County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
10/23/2019
Page 2 of 4
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
ChA Chewacla and
Wehadkee soils, 0 to
2 percent slopes,
frequently flooded
B/D 3.6 10.5%
CrB Creedmoor-Green Level
complex, 2 to 6
percent slopes
C/D 4.4 12.9%
CrC Creedmoor-Green Level
complex, 6 to 10
percent slopes
C/D 1.1 3.2%
CrD Creedmoor-Green Level
complex, 10 to 15
percent slopes
C/D 4.3 12.6%
Ur Urban land 20.9 60.8%
Totals for Area of Interest 34.4 100.0%
Hydrologic Soil Group—Wake County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
10/23/2019
Page 3 of 4
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Wake County, North Carolina
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
10/23/2019
Page 4 of 4

APPENDIX B:

Water Quality Calculations

Stormwater Management, Water Quality, and Nutrient Calculations
Please refer to pre and post tributary maps
Depth to seasonal high water table (SHWT) inches
Surface elevation of boring ft
Elevation of SHWT ft
Bottom of Sand Filter Elevation 367.5 and 375.5 ft
Step 1: Determine predeveloped peak flow rates
Predeveloped Rainfall Depths
Subarea Pre Outfall 01 Pre Outfall 02 Year 24-hr Rain (in)
Area (ac) 6.499 4.285 1 3.00
Tc (min) 23.5 19.0 2 3.60
Soil Type B/C C 5 4.56
Land Use
Existing Impervious, Woods, Fair
Condition
Existing Impervious,
Woods, Fair Condition 10 5.28
RCN 75 84 25 6.48
50 7.20
100 8.00
Note: Predeveloped area is equal to post-developed area tributary to onsite BMP system, perimeter areas not able to be treated are mainly
grass areas with a small area of sidewalk that sheet flows through open space.
Predeveloped Peak Flow Rates Outfall 01 Outfall 02
Year (cfs) (cfs)
1 8.75 8.65
2 10.97 10.88
5 14.89 14.61
10 17.98 17.49
25 23.33 22.42
50 26.63 25.42
100 30.37 28.80
Step 2: Determine post-developed peak flow rates
Post-developed
Subarea Post 02 Post 01 Undetained 01 Undetained 02
Area (sf) 233917 153767 73442 7318
Tc (min) 5.0 5.0 5.0 5.0
Soil Type C C C C
Impervious Area (sf) 182647 126455 67213 7318
RCN 93 93 96 98
Post-developed Peak Flow Rates (w/o detention)
Storm Event Post 02 Post 01 Undetained 01 Undetained 02
(yr) (cfs) (cfs) (cfs) (cfs)
1 21.04 13.83 7.13 0.73
2 26.03 17.11 8.66 0.88
5 33.95 22.32 11.10 1.12
10 39.86 26.20 12.92 1.30
25 49.63 32.63 15.94 1.60
50 55.47 36.46 17.75 1.78
100 61.93 40.71 19.76 1.98
Step 3: Design Sand Filter for Post 02 Area
Sand Filter Design - NC DENR Chapter 11
Onsite Area = 5.37 acres
Offsite Area = 0 acres
%Impervious = 78%
Rv = 0.75
WQ Rain = 1 "
WQv = 14673 cu-ft
75% WQV = 11005 cu-ft
Determine filter bed and sedimentation basin surface areas with respect to water quality volume and maximum head
Hmax = WQv(adj)/(As +Af)
Hmax = 2.00 ft
As + Af = 5502 sq-ft
Minimum surface area of filter bed
Minimum Af = (WQv)(df)/(k)(t)(ha +df)
WQv = 14673 cu-ft water quality volume
df = 1.5 ft depth of sand filter bed
k = 3.5 ft/day coefficient of permeability
t = 1.66 days time required to drain
ha = 1.00 ft average head
Min. Af = 1515 sq-ft
Width of Chamber = 83.5 ft
Minimum Length = 18.15 ft
Design Length = 25 ft
Actual Area = 2088 sq-ft
Volume Contained = 4175 cu-ft
Minimum surface area of sedimentation chamber
Min. As = 3415 sq-ft (per As + Af)
Min. As = 970 sq-ft (per Camp Hazen Equation)
Width of Chamber = 83.5 ft
Minimum Length = 11.62 ft
Design Length = 65 ft
Actual Area = 5428
Volume Contained = 10855 cu-ft
Stage Discharge Calculation - Sand Filter Only
Qo = Af(k)(hf+df)/df
Af = 2088 sf
k = 3.5 ft/day
df = 1.5 ft
hf Qo Qo (ft)
0.00 0.00 cf/day 0.000 cfs 380.0
0.10 7793 cf/day 0.090 cfs 380.1
0.20 8280 cf/day 0.096 cfs 380.2
0.50 9742 cf/day 0.113 cfs 380.5
1.00 12177 cf/day 0.141 cfs 381.0
2.00 17048 cf/day 0.197 cfs 382.0
3.00 21919 cf/day 0.254 cfs 383.0
4.00 26790 cf/day 0.310 cfs 384.0
5.00 31660 cf/day 0.366 cfs 385.0
6.00 36531 cf/day 0.423 cfs 386.0
Determine Drawdown Time of Sand Filter
Drawdown time must be less than 40 hours
Drainage Area = 5.37 acres
WQv = 14673 cu-ft
Water Quality Event: 1", 6-hr event, Type II distribution
Drawdown Time = 44 hours (see HydroCAD output)
Step 3: Design Sand Filter for Post 01 Area
Sand Filter Design - NC DENR Chapter 11
Onsite Area = 3.53 acres
Offsite Area = 0 acres
%Impervious = 82%
Rv = 0.79
WQ Rain = 1 "
WQv = 10125 cu-ft
75% WQV = 7594 cu-ft
Determine filter bed and sedimentation basin surface areas with respect to water quality volume and maximum head
Hmax = WQv(adj)/(As +Af)
Hmax = 2.00 ft
As + Af = 3797 sq-ft
Minimum surface area of filter bed
Minimum Af = (WQv)(df)/(k)(t)(ha +df)
WQv = 10125 cu-ft water quality volume
df = 1.5 ft depth of sand filter bed
k = 3.5 ft/day coefficient of permeability
t = 1.66 days time required to drain
ha = 1.00 ft average head
Min. Af = 1046 sq-ft
Width of Chamber = 58 ft
Minimum Length = 18.03 ft
Design Length = 28 ft
Actual Area = 1624 sq-ft
Volume Contained = 3248 cu-ft
Minimum surface area of sedimentation chamber
Min. As = 2173 sq-ft (per As + Af)
Min. As = 669 sq-ft (per Camp Hazen Equation)
Width of Chamber = 58 ft
Minimum Length = 11.54 ft
Design Length = 65 ft
Actual Area = 3768
Volume Contained = 7536 cu-ft
Stage Discharge Calculation - Sand Filter Only
Qo = Af(k)(hf+df)/df
Af = 1624 sf
k = 3.5 ft/day
df = 1.5 ft
hf Qo Qo (ft)
0.00 0.00 cf/day 0.000 cfs 380.0
0.10 6063 cf/day 0.070 cfs 380.1
0.20 6442 cf/day 0.075 cfs 380.2
0.50 7579 cf/day 0.088 cfs 380.5
1.00 9473 cf/day 0.110 cfs 381.0
2.00 13263 cf/day 0.154 cfs 382.0
3.00 17052 cf/day 0.197 cfs 383.0
4.00 20841 cf/day 0.241 cfs 384.0
5.00 24631 cf/day 0.285 cfs 385.0
6.00 28420 cf/day 0.329 cfs 386.0
Determine Drawdown Time of Sand Filter
Drawdown time must be less than 40 hours
Drainage Area = 3.53 acres
WQv = 10125 cu-ft
Water Quality Event: 1", 6-hr event, Type II distribution
Drawdown Time = 40 hours (see HydroCAD output)
Step 5: Check flow rate criteria
Storm event Existing 01 Flow Rates Allowable Release rates Proposed Release Rates
(years) (cfs) (cfs) (cfs)
1 8.75 8.75 7.14
2 10.97 10.97 9.12
5 14.89 14.89 12.02
10 17.98 17.98 17.50
25 23.33 23.33 22.62
50 26.63 26.63 25.07
100 30.37 30.37 27.61
Storm event Existing 02 Flow Rates Allowable Release rates Proposed Release Rates
(years) (cfs) (cfs) (cfs)
1 8.65 8.65 2.92
2 10.88 10.88 5.81
5 14.61 14.61 8.83
10 17.49 17.49 10.92
25 22.42 22.42 13.62
50 25.42 25.42 14.93
100 28.80 28.80 16.12
Type of Land Cover Site Area (acres) TN Export Coeff. (lbs/ac/yr)
TN Export Coeff. With Sand Filter
35% reduction (lbs/ac/yr) TN Export by Land Use (lbs/yr)
TN Export from Site
(lbs/ac/yr)
Impervious surfaces - Undetained Driveways 0.17 21.2 21.2 3.56
Permanently preserved undisturbed open space 0.60 0.6 0.6 0.36
Permanently preserved managed open space 1.56 1.2 1.2 1.88
BMP - Permanently preserved undisturbed open space 0.22 0.6 0.39 0.09
BMP - Permanently preserved managed open space 1.58 1.2 0.78 1.23
BMP - Impervious surfaces 7.10 21.2 13.78 97.78
Total 11.23 104.90
Average for site 9.34
Requirement is 3.6 lbs/ac/yr, therefore mitigation payment is: 9.34
- 3.60
5.74 lbs/ac/yr
The site acre over 30 years will produce:1934.25 lbs of nitrogen
16P
SW Sediment and Sand
Filter WQ @ 377.46
18P
NE Basin Sediment and
Sand Filter WQ
@369.40
Routing Diagram for 2019-1012 Prelim SW 2019-11-12
Prepared by Symanetc, Printed 11/14/2019
HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
Type II 6-hr WQ 1" Rainfall=1.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 2HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 16P: SW Sediment and Sand Filter WQ @ 377.46
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Outflow = 0.19 cfs @ 0.00 hrs, Volume= 0.338 af, Atten= 0%, Lag= 0.0 min
Primary = 0.19 cfs @ 0.00 hrs, Volume= 0.338 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Starting Elev= 377.46' Surf.Area= 7,516 sf Storage= 14,731 cf
Peak Elev= 377.46' @ 0.00 hrs Surf.Area= 7,516 sf Storage= 14,731 cf
Plug-Flow detention time= (not calculated: no plugs found)
Center-of-Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.19 cfs @ 0.00 hrs HW=377.46' (Free Discharge)
1=Sand Filter (Custom Controls 0.19 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=377.46' (Free Discharge)
2=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 6-hr WQ 1" Rainfall=1.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 3HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 16P: SW Sediment and Sand Filter WQ @ 377.46
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)0.21
0.2
0.19
0.18
0.17
0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Peak Elev=377.46'
Storage=14,731 cf
0.00 cfs
0.19 cfs
0.19 cfs
0.00 cfs
Type II 6-hr WQ 1" Rainfall=1.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 4HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Hydrograph for Pond 16P: SW Sediment and Sand Filter WQ @ 377.46
Time
(hours)
Inflow
(cfs)
Storage
(cubic-feet)
Elevation
(feet)
Outflow
(cfs)
Primary
(cfs)
Secondary
(cfs)
0.00 0.00 14,731 377.46 0.19 0.19 0.00
2.00 0.00 13,366 377.28 0.18 0.18 0.00
4.00 0.00 12,072 377.11 0.17 0.17 0.00
6.00 0.00 10,846 376.94 0.17 0.17 0.00
8.00 0.00 9,683 376.79 0.16 0.16 0.00
10.00 0.00 8,582 376.64 0.15 0.15 0.00
12.00 0.00 7,537 376.50 0.14 0.14 0.00
14.00 0.00 6,548 376.37 0.13 0.13 0.00
16.00 0.00 5,610 376.25 0.13 0.13 0.00
18.00 0.00 4,721 376.13 0.12 0.12 0.00
20.00 0.00 3,879 376.02 0.11 0.11 0.00
22.00 0.00 3,080 375.91 0.11 0.11 0.00
24.00 0.00 2,324 375.81 0.10 0.10 0.00
26.00 0.00 1,608 375.71 0.10 0.10 0.00
28.00 0.00 931 375.62 0.09 0.09 0.00
30.00 0.00 402 375.55 0.05 0.05 0.00
32.00 0.00 170 375.52 0.02 0.02 0.00
34.00 0.00 72 375.51 0.01 0.01 0.00
36.00 0.00 30 375.50 0.00 0.00 0.00
38.00 0.00 13 375.50 0.00 0.00 0.00
40.00 0.00 5 375.50 0.00 0.00 0.00
42.00 0.00 2 375.50 0.00 0.00 0.00
44.00 0.00 1 375.50 0.00 0.00 0.00
46.00 0.00 0 375.50 0.00 0.00 0.00
48.00 0.00 0 375.50 0.00 0.00 0.00
50.00 0.00 0 375.50 0.00 0.00 0.00
52.00 0.00 0 375.50 0.00 0.00 0.00
54.00 0.00 0 375.50 0.00 0.00 0.00
56.00 0.00 0 375.50 0.00 0.00 0.00
58.00 0.00 0 375.50 0.00 0.00 0.00
60.00 0.00 0 375.50 0.00 0.00 0.00
Type II 6-hr WQ 1" Rainfall=1.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 5HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 18P: NE Basin Sediment and Sand Filter WQ @369.40
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Outflow = 0.15 cfs @ 0.00 hrs, Volume= 0.235 af, Atten= 0%, Lag= 0.0 min
Primary = 0.15 cfs @ 0.00 hrs, Volume= 0.235 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Starting Elev= 369.40' Surf.Area= 5,392 sf Storage= 10,245 cf
Peak Elev= 369.40' @ 0.00 hrs Surf.Area= 5,392 sf Storage= 10,245 cf
Plug-Flow detention time= (not calculated: no plugs found)
Center-of-Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.15 cfs @ 0.00 hrs HW=369.40' (Free Discharge)
1=Sand Filter (Custom Controls 0.15 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=369.40' (Free Discharge)
2=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 6-hr WQ 1" Rainfall=1.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 6HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 18P: NE Basin Sediment and Sand Filter WQ @369.40
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Peak Elev=369.40'
Storage=10,245 cf
0.00 cfs
0.15 cfs
0.15 cfs
0.00 cfs
Type II 6-hr WQ 1" Rainfall=1.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 7HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Hydrograph for Pond 18P: NE Basin Sediment and Sand Filter WQ @369.40
Time
(hours)
Inflow
(cfs)
Storage
(cubic-feet)
Elevation
(feet)
Outflow
(cfs)
Primary
(cfs)
Secondary
(cfs)
0.00 0.00 10,245 369.40 0.15 0.15 0.00
2.00 0.00 9,199 369.21 0.14 0.14 0.00
4.00 0.00 8,212 369.02 0.13 0.13 0.00
6.00 0.00 7,282 368.85 0.13 0.13 0.00
8.00 0.00 6,405 368.69 0.12 0.12 0.00
10.00 0.00 5,578 368.53 0.11 0.11 0.00
12.00 0.00 4,798 368.39 0.11 0.11 0.00
14.00 0.00 4,063 368.25 0.10 0.10 0.00
16.00 0.00 3,370 368.12 0.09 0.09 0.00
18.00 0.00 2,716 368.00 0.09 0.09 0.00
20.00 0.00 2,099 367.89 0.08 0.08 0.00
22.00 0.00 1,517 367.78 0.08 0.08 0.00
24.00 0.00 968 367.68 0.07 0.07 0.00
26.00 0.00 459 367.59 0.06 0.06 0.00
28.00 0.00 180 367.53 0.02 0.02 0.00
30.00 0.00 71 367.51 0.01 0.01 0.00
32.00 0.00 28 367.51 0.00 0.00 0.00
34.00 0.00 11 367.50 0.00 0.00 0.00
36.00 0.00 4 367.50 0.00 0.00 0.00
38.00 0.00 2 367.50 0.00 0.00 0.00
40.00 0.00 1 367.50 0.00 0.00 0.00
42.00 0.00 0 367.50 0.00 0.00 0.00
44.00 0.00 0 367.50 0.00 0.00 0.00
46.00 0.00 0 367.50 0.00 0.00 0.00
48.00 0.00 0 367.50 0.00 0.00 0.00
50.00 0.00 0 367.50 0.00 0.00 0.00
52.00 0.00 0 367.50 0.00 0.00 0.00
54.00 0.00 0 367.50 0.00 0.00 0.00
56.00 0.00 0 367.50 0.00 0.00 0.00
58.00 0.00 0 367.50 0.00 0.00 0.00
60.00 0.00 0 367.50 0.00 0.00 0.00

APPENDIX C:

HydroCAD Output

Use for Storm Sewer
calcs
2S
Existing 03
3S
Post 02 (SW-blue)
4S
Post 01 (NE-purple)
11S
Undetained 02
20S
Existing 02
22S
Undetained 01
24S
Existing 01
27S
Existing 04
29S
Existing 06
30S
Offsite Tributary Pre
31S
Existing 05
33S
Offsite Tributary Post
35S
Post 04
36S
Post 03
6P
NE Basin Sediment and
Sand Filter
10P
SW Sediment and Sand
Filter
11P
SW vault
19P
NE vault
21P
Post Total 02
25P
Pre Total 01
26PCB
Pre Total 02
28P
Post Total 01
Routing Diagram for 2019-1012 Prelim SW 2019-11-12
Prepared by Symanetc, Printed 11/14/2019
HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 2HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 1.56 cfs @ 12.22 hrs, Volume= 0.176 af, Depth= 0.51"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=4.165 ac
Runoff Volume=0.176 af
Runoff Depth=0.51"
Flow Length=481'
Tc=23.5 min
CN=65
1.56 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 3HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 21.04 cfs @ 11.96 hrs, Volume= 1.009 af, Depth= 2.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=5.370 ac
Runoff Volume=1.009 af
Runoff Depth=2.25"
Tc=5.0 min
CN=93
21.04 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 4HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 13.83 cfs @ 11.96 hrs, Volume= 0.663 af, Depth= 2.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=3.530 ac
Runoff Volume=0.663 af
Runoff Depth=2.25"
Tc=5.0 min
CN=93
13.83 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 5HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 0.73 cfs @ 11.96 hrs, Volume= 0.039 af, Depth= 2.77"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=0.168 ac
Runoff Volume=0.039 af
Runoff Depth=2.77"
Tc=5.0 min
CN=98
0.73 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 6HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 8.06 cfs @ 11.96 hrs, Volume= 0.414 af, Depth= 2.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=1.871 ac
Runoff Volume=0.414 af
Runoff Depth=2.66"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
8.06 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 7HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 7.13 cfs @ 11.96 hrs, Volume= 0.359 af, Depth= 2.55"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)7
6
5
4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=1.686 ac
Runoff Volume=0.359 af
Runoff Depth=2.55"
Tc=5.0 min
CN=96
7.13 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 8HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 8.61 cfs @ 11.96 hrs, Volume= 0.443 af, Depth= 2.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=2.000 ac
Runoff Volume=0.443 af
Runoff Depth=2.66"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
8.61 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 9HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 1.72 cfs @ 12.14 hrs, Volume= 0.144 af, Depth= 0.71"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=2.414 ac
Runoff Volume=0.144 af
Runoff Depth=0.71"
Flow Length=382'
Tc=19.1 min
CN=70
1.72 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 10HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 3.86 cfs @ 11.96 hrs, Volume= 0.203 af, Depth= 2.77"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=0.882 ac
Runoff Volume=0.203 af
Runoff Depth=2.77"
Flow Length=342'
Tc=5.0 min
CN=98
3.86 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 11HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 50.13 cfs @ 12.14 hrs, Volume= 3.909 af, Depth= 1.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 12HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=37.523 ac
Runoff Volume=3.909 af
Runoff Depth=1.25"
Flow Length=2,145'
Tc=20.9 min
CN=80
50.13 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 13HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 2.20 cfs @ 11.96 hrs, Volume= 0.113 af, Depth= 2.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=0.510 ac
Runoff Volume=0.113 af
Runoff Depth=2.66"
Tc=5.0 min
CN=97
2.20 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 14HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 45.04 cfs @ 12.13 hrs, Volume= 3.380 af, Depth= 1.31"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 15HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)50
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
1-yearRaleigh Rainfall=3.00"
Runoff Area=30.883 ac
Runoff Volume=3.380 af
Runoff Depth=1.31"
Flow Length=1,655'
Tc=19.7 min
CN=81
45.04 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 16HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 3.86 cfs @ 11.96 hrs, Volume= 0.203 af, Depth= 2.77"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)4
3
2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=0.882 ac
Runoff Volume=0.203 af
Runoff Depth=2.77"
Flow Length=342'
Tc=5.0 min
CN=98
3.86 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 17HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 2.20 cfs @ 11.96 hrs, Volume= 0.113 af, Depth= 2.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)2
1
0
Type II 24-hr
1-yearRaleigh Rainfall=3.00"
Runoff Area=0.510 ac
Runoff Volume=0.113 af
Runoff Depth=2.66"
Tc=5.0 min
CN=97
2.20 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 18HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 2.25" for 1-yearRaleigh event
Inflow = 13.83 cfs @ 11.96 hrs, Volume= 0.663 af
Outflow = 12.08 cfs @ 12.00 hrs, Volume= 0.663 af, Atten= 13%, Lag= 2.2 min
Primary = 0.16 cfs @ 12.00 hrs, Volume= 0.421 af
Secondary = 11.92 cfs @ 12.00 hrs, Volume= 0.242 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.66' @ 12.00 hrs Surf.Area= 5,392 sf Storage= 11,637 cf
Plug-Flow detention time= 544.5 min calculated for 0.663 af (100% of inflow)
Center-of-Mass det. time= 544.7 min ( 1,335.5 - 790.8 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.16 cfs @ 12.00 hrs HW=369.66' TW=365.33' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.16 cfs)
Secondary OutFlow Max=11.85 cfs @ 12.00 hrs HW=369.66' TW=365.33' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 11.85 cfs @ 1.30 fps)
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 19HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=3.530 ac
Peak Elev=369.66'
Storage=11,637 cf
13.83 cfs
12.08 cfs
0.16 cfs
11.92 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 20HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 2.25" for 1-yearRaleigh event
Inflow = 21.04 cfs @ 11.96 hrs, Volume= 1.009 af
Outflow = 20.05 cfs @ 11.98 hrs, Volume= 1.008 af, Atten= 5%, Lag= 1.4 min
Primary = 0.21 cfs @ 11.98 hrs, Volume= 0.579 af
Secondary = 19.85 cfs @ 11.98 hrs, Volume= 0.429 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.67' @ 11.98 hrs Surf.Area= 7,516 sf Storage= 16,341 cf
Plug-Flow detention time= 536.1 min calculated for 1.008 af (100% of inflow)
Center-of-Mass det. time= 535.9 min ( 1,326.7 - 790.8 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.21 cfs @ 11.98 hrs HW=377.67' TW=373.41' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.21 cfs)
Secondary OutFlow Max=19.82 cfs @ 11.98 hrs HW=377.67' TW=373.41' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 19.82 cfs @ 1.36 fps)
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 21HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=377.67'
Storage=16,341 cf
21.04 cfs
20.05 cfs
0.21 cfs
19.85 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 22HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth > 2.25" for 1-yearRaleigh event
Inflow = 20.05 cfs @ 11.98 hrs, Volume= 1.008 af
Outflow = 2.83 cfs @ 12.20 hrs, Volume= 0.988 af, Atten= 86%, Lag= 13.3 min
Primary = 2.83 cfs @ 12.20 hrs, Volume= 0.988 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 373.96' @ 12.20 hrs Surf.Area= 9,436 sf Storage= 9,075 cf
Plug-Flow detention time= 151.1 min calculated for 0.988 af (98% of inflow)
Center-of-Mass det. time= 111.9 min ( 1,438.6 - 1,326.7 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=2.83 cfs @ 12.20 hrs HW=373.96' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 2.83 cfs @ 3.37 fps)
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 23HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.370 ac
Peak Elev=373.96'
Storage=9,075 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
20.05 cfs
2.83 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 24HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 2.25" for 1-yearRaleigh event
Inflow = 12.08 cfs @ 12.00 hrs, Volume= 0.663 af
Outflow = 0.81 cfs @ 12.73 hrs, Volume= 0.654 af, Atten= 93%, Lag= 43.8 min
Primary = 0.81 cfs @ 12.73 hrs, Volume= 0.654 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.98' @ 12.73 hrs Surf.Area= 6,605 sf Storage= 6,464 cf
Plug-Flow detention time= 162.4 min calculated for 0.654 af (99% of inflow)
Center-of-Mass det. time= 138.7 min ( 1,474.2 - 1,335.5 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.81 cfs @ 12.73 hrs HW=365.98' TW=364.22' (Dynamic Tailwater)
1=Culvert (Passes 0.81 cfs of 3.26 cfs potential flow)
2=Orifice Plate (Passes 0.81 cfs of 2.95 cfs potential flow)
3=Small Orifice (Orifice Controls 0.81 cfs @ 4.11 fps)
4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 25HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=3.530 ac
Peak Elev=365.98'
Storage=6,464 cf
12.08 cfs
0.81 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 26HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 2.22" for 1-yearRaleigh event
Inflow = 2.92 cfs @ 12.19 hrs, Volume= 1.027 af
Primary = 2.92 cfs @ 12.19 hrs, Volume= 1.027 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)3
2
1
0
Inflow Area=5.538 ac
2.92 cfs
2.92 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 27HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 1.20" for 1-yearRaleigh event
Inflow = 8.81 cfs @ 11.96 hrs, Volume= 0.619 af
Outflow = 8.75 cfs @ 11.97 hrs, Volume= 0.619 af, Atten= 1%, Lag= 0.5 min
Primary = 8.75 cfs @ 11.97 hrs, Volume= 0.619 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 364.84' @ 11.97 hrs Surf.Area= 575 sf Storage= 348 cf
Plug-Flow detention time= 1.1 min calculated for 0.619 af (100% of inflow)
Center-of-Mass det. time= 1.1 min ( 807.7 - 806.6 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=8.74 cfs @ 11.97 hrs HW=364.83' (Free Discharge)
1=Culvert (Inlet Controls 8.74 cfs @ 2.82 fps)
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 28HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Inflow Area=6.165 ac
Peak Elev=364.84'
Storage=348 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
8.81 cfs
8.75 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 29HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 1.56" for 1-yearRaleigh event
Inflow = 8.65 cfs @ 11.96 hrs, Volume= 0.558 af
Outflow = 8.65 cfs @ 11.96 hrs, Volume= 0.558 af, Atten= 0%, Lag= 0.0 min
Primary = 8.65 cfs @ 11.96 hrs, Volume= 0.558 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 383.61' @ 11.96 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=8.64 cfs @ 11.96 hrs HW=383.60' (Free Discharge)
1=Culvert (Inlet Controls 8.64 cfs @ 11.00 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Inflow Area=4.285 ac
Peak Elev=383.61'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
8.65 cfs
8.65 cfs
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 30HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 2.33" for 1-yearRaleigh event
Inflow = 7.19 cfs @ 11.96 hrs, Volume= 1.013 af
Outflow = 7.14 cfs @ 11.97 hrs, Volume= 1.013 af, Atten= 1%, Lag= 0.5 min
Primary = 7.14 cfs @ 11.97 hrs, Volume= 1.013 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 364.74' @ 11.97 hrs Surf.Area= 535 sf Storage= 294 cf
Plug-Flow detention time= 1.2 min calculated for 1.013 af (100% of inflow)
Center-of-Mass det. time= 1.2 min ( 1,226.6 - 1,225.4 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=7.12 cfs @ 11.97 hrs HW=364.74' (Free Discharge)
1=Culvert (Inlet Controls 7.12 cfs @ 2.67 fps)
Type II 24-hr 1-yearRaleigh Rainfall=3.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 31HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)8
7
6
5
4
3
2
1
0
Inflow Area=5.216 ac
Peak Elev=364.74'
Storage=294 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
7.19 cfs
7.14 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 32HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 2.86 cfs @ 12.20 hrs, Volume= 0.279 af, Depth= 0.81"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=4.165 ac
Runoff Volume=0.279 af
Runoff Depth=0.81"
Flow Length=481'
Tc=23.5 min
CN=65
2.86 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 33HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 26.03 cfs @ 11.96 hrs, Volume= 1.267 af, Depth= 2.83"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=5.370 ac
Runoff Volume=1.267 af
Runoff Depth=2.83"
Tc=5.0 min
CN=93
26.03 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 34HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 17.11 cfs @ 11.96 hrs, Volume= 0.833 af, Depth= 2.83"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (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-yearRaleigh Rainfall=3.60"
Runoff Area=3.530 ac
Runoff Volume=0.833 af
Runoff Depth=2.83"
Tc=5.0 min
CN=93
17.11 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 35HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 0.88 cfs @ 11.96 hrs, Volume= 0.047 af, Depth= 3.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=0.168 ac
Runoff Volume=0.047 af
Runoff Depth=3.37"
Tc=5.0 min
CN=98
0.88 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 36HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 9.75 cfs @ 11.96 hrs, Volume= 0.507 af, Depth= 3.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=1.871 ac
Runoff Volume=0.507 af
Runoff Depth=3.25"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
9.75 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 37HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 8.66 cfs @ 11.96 hrs, Volume= 0.442 af, Depth= 3.14"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=1.686 ac
Runoff Volume=0.442 af
Runoff Depth=3.14"
Tc=5.0 min
CN=96
8.66 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 38HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 10.42 cfs @ 11.96 hrs, Volume= 0.542 af, Depth= 3.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=2.000 ac
Runoff Volume=0.542 af
Runoff Depth=3.25"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
10.42 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 39HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 2.75 cfs @ 12.13 hrs, Volume= 0.215 af, Depth= 1.07"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=2.414 ac
Runoff Volume=0.215 af
Runoff Depth=1.07"
Flow Length=382'
Tc=19.1 min
CN=70
2.75 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 40HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 4.64 cfs @ 11.96 hrs, Volume= 0.247 af, Depth= 3.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)5
4
3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=0.882 ac
Runoff Volume=0.247 af
Runoff Depth=3.37"
Flow Length=342'
Tc=5.0 min
CN=98
4.64 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 41HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 69.61 cfs @ 12.14 hrs, Volume= 5.366 af, Depth= 1.72"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 42HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=37.523 ac
Runoff Volume=5.366 af
Runoff Depth=1.72"
Flow Length=2,145'
Tc=20.9 min
CN=80
69.61 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 43HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 2.66 cfs @ 11.96 hrs, Volume= 0.138 af, Depth= 3.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=0.510 ac
Runoff Volume=0.138 af
Runoff Depth=3.25"
Tc=5.0 min
CN=97
2.66 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 44HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 61.88 cfs @ 12.13 hrs, Volume= 4.606 af, Depth= 1.79"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 45HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)65
60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=30.883 ac
Runoff Volume=4.606 af
Runoff Depth=1.79"
Flow Length=1,655'
Tc=19.7 min
CN=81
61.88 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 46HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 4.64 cfs @ 11.96 hrs, Volume= 0.247 af, Depth= 3.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)5
4
3
2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=0.882 ac
Runoff Volume=0.247 af
Runoff Depth=3.37"
Flow Length=342'
Tc=5.0 min
CN=98
4.64 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 47HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 2.66 cfs @ 11.96 hrs, Volume= 0.138 af, Depth= 3.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)2
1
0
Type II 24-hr
2-yearRaleigh Rainfall=3.60"
Runoff Area=0.510 ac
Runoff Volume=0.138 af
Runoff Depth=3.25"
Tc=5.0 min
CN=97
2.66 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 48HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 2.83" for 2-yearRaleigh event
Inflow = 17.11 cfs @ 11.96 hrs, Volume= 0.833 af
Outflow = 16.87 cfs @ 11.97 hrs, Volume= 0.833 af, Atten= 1%, Lag= 0.7 min
Primary = 0.16 cfs @ 11.97 hrs, Volume= 0.437 af
Secondary = 16.71 cfs @ 11.97 hrs, Volume= 0.396 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.70' @ 11.97 hrs Surf.Area= 5,392 sf Storage= 11,852 cf
Plug-Flow detention time= 452.1 min calculated for 0.833 af (100% of inflow)
Center-of-Mass det. time= 452.2 min ( 1,236.7 - 784.5 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.16 cfs @ 11.97 hrs HW=369.70' TW=365.67' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.16 cfs)
Secondary OutFlow Max=16.70 cfs @ 11.97 hrs HW=369.70' TW=365.67' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 16.70 cfs @ 1.46 fps)
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 49HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=3.530 ac
Peak Elev=369.70'
Storage=11,852 cf
17.11 cfs
16.87 cfs
0.16 cfs
16.71 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 50HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 2.83" for 2-yearRaleigh event
Inflow = 26.03 cfs @ 11.96 hrs, Volume= 1.267 af
Outflow = 25.73 cfs @ 11.97 hrs, Volume= 1.266 af, Atten= 1%, Lag= 0.6 min
Primary = 0.21 cfs @ 11.97 hrs, Volume= 0.592 af
Secondary = 25.52 cfs @ 11.97 hrs, Volume= 0.674 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.71' @ 11.97 hrs Surf.Area= 7,516 sf Storage= 16,581 cf
Plug-Flow detention time= 436.2 min calculated for 1.266 af (100% of inflow)
Center-of-Mass det. time= 436.0 min ( 1,220.5 - 784.5 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.21 cfs @ 11.97 hrs HW=377.71' TW=373.86' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.21 cfs)
Secondary OutFlow Max=25.49 cfs @ 11.97 hrs HW=377.71' TW=373.86' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 25.49 cfs @ 1.48 fps)
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 51HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=377.71'
Storage=16,581 cf
26.03 cfs
25.73 cfs
0.21 cfs
25.52 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 52HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth > 2.83" for 2-yearRaleigh event
Inflow = 25.73 cfs @ 11.97 hrs, Volume= 1.266 af
Outflow = 5.65 cfs @ 12.12 hrs, Volume= 1.246 af, Atten= 78%, Lag= 9.0 min
Primary = 5.65 cfs @ 12.12 hrs, Volume= 1.246 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 374.49' @ 12.12 hrs Surf.Area= 9,436 sf Storage= 14,038 cf
Plug-Flow detention time= 129.8 min calculated for 1.246 af (98% of inflow)
Center-of-Mass det. time= 96.1 min ( 1,316.6 - 1,220.5 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=5.65 cfs @ 12.12 hrs HW=374.49' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 5.65 cfs @ 4.01 fps)
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 53HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=374.49'
Storage=14,038 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
25.73 cfs
5.65 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 54HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 2.83" for 2-yearRaleigh event
Inflow = 16.87 cfs @ 11.97 hrs, Volume= 0.833 af
Outflow = 1.11 cfs @ 12.60 hrs, Volume= 0.824 af, Atten= 93%, Lag= 37.8 min
Primary = 1.11 cfs @ 12.60 hrs, Volume= 0.824 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 366.62' @ 12.60 hrs Surf.Area= 6,605 sf Storage= 10,721 cf
Plug-Flow detention time= 162.7 min calculated for 0.824 af (99% of inflow)
Center-of-Mass det. time= 141.3 min ( 1,378.0 - 1,236.7 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=1.11 cfs @ 12.60 hrs HW=366.62' TW=364.28' (Dynamic Tailwater)
1=Culvert (Passes 1.11 cfs of 5.86 cfs potential flow)
2=Orifice Plate (Passes 1.11 cfs of 4.62 cfs potential flow)
3=Small Orifice (Orifice Controls 1.11 cfs @ 5.64 fps)
4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 55HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=3.530 ac
Peak Elev=366.62'
Storage=10,721 cf
16.87 cfs
1.11 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 56HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 2.80" for 2-yearRaleigh event
Inflow = 5.81 cfs @ 12.10 hrs, Volume= 1.293 af
Primary = 5.81 cfs @ 12.10 hrs, Volume= 1.293 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Inflow Area=5.538 ac
5.81 cfs
5.81 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 57HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 1.60" for 2-yearRaleigh event
Inflow = 11.05 cfs @ 11.96 hrs, Volume= 0.822 af
Outflow = 10.97 cfs @ 11.97 hrs, Volume= 0.822 af, Atten= 1%, Lag= 0.5 min
Primary = 10.97 cfs @ 11.97 hrs, Volume= 0.822 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 364.96' @ 11.97 hrs Surf.Area= 626 sf Storage= 420 cf
Plug-Flow detention time= 1.1 min calculated for 0.822 af (100% of inflow)
Center-of-Mass det. time= 1.1 min ( 806.9 - 805.9 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=10.96 cfs @ 11.97 hrs HW=364.96' (Free Discharge)
1=Culvert (Inlet Controls 10.96 cfs @ 3.00 fps)
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 58HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=6.165 ac
Peak Elev=364.96'
Storage=420 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
11.05 cfs
10.97 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 59HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 2.02" for 2-yearRaleigh event
Inflow = 10.88 cfs @ 11.96 hrs, Volume= 0.723 af
Outflow = 10.88 cfs @ 11.96 hrs, Volume= 0.723 af, Atten= 0%, Lag= 0.0 min
Primary = 10.88 cfs @ 11.96 hrs, Volume= 0.723 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 387.04' @ 11.96 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=10.87 cfs @ 11.96 hrs HW=387.01' (Free Discharge)
1=Culvert (Barrel Controls 10.87 cfs @ 13.84 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=4.285 ac
Peak Elev=387.04'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
10.88 cfs
10.88 cfs
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 60HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 2.91" for 2-yearRaleigh event
Inflow = 9.19 cfs @ 11.96 hrs, Volume= 1.265 af
Outflow = 9.12 cfs @ 11.97 hrs, Volume= 1.265 af, Atten= 1%, Lag= 0.5 min
Primary = 9.12 cfs @ 11.97 hrs, Volume= 1.265 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 364.86' @ 11.97 hrs Surf.Area= 584 sf Storage= 360 cf
Plug-Flow detention time= 1.2 min calculated for 1.265 af (100% of inflow)
Center-of-Mass det. time= 1.1 min ( 1,165.6 - 1,164.5 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=9.12 cfs @ 11.97 hrs HW=364.86' (Free Discharge)
1=Culvert (Inlet Controls 9.12 cfs @ 2.85 fps)
Type II 24-hr 2-yearRaleigh Rainfall=3.60"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 61HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.216 ac
Peak Elev=364.86'
Storage=360 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
9.19 cfs
9.12 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 62HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 5.33 cfs @ 12.19 hrs, Volume= 0.475 af, Depth= 1.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=4.165 ac
Runoff Volume=0.475 af
Runoff Depth=1.37"
Flow Length=481'
Tc=23.5 min
CN=65
5.33 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 63HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 33.95 cfs @ 11.96 hrs, Volume= 1.686 af, Depth= 3.77"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=5.370 ac
Runoff Volume=1.686 af
Runoff Depth=3.77"
Tc=5.0 min
CN=93
33.95 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 64HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 22.32 cfs @ 11.96 hrs, Volume= 1.108 af, Depth= 3.77"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=3.530 ac
Runoff Volume=1.108 af
Runoff Depth=3.77"
Tc=5.0 min
CN=93
22.32 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 65HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 1.12 cfs @ 11.96 hrs, Volume= 0.061 af, Depth= 4.32"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=0.168 ac
Runoff Volume=0.061 af
Runoff Depth=4.32"
Tc=5.0 min
CN=98
1.12 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 66HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 12.43 cfs @ 11.96 hrs, Volume= 0.656 af, Depth= 4.21"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=1.871 ac
Runoff Volume=0.656 af
Runoff Depth=4.21"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
12.43 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 67HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 11.10 cfs @ 11.96 hrs, Volume= 0.575 af, Depth= 4.10"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=1.686 ac
Runoff Volume=0.575 af
Runoff Depth=4.10"
Tc=5.0 min
CN=96
11.10 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 68HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 13.29 cfs @ 11.96 hrs, Volume= 0.701 af, Depth= 4.21"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=2.000 ac
Runoff Volume=0.701 af
Runoff Depth=4.21"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
13.29 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 69HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 4.61 cfs @ 12.12 hrs, Volume= 0.345 af, Depth= 1.72"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=2.414 ac
Runoff Volume=0.345 af
Runoff Depth=1.72"
Flow Length=382'
Tc=19.1 min
CN=70
4.61 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 70HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 5.90 cfs @ 11.96 hrs, Volume= 0.318 af, Depth= 4.32"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=0.882 ac
Runoff Volume=0.318 af
Runoff Depth=4.32"
Flow Length=342'
Tc=5.0 min
CN=98
5.90 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 71HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 102.44 cfs @ 12.14 hrs, Volume= 7.857 af, Depth= 2.51"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 72HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)110
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=37.523 ac
Runoff Volume=7.857 af
Runoff Depth=2.51"
Flow Length=2,145'
Tc=20.9 min
CN=80
102.44 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 73HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 3.39 cfs @ 11.96 hrs, Volume= 0.179 af, Depth= 4.21"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=0.510 ac
Runoff Volume=0.179 af
Runoff Depth=4.21"
Tc=5.0 min
CN=97
3.39 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 74HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 90.07 cfs @ 12.12 hrs, Volume= 6.691 af, Depth= 2.60"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 75HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=30.883 ac
Runoff Volume=6.691 af
Runoff Depth=2.60"
Flow Length=1,655'
Tc=19.7 min
CN=81
90.07 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 76HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 5.90 cfs @ 11.96 hrs, Volume= 0.318 af, Depth= 4.32"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=0.882 ac
Runoff Volume=0.318 af
Runoff Depth=4.32"
Flow Length=342'
Tc=5.0 min
CN=98
5.90 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 77HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 3.39 cfs @ 11.96 hrs, Volume= 0.179 af, Depth= 4.21"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)3
2
1
0
Type II 24-hr
5-yearRaleigh Rainfall=4.56"
Runoff Area=0.510 ac
Runoff Volume=0.179 af
Runoff Depth=4.21"
Tc=5.0 min
CN=97
3.39 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 78HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 3.77" for 5-yearRaleigh event
Inflow = 22.32 cfs @ 11.96 hrs, Volume= 1.108 af
Outflow = 22.09 cfs @ 11.97 hrs, Volume= 1.108 af, Atten= 1%, Lag= 0.6 min
Primary = 0.16 cfs @ 11.97 hrs, Volume= 0.449 af
Secondary = 21.92 cfs @ 11.97 hrs, Volume= 0.659 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.74' @ 11.97 hrs Surf.Area= 5,392 sf Storage= 12,064 cf
Plug-Flow detention time= 350.3 min calculated for 1.108 af (100% of inflow)
Center-of-Mass det. time= 350.2 min ( 1,127.0 - 776.8 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.16 cfs @ 11.97 hrs HW=369.74' TW=366.49' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.16 cfs)
Secondary OutFlow Max=21.88 cfs @ 11.97 hrs HW=369.74' TW=366.49' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 21.88 cfs @ 1.59 fps)
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 79HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.74'
Storage=12,064 cf
22.32 cfs
22.09 cfs
0.16 cfs
21.92 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 80HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 3.77" for 5-yearRaleigh event
Inflow = 33.95 cfs @ 11.96 hrs, Volume= 1.686 af
Outflow = 33.63 cfs @ 11.97 hrs, Volume= 1.685 af, Atten= 1%, Lag= 0.6 min
Primary = 0.21 cfs @ 11.97 hrs, Volume= 0.606 af
Secondary = 33.42 cfs @ 11.97 hrs, Volume= 1.079 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.75' @ 11.97 hrs Surf.Area= 7,516 sf Storage= 16,886 cf
Plug-Flow detention time= 336.2 min calculated for 1.685 af (100% of inflow)
Center-of-Mass det. time= 335.9 min ( 1,112.7 - 776.8 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.21 cfs @ 11.97 hrs HW=377.75' TW=374.65' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.21 cfs)
Secondary OutFlow Max=33.35 cfs @ 11.97 hrs HW=377.75' TW=374.65' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 33.35 cfs @ 1.62 fps)
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 81HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=377.75'
Storage=16,886 cf
33.95 cfs
33.63 cfs
0.21 cfs
33.42 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 82HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth > 3.76" for 5-yearRaleigh event
Inflow = 33.63 cfs @ 11.97 hrs, Volume= 1.685 af
Outflow = 8.57 cfs @ 12.10 hrs, Volume= 1.664 af, Atten= 75%, Lag= 8.1 min
Primary = 8.57 cfs @ 12.10 hrs, Volume= 1.664 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 375.37' @ 12.10 hrs Surf.Area= 9,436 sf Storage= 22,354 cf
Plug-Flow detention time= 109.1 min calculated for 1.664 af (99% of inflow)
Center-of-Mass det. time= 82.5 min ( 1,195.2 - 1,112.7 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=8.57 cfs @ 12.10 hrs HW=375.37' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 8.57 cfs @ 4.85 fps)
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 83HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=375.37'
Storage=22,354 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
33.63 cfs
8.57 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 84HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 3.77" for 5-yearRaleigh event
Inflow = 22.09 cfs @ 11.97 hrs, Volume= 1.108 af
Outflow = 5.87 cfs @ 12.10 hrs, Volume= 1.099 af, Atten= 73%, Lag= 7.9 min
Primary = 5.87 cfs @ 12.10 hrs, Volume= 1.099 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 367.29' @ 12.10 hrs Surf.Area= 6,605 sf Storage= 15,128 cf
Plug-Flow detention time= 148.4 min calculated for 1.098 af (99% of inflow)
Center-of-Mass det. time= 131.0 min ( 1,258.0 - 1,127.0 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=5.87 cfs @ 12.10 hrs HW=367.29' TW=364.82' (Dynamic Tailwater)
1=Culvert (Passes 5.87 cfs of 7.49 cfs potential flow)
2=Orifice Plate (Orifice Controls 5.87 cfs @ 6.37 fps)
3=Small Orifice (Passes < 1.35 cfs potential flow)
4=Sharp-Crested Rectangular Weir (Passes < 6.11 cfs potential flow)
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 85HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=3.530 ac
Peak Elev=367.29'
Storage=15,128 cf
22.09 cfs
5.87 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 86HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 3.74" for 5-yearRaleigh event
Inflow = 8.83 cfs @ 12.08 hrs, Volume= 1.725 af
Primary = 8.83 cfs @ 12.08 hrs, Volume= 1.725 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Inflow Area=5.538 ac
8.83 cfs
8.83 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 87HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 2.29" for 5-yearRaleigh event
Inflow = 14.99 cfs @ 11.96 hrs, Volume= 1.176 af
Outflow = 14.89 cfs @ 11.97 hrs, Volume= 1.176 af, Atten= 1%, Lag= 0.5 min
Primary = 14.89 cfs @ 11.97 hrs, Volume= 1.176 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.14' @ 11.97 hrs Surf.Area= 725 sf Storage= 547 cf
Plug-Flow detention time= 1.0 min calculated for 1.176 af (100% of inflow)
Center-of-Mass det. time= 1.0 min ( 805.1 - 804.1 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=14.88 cfs @ 11.97 hrs HW=365.14' (Free Discharge)
1=Culvert (Inlet Controls 14.88 cfs @ 3.27 fps)
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 88HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=6.165 ac
Peak Elev=365.14'
Storage=547 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
14.99 cfs
14.89 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 89HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 2.80" for 5-yearRaleigh event
Inflow = 14.61 cfs @ 11.96 hrs, Volume= 1.001 af
Outflow = 14.61 cfs @ 11.96 hrs, Volume= 1.001 af, Atten= 0%, Lag= 0.0 min
Primary = 14.61 cfs @ 11.96 hrs, Volume= 1.001 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 396.17' @ 11.96 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=14.58 cfs @ 11.96 hrs HW=396.10' (Free Discharge)
1=Culvert (Barrel Controls 14.58 cfs @ 18.57 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=4.285 ac
Peak Elev=396.17'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
14.61 cfs
14.61 cfs
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 90HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 3.85" for 5-yearRaleigh event
Inflow = 12.10 cfs @ 11.96 hrs, Volume= 1.674 af
Outflow = 12.02 cfs @ 11.97 hrs, Volume= 1.674 af, Atten= 1%, Lag= 0.5 min
Primary = 12.02 cfs @ 11.97 hrs, Volume= 1.674 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.01' @ 11.97 hrs Surf.Area= 649 sf Storage= 454 cf
Plug-Flow detention time= 1.1 min calculated for 1.674 af (100% of inflow)
Center-of-Mass det. time= 1.0 min ( 1,087.9 - 1,086.8 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=12.00 cfs @ 11.97 hrs HW=365.01' (Free Discharge)
1=Culvert (Inlet Controls 12.00 cfs @ 3.08 fps)
Type II 24-hr 5-yearRaleigh Rainfall=4.56"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 91HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.216 ac
Peak Elev=365.01'
Storage=454 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
12.10 cfs
12.02 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 92HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 7.41 cfs @ 12.19 hrs, Volume= 0.640 af, Depth= 1.84"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)8
7
6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=4.165 ac
Runoff Volume=0.640 af
Runoff Depth=1.84"
Flow Length=481'
Tc=23.5 min
CN=65
7.41 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 93HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 39.86 cfs @ 11.96 hrs, Volume= 2.002 af, Depth= 4.47"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)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
10-yearRaleigh Rainfall=5.28"
Runoff Area=5.370 ac
Runoff Volume=2.002 af
Runoff Depth=4.47"
Tc=5.0 min
CN=93
39.86 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 94HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 26.20 cfs @ 11.96 hrs, Volume= 1.316 af, Depth= 4.47"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=3.530 ac
Runoff Volume=1.316 af
Runoff Depth=4.47"
Tc=5.0 min
CN=93
26.20 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 95HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 1.30 cfs @ 11.96 hrs, Volume= 0.071 af, Depth= 5.04"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=0.168 ac
Runoff Volume=0.071 af
Runoff Depth=5.04"
Tc=5.0 min
CN=98
1.30 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 96HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 14.44 cfs @ 11.96 hrs, Volume= 0.768 af, Depth= 4.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=1.871 ac
Runoff Volume=0.768 af
Runoff Depth=4.93"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
14.44 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 97HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 12.92 cfs @ 11.96 hrs, Volume= 0.676 af, Depth= 4.81"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=1.686 ac
Runoff Volume=0.676 af
Runoff Depth=4.81"
Tc=5.0 min
CN=96
12.92 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 98HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 15.44 cfs @ 11.96 hrs, Volume= 0.821 af, Depth= 4.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=2.000 ac
Runoff Volume=0.821 af
Runoff Depth=4.93"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
15.44 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 99HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 6.12 cfs @ 12.12 hrs, Volume= 0.452 af, Depth= 2.25"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=2.414 ac
Runoff Volume=0.452 af
Runoff Depth=2.25"
Flow Length=382'
Tc=19.1 min
CN=70
6.12 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 100HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 6.84 cfs @ 11.96 hrs, Volume= 0.371 af, Depth= 5.04"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)7
6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=0.882 ac
Runoff Volume=0.371 af
Runoff Depth=5.04"
Flow Length=342'
Tc=5.0 min
CN=98
6.84 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 101HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 127.84 cfs @ 12.14 hrs, Volume= 9.814 af, Depth= 3.14"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
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Page 102HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=37.523 ac
Runoff Volume=9.814 af
Runoff Depth=3.14"
Flow Length=2,145'
Tc=20.9 min
CN=80
127.84 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 103HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 3.94 cfs @ 11.96 hrs, Volume= 0.209 af, Depth= 4.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=0.510 ac
Runoff Volume=0.209 af
Runoff Depth=4.93"
Tc=5.0 min
CN=97
3.94 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 104HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 111.81 cfs @ 12.12 hrs, Volume= 8.323 af, Depth= 3.23"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 105HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)125
120
115
110
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=30.883 ac
Runoff Volume=8.323 af
Runoff Depth=3.23"
Flow Length=1,655'
Tc=19.7 min
CN=81
111.81 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
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Page 106HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 6.84 cfs @ 11.96 hrs, Volume= 0.371 af, Depth= 5.04"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)7
6
5
4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=0.882 ac
Runoff Volume=0.371 af
Runoff Depth=5.04"
Flow Length=342'
Tc=5.0 min
CN=98
6.84 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 107HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 3.94 cfs @ 11.96 hrs, Volume= 0.209 af, Depth= 4.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)4
3
2
1
0
Type II 24-hr
10-yearRaleigh Rainfall=5.28"
Runoff Area=0.510 ac
Runoff Volume=0.209 af
Runoff Depth=4.93"
Tc=5.0 min
CN=97
3.94 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 108HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 4.47" for 10-yearRaleigh event
Inflow = 26.20 cfs @ 11.96 hrs, Volume= 1.316 af
Outflow = 25.95 cfs @ 11.97 hrs, Volume= 1.316 af, Atten= 1%, Lag= 0.6 min
Primary = 0.17 cfs @ 11.97 hrs, Volume= 0.456 af
Secondary = 25.79 cfs @ 11.97 hrs, Volume= 0.859 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.76' @ 11.97 hrs Surf.Area= 5,392 sf Storage= 12,211 cf
Plug-Flow detention time= 300.2 min calculated for 1.315 af (100% of inflow)
Center-of-Mass det. time= 300.4 min ( 1,072.7 - 772.3 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.17 cfs @ 11.97 hrs HW=369.76' TW=367.12' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.17 cfs)
Secondary OutFlow Max=25.73 cfs @ 11.97 hrs HW=369.76' TW=367.12' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 25.73 cfs @ 1.68 fps)
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 109HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.76'
Storage=12,211 cf
26.20 cfs
25.95 cfs
0.17 cfs
25.79 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 110HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 4.47" for 10-yearRaleigh event
Inflow = 39.86 cfs @ 11.96 hrs, Volume= 2.002 af
Outflow = 39.51 cfs @ 11.97 hrs, Volume= 2.001 af, Atten= 1%, Lag= 0.6 min
Primary = 0.21 cfs @ 11.97 hrs, Volume= 0.615 af
Secondary = 39.30 cfs @ 11.97 hrs, Volume= 1.386 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.77' @ 11.97 hrs Surf.Area= 7,516 sf Storage= 17,097 cf
Plug-Flow detention time= 288.3 min calculated for 2.000 af (100% of inflow)
Center-of-Mass det. time= 288.3 min ( 1,060.6 - 772.3 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.21 cfs @ 11.97 hrs HW=377.77' TW=375.21' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.21 cfs)
Secondary OutFlow Max=39.21 cfs @ 11.97 hrs HW=377.77' TW=375.21' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 39.21 cfs @ 1.71 fps)
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 111HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=377.77'
Storage=17,097 cf
39.86 cfs
39.51 cfs
0.21 cfs
39.30 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 112HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth > 4.47" for 10-yearRaleigh event
Inflow = 39.51 cfs @ 11.97 hrs, Volume= 2.001 af
Outflow = 10.58 cfs @ 12.10 hrs, Volume= 1.980 af, Atten= 73%, Lag= 7.8 min
Primary = 10.58 cfs @ 12.10 hrs, Volume= 1.980 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 376.02' @ 12.10 hrs Surf.Area= 9,436 sf Storage= 28,473 cf
Plug-Flow detention time= 99.4 min calculated for 1.980 af (99% of inflow)
Center-of-Mass det. time= 76.5 min ( 1,137.1 - 1,060.6 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=10.58 cfs @ 12.10 hrs HW=376.02' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 10.58 cfs @ 5.99 fps)
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 113HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.370 ac
Peak Elev=376.02'
Storage=28,473 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
39.51 cfs
10.58 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 114HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 4.47" for 10-yearRaleigh event
Inflow = 25.95 cfs @ 11.97 hrs, Volume= 1.316 af
Outflow = 6.80 cfs @ 12.10 hrs, Volume= 1.306 af, Atten= 74%, Lag= 8.0 min
Primary = 6.80 cfs @ 12.10 hrs, Volume= 1.306 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 367.89' @ 12.10 hrs Surf.Area= 6,605 sf Storage= 19,103 cf
Plug-Flow detention time= 134.0 min calculated for 1.306 af (99% of inflow)
Center-of-Mass det. time= 119.1 min ( 1,191.8 - 1,072.7 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=6.80 cfs @ 12.10 hrs HW=367.89' TW=364.89' (Dynamic Tailwater)
1=Culvert (Passes 6.80 cfs of 8.83 cfs potential flow)
2=Orifice Plate (Orifice Controls 6.80 cfs @ 7.38 fps)
3=Small Orifice (Passes < 1.54 cfs potential flow)
4=Sharp-Crested Rectangular Weir (Passes < 32.56 cfs potential flow)
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 115HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=367.89'
Storage=19,103 cf
25.95 cfs
6.80 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 116HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 4.44" for 10-yearRaleigh event
Inflow = 10.92 cfs @ 12.06 hrs, Volume= 2.051 af
Primary = 10.92 cfs @ 12.06 hrs, Volume= 2.051 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.538 ac
10.92 cfs
10.92 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 117HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 2.84" for 10-yearRaleigh event
Inflow = 18.10 cfs @ 11.96 hrs, Volume= 1.461 af
Outflow = 17.98 cfs @ 11.97 hrs, Volume= 1.461 af, Atten= 1%, Lag= 0.5 min
Primary = 17.98 cfs @ 11.97 hrs, Volume= 1.461 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.28' @ 11.97 hrs Surf.Area= 800 sf Storage= 649 cf
Plug-Flow detention time= 1.0 min calculated for 1.460 af (100% of inflow)
Center-of-Mass det. time= 1.0 min ( 803.5 - 802.6 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=17.96 cfs @ 11.97 hrs HW=365.28' (Free Discharge)
1=Culvert (Inlet Controls 17.96 cfs @ 3.45 fps)
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 118HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=6.165 ac
Peak Elev=365.28'
Storage=649 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
18.10 cfs
17.98 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 119HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 3.42" for 10-yearRaleigh event
Inflow = 17.49 cfs @ 11.96 hrs, Volume= 1.220 af
Outflow = 17.49 cfs @ 11.96 hrs, Volume= 1.220 af, Atten= 0%, Lag= 0.0 min
Primary = 17.49 cfs @ 11.96 hrs, Volume= 1.220 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 405.07' @ 11.96 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=17.46 cfs @ 11.96 hrs HW=404.95' (Free Discharge)
1=Culvert (Barrel Controls 17.46 cfs @ 22.23 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=4.285 ac
Peak Elev=405.07'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
17.49 cfs
17.49 cfs
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 120HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 4.56" for 10-yearRaleigh event
Inflow = 18.11 cfs @ 11.98 hrs, Volume= 1.982 af
Outflow = 17.50 cfs @ 11.99 hrs, Volume= 1.982 af, Atten= 3%, Lag= 0.6 min
Primary = 17.50 cfs @ 11.99 hrs, Volume= 1.982 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.26' @ 11.99 hrs Surf.Area= 788 sf Storage= 633 cf
Plug-Flow detention time= 1.0 min calculated for 1.982 af (100% of inflow)
Center-of-Mass det. time= 1.0 min ( 1,044.3 - 1,043.3 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=17.40 cfs @ 11.99 hrs HW=365.25' (Free Discharge)
1=Culvert (Inlet Controls 17.40 cfs @ 3.42 fps)
Type II 24-hr 10-yearRaleigh Rainfall=5.28"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 121HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.216 ac
Peak Elev=365.26'
Storage=633 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
18.11 cfs
17.50 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 122HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 11.18 cfs @ 12.17 hrs, Volume= 0.939 af, Depth= 2.71"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=4.165 ac
Runoff Volume=0.939 af
Runoff Depth=2.71"
Flow Length=481'
Tc=23.5 min
CN=65
11.18 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 123HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 49.63 cfs @ 11.96 hrs, Volume= 2.531 af, Depth= 5.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=5.370 ac
Runoff Volume=2.531 af
Runoff Depth=5.66"
Tc=5.0 min
CN=93
49.63 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 124HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 32.63 cfs @ 11.96 hrs, Volume= 1.664 af, Depth= 5.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=3.530 ac
Runoff Volume=1.664 af
Runoff Depth=5.66"
Tc=5.0 min
CN=93
32.63 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 125HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 1.60 cfs @ 11.96 hrs, Volume= 0.087 af, Depth= 6.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=0.168 ac
Runoff Volume=0.087 af
Runoff Depth=6.24"
Tc=5.0 min
CN=98
1.60 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 126HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 17.78 cfs @ 11.96 hrs, Volume= 0.955 af, Depth= 6.12"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (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
25-yearRaleigh Rainfall=6.48"
Runoff Area=1.871 ac
Runoff Volume=0.955 af
Runoff Depth=6.12"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
17.78 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 127HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 15.94 cfs @ 11.96 hrs, Volume= 0.844 af, Depth= 6.01"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=1.686 ac
Runoff Volume=0.844 af
Runoff Depth=6.01"
Tc=5.0 min
CN=96
15.94 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 128HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 19.01 cfs @ 11.96 hrs, Volume= 1.021 af, Depth= 6.12"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=2.000 ac
Runoff Volume=1.021 af
Runoff Depth=6.12"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
19.01 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 129HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 8.79 cfs @ 12.12 hrs, Volume= 0.642 af, Depth= 3.19"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=2.414 ac
Runoff Volume=0.642 af
Runoff Depth=3.19"
Flow Length=382'
Tc=19.1 min
CN=70
8.79 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 130HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 8.41 cfs @ 11.96 hrs, Volume= 0.459 af, Depth= 6.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=0.882 ac
Runoff Volume=0.459 af
Runoff Depth=6.24"
Flow Length=342'
Tc=5.0 min
CN=98
8.41 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 131HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 170.93 cfs @ 12.14 hrs, Volume= 13.186 af, Depth= 4.22"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 132HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=37.523 ac
Runoff Volume=13.186 af
Runoff Depth=4.22"
Flow Length=2,145'
Tc=20.9 min
CN=80
170.93 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 133HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 4.85 cfs @ 11.96 hrs, Volume= 0.260 af, Depth= 6.12"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=0.510 ac
Runoff Volume=0.260 af
Runoff Depth=6.12"
Tc=5.0 min
CN=97
4.85 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 134HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 148.60 cfs @ 12.12 hrs, Volume= 11.127 af, Depth= 4.32"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 135HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=30.883 ac
Runoff Volume=11.127 af
Runoff Depth=4.32"
Flow Length=1,655'
Tc=19.7 min
CN=81
148.60 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 136HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 8.41 cfs @ 11.96 hrs, Volume= 0.459 af, Depth= 6.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)9
8
7
6
5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=0.882 ac
Runoff Volume=0.459 af
Runoff Depth=6.24"
Flow Length=342'
Tc=5.0 min
CN=98
8.41 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 137HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 4.85 cfs @ 11.96 hrs, Volume= 0.260 af, Depth= 6.12"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)5
4
3
2
1
0
Type II 24-hr
25-yearRaleigh Rainfall=6.48"
Runoff Area=0.510 ac
Runoff Volume=0.260 af
Runoff Depth=6.12"
Tc=5.0 min
CN=97
4.85 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 138HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 5.66" for 25-yearRaleigh event
Inflow = 32.63 cfs @ 11.96 hrs, Volume= 1.664 af
Outflow = 32.36 cfs @ 11.97 hrs, Volume= 1.664 af, Atten= 1%, Lag= 0.5 min
Primary = 0.17 cfs @ 11.97 hrs, Volume= 0.467 af
Secondary = 32.19 cfs @ 11.97 hrs, Volume= 1.197 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.81' @ 11.97 hrs Surf.Area= 5,392 sf Storage= 12,438 cf
Plug-Flow detention time= 245.2 min calculated for 1.664 af (100% of inflow)
Center-of-Mass det. time= 245.1 min ( 1,011.5 - 766.4 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.17 cfs @ 11.97 hrs HW=369.81' TW=367.99' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.17 cfs)
Secondary OutFlow Max=32.12 cfs @ 11.97 hrs HW=369.81' TW=367.99' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 32.12 cfs @ 1.81 fps)
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 139HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.81'
Storage=12,438 cf
32.63 cfs
32.36 cfs
0.17 cfs
32.19 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 140HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 5.66" for 25-yearRaleigh event
Inflow = 49.63 cfs @ 11.96 hrs, Volume= 2.531 af
Outflow = 49.26 cfs @ 11.97 hrs, Volume= 2.531 af, Atten= 1%, Lag= 0.5 min
Primary = 0.22 cfs @ 11.97 hrs, Volume= 0.629 af
Secondary = 49.05 cfs @ 11.97 hrs, Volume= 1.902 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.82' @ 11.97 hrs Surf.Area= 7,516 sf Storage= 17,426 cf
Plug-Flow detention time= 235.6 min calculated for 2.531 af (100% of inflow)
Center-of-Mass det. time= 235.3 min ( 1,001.7 - 766.4 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.22 cfs @ 11.97 hrs HW=377.82' TW=376.05' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.22 cfs)
Secondary OutFlow Max=48.93 cfs @ 11.97 hrs HW=377.82' TW=376.05' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 48.93 cfs @ 1.84 fps)
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 141HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.370 ac
Peak Elev=377.82'
Storage=17,426 cf
49.63 cfs
49.26 cfs
0.22 cfs
49.05 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 142HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 5.65" for 25-yearRaleigh event
Inflow = 49.26 cfs @ 11.97 hrs, Volume= 2.531 af
Outflow = 13.15 cfs @ 12.09 hrs, Volume= 2.510 af, Atten= 73%, Lag= 7.8 min
Primary = 13.15 cfs @ 12.09 hrs, Volume= 2.510 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.05' @ 12.09 hrs Surf.Area= 9,436 sf Storage= 38,190 cf
Plug-Flow detention time= 89.0 min calculated for 2.510 af (99% of inflow)
Center-of-Mass det. time= 70.5 min ( 1,072.2 - 1,001.7 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=13.15 cfs @ 12.09 hrs HW=377.05' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 13.15 cfs @ 7.44 fps)
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 143HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.370 ac
Peak Elev=377.05'
Storage=38,190 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
49.26 cfs
13.15 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 144HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 5.66" for 25-yearRaleigh event
Inflow = 32.36 cfs @ 11.97 hrs, Volume= 1.664 af
Outflow = 8.20 cfs @ 12.10 hrs, Volume= 1.655 af, Atten= 75%, Lag= 8.1 min
Primary = 8.20 cfs @ 12.10 hrs, Volume= 1.655 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 368.96' @ 12.10 hrs Surf.Area= 6,605 sf Storage= 26,131 cf
Plug-Flow detention time= 119.8 min calculated for 1.655 af (99% of inflow)
Center-of-Mass det. time= 107.6 min ( 1,119.1 - 1,011.5 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=8.20 cfs @ 12.10 hrs HW=368.96' TW=365.00' (Dynamic Tailwater)
1=Culvert (Passes 8.20 cfs of 10.78 cfs potential flow)
2=Orifice Plate (Orifice Controls 8.20 cfs @ 8.90 fps)
3=Small Orifice (Passes < 1.82 cfs potential flow)
4=Sharp-Crested Rectangular Weir (Passes < 103.86 cfs potential flow)
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 145HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=368.96'
Storage=26,131 cf
32.36 cfs
8.20 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 146HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 5.63" for 25-yearRaleigh event
Inflow = 13.62 cfs @ 12.05 hrs, Volume= 2.597 af
Primary = 13.62 cfs @ 12.05 hrs, Volume= 2.597 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.538 ac
13.62 cfs
13.62 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 147HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 3.81" for 25-yearRaleigh event
Inflow = 23.49 cfs @ 11.97 hrs, Volume= 1.960 af
Outflow = 23.33 cfs @ 11.97 hrs, Volume= 1.960 af, Atten= 1%, Lag= 0.6 min
Primary = 23.33 cfs @ 11.97 hrs, Volume= 1.960 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.49' @ 11.97 hrs Surf.Area= 918 sf Storage= 831 cf
Plug-Flow detention time= 0.9 min calculated for 1.959 af (100% of inflow)
Center-of-Mass det. time= 0.9 min ( 800.9 - 800.0 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=23.29 cfs @ 11.97 hrs HW=365.49' (Free Discharge)
1=Culvert (Inlet Controls 23.29 cfs @ 3.72 fps)
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 148HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=6.165 ac
Peak Elev=365.49'
Storage=831 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
23.49 cfs
23.33 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 149HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 4.47" for 25-yearRaleigh event
Inflow = 22.42 cfs @ 11.97 hrs, Volume= 1.597 af
Outflow = 22.42 cfs @ 11.97 hrs, Volume= 1.597 af, Atten= 0%, Lag= 0.0 min
Primary = 22.42 cfs @ 11.97 hrs, Volume= 1.597 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 423.94' @ 11.97 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=22.38 cfs @ 11.97 hrs HW=423.77' (Free Discharge)
1=Culvert (Barrel Controls 22.38 cfs @ 28.49 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=4.285 ac
Peak Elev=423.94'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
22.42 cfs
22.42 cfs
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 150HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 5.75" for 25-yearRaleigh event
Inflow = 22.76 cfs @ 11.96 hrs, Volume= 2.498 af
Outflow = 22.62 cfs @ 11.97 hrs, Volume= 2.498 af, Atten= 1%, Lag= 0.6 min
Primary = 22.62 cfs @ 11.97 hrs, Volume= 2.498 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.46' @ 11.97 hrs Surf.Area= 903 sf Storage= 807 cf
Plug-Flow detention time= 1.0 min calculated for 2.498 af (100% of inflow)
Center-of-Mass det. time= 0.9 min ( 995.9 - 995.0 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=22.60 cfs @ 11.97 hrs HW=365.46' (Free Discharge)
1=Culvert (Inlet Controls 22.60 cfs @ 3.69 fps)
Type II 24-hr 25-yearRaleigh Rainfall=6.48"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 151HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.216 ac
Peak Elev=365.46'
Storage=807 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
22.76 cfs
22.62 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 152HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 13.57 cfs @ 12.17 hrs, Volume= 1.131 af, Depth= 3.26"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=4.165 ac
Runoff Volume=1.131 af
Runoff Depth=3.26"
Flow Length=481'
Tc=23.5 min
CN=65
13.57 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 153HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 55.47 cfs @ 11.96 hrs, Volume= 2.850 af, Depth= 6.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=5.370 ac
Runoff Volume=2.850 af
Runoff Depth=6.37"
Tc=5.0 min
CN=93
55.47 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 154HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 36.46 cfs @ 11.96 hrs, Volume= 1.874 af, Depth= 6.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)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-yearRaleigh Rainfall=7.20"
Runoff Area=3.530 ac
Runoff Volume=1.874 af
Runoff Depth=6.37"
Tc=5.0 min
CN=93
36.46 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 155HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 1.78 cfs @ 11.96 hrs, Volume= 0.097 af, Depth= 6.96"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=0.168 ac
Runoff Volume=0.097 af
Runoff Depth=6.96"
Tc=5.0 min
CN=98
1.78 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 156HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 19.78 cfs @ 11.96 hrs, Volume= 1.067 af, Depth= 6.84"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=1.871 ac
Runoff Volume=1.067 af
Runoff Depth=6.84"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
19.78 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 157HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 17.75 cfs @ 11.96 hrs, Volume= 0.945 af, Depth= 6.72"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (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
50-yearRaleigh Rainfall=7.20"
Runoff Area=1.686 ac
Runoff Volume=0.945 af
Runoff Depth=6.72"
Tc=5.0 min
CN=96
17.75 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 158HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 21.14 cfs @ 11.96 hrs, Volume= 1.140 af, Depth= 6.84"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=2.000 ac
Runoff Volume=1.140 af
Runoff Depth=6.84"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
21.14 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 159HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 10.45 cfs @ 12.12 hrs, Volume= 0.761 af, Depth= 3.79"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=2.414 ac
Runoff Volume=0.761 af
Runoff Depth=3.79"
Flow Length=382'
Tc=19.1 min
CN=70
10.45 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 160HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 9.35 cfs @ 11.96 hrs, Volume= 0.512 af, Depth= 6.96"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=0.882 ac
Runoff Volume=0.512 af
Runoff Depth=6.96"
Flow Length=342'
Tc=5.0 min
CN=98
9.35 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 161HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 197.01 cfs @ 12.14 hrs, Volume= 15.257 af, Depth= 4.88"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 162HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)220
210
200
190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=37.523 ac
Runoff Volume=15.257 af
Runoff Depth=4.88"
Flow Length=2,145'
Tc=20.9 min
CN=80
197.01 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 163HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 5.39 cfs @ 11.96 hrs, Volume= 0.291 af, Depth= 6.84"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=0.510 ac
Runoff Volume=0.291 af
Runoff Depth=6.84"
Tc=5.0 min
CN=97
5.39 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 164HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 170.90 cfs @ 12.11 hrs, Volume= 12.846 af, Depth= 4.99"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 165HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=30.883 ac
Runoff Volume=12.846 af
Runoff Depth=4.99"
Flow Length=1,655'
Tc=19.7 min
CN=81
170.90 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 166HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 9.35 cfs @ 11.96 hrs, Volume= 0.512 af, Depth= 6.96"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=0.882 ac
Runoff Volume=0.512 af
Runoff Depth=6.96"
Flow Length=342'
Tc=5.0 min
CN=98
9.35 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 167HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 5.39 cfs @ 11.96 hrs, Volume= 0.291 af, Depth= 6.84"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
50-yearRaleigh Rainfall=7.20"
Runoff Area=0.510 ac
Runoff Volume=0.291 af
Runoff Depth=6.84"
Tc=5.0 min
CN=97
5.39 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 168HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 6.37" for 50-yearRaleigh event
Inflow = 36.46 cfs @ 11.96 hrs, Volume= 1.874 af
Outflow = 36.18 cfs @ 11.97 hrs, Volume= 1.873 af, Atten= 1%, Lag= 0.5 min
Primary = 0.17 cfs @ 11.97 hrs, Volume= 0.472 af
Secondary = 36.02 cfs @ 11.97 hrs, Volume= 1.401 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.83' @ 11.97 hrs Surf.Area= 5,392 sf Storage= 12,567 cf
Plug-Flow detention time= 221.3 min calculated for 1.873 af (100% of inflow)
Center-of-Mass det. time= 221.6 min ( 985.1 - 763.5 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.17 cfs @ 11.97 hrs HW=369.83' TW=368.48' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.17 cfs)
Secondary OutFlow Max=35.93 cfs @ 11.97 hrs HW=369.83' TW=368.48' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 35.93 cfs @ 1.88 fps)
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 169HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.83'
Storage=12,567 cf
36.46 cfs
36.18 cfs
0.17 cfs
36.02 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 170HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 6.37" for 50-yearRaleigh event
Inflow = 55.47 cfs @ 11.96 hrs, Volume= 2.850 af
Outflow = 55.07 cfs @ 11.96 hrs, Volume= 2.849 af, Atten= 1%, Lag= 0.5 min
Primary = 0.22 cfs @ 11.96 hrs, Volume= 0.636 af
Secondary = 54.86 cfs @ 11.96 hrs, Volume= 2.214 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.84' @ 11.96 hrs Surf.Area= 7,516 sf Storage= 17,612 cf
Plug-Flow detention time= 212.9 min calculated for 2.849 af (100% of inflow)
Center-of-Mass det. time= 212.7 min ( 976.2 - 763.5 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.22 cfs @ 11.96 hrs HW=377.84' TW=376.49' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.22 cfs)
Secondary OutFlow Max=54.73 cfs @ 11.96 hrs HW=377.84' TW=376.49' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 54.73 cfs @ 1.91 fps)
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 171HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.370 ac
Peak Elev=377.84'
Storage=17,612 cf
55.47 cfs
55.07 cfs
0.22 cfs
54.86 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 172HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 6.37" for 50-yearRaleigh event
Inflow = 55.07 cfs @ 11.96 hrs, Volume= 2.849 af
Outflow = 14.36 cfs @ 12.09 hrs, Volume= 2.829 af, Atten= 74%, Lag= 7.5 min
Primary = 14.36 cfs @ 12.09 hrs, Volume= 2.829 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.61' @ 12.09 hrs Surf.Area= 9,436 sf Storage= 43,460 cf
Plug-Flow detention time= 84.8 min calculated for 2.828 af (99% of inflow)
Center-of-Mass det. time= 68.2 min ( 1,044.4 - 976.2 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=14.36 cfs @ 12.09 hrs HW=377.61' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 14.36 cfs @ 8.12 fps)
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 173HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.370 ac
Peak Elev=377.61'
Storage=43,460 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
55.07 cfs
14.36 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 174HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 6.37" for 50-yearRaleigh event
Inflow = 36.18 cfs @ 11.97 hrs, Volume= 1.873 af
Outflow = 8.90 cfs @ 12.10 hrs, Volume= 1.864 af, Atten= 75%, Lag= 7.9 min
Primary = 8.90 cfs @ 12.10 hrs, Volume= 1.864 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.57' @ 12.10 hrs Surf.Area= 6,605 sf Storage= 30,166 cf
Plug-Flow detention time= 114.4 min calculated for 1.864 af (99% of inflow)
Center-of-Mass det. time= 103.5 min ( 1,088.6 - 985.1 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=8.90 cfs @ 12.10 hrs HW=369.57' TW=365.06' (Dynamic Tailwater)
1=Culvert (Passes 8.90 cfs of 11.73 cfs potential flow)
2=Orifice Plate (Orifice Controls 8.90 cfs @ 9.66 fps)
3=Small Orifice (Passes < 1.96 cfs potential flow)
4=Sharp-Crested Rectangular Weir (Passes < 154.44 cfs potential flow)
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 175HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.57'
Storage=30,166 cf
36.18 cfs
8.90 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 176HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 6.34" for 50-yearRaleigh event
Inflow = 14.93 cfs @ 12.04 hrs, Volume= 2.926 af
Primary = 14.93 cfs @ 12.04 hrs, Volume= 2.926 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.538 ac
14.93 cfs
14.93 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
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Page 177HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 4.42" for 50-yearRaleigh event
Inflow = 26.81 cfs @ 11.97 hrs, Volume= 2.271 af
Outflow = 26.63 cfs @ 11.98 hrs, Volume= 2.271 af, Atten= 1%, Lag= 0.6 min
Primary = 26.63 cfs @ 11.98 hrs, Volume= 2.271 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.61' @ 11.98 hrs Surf.Area= 986 sf Storage= 947 cf
Plug-Flow detention time= 0.9 min calculated for 2.271 af (100% of inflow)
Center-of-Mass det. time= 0.9 min ( 799.3 - 798.5 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=26.59 cfs @ 11.98 hrs HW=365.61' (Free Discharge)
1=Culvert (Inlet Controls 26.59 cfs @ 3.87 fps)
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 178HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=6.165 ac
Peak Elev=365.61'
Storage=947 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
26.81 cfs
26.63 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 179HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 5.12" for 50-yearRaleigh event
Inflow = 25.42 cfs @ 11.97 hrs, Volume= 1.828 af
Outflow = 25.42 cfs @ 11.97 hrs, Volume= 1.828 af, Atten= 0%, Lag= 0.0 min
Primary = 25.42 cfs @ 11.97 hrs, Volume= 1.828 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 437.76' @ 11.97 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=25.38 cfs @ 11.97 hrs HW=437.56' (Free Discharge)
1=Culvert (Barrel Controls 25.38 cfs @ 32.32 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=4.285 ac
Peak Elev=437.76'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
25.42 cfs
25.42 cfs
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
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Page 180HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 6.46" for 50-yearRaleigh event
Inflow = 25.23 cfs @ 11.96 hrs, Volume= 2.809 af
Outflow = 25.07 cfs @ 11.97 hrs, Volume= 2.809 af, Atten= 1%, Lag= 0.6 min
Primary = 25.07 cfs @ 11.97 hrs, Volume= 2.809 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.56' @ 11.97 hrs Surf.Area= 954 sf Storage= 892 cf
Plug-Flow detention time= 0.9 min calculated for 2.808 af (100% of inflow)
Center-of-Mass det. time= 0.9 min ( 975.5 - 974.5 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=25.05 cfs @ 11.97 hrs HW=365.55' (Free Discharge)
1=Culvert (Inlet Controls 25.05 cfs @ 3.80 fps)
Type II 24-hr 50-yearRaleigh Rainfall=7.20"2019-1012 Prelim SW 2019-11-12
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Page 181HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.216 ac
Peak Elev=365.56'
Storage=892 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
25.23 cfs
25.07 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 182HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: Existing 03
Runoff = 16.32 cfs @ 12.17 hrs, Volume= 1.352 af, Depth= 3.89"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
2.797 70 Woods, Good, HSG C
1.368 55 Woods, Good, HSG B
4.165 65 Weighted Average
4.165 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.5 100 0.0773 0.08 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.60"
2.6 255 0.1084 1.65 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.4 126 0.0124 5.66 90.58 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
23.5 481 Total
Subcatchment 2S: Existing 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=4.165 ac
Runoff Volume=1.352 af
Runoff Depth=3.89"
Flow Length=481'
Tc=23.5 min
CN=65
16.32 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 183HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 3S: Post 02 (SW-blue)
Runoff = 61.93 cfs @ 11.96 hrs, Volume= 3.205 af, Depth= 7.16"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
4.193 98 Paved parking, HSG C
1.177 74 >75% Grass cover, Good, HSG C
5.370 93 Weighted Average
1.177 21.92% Pervious Area
4.193 78.08% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 3S: Post 02 (SW-blue)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)65
60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=5.370 ac
Runoff Volume=3.205 af
Runoff Depth=7.16"
Tc=5.0 min
CN=93
61.93 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 184HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 4S: Post 01 (NE-purple)
Runoff = 40.71 cfs @ 11.96 hrs, Volume= 2.107 af, Depth= 7.16"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
2.903 98 Paved parking, HSG C
0.406 74 >75% Grass cover, Good, HSG C
0.221 70 Woods, Good, HSG C
3.530 93 Weighted Average
0.627 17.76% Pervious Area
2.903 82.24% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 4S: Post 01 (NE-purple)
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)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
100-yearRaleigh Rainfall=8.00"
Runoff Area=3.530 ac
Runoff Volume=2.107 af
Runoff Depth=7.16"
Tc=5.0 min
CN=93
40.71 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 185HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 11S: Undetained 02
Runoff = 1.98 cfs @ 11.96 hrs, Volume= 0.109 af, Depth= 7.76"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
* 0.168 98
0.168 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 11S: Undetained 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=0.168 ac
Runoff Volume=0.109 af
Runoff Depth=7.76"
Tc=5.0 min
CN=98
1.98 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 186HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 20S: Existing 02
Runoff = 22.00 cfs @ 11.96 hrs, Volume= 1.191 af, Depth= 7.64"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
* 1.828 98
0.043 74 >75% Grass cover, Good, HSG C
1.871 97 Weighted Average
0.043 2.30% Pervious Area
1.828 97.70% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.0 100 0.0268 1.64 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
3.1 621 0.0268 3.32 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.2 36 3.00 Direct Entry, pipe flow
0.7 Direct Entry, to 5 minute minimum TC
5.0 757 Total
Subcatchment 20S: Existing 02
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=1.871 ac
Runoff Volume=1.191 af
Runoff Depth=7.64"
Flow Length=757'
Slope=0.0268 '/'
Tc=5.0 min
CN=97
22.00 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 187HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 22S: Undetained 01
Runoff = 19.76 cfs @ 11.96 hrs, Volume= 1.057 af, Depth= 7.52"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
* 0.143 74 grass
* 1.543 98
1.686 96 Weighted Average
0.143 8.48% Pervious Area
1.543 91.52% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 22S: Undetained 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=1.686 ac
Runoff Volume=1.057 af
Runoff Depth=7.52"
Tc=5.0 min
CN=96
19.76 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 188HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 24S: Existing 01
Runoff = 23.52 cfs @ 11.96 hrs, Volume= 1.273 af, Depth= 7.64"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
1.949 98 Paved parking, HSG C
0.051 74 >75% Grass cover, Good, HSG C
2.000 97 Weighted Average
0.051 2.55% Pervious Area
1.949 97.45% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.5 100 0.0100 1.11 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
2.6 320 0.0100 2.03 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
0.9 Direct Entry,
5.0 420 Total
Subcatchment 24S: Existing 01
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=2.000 ac
Runoff Volume=1.273 af
Runoff Depth=7.64"
Flow Length=420'
Slope=0.0100 '/'
Tc=5.0 min
CN=97
23.52 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 189HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 27S: Existing 04
Runoff = 12.33 cfs @ 12.12 hrs, Volume= 0.898 af, Depth= 4.46"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
2.414 70 Woods, Good, HSG C
2.414 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
15.3 101 0.0414 0.11 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.60"
3.5 226 0.0476 1.09 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3 55 3.00 Direct Entry, pipe flow
19.1 382 Total
Subcatchment 27S: Existing 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=2.414 ac
Runoff Volume=0.898 af
Runoff Depth=4.46"
Flow Length=382'
Tc=19.1 min
CN=70
12.33 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 190HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 29S: Existing 06
Runoff = 10.40 cfs @ 11.96 hrs, Volume= 0.570 af, Depth= 7.76"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 29S: Existing 06
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=0.882 ac
Runoff Volume=0.570 af
Runoff Depth=7.76"
Flow Length=342'
Tc=5.0 min
CN=98
10.40 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 191HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 30S: Offsite Tributary Pre
Runoff = 225.97 cfs @ 12.13 hrs, Volume= 17.589 af, Depth= 5.63"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
4.603 55 Woods, Good, HSG B
12.777 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 14.390 98 impervious
37.523 80 Weighted Average
23.133 61.65% Pervious Area
14.390 38.35% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
1.3 538 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
20.9 2,145 Total
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 192HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 30S: Offsite Tributary Pre
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)250
240
230
220
210
200
190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=37.523 ac
Runoff Volume=17.589 af
Runoff Depth=5.63"
Flow Length=2,145'
Tc=20.9 min
CN=80
225.97 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 193HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 31S: Existing 05
Runoff = 6.00 cfs @ 11.96 hrs, Volume= 0.325 af, Depth= 7.64"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 31S: Existing 05
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=0.510 ac
Runoff Volume=0.325 af
Runoff Depth=7.64"
Tc=5.0 min
CN=97
6.00 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 194HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 33S: Offsite Tributary Post
Runoff = 195.66 cfs @ 12.11 hrs, Volume= 14.778 af, Depth= 5.74"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
2.868 55 Woods, Good, HSG B
9.921 70 Woods, Good, HSG C
2.886 74 >75% Grass cover, Good, HSG C
2.867 78 Small grain, C&T + CR, Poor, HSG C
* 12.341 98 impervious
30.883 81 Weighted Average
18.542 60.04% Pervious Area
12.341 39.96% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
3.7 104 0.0340 0.47 Sheet Flow,
Cultivated: Residue<=20% n= 0.060 P2= 3.60"
6.0 597 0.0340 1.66 Shallow Concentrated Flow,
Cultivated Straight Rows Kv= 9.0 fps
1.5 269 3.00 Direct Entry,
1.4 131 0.0526 1.61 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.2 40 3.00 Direct Entry,
6.8 466 0.0527 1.15 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.1 48 0.0178 6.78 108.52 Trap/Vee/Rect Channel Flow,
Bot.W=5.00' D=2.00' Z= 1.5 '/' Top.W=11.00'
n= 0.035 Earth, dense weeds
19.7 1,655 Total
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 195HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Subcatchment 33S: Offsite Tributary Post
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)210
200
190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=30.883 ac
Runoff Volume=14.778 af
Runoff Depth=5.74"
Flow Length=1,655'
Tc=19.7 min
CN=81
195.66 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 196HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 35S: Post 04
Runoff = 10.40 cfs @ 11.96 hrs, Volume= 0.570 af, Depth= 7.76"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
0.006 74 >75% Grass cover, Good, HSG C
* 0.876 98
0.882 98 Weighted Average
0.006 0.68% Pervious Area
0.876 99.32% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0.9 100 0.0341 1.81 Sheet Flow,
Smooth surfaces n= 0.011 P2= 3.60"
0.9 242 0.0509 4.58 Shallow Concentrated Flow,
Paved Kv= 20.3 fps
3.2 Direct Entry, to minimum TC of 5 minutes
5.0 342 Total
Subcatchment 35S: Post 04
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=0.882 ac
Runoff Volume=0.570 af
Runoff Depth=7.76"
Flow Length=342'
Tc=5.0 min
CN=98
10.40 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 197HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 36S: Post 03
Runoff = 6.00 cfs @ 11.96 hrs, Volume= 0.325 af, Depth= 7.64"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"
Area (ac) CN Description
0.024 74 >75% Grass cover, Good, HSG C
* 0.486 98
0.510 97 Weighted Average
0.024 4.71% Pervious Area
0.486 95.29% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 36S: Post 03
Runoff
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr
100-yearRaleigh Rainfall=8.00"
Runoff Area=0.510 ac
Runoff Volume=0.325 af
Runoff Depth=7.64"
Tc=5.0 min
CN=97
6.00 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 198HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 6P: NE Basin Sediment and Sand Filter
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 7.16" for 100-yearRaleigh event
Inflow = 40.71 cfs @ 11.96 hrs, Volume= 2.107 af
Outflow = 40.42 cfs @ 11.96 hrs, Volume= 2.107 af, Atten= 1%, Lag= 0.5 min
Primary = 0.17 cfs @ 12.10 hrs, Volume= 0.478 af
Secondary = 40.25 cfs @ 11.96 hrs, Volume= 1.629 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.98' @ 12.10 hrs Surf.Area= 5,392 sf Storage= 13,380 cf
Plug-Flow detention time= 201.1 min calculated for 2.107 af (100% of inflow)
Center-of-Mass det. time= 201.0 min ( 961.7 - 760.7 )
Volume Invert Avail.Storage Storage Description
#1 367.50' 4,060 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 367.50' 9,420 cf Sediment Chamber (Prismatic) Listed below (Recalc)
13,480 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 1,624 0 0
370.00 1,624 4,060 4,060
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
367.50 3,768 0 0
370.00 3,768 9,420 9,420
Device Routing Invert Outlet Devices
#1 Primary 367.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.070 0.075 0.088 0.110 0.154 0.197 0.241
0.285 0.329
#2 Secondary 369.50'58.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.17 cfs @ 12.10 hrs HW=369.98' TW=369.98' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.17 cfs)
Secondary OutFlow Max=40.16 cfs @ 11.96 hrs HW=369.86' TW=369.00' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 40.16 cfs @ 1.95 fps)
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 199HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 6P: NE Basin Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.98'
Storage=13,380 cf
40.71 cfs
40.42 cfs
0.17 cfs
40.25 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
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Page 200HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 10P: SW Sediment and Sand Filter
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 7.16" for 100-yearRaleigh event
Inflow = 61.93 cfs @ 11.96 hrs, Volume= 3.205 af
Outflow = 61.52 cfs @ 11.96 hrs, Volume= 3.204 af, Atten= 1%, Lag= 0.5 min
Primary = 0.22 cfs @ 12.09 hrs, Volume= 0.643 af
Secondary = 61.30 cfs @ 11.96 hrs, Volume= 2.561 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.98' @ 12.09 hrs Surf.Area= 7,516 sf Storage= 18,647 cf
Plug-Flow detention time= 193.0 min calculated for 3.204 af (100% of inflow)
Center-of-Mass det. time= 192.8 min ( 953.5 - 760.7 )
Volume Invert Avail.Storage Storage Description
#1 375.50' 5,220 cf Sand Filter (Prismatic) Listed below (Recalc)
#2 375.50' 13,570 cf Sediment Chamber (Prismatic) Listed below (Recalc)
18,790 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 2,088 0 0
378.00 2,088 5,220 5,220
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
375.50 5,428 0 0
378.00 5,428 13,570 13,570
Device Routing Invert Outlet Devices
#1 Primary 375.50'Sand Filter
Head (feet) 0.00 0.10 0.20 0.50 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.090 0.096 0.113 0.141 0.197 0.254 0.310
0.366 0.423
#2 Secondary 377.50'83.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.22 cfs @ 12.09 hrs HW=377.98' TW=377.98' (Dynamic Tailwater)
1=Sand Filter (Custom Controls 0.22 cfs)
Secondary OutFlow Max=61.17 cfs @ 11.96 hrs HW=377.87' TW=376.95' (Dynamic Tailwater)
2=Sharp-Crested Rectangular Weir (Weir Controls 61.17 cfs @ 1.99 fps)
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 201HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 10P: SW Sediment and Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)65
60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.370 ac
Peak Elev=377.98'
Storage=18,647 cf
61.93 cfs
61.52 cfs
0.22 cfs
61.30 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 202HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 11P: SW vault
Inflow Area = 5.370 ac, 78.08% Impervious, Inflow Depth = 7.16" for 100-yearRaleigh event
Inflow = 61.52 cfs @ 11.96 hrs, Volume= 3.204 af
Outflow = 15.11 cfs @ 12.08 hrs, Volume= 3.184 af, Atten= 75%, Lag= 7.1 min
Primary = 15.11 cfs @ 12.08 hrs, Volume= 3.184 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 377.98' @ 12.08 hrs Surf.Area= 9,436 sf Storage= 46,983 cf
Plug-Flow detention time= 81.2 min calculated for 3.183 af (99% of inflow)
Center-of-Mass det. time= 66.2 min ( 1,019.7 - 953.5 )
Volume Invert Avail.Storage Storage Description
#1 373.00' 47,180 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
373.00 9,436 0 0
378.00 9,436 47,180 47,180
Device Routing Invert Outlet Devices
#1 Primary 373.00'18.0" Round Culvert
L= 103.4' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 373.00' / 372.63' S= 0.0036 '/' Cc= 0.900
n= 0.013, Flow Area= 1.77 sf
Primary OutFlow Max=15.11 cfs @ 12.08 hrs HW=377.98' TW=0.00' (Dynamic Tailwater)
1=Culvert (Barrel Controls 15.11 cfs @ 8.55 fps)
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 203HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 11P: SW vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)65
60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.370 ac
Peak Elev=377.98'
Storage=46,983 cf
18.0"
Round Culvert
n=0.013
L=103.4'
S=0.0036 '/'
61.52 cfs
15.11 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 204HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 19P: NE vault
Inflow Area = 3.530 ac, 82.24% Impervious, Inflow Depth = 7.16" for 100-yearRaleigh event
Inflow = 40.42 cfs @ 11.96 hrs, Volume= 2.107 af
Outflow = 9.35 cfs @ 12.08 hrs, Volume= 2.098 af, Atten= 77%, Lag= 7.2 min
Primary = 9.35 cfs @ 12.08 hrs, Volume= 2.098 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 369.98' @ 12.08 hrs Surf.Area= 6,605 sf Storage= 32,891 cf
Plug-Flow detention time= 110.2 min calculated for 2.098 af (100% of inflow)
Center-of-Mass det. time= 100.3 min ( 1,062.0 - 961.7 )
Volume Invert Avail.Storage Storage Description
#1 365.00' 33,025 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
365.00 6,605 0 0
370.00 6,605 33,025 33,025
Device Routing Invert Outlet Devices
#1 Primary 365.00'15.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 365.00' / 364.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 1.23 sf
#2 Device 1 365.00'13.0" Vert. Orifice Plate C= 0.600 Limited to weir flow at low heads
#3 Device 2 365.00'6.0" Vert. Small Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 367.00'12.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=9.35 cfs @ 12.08 hrs HW=369.98' TW=365.15' (Dynamic Tailwater)
1=Culvert (Passes 9.35 cfs of 12.33 cfs potential flow)
2=Orifice Plate (Orifice Controls 9.35 cfs @ 10.14 fps)
3=Small Orifice (Passes < 2.06 cfs potential flow)
4=Sharp-Crested Rectangular Weir (Passes < 191.74 cfs potential flow)
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 205HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 19P: NE vault
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=3.530 ac
Peak Elev=369.98'
Storage=32,891 cf
40.42 cfs
9.35 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 206HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 21P: Post Total 02
Inflow Area = 5.538 ac, 78.75% Impervious, Inflow Depth > 7.13" for 100-yearRaleigh event
Inflow = 16.12 cfs @ 12.02 hrs, Volume= 3.292 af
Primary = 16.12 cfs @ 12.02 hrs, Volume= 3.292 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Pond 21P: Post Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=5.538 ac
16.12 cfs
16.12 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 207HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 25P: Pre Total 01
Inflow Area = 6.165 ac, 31.61% Impervious, Inflow Depth = 5.11" for 100-yearRaleigh event
Inflow = 30.58 cfs @ 11.97 hrs, Volume= 2.625 af
Outflow = 30.37 cfs @ 11.98 hrs, Volume= 2.625 af, Atten= 1%, Lag= 0.6 min
Primary = 30.37 cfs @ 11.98 hrs, Volume= 2.625 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.74' @ 11.98 hrs Surf.Area= 1,058 sf Storage= 1,080 cf
Plug-Flow detention time= 0.9 min calculated for 2.625 af (100% of inflow)
Center-of-Mass det. time= 0.9 min ( 797.7 - 796.8 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=30.33 cfs @ 11.98 hrs HW=365.74' (Free Discharge)
1=Culvert (Inlet Controls 30.33 cfs @ 4.03 fps)
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 208HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 25P: Pre Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=6.165 ac
Peak Elev=365.74'
Storage=1,080 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
30.58 cfs
30.37 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 209HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 26P: Pre Total 02
Inflow Area = 4.285 ac, 42.66% Impervious, Inflow Depth = 5.85" for 100-yearRaleigh event
Inflow = 28.80 cfs @ 11.97 hrs, Volume= 2.089 af
Outflow = 28.80 cfs @ 11.97 hrs, Volume= 2.089 af, Atten= 0%, Lag= 0.0 min
Primary = 28.80 cfs @ 11.97 hrs, Volume= 2.089 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 455.35' @ 11.97 hrs
Device Routing Invert Outlet Devices
#1 Primary 377.88'12.0" Round Culvert
L= 73.8' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 377.88' / 374.66' S= 0.0436 '/' Cc= 0.900
n= 0.013, Flow Area= 0.79 sf
Primary OutFlow Max=28.75 cfs @ 11.97 hrs HW=455.11' (Free Discharge)
1=Culvert (Barrel Controls 28.75 cfs @ 36.61 fps)
Pond 26P: Pre Total 02
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=4.285 ac
Peak Elev=455.35'
12.0"
Round Culvert
n=0.013
L=73.8'
S=0.0436 '/'
28.80 cfs
28.80 cfs
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 210HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 28P: Post Total 01
Inflow Area = 5.216 ac, 85.24% Impervious, Inflow Depth > 7.26" for 100-yearRaleigh event
Inflow = 27.78 cfs @ 11.96 hrs, Volume= 3.154 af
Outflow = 27.61 cfs @ 11.97 hrs, Volume= 3.154 af, Atten= 1%, Lag= 0.6 min
Primary = 27.61 cfs @ 11.97 hrs, Volume= 3.154 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs
Peak Elev= 365.65' @ 11.97 hrs Surf.Area= 1,005 sf Storage= 981 cf
Plug-Flow detention time= 0.9 min calculated for 3.154 af (100% of inflow)
Center-of-Mass det. time= 0.9 min ( 957.5 - 956.6 )
Volume Invert Avail.Storage Storage Description
#1 363.88' 4,698 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
363.88 0 0 0
364.00 225 14 14
365.00 644 435 448
366.00 1,202 923 1,371
367.00 1,451 1,327 2,698
368.00 2,550 2,001 4,698
Device Routing Invert Outlet Devices
#1 Primary 363.88'60.0" W x 40.0" H Ellipse Culvert
L= 110.2' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 363.88' / 362.16' S= 0.0156 '/' Cc= 0.900
n= 0.013, Flow Area= 13.09 sf
Primary OutFlow Max=27.60 cfs @ 11.97 hrs HW=365.65' (Free Discharge)
1=Culvert (Inlet Controls 27.60 cfs @ 3.92 fps)
Type II 24-hr 100-yearRaleigh Rainfall=8.00"2019-1012 Prelim SW 2019-11-12
Printed 11/14/2019Prepared by Symanetc
Page 211HydroCAD® 10.10-1 s/n 03828 © 2019 HydroCAD Software Solutions LLC
Pond 28P: Post Total 01
Inflow
Primary
Hydrograph
Time (hours)
605856545250484644424038363432302826242220181614121086420Flow (cfs)30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.216 ac
Peak Elev=365.65'
Storage=981 cf
60.0" x 40.0"
Ellipse Culvert
n=0.013
L=110.2'
S=0.0156 '/'
27.78 cfs
27.61 cfs

APPENDIX D:

Exhibits

GLENWOOD AVENUEPUBLIC 6 LAND DIVIDEDLUMLEY ROAD
PUBLIC 4 LANE DIVI
D
E
D
MT.
H
E
R
M
A
N
R
O
A
D
(TO
B
E
A
B
A
N
D
O
N
E
D
P
E
R
R
D
U 2040
P
L
A
N)
GRAPHIC SCALE
0 30 60 120
1 inch = 60 feet
1/3
2019-1012
November 14, 2019
1" = 60'
DATEREVISIONSDATEDESCRIPTIONMARK
SCALE
JOB NO.
SHEET
PRELIMINARY..........................
PLAN SET DATE
NOT TO BE USED FOR
CONSTRUCTION
November 14, 2019 CITY OF RALEIGH, WAKE COUNTY, NORTH CAROLINASTORMWATER MANAGEMENTFORLUMLEY ROAD HONDAEXISTING CONDITIONS TRIBUTARY MAPAUTOMOTIVE GROUP
GLENWOOD AVENUEPUBLIC 6 LAND DIVIDEDLUMLEY ROAD
PUBLIC 4 LANE DIVI
D
E
D
MT. HERMAN ROAD
(TO BE ABANDONED
PER RDU 2040 PLAN)
GRAPHIC SCALE
0 50 100 200
1 inch = 100 feet
2/3
2019-1012
November 14, 2019
1" = 100'
DATEREVISIONSDATEDESCRIPTIONMARK
SCALE
JOB NO.
SHEET
PRELIMINARY..........................
PLAN SET DATE
NOT TO BE USED FOR
CONSTRUCTION
November 14, 2019 CITY OF RALEIGH, WAKE COUNTY, NORTH CAROLINASTORMWATER MANAGEMENTFORLUMLEY ROAD HONDAEXISTING CONDITIONS WATERSHED MAPAUTOMOTIVE GROUP
GLENWOOD AVENUEPUBLIC 6 LAND DIVIDEDLUMLEY ROAD
PUBLIC 4 LANE DIVI
D
E
D
MT. HERMAN ROAD
(TO BE ABANDONED
PER RDU 2040 PLAN)
LUMLEY ROAD
REALIGNMENT
GRAPHIC SCALE
0 50 100 200
1 inch = 100 feet
3/3
2019-1012
November 15, 2019
1" = 100'
DATEREVISIONSDATEDESCRIPTIONMARK
SCALE
JOB NO.
SHEET
PRELIMINARY..........................
PLAN SET DATE
NOT TO BE USED FOR
CONSTRUCTION
November 15, 2019 CITY OF RALEIGH, WAKE COUNTY, NORTH CAROLINASTORMWATER MANAGEMENTFORLUMLEY ROAD HONDAPROPOSED CONDITIONS TRIBUTARY MAP ANDWATERSHED MAPAUTOMOTIVE GROUP