SW1190501_storm calculations_7/12/2019

STORMWATER AND EROSION CONTROL
DESIGN REPORT
for
NORTH BUNCOMBE MIDDLE SCHOOL
51 N BUNCOMBE SCHOOL RD
WEAVERVILLE, NC 28787
BEA No. 487919
Date: 7/11 /2019
l>j141I III}tllJ
CAT{a
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SEAL
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Prepared for:
BUNCOMBE COUNTY BOARD OF EDUCATION
CONTACT: TIM FIERLE
175 BINGHAM RD
ASHEVILLE NC 28806
Prepared by:
BRIC"KS
EN G 1 NEER IN G ASS C1 C I ATE S
17 Arlington Street Asheville, NC 28801 828-232-4700

Table of Contents
Introduction
Erosion Control ...........................................
Runoff Control Measures......
Sediment Traps and Barriers
Stormwater Management ..................................
Pre -Developed Conditions ........
Post -Developed Conditions........
Energy Dissipation ......................
Methodology..............................................................................
Erosion Control Modeling Methodology ..............
Stormwater Quality Modeling Methodology.........
Stormwater Conveyance Modeling Methodology
Results
Erosion Control Results......
Stormwater Quality Control.
Conclusions
Exhibits:
Exhibit A USGS Map
Exhibit B Erosion Control Drainage Map
Exhibit C NRCS Soil Survey
Exhibit D Existing Conditions Map
Exhibit E Proposed Conditions Drainage Map
Exhibit F Storm Collection Drainage Map
Appendices:
Appendix A Erosion Control Calculations
Sediment Basin Calculations
Temporary Diversion Ditch Calculations
1
1
1
1
1
1
1
6
1
3
3
3
............................... 4
.............................. 4
.............................. 5
Appendix B Stormwater Quantity Management Calculation Pond Report
Hydrocad Hydrographs Summary Report
Hydrocad Hydrographs for 2,10 and 50 Year Report
Water Quality Calculations
Conveyance System Calculations
Rip -Rap Calculations
............... 7

Introduction
page 1
The subject site is located at 51 N BUNCOMBE SCHOOL RD WEAVERVILLE, NC 28787, PIN 9743-44-1042-00000. See Exhibit A,
USGS MAP with site location. The 28.95-acre site is currently Public Middle School. The proposed development involves the
construction of Bus Lot Expansion.
This report addresses requirements to meet current NPDES Construction and Post Construction Activities
All design is based on NCDEQ design Criteria.
Erosion Control
Runoff Control Measures
The Proposed Develoment will be subject to erosion during construction activities. The site is susceptible to concentrated sediment
loss in one location shown on Exhibit B. This location is at the downstream end of the proposed construction and will employ a
skimmer sedimate basin for sediment control. All other areas should not receive concentrated sediment runoff and will be protected
with silt fence with stabilized outlets.
Sediment Traps and Barriers
Runoff draining to the North Eastern discharge point will be captured using a skimmer type sediment basin. This basin is designed
for the worst case condition where the entire site has been disturbed. The basin will drain the design volume at a minimum of 3
days as required by the NCDEQ Guidelines. Inlet protection is provided for later phases as the site is brought up to grade.
Site Stabilization
The site will be stabilized with a combination of seeding and slope matting. Inlet protection and perimeter silt fencing will remain
until the site is stabilized.
Stormwater Management
Pre -Developed Conditions
The site is currently an existing Public Middle School site The soils for the site are classified by NRCS as Ud, Ux, CkC2, CkD2
which are characterized as having runoff characteristics of a CLASS B SOIL. See Exhibit C for the current NRCS soils map for the
project.
The proposed development will drain pre-dominately to the North East.
Post -Developed Conditions
Stormwater discharge will be controlled to maintain the same drainage pattern and rate as predevelopment. Additional impervious
area will consist of concrete sidewalk and asphalt pavement. A large percentage of this area is currently building construction which
will be removed and replaced with asphalt. Stormwater will be treated by a Bioswale basin per NCDEQ speicifications.. See Exhibit
C for a soils report and Exhibit E for proposed drainage area map and quantities.
Stormwater quantity and quality will be controlled by the bioswale basin. This system meets the required 85% tss removal for
stormwater and provides stormwater detention.

Collection System
page 2
An existing storm pipe system will be modified to allow for the construction of the proposed BMP. This system will be lowered below
the proposed BMP which will divert existing drainage away from the proposed stormwater treatment area.
Stormwater runoff will be conveyed by surface runoff See Exhibit "F" for delineated storm drainage areas, curve numbers and area
totals.
Energy dissipation will be handled with a RIP -RAP pad. Level spreaders are not proposed since the proposed system discharges in
the same location as the existing and that up to the 50-year storm event will be attenuated to below pre -developed levels.

Methodology page 3
Erosion Control Modeling Methodology
Please note detailed Erosion Control Calculations are contained in Appendix "A"
Temporary diversion swales were designed to carry the 25-year storm event. The drainage area, time of concentration and
estimated construction land cover was used to estimate the 25-year storm event using the rational method.
The Skimmer Basin was sized using NCDEQ guidelines where the required volume is based on disturbed drainage area and
required surface area is sized based on the 10-year storm event. It is also shown that the 25-year storm event will pass over the
emergency spillway. The rational method was used to estimate both the 10-year and 25-year storm.
STORMWATER QUALITY MODELING METHODOLOGY
Stormwater quality control requirements were determined using NCDEQ recommended methods and post drainage data shown in
Exhibit E. To obtained 85% total suspended solids removed, the proposed Bioswale Pond is designed to capture and discharge the
first 1" of stormwater runoff as defined by the "simple method" for. In addition, the first 1" of runoff must discharge the system over
a minimum of 48 hours.
The volume of water quality runoff calculated using the "Simple Method" was routed through the chamber system using a rainfall
total equal to the amount necessary to create the water quality volume.
See Appendix B for detailed water quality calculations.
STORMWATER CONVEYANCE MODELING METHODOLOGY
Energy dissipation was calculate using the nomograph provided in the Appendix section of the NCDEQ Erosion Control Manual.
Stormwater conveyance calculations are provided in Appendix B.

Results
Erosion Control Results
page 4
Temporary Diversion Swale Calculation Results
The following table represenst the temporary diversions flow parameters. As can been seen in the table, the depth of flow for the 25-
year storm is less than the diversion depth. This indicates the swales are capable of carrying the 25-year storm event.
u,
Z
H
U
(7
(ACRE)
(IN/HR)
(CFS)
td-1
0.93
5
0.6
6.46
3.60
Channel Design (Non -Erodible)
Channel Type: Trapezoidal, Unequal Side Slopes
Dimensions: Left Side Slope 20.00:
Right Side Slope 3.00:1
Base Dimension: 0.00
Wetted Perimeter: 8.42 _
Area of Wetted Cross Section: 1.52
Channel Slope: 1.0000
Manning's n of Channel: 0.0250 (sub -base)
Discharge: 2.88 cfs
Depth of Flow: 0.36
Velocity: 1.90fps
Freeboard: 1 feet
See Appendix A for detailed calculations
Temporary Skimmer Basin Calculation Results
The following table represents the results of Sediment Basin sizing Calculations.
SKIMMER TYPE
SEDIMENT BASIN
Lu
w
Lu
OJ
N
U
Q
�
Q
ILL
Z
0
W
Q
Q
Lu
W
U
W
U
w
w
Z
W
LL
LL>
>
>
Q
U
Q
o
U�
w=)
�O
=) 0�
U_j
w 0
_jO
O�
w
w
z
o
o
11� U
U d
0�>
> d
0 H
ACRE
ACRE
(CFS)
(SF)
(SF)
(CF)
(CF)
(DAYS)
BASIN 1-1.51 N
0.93
0.93
3.93
1278
2600
1671
6706
3.9
See Appendix A for detailed calculations

STORMWATER QUANTITY CONTROL
Stormwater Quality Control
page 5
The following are the results of the stormwater Quality Calculations for required treatment volume, treatment volume provided and
discharge time for treatment volume for 85% TSS removal.
ADS UNDERGROUND CHAMBER SYSTEM
Ll
Lu
a
O
z
w
W
w
a
w
o
Q
z
�
�
O
�
a
m
Q
W
O
O
U
w
Q
U)
H
(ACRE)
(IN)
(CF)
(CF)
(hrs)
NET INCREASE
0.376
1
0.95
1
1297
2917
3
See Appendix B for detailed calculations

Energy Dissipation page 6
The following table represents the pipe discharge into the proposed riprap pads for the 25-year storm event.
Energy Dissipation
The following chart represents the rip -rap pads provided and design criteria. See Appendix "B" for detailed calculations.
Structure 25-Year Flow Pipe Diameter D50 Length Width Depth
# (cfs) (in) (ft) (ft) (ft) (in)
1 TO2 11.64 24 12 12 14 12

Conclusions page 7
This report illustrates that NCDEQ Design Criteria has been met for Construction and Post Construction Activities for the subject
property.

Exhibit A USGS Map

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z. I.
25
70
CL
ONrICEtL
RD
cr
TO FRENCH BROAD
RIVER
Z)
19
2
Bus
19
t,7 Iv
Bus
ME
:I
ar J.J;
A
PROJECT SITE
NORTH BUNCOMBE
MIDDLE SCHOOL
e vl j'!
W 0
LITTLE FLAT CREEK
TO DRAIN TO
FRENCH BROAD RIVER
Springs
_,SARINGS-RD
0 1000 2000 3000
EXHIBIT "All SCALE: 1 "= 1000
USGS QUAD MAP

Exhibit 6 Erosion Control Drainage Map

.0

Exhibit C NRCS Soil Survey

100 200 300
immmmm EXHIBIT "C"
SCALE: 1 "= 100 SOILS MAP

Exhibit D Existing Conditions Map

100 200 300
SCALE: 1 "= 100
200 400 600
EXHIBIT "D"
EXISTING CONDITIONS MAP

Exhibit E Proposed Conditions Drainage Map

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n \ 11 1 t I I I I I► I \ '� �,
- 't •t 1 I II "I I " I I�",III I I - I I I11 1 ` I � "\�
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•. � .. ••• •. \\o\Ilj/t I I �tt�\\ \` I I l I I l 1 �\

Exhibit F Storm Collection Drainage Map

F U
MAI W w 210 1 Q FAUT

UNDERDRAIN DESIGN
FLOWRATE THROUGH MEDIA=
SURFACE AREA= 3114 SF
SOIL PERMEABILITY 5 IN/HR
1297.5 CF/HR
0.360416667 CF/SEC
*Studies show for perforated underdains greater than 10' long, the system
can be modeled with the orifice equation where
Q=CdAo(2gh)A.5
where Cd=
0.34 6" perforated
Ao=
14.04307624 inA2 6" pipe diameter
g= 32.2 ft/sec^2gravity
H= varies Head
underdrain discharge rate is controlled by reducing H on the system
by adding and upturned elbow inside the outlet structure
The following represents stage discharge using a 6" underdrain as outlet control
with top of internal water storage at elev= 2197
stage(ft elev) H Discharge(cfs)
2197 0 0
2198 1 0.46
2199 2 0.71
2200 3 0.89
*Murphy, P., Kaye, N. B., & Khan, A. A. (2014) "Hydraulic performance of
aggregate beds with perforated pipe underdrains flowing full." A.S.C.E. Journal of
Irrigation & Drainage Engineering 140(8), 04014023-1-7.

UNDERDRAIN DESIGN
FLOWRATE THROUGH MEDIA=
SURFACE AREA= 3114 SF
SOIL PERMEABILITY 5 IN/HR
1297.5 CF/HR
0.360416667 CF/SEC
*Studies show for perforated underdains greater than 10' long, the system
can be modeled with the orifice equation where
Q=CdAo(2gh)A.5
where Cd= 0.49 4" perforated
0.34 6" perforated
Ao= 6.314640504 inA2 4" pipe diameter
14.04307624 inA2 6" pipe diameter
g= 32.2 ft/sec^2gravity
H= varies Head
underdrain discharge rate is controlled by reducing H on the system
by adding and upturned elbow inside the outlet structure
The following represents stage discharge using a 4" underdrain as outlet control
with top of internal water storage at elev= 2197
stage(ft elev) H Discharge(cfs)
2197 0 0
2198 1 0.31
2199 2 0.46
2200 3 0.58
The following represents stage discharge using a 6" underdrain as outlet control
with top of internal water storage at elev= 2197
stage(ft elev) H Discharge(cfs)
2197 0 0
2198 1 0.46
2199 2 0.71
2200 3 0.89
*Murphy, P., Kaye, N. B., & Khan, A. A. (2014) "Hydraulic performance of
aggregate beds with perforated pipe underdrains flowing full." A.S.C.E. Journal of
Irrigation & Drainage Engineering 140(8), 04014023-1-7.

TEMPORARY DIVERSION SWALES
w
2
Q
Z
Q
0
H
U
N
CJ
(ACRE)
(IN/HR)
(CFS)
td-1
0.93
5
0.6
6.46
3.60
Channel Design (Non -Erodible)
Channel Type: Trapezoidal, Unequal Side Slopes
Dimensions: Left Side Slope 20.00:1
Right Side Slope 3.00:1
Base Dimension: 0.00
Wetted Perimeter: 8.42
Area of Wetted Cross Section: 1.52
Channel Slope: 1.0000
Manning's n of Channel: 0.0250 (sub -base)
Discharge: 2.88 cfs
Depth of Flow: 0.36 feet
Velocity: 1.90 fps

1T02
313— ----IT
POND RIPRAP OUTLET
Appendices
O 25-YEAR FLOW= 11.64CFS
O PIPE SIZE= 241N.
O RIP RAP PAD PARAMETERS
O L= 12 FT
O W=14 FT
3 5 10 20 50 100 200 500 1000
Discharge (0/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full, minimum tailwater condition (T. < 0.5 diameter).
Rev.12/93 8.06.3

UMAI W w 210 1 Q VA4i

DRAINAGE AREA SUMMARY 1 0.023048669 0.56533517
EXISTING DRAINAGE AREA
pervious
IMPERVIOUS
IMPERVIOUS
DA NAME
GRASS
SIDEWALK
PAVEMENT
EWS Al
27232
773
3182
EWS B1
28322
2942
490
0-0.212258953
IMPERVIOUS IMPERVIOUS
ROOFS BUILDING TOTAL(P
9246 0.928
36968 1.578
0
2.506
-16383 1004 24626 1 -9246

PIPE NETWORK RESULTS 25-YEAR FLOW MATERIAL PIPE SIZE SLOPE n DEPTH OF FLOW VELOCITY
8THS FULL
25-YEAR 25-YEAR
25-YEAR
25-YEAR
25-YEAR
25-YEAR
(CFS) (IN)
N
(n)
(IN)
(fps)
1TO2 11.66 HDPE 24
1.13
0.011
10.68
8.59
3.2/8ths
2TO3 7.53 HDPE 18
0.85
0.011
10.68
6.91
4.8/8ths

DETENTION RESULTS
1-YEAR 10-YEAR 25-YEAR
50-YEAR
PRE DEVELOPED
EWS Al
0.63 3.16
3.87
POST DEVELOPED
EWS B1
2.35 7.53
8.84
ELx
PWS Al
2.97 10.68
1.9 5.1
12.71
5.88
PWS B1
2.35 7.53
8.84
BMPA
0.3 4.39
5.27
ELp
rITO2
2.61 11.64
2.61 11.64
13.9
13.9
2TO3
2.34 7.5
8.81

WATER QUALITY DESIGN
Proposed Drainage Area NET INCREASE
85% TSS Removal Calculations
The following calculations are to determine the dimensions of a bioswale based on the
procedure provided by NCDENR, NCDENR BMP Manual Chapter 11 for
85% TSS removal for the proposed development.
Since the site has a large percentage of existing impervious area, runoff volume is
calculated by the increase in impervious area
The area draining to the proposed BMP is in the North Eastern portion of the property
Soil in this area is Hydraulic Class B
Drainage Area Ground Covers
SCS
Rational
Cn
C
Area(acres
GRASS
61
0.30
0.000
SIDEWALK
98
0.95
0.023
BUILDING
98
0.95
-0.212
PAVEMENT
98
0.95
0.565
1 98.0 1 0.95 1 0.376 1
The proposed INCREASE will be 0.38 acres with an SCS runoff coefficient
of 98 and a rational runoff coefficient of 0.95
Required treatment volume is as follows: WQv
NCDEQ requires the first 1 inch of runoff to be treated.
treated for the increase in impervious surface. This volume is as follows:
RV = 0.05 +0.9 * IA
WQv = 3630 * RD * Rv * A
IA 1
Rv 0.95
RD 1 (in)
A 0.376 (ac)
WQV= 1297 (ft3) 0.030
RV = Runoff coefficient [storm runoff (in)/storm rainfall (in)]
IA= [impervious portion of drainage area (ac)/ drainage area (ac)]
WQv = Volume of runoff that must be controlled for the design storm (ft)
Rd = Design storm rainfall depth (in)
A = Watershed area (ac)
Storage Provided
Stage 2199
Total WQ storage= 2917 1 (ft3)
WQ Orifice Provided
2.5 inch
Time to Drain 3 hrs

OPWSA1
PWS B1
(new St
at)
OEWSA1 t�/neW Subcat)
cs
1P
(new S cat)
MPA
Ews_B1 (new Pond)
(new nd) 2T03
(new Subcat)
( ew Reach)
F
T02
E Lx
(new each)
(new Link)
ELp
(new Link)
Subcat Reach on Link Routing Diagram for NORTH BUNCOMBE STORM SYSTEM
Prepared by Brooks Engineering Associates, PA, Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 O 2015 HydroCAD Software Solutions LLC

NORTH BUNCOMBE STORM SYSTEM
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
1.910 98 BUILDING (EWS_A1, EWS_B1, PWS_B1)
2.175 61 GRASS (EWS_A1, EWS_B1, PWS_A1, PWS_B1)
0.734 98 PAVEMENT (EWS_A1, EWS_B1, PWS_A1, PWS_B1)
0.194 98 SIDEWALK (EWS_A1, EWS_B1, PWS_A1, PWS_B1)
5.012 82 TOTAL AREA

NORTH BUNCOMBE STORM SYSTEM
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 3
Soil Listing (all nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000 HSG A
0.000 HSG B
0.000 HSG C
0.000 HSG D
5.012 Other EWS_A1, EWS_131, PWS_A1, PWS_131
5.012 TOTAL AREA

NORTH BUNCOMBE STORM SYSTEM
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 4
Ground Covers (all nodes)
HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment
(acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers
0.000
0.000
0.000
0.000
1.910
1.910
BUILDING
EWS_A1,
EWS_131, PWS_B1
0.000
0.000
0.000
0.000
2.175
2.175
GRASS
EWS_A1,
EWS_B1,
PWS_Al, PWS_B1
0.000
0.000
0.000
0.000
0.734
0.734
PAVEMENT
EWS_A1,
EWS_B1,
PWS_Al, PWS_B1
0.000
0.000
0.000
0.000
0.194
0.194
SIDEWALK
EWS_A1,
EWS_B1,
PWS_A1, PWS_B1
0.000
0.000
0.000
0.000
5.012
5.012
TOTAL AREA

NORTH BUNCOMBE STORM SYSTEM
Prepared by Brooks Engineering Associates, PA
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC
Printed
7/11/2019
Page 5
Pipe Listing (all
nodes)
Line# Node
In -Invert
Out -Invert Length
Slope n
Diam/Width
Height
Inside -Fill
Number
(feet)
(feet) (feet)
(ft/ft)
(inches)
(inches)
(inches)
1 1 T02
2,192.00
2,191.53 41.7
0.0113 0.011
24.0
0.0
0.0
2 2TO3
2,193.00
2,192.00 117.7
0.0085 0.011
18.0
0.0
0.0
3 BMPA
2,192.00
2,191.53 41.7
0.0113 0.011
24.0
0.0
0.0

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 6
Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment EWS_A1: (new Subcat) Runoff Area=40,434 sf 32.65% Impervious Runoff Depth=0.40"
Tc=5.0 min CN=73 Runoff=0.63 cfs 0.031 of
Subcatchment EWS_B1: (new Subcat) Runoff Area=68,722 sf 58.79% Impervious Runoff Depth=0.80"
Tc=5.0 min CN=83 Runoff=2.35 cfs 0.105 of
Subcatchment PWS_A1: (new Subcat) Runoff Area=40,434 sf 73.17% Impervious Runoff Depth=1.11"
Tc=5.0 min CN=88 Runoff=1.90 cfs 0.086 of
Subcatchment PWS_B1: (new Subcat) Runoff Area=68,722 sf 58.79% Impervious Runoff Depth=0.80"
Tc=5.0 min CN=83 Runoff=2.35 cfs 0.105 of
Reach 1T02: (new Reach) Avg. Flow Depth=0.41' Max Vet=5.64 fps Inflow=2.61 cfs 0.190 of
24.0" Round Pipe n=0.011 L=41.7' S=0.0113 T Capacity=28.38 cfs Outflow=2.61 cfs 0.190 of
Reach 2TO3: (new Reach) Avg. Flow Depth=0.46' Max Vet=5.09 fps Inflow=2.35 cfs 0.105 of
18.0" Round Pipe n=0.011 L=117.7' S=0.0085 T Capacity=11.44 cfs Outflow=2.34 cfs 0.105 of
Pond 1P: (new Pond) Peak EIev=2,204.32' Inflow=2.35 cfs 0.105 of
Outflow=2.35 cfs 0.105 of
Pond BMPA: (new Pond) Peak EIev=2,198.43' Storage=1,217 cf Inflow=1.90 cfs 0.086 of
Outflow=0.30 cfs 0.085 of
Link ELp: (new Link) Inflow=2.61 cfs 0.190 of
Primary=2.61 cfs 0.190 of
Link ELx: (new Link) Inflow=2.97 cfs 0.136 of
Primary=2.97 cfs 0.136 of
Total Runoff Area = 5.012 ac Runoff Volume = 0.327 of Average Runoff Depth = 0.78"
43.39% Pervious = 2.175 ac 56.61% Impervious = 2.837 ac

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment EWS_A1: (new Subcat)
Runoff = 0.63 cfs @ 11.98 hrs, Volume= 0.031 af, Depth= 0.40"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-YEAR Rainfall=2.17"
Area (sf) CN Description
774
98
SIDEWALK
3,182
98
PAVEMENT
9,246
98
BUILDING
27,232
61
GRASS
40,434
73
Weighted Average
27,232
67.35% Pervious Area
13,202
32.65% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment EWS_A1: (new Subcat)
Hydrograph
07
--------li----�---------- it-------------li------------------------
0.65 0.63 cfs i i i
o.s - -- - -- - -----Ourio0tiO 03,cf$-
0.55 ----r--Type -1 124-h r
--r--i--r--r--r --i--r--r--t--r--r--i--r--r--+ri--r-+--r--r-
0.5 1-YEAR Raihfall�2.'17�"
-- - - -- -- ------------- --,T----------------Q-�- - -
--
Aufl
w 0.4
---1-- 1--L -- --+---R-Unoff Ibt0EUfM=-0.031-af
3 0.35
EL 0.3 +-+-- -- ----+-+-- --+-- --+----Run6ff'D6pfhT0:4ii;F"
T——T--T----+— —T--� --�— T-- T—— T——F--I---— T—C—T--T—.—F —
0.25 1'iCi= - -- M111
0.2 �N=7
---1-- 1--L -- 1--1-- 1-- --L-- --1-- L----
0.15
0.1
--r--i--r--r--r -i--r--r--r--r--r--i--r--r--r--r--r--i--r--+--r--r-
0.05 1 I I I I I I 1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)
■ RunoH

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment EWS_B1: (new Subcat)
Runoff = 2.35 cfs @ 11.97 hrs, Volume= 0.105 af, Depth= 0.80"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-YEAR Rainfall=2.17"
Area (sf) CN Description
490
98
PAVEMENT
2,942
98
SIDEWALK
36,968
98
BUILDING
28,322
61
GRASS
68,722
83
Weighted Average
28,322
41.21 % Pervious Area
40,400
58.79% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
2-
EL
-----I---I I--1--7
1
I I I I I
Subcatchment EWS_B1: (new Subcat)
Hydrograph
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ❑Runoff
Runoff='12.$5'Icfs
1-YEAR R''ainfadl=2.17"
ku'Inoff Area=6j8,�2� sf
Runoff Vol umle�0.105 aif
-- ;--7--! --! -- Ru'�b6ff �D6pth�0.,'80'Iif
TC=5.0 m i n
6N-83
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment PWS_A1: (new Subcat)
Runoff = 1.90 cfs @ 11.96 hrs, Volume= 0.086 af, Depth= 1.11"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-YEAR Rainfall=2.17"
Area (so
CN
Description
27,808
98
PAVEMENT
1,777
98
SIDEWALK
10,849
61
GRASS
0
98
BUILDING
40,434 88 Weighted Average
10,849 26.83% Pervious Area
29,585 73.17% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment PWS_A1: (new Subcat)
Hydrograph
--�---�---�--�--+--�--�---�---�--�--�--+--�--�--�---�---�--+--�--�---�---�-- ■Runoff
2 1.90 cfs
Runoff=',1.00',cf$
Type II 24-hr
1-YEAR RainfaIl=2.17"
ku'noff Area=40,434 sf
Runoff Vol--ume=0.086 -of
- -------------- ----------------------------------------------
1 Rundff D6pthT1.'11UL
';..
tc=5.0 m i 0
ON=88
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment PWS_B1: (new Subcat)
Runoff = 2.35 cfs @ 11.97 hrs, Volume= 0.105 af, Depth= 0.80"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-YEAR Rainfall=2.17"
Area (sf) CN Description
490
98
PAVEMENT
2,942
98
SIDEWALK
36,968
98
BUILDING
28,322
61
GRASS
68,722
83
Weighted Average
28,322
41.21 % Pervious Area
40,400
58.79% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
2-
EL
-----I---I I--1--7
1
I I I I I
Subcatchment PWS_B1: (new Subcat)
Hydrograph
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ❑Runoff
Runoff='12.$5'Icfs
1-YEAR R''ainfadl=2.17"
ku'Inoff Area=6j8,�2� sf
Runoff Vol umle�0.105 aif
-- ;--7--! --! -- Ru'�b6ff �D6pth�0.,'80'Iif
TC=5.0 m i n
6N-83
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 11
Summary for Reach 1T02: (new Reach)
[52] Hint: Inlet/Outlet conditions not evaluated
[62] Hint: Exceeded Reach 2TO3 OUTLET depth by 0.05' @ 13.58 hrs
[79] Warning: Submerged Pond BMPA Primary device # 1 INLET by 0.41'
Inflow Area = 2.506 ac, 64.11% Impervious, Inflow Depth = 0.91" for 1-YEAR event
Inflow = 2.61 cfs @ 11.98 hrs, Volume= 0.190 of
Outflow = 2.61 cfs @ 11.98 hrs, Volume= 0.190 af, Atten= 0%, Lag= 0.2 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Max. Velocity= 5.64 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 2.13 fps, Avg. Travel Time= 0.3 min
Peak Storage= 19 cf @ 11.98 hrs
Average Depth at Peak Storage= 0.41'
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 28.38 cfs
24.0" Round Pipe
n= 0.011
Length= 41.7' Slope= 0.0113 '/'
Inlet Invert= 2,192.00', Outlet Invert= 2,191.53'
0

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 12
Reach 1 T02: (new Reach)
Hydrograph
[ Inflow
2.61 cfs I ❑ Outflow
12.61cfs Inflow Area=21.5016 ac
Inflow=�.61 cfs
-------- --- ----- ------ Outflow=161-cfs-
Avg, F1'oW Dopth=0.41'
Max Veal=�.64 fps
24.0"
Round Pipe
--1--J--L--L- -L --
--1---1--L--L-----'----L--1---1--L--L-=OA1�'l-
I-=41.7'
S,=0,01 �137/'
CaoaclityT28.38 cfs
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 13
Summary for Reach 2TO3: (new Reach)
[52] Hint: Inlet/Outlet conditions not evaluated
Inflow Area = 1.578 ac, 58.79% Impervious, Inflow Depth = 0.80" for 1-YEAR event
Inflow = 2.35 cfs @ 11.97 hrs, Volume= 0.105 of
Outflow = 2.34 cfs @ 11.98 hrs, Volume= 0.105 af, Atten= 0%, Lag= 0.7 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Max. Velocity= 5.09 fps, Min. Travel Time= 0.4 min
Avg. Velocity = 1.65 fps, Avg. Travel Time= 1.2 min
Peak Storage= 54 cf @ 11.97 hrs
Average Depth at Peak Storage= 0.46'
Bank -Full Depth= 1.50' Flow Area= 1.8 sf, Capacity= 11.44 cfs
18.0" Round Pipe
n= 0.011
Length= 117.7' Slope= 0.0085 7'
Inlet Invert= 2,193.00', Outlet Invert= 2,192.00'
0
Reach 2TO3: (new Reach)
Hydrograph
■ Inflow
2.35 cfs El Outflow
12.34cfs Inflow Area=t.578 aic
--I-- ---I-- - ---I-- ---I-- I ---I-- lnflow=�_3�-cfs -
Out#low=2.34 cfs
2 I I I
Avgll. Flow Depth=0.46'
Maxl Vet=5.0§ fps
18.01,
3 Round Pipe
Q—7--T--I—--T-------7--r--r----7--T--I---I--T--r-----I— —
LL I I I I I I I I I I I I I I I I I
1 LI=117.7'
S40085 I/'
Ca0acity=11.414 cfs
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM
Type // 24-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 14
Summary for Pond 1 P: (new Pond)
[57] Hint: Peaked at 2,204.32' (Flood elevation advised)
Inflow Area = 1.578 ac, 58.79% Impervious, Inflow Depth = 0.80" for 1-YEAR event
Inflow = 2.35 cfs @ 11.97 hrs, Volume= 0.105 of
Outflow = 2.35 cfs @ 11.97 hrs, Volume= 0.105 af, Atten= 0%, Lag= 0.0 min
Primary = 2.35 cfs @ 11.97 hrs, Volume= 0.105 of
Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Peak Elev= 2,204.32' @ 11.97 hrs
Device Routing Invert Outlet Devices
#1 Primary 2,204.00' 48.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Primary OutFlow Max=2.34 cfs @ 11.97 hrs HW=2,204.32' (Free Discharge)
L1=0rifice/Grate (Orifice Controls 2.34 cfs @ 1.82 fps)
Pond 1 P: (new Pond)
Hydrograph
❑ Inflow
I 2.3e er5 ❑ Primary
2.3ser5 Ill,n low II,Area=1:I157r8 Iliac
Ifo 21.35 0f$
2
I?rimlaeyEII I; 3� eft
Peak IIIElev=2,204.3l
wII II II II II II II II II II II II II II II II II II II II
3 I I I I I I I I I I I I I I I I I I I I I
O �--I--y--t--r- t--r--I--y--t--r--r--I--rt--r--I--y--t--r--r--I--t--
LL I I I I I I I I I I I I I I I I I I I I I
1 I I I I I I I I I I I I I I I I I I I I I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type // 24-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 15
Summary for Pond BMPA: (new Pond)
Inflow Area = 0.928 ac, 73.17% Impervious, Inflow Depth = 1.11" for 1-YEAR event
Inflow = 1.90 cfs @ 11.96 hrs, Volume= 0.086 of
Outflow = 0.30 cfs @ 12.15 hrs, Volume= 0.085 af, Atten= 84%, Lag= 11.3 min
Primary = 0.30 cfs @ 12.15 hrs, Volume= 0.085 of
Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Peak Elev= 2,198.43' @ 12.15 hrs Surf.Area= 2,832 sf Storage= 1,217 cf
Plug -Flow detention time= 36.2 min calculated for 0.085 of (99% of inflow)
Center -of -Mass det. time= 29.8 min ( 857.4 - 827.7 )
Volume Invert
Avail.Storage Storage Description
#1 2,198.00'
6,243 cf Custom Stage Data (Prismatic) Listed below (Recalc)
#2 2,195.00'
96 cf 4.00'W x 4.00'L x 6.00'H Prismatoid
6,339 cf Total Available Storage
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft) (cubic -feet) (cubic -feet)
2,198.00
2,592 0 0
2,199.00
3,114 2,853 2,853
2,200.00
3,666 3,390 6,243
Device Routing
Invert Outlet Devices
#1 Primary
2,192.00' 24.0" Round Culvert
L= 41.7' Box, 00 wingwalls, square crown edge, Ke= 0.700
Inlet / Outlet Invert= 2,192.00' / 2,191.53' S= 0.0113'/' Cc= 0.900
n= 0.011, Flow Area= 3.14 sf
#2 Primary
2,198.50' 10.0' long x 6.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#3 Device 1
2,197.50' 4.0" Vert. Orifice/Grate C= 0.490
Primary OutFlow Max=0.30 cfs @ 12.15 hrs HW=2,198.43' (Free Discharge)
1=Culvert (Passes 0.30 cfs of 31.10 cfs potential flow)
L3=Orifice/Grate (Orifice Controls 0.30 cfs @ 3.44 fps)
2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 16
Pond BMPA: (new Pond)
Hydrograph
----+--------+--------+--------+--------+--------+-- ❑ Inflow
1.90 cfs ❑ Primary
2 10fllow',Area=0.928 'ar,
1?rimla y-III. '; 30 eft
Peak IIEII�Iev=1,� 98.431I'
wI I I
,I --I-- -I----I---I -------I---I-------I---I--$tprage=1'I,2171I cf
c 1
LL
0.30 cfs
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 17
Summary for Link ELp: (new Link)
Inflow Area = 2.506 ac, 64.11% Impervious, Inflow Depth = 0.91" for 1-YEAR event
Inflow = 2.61 cfs @ 11.98 hrs, Volume= 0.190 of
Primary = 2.61 cfs @ 11.98 hrs, Volume= 0.190 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Link ELp: (new Link)
Hydrograph
C Inflow
1 z.61 er5 ❑ Primary
2.61 ef5 I01ow Are0=2.S06 ��ac
1010 --�:Z,.6 J,1 Of$
PrimlatyT2; 61 eft
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 1-YEAR Rainfall=2.17"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 18
Summary for Link ELx: (new Link)
Inflow Area = 2.506 ac, 49.11% Impervious, Inflow Depth = 0.65" for 1-YEAR event
Inflow = 2.97 cfs @ 11.97 hrs, Volume= 0.136 of
Primary = 2.97 cfs @ 11.97 hrs, Volume= 0.136 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
3
2
w
II II
II
II
3
c
I I
I
I
LL
I I
I
I
Link ELx: (new Link)
Hydrograph
Time (hours)
C Inflow
--'-------'---'------'-- ❑Primary
I01owArea=Z506 �lac
I�fjoW--�:2.97 Of$
_hrimht/T21

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 19
Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment EWS_A1: (new Subcat) Runoff Area=40,434 sf 32.65% Impervious Runoff Depth=1.83"
Tc=5.0 min CN=73 Runoff=3.16 cfs 0.141 of
Subcatchment EWS_B1: (new Subcat) Runoff Area=68,722 sf 58.79% Impervious Runoff Depth=2.61"
Tc=5.0 min CN=83 Runoff=7.53 cfs 0.344 of
Subcatchment PWS_A1: (new Subcat) Runoff Area=40,434 sf 73.17% Impervious Runoff Depth=3.11"
Tc=5.0 min CN=88 Runoff=5.10 cfs 0.241 of
Subcatchment PWS_B1: (new Subcat) Runoff Area=68,722 sf 58.79% Impervious Runoff Depth=2.61"
Tc=5.0 min CN=83 Runoff=7.53 cfs 0.344 of
Reach 1T02: (new Reach) Avg. Flow Depth=0.89' Max Vet=8.59 fps Inflow=11.66 cfs 0.583 of
24.0" Round Pipe n=0.011 L=41.7' S=0.0113 T Capacity=28.38 cfs Outflow=11.64 cfs 0.583 of
Reach 2TO3: (new Reach) Avg. Flow Depth=0.89' Max Vet=6.91 fps Inflow=7.53 cfs 0.344 of
18.0" Round Pipe n=0.011 L=117.7' S=0.0085 T Capacity=11.44 cfs Outflow=7.50 cfs 0.344 of
Pond 1P: (new Pond) Peak EIev=2,204.87' Inflow=7.53 cfs 0.344 of
Outflow=7.53 cfs 0.344 of
Pond BMPA: (new Pond) Peak EIev=2,198.80' Storage=2,301 cf Inflow=5.10 cfs 0.241 of
Outflow=4.39 cfs 0.240 of
Link ELp: (new Link) Inflow=11.64 cfs 0.583 of
Primary=11.64 cfs 0.583 of
Link ELx: (new Link) Inflow=10.68 cfs 0.485 of
Primary=10.68 cfs 0.485 of
Total Runoff Area = 5.012 ac Runoff Volume = 1.069 of Average Runoff Depth = 2.56"
43.39% Pervious = 2.175 ac 56.61% Impervious = 2.837 ac

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 20
Summary for Subcatchment EWS_A1: (new Subcat)
Runoff = 3.16 cfs @ 11.96 hrs, Volume= 0.141 af, Depth= 1.83"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-Year Rainfall=4.40"
Area (sf) CN Description
774
98
SIDEWALK
3,182
98
PAVEMENT
9,246
98
BUILDING
27,232
61
GRASS
40,434
73
Weighted Average
27,232
67.35% Pervious Area
13,202
32.65% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
3
w 2
------------+
I I I I I
LL
1
--------I-- --,
I I I I I
Subcatchment EWS_A1: (new Subcat)
Hydrograph
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ■Runoff
faunoff=3.'I�6 -
IType 1I 24-hlr
25,Ydae R''ainfaill=4.40"
- - -III- - -- -- ---Au'InoffAmat =4Dr434-pf-
Runoff Volume=0.141 aif
Rundff Depth--1.�'8ii..
Tc=5--0 m i n
ON=73
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 21
Summary for Subcatchment EWS_B1: (new Subcat)
Runoff = 7.53 cfs @ 11.96 hrs, Volume= 0.344 af, Depth= 2.61"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-Year Rainfall=4.40"
Area (sf) CN Description
490
98
PAVEMENT
2,942
98
SIDEWALK
36,968
98
BUILDING
28,322
61
GRASS
68,722
83
Weighted Average
28,322
41.21 % Pervious Area
40,400
58.79% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment EWS_B1: (new Subcat)
Hydrograph
--�I---�I---�I-- �I-- �I -- �,--�I---�I---�I---�I-- �I -- �I -- �, --�,--�I---�I---�I-- �I -- �, --�,--�I---�I---�I-- ■ RunoH
8
Z53 cfs
--------I-------------I-------- -0u off=:-7.$3;cf$
7
Type II'124-h'Ir
--'I---'I---'I--�--t--'I---'I---'I--�--rt--t--r--'r--'I---'I---'I--t--t--r--I---I---I--
6 25,Ydae R'aWail1=4.40"
-- -- -- -+- iu';rraff-4Yea';=5$� �1f-
5
I I I I I I I I I I I I I
- ------------ -- ----RunofflVolume=C344 af-
4
I I I
RundfD,6pthT2.5I1..
—t—r—r—r5.—I— —i—I —
—
3 'I'C =I�Ih1 1 �p
------- -- -----I ---- -- —
�-
2 -- I I -- - I I I -- -- --I ---I ---I -- -- -- I I I
-------- --
1 I I I I I I I I I I I I I I I I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 22
Summary for Subcatchment PWS_A1: (new Subcat)
Runoff = 5.10 cfs @ 11.96 hrs, Volume= 0.241 af, Depth= 3.11"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-Year Rainfall=4.40"
Area (so
CN
Description
27,808
98
PAVEMENT
1,777
98
SIDEWALK
10,849
61
GRASS
0
98
BUILDING
40,434 88 Weighted Average
10,849 26.83% Pervious Area
29,585 73.17% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment PWS_A1: (new Subcat)
Hydrograph
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ■Runoff
--�---�---�---�-- it -- it -- I, --�i--�---�----- �i-----�i--�---�---�--
Runoff=15.10'Icf$
(Type 1I 24-hlr
25,Ydar` R''aiiifaill=4.40"
'lI I '�I '�I '�I '�I I I Zu�Inoff Area=40,434 $f
Runoff lVolumle=0.241 of
Ru'b6ff DWh�3.11';..
ON=88
-- -- -- -- ------------ -- ------------
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 23
Summary for Subcatchment PWS_B1: (new Subcat)
Runoff = 7.53 cfs @ 11.96 hrs, Volume= 0.344 af, Depth= 2.61"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-Year Rainfall=4.40"
Area (sf) CN Description
490
98
PAVEMENT
2,942
98
SIDEWALK
36,968
98
BUILDING
28,322
61
GRASS
68,722
83
Weighted Average
28,322
41.21 % Pervious Area
40,400
58.79% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment PWS_B1: (new Subcat)
Hydrograph
--�I---�I---�I-- �I-- �I -- �,--�I---�I---�I---�I-- �I -- �I -- �, --�,--�I---�I---�I-- �I -- �, --�,--�I---�I---�I-- ■ RunoH
8
Z53 cfs
--------I-------------I-------- -0u off=:-7.$3;cf$
7
Type II'124-h'Ir
--'I---'I---'I--�--t--'I---'I---'I--�--rt--t--r--'r--'I---'I---'I--t--t--r--I---I---I--
6 25,Ydae R'aWail1=4.40"
-- -- -- -+- iu';rraff-4Yea';=5$� �1f-
5
I I I I I I I I I I I I I
- ------------ -- ----RunofflVolume=C344 af-
4
I I I
RundfD,6pthT2.5I1..
—t—r—r—r5.—I— —i—I —
—
3 'I'C =I�Ih1 1 �p
------- -- -----I ---- -- —
�-
2 -- I I -- - I I I -- -- --I ---I ---I -- -- -- I I I
-------- --
1 I I I I I I I I I I I I I I I I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 24
Summary for Reach 1T02: (new Reach)
[52] Hint: Inlet/Outlet conditions not evaluated
[62] Hint: Exceeded Reach 2TO3 OUTLET depth by 0.13' @ 12.07 hrs
[79] Warning: Submerged Pond BMPA Primary device # 1 INLET by 0.89'
Inflow Area = 2.506 ac, 64.11 % Impervious, Inflow Depth = 2.79" for 25-Year event
Inflow = 11.66 cfs @ 11.98 hrs, Volume= 0.583 of
Outflow = 11.64 cfs @ 11.98 hrs, Volume= 0.583 af, Atten= 0%, Lag= 0.1 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.59 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 2.68 fps, Avg. Travel Time= 0.3 min
Peak Storage= 57 cf @ 11.98 hrs
Average Depth at Peak Storage= 0.89'
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 28.38 cfs
24.0" Round Pipe
n= 0.011
Length= 41.7' Slope= 0.0113 '/'
Inlet Invert= 2,192.00', Outlet Invert= 2,191.53'
0

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 25
Reach 1 T02: (new Reach)
Hydrograph
13
--r----r--r--r----r--r--r--r-r--r--r--r-r--r--r--r--r-r--r--r--r-
-- -- -
�- �- rr------
11 � � I I I � �
-rr--r--�--rrr--r-rr--r--r--�--rr-_r--r
■ Inflow
11.66
cfs
ii�^`iL,
■Outflow
12
i
--------- 11.64 cfs
/�i ,{i ryi�
----I --I---------I------- IEn F1 VMY �AreQ�r.SV�TAc-
nnf�_(��
F fl 1
---------'i -
----'i --i-----'i-- - - - - Outfl(>Wl-t 54 ds-
10
i-
---------i -
----i --i----Ji----i --'i Ji Avg, Flr W_D0_pt:b=
g
fPs
r
8
�,
-------4--r-
-Max*1=4.5*
----r--r--------------r-I----r--r--
--
24.0"
7
-------rt--r-
----r--r----y--rt--r--r-y----r--r----y--r--r--r-
Round Pipe
3
0 6
LL
--�--r--r--r-
--r--r--r--�--r--r--r--r-r--r--r--r--�--r--r--r--r-
n=0.01�1
q
---------il -
----il --il---------il-----'i-- il- = r
g
i
-------1--L-
-1--L----1--J--1--L--1-- -- __
Calpac"'_ 8 �1~s
------- --r-
---r--r---- ----r---- ----r------- -- -- ----
1
Time (hours)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 26
Summary for Reach 2TO3: (new Reach)
[52] Hint: Inlet/Outlet conditions not evaluated
Inflow Area = 1.578 ac, 58.79% Impervious, Inflow Depth = 2.61" for 25-Year event
Inflow = 7.53 cfs @ 11.96 hrs, Volume= 0.344 of
Outflow = 7.50 cfs @ 11.97 hrs, Volume= 0.344 af, Atten= 0%, Lag= 0.5 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Max. Velocity= 6.91 fps, Min. Travel Time= 0.3 min
Avg. Velocity = 2.11 fps, Avg. Travel Time= 0.9 min
Peak Storage= 128 cf @ 11.96 hrs
Average Depth at Peak Storage= 0.89'
Bank -Full Depth= 1.50' Flow Area= 1.8 sf, Capacity= 11.44 cfs
18.0" Round Pipe
n= 0.011
Length= 117.7' Slope= 0.0085 7'
Inlet Invert= 2,193.00', Outlet Invert= 2,192.00'
0
Reach 2TO3: (new Reach)
Hydrograph
--' - -' --' --' -' --' --' - --' --' --I - --' --I --I -' --' --'
r r I � �--�- � � r � r + r � r � r � r �- r � r-- ■Inflow
7.53 cfs ❑ Outflow
8 I I I I I I I I I I I I I I I
----+--+_ 7.50 cfs __+-------+--+--+----+--+_ - an#lo �4r=1�.58c -
Inflow=7.5� cfs
- -- -- - -- -- - -- -- - -- ---------{outflow=1.50-cfs-
6 Avg'I. F[oW Dopt'Ih=Q.89'
--I--r--r--r---r--r--I--r--r--r--I--r--r--I---I- -r -I- r--
ax, Vel= .9 fps
y 5-�--L--'--1--1---I--1--L--L--1--1--L--1---1--1--�--'---'--18.0„
vI I I I I I I I I I I I I I I I I
Ro u n, d����}{P iir{pJ��Jie
.2 4 - -I- - 7 -- T --II -- T --II --II-- 7 -- 7 --IF --II-- 7 -- T-----II-- T -- 7 --II-- I -_ .V ,'I--
3 L.,=1'17.7'
----+--+--I- --+-------+--+--+----+--+-------+--+-------+--
S=0:0085 I P
2 Cabacity;=11.44_cfs -
--II-- - --I, - --II-- - --II-- - -
1 II II II II II II II II II II II II II II II II II II II
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 27
Summary for Pond 1 P: (new Pond)
[57] Hint: Peaked at 2,204.87' (Flood elevation advised)
Inflow Area = 1.578 ac, 58.79% Impervious, Inflow Depth = 2.61" for 25-Year event
Inflow = 7.53 cfs @ 11.96 hrs, Volume= 0.344 of
Outflow = 7.53 cfs @ 11.96 hrs, Volume= 0.344 af, Atten= 0%, Lag= 0.0 min
Primary = 7.53 cfs @ 11.96 hrs, Volume= 0.344 of
Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Peak Elev= 2,204.87' @ 11.96 hrs
Device Routing Invert Outlet Devices
#1 Primary 2,204.00' 48.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Primary OutFlow Max=7.52 cfs @ 11.96 hrs HW=2,204.87' (Free Discharge)
L1=0rifice/Grate (Orifice Controls 7.52 cfs @ 3.76 fps)
Pond 1 P: (new Pond)
Hydrograph
C' Inflow
i 53 cfs i11 ii❑ Primary
87.53 cfs
-------+-- 1V-iar, -
[VWArea,5
6 ' P_rim_ I_a_ T7'.5_eft
--
-i
5 Peak Elev=1,2041 .$7�,
0 4
LL i----7--t--r- --Yr--__7--t--r----7--Y--r----7--t--r----7--Y--
3
2
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 28
Summary for Pond BMPA: (new Pond)
Inflow Area = 0.928 ac, 73.17% Impervious, Inflow Depth = 3.11" for 25-Year event
Inflow = 5.10 cfs @ 11.96 hrs, Volume= 0.241 of
Outflow = 4.39 cfs @ 12.00 hrs, Volume= 0.240 af, Atten= 14%, Lag= 2.3 min
Primary = 4.39 cfs @ 12.00 hrs, Volume= 0.240 of
Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Peak Elev= 2,198.80' @ 12.00 hrs Surf.Area= 3,026 sf Storage= 2,301 cf
Plug -Flow detention time= 27.8 min calculated for 0.240 of (100% of inflow)
Center -of -Mass det. time= 25.4 min ( 823.7 - 798.3 )
Volume Invert
Avail.Storage Storage Description
#1 2,198.00'
6,243 cf Custom Stage Data (Prismatic) Listed below (Recalc)
#2 2,195.00'
96 cf 4.00'W x 4.00'L x 6.00'H Prismatoid
6,339 cf Total Available Storage
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft) (cubic -feet) (cubic -feet)
2,198.00
2,592 0 0
2,199.00
3,114 2,853 2,853
2,200.00
3,666 3,390 6,243
Device Routing
Invert Outlet Devices
#1 Primary
2,192.00' 24.0" Round Culvert
L= 41.7' Box, 00 wingwalls, square crown edge, Ke= 0.700
Inlet / Outlet Invert= 2,192.00' / 2,191.53' S= 0.0113'/' Cc= 0.900
n= 0.011, Flow Area= 3.14 sf
#2 Primary
2,198.50' 10.0' long x 6.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#3 Device 1
2,197.50' 4.0" Vert. Orifice/Grate C= 0.490
Primary OutFlow Max=4.36 cfs @ 12.00 hrs HW=2,198.80' (Free Discharge)
1=Culvert (Passes 0.37 cfs of 32.14 cfs potential flow)
L3=Orifice/Grate (Orifice Controls 0.37 cfs @ 4.19 fps)
2=Broad-Crested Rectangular Weir (Weir Controls 4.00 cfs @ 1.34 fps)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 29
5
--I-
4
3
3
I I
I
I
0
LL
2
Pond BMPA: (new Pond)
Hydrograph
---'--' ❑Inflow
❑Primary
------------------------
I'Infllow'IArea=0.928 'ac
f �wy5'
Primla y-4; 39 eft
Storage=2,301 cf
I II II II II II II II II II II II II II II II II
f�/////////////////////%/I/////////////////////////////////////////////////////////////

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 30
Summary for Link ELp: (new Link)
Inflow Area = 2.506 ac, 64.11 % Impervious, Inflow Depth = 2.79" for 25-Year event
Inflow = 11.64 cfs @ 11.98 hrs, Volume= 0.583 of
Primary = 11.64 cfs @ 11.98 hrs, Volume= 0.583 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Link ELp: (new Link)
Hydrograph
--I--r--r--r--r--I--r--r--r--I--r--r----r-r- ---r--I---I--r--r--r--I--
13 I C Inflow
I- r--r--r- - -- -- r --r --r -- I- r-- r --r --r rrr--I - - -
----I- rr
----r--I-- Primary
I I I 11.64 cfs I I I I I I I I I I I I I I II I I
11.64 cfs
I I
�I= 0 _-
� I
—JinfloWArel 5
-----------�-- ——--y—__
lflc_164 Of$
LL�
10--I -
�' I I I I I I I I I I I I I I I I I I I I
$----+--+--r- --+--+-------+--+--+----+--+--+-------+--r--+--I--
y I I I I I I I I I I I I I I I I I I I I
i
O 6 I--�--�--r- �--r--r--I--�--r--r--r-r--r--r--I---I--�--r--r--I--
LL I I I I I I I I I I I I I I I I I I I I I
cJ
I 1 1 I I I I I T I I I I I I I I I I I
i I I I I I I I I I I I I I I I I I I I I I I
g---------li - - - -li --li-----IIII--Ii --li---------li---------li --li --II--
I I I I I I I I I I I I I I I I I I I I I I
2 -- I I I I I I I I --
1
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 25-Year Rainfall=4.40"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 31
Summary for Link ELx: (new Link)
Inflow Area = 2.506 ac, 49.11 % Impervious, Inflow Depth = 2.32" for 25-Year event
Inflow = 10.68 cfs @ 11.96 hrs, Volume= 0.485 of
Primary = 10.68 cfs @ 11.96 hrs, Volume= 0.485 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
10
110.68 c
10
----+--+--+-
g
----+--+--+-
s
--J--1--L-
-
w
3 6
------
--
-
c
I I
I
I
LL 5
4
Ali
------7--r-
3
--li-- --
--T-
1
Link ELx: (new Link)
Hydrograph
C Inflow
❑
cfs Primary
-- - ----rnfloiw;Area' ='2 5dCaac-
11
-- --}--'I--- --+--'+-- An ovy-- 10.68 Of$--
--+--+--+----+--+--+--I--+--+--+--1---I--+--+--+--I--
Pdmalry=10.68 eft -
I I I I I I
---Ir --i-------Ir-- r---- -i-- III-- r------- --Ir--Ir--II--
-T--T--T--li----T--T--li-- --T——T--li---li--T——T—
-T-
-li--
--T--I---I--T--T--r--I--T--T--T--I---I--T--T--r--I--
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 32
Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment EWS_A1: (new Subcat) Runoff Area=40,434 sf 32.65% Impervious Runoff Depth=2.24"
Tc=5.0 min CN=73 Runoff=3.87 cfs 0.173 of
Subcatchment EWS_B1: (new Subcat) Runoff Area=68,722 sf 58.79% Impervious Runoff Depth=3.10"
Tc=5.0 min CN=83 Runoff=8.84 cfs 0.407 of
Subcatchment PWS_A1: (new Subcat) Runoff Area=40,434 sf 73.17% Impervious Runoff Depth=3.62"
Tc=5.0 min CN=88 Runoff=5.88 cfs 0.280 of
Subcatchment PWS_B1: (new Subcat) Runoff Area=68,722 sf 58.79% Impervious Runoff Depth=3.10"
Tc=5.0 min CN=83 Runoff=8.84 cfs 0.407 of
Reach 1T02: (new Reach) Avg. Flow Depth=0.99' Max Vet=8.99 fps Inflow=13.92 cfs 0.686 of
24.0" Round Pipe n=0.011 L=41.7' S=0.0113 T Capacity=28.38 cfs Outflow=13.90 cfs 0.686 of
Reach 2TO3: (new Reach) Avg. Flow Depth=0.99' Max Vet=7.14 fps Inflow=8.84 cfs 0.407 of
18.0" Round Pipe n=0.011 L=117.7' S=0.0085 T Capacity=11.44 cfs Outflow=8.81 cfs 0.407 of
Pond 1P: (new Pond) Peak EIev=2,205.10' Inflow=8.84 cfs 0.407 of
Outflow=8.84 cfs 0.407 of
Pond BMPA: (new Pond) Peak EIev=2,198.84' Storage=2,424 cf Inflow=5.88 cfs 0.280 of
Outflow=5.27 cfs 0.279 of
Link ELp: (new Link) Inflow=13.90 cfs 0.686 of
Primary=13.90 cfs 0.686 of
Link ELx: (new Link) Inflow=12.71 cfs 0.580 of
Primary=12.71 cfs 0.580 of
Total Runoff Area = 5.012 ac Runoff Volume = 1.267 of Average Runoff Depth = 3.03"
43.39% Pervious = 2.175 ac 56.61% Impervious = 2.837 ac

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 33
Summary for Subcatchment EWS_A1: (new Subcat)
Runoff = 3.87 cfs @ 11.96 hrs, Volume= 0.173 af, Depth= 2.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-Year Rainfall=4.94"
Area (sf) CN Description
774
98
SIDEWALK
3,182
98
PAVEMENT
9,246
98
BUILDING
27,232
61
GRASS
40,434
73
Weighted Average
27,232
67.35% Pervious Area
13,202
32.65% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment EWS_A1: (new Subcat)
Hydrograph
I I I 7--T--r--i --r I- 7--7--T--r--7--r--I- I- T r__i - -
I- I-
4 3.87 cfs
Runoff='13.07'Icf$
(Type II 24-hIr
-7 --I,-----'I----T--T--r-5O�Yaae- ajfifdll=4:�4�-
3 I
ku'Inoff Area=4;0,434 sf
Runoff i Vol umle=O.173 aif
---I
— I — — — I — — —I T — — — — — — —I — — 7 — — 7 — — T — — T — — 7 — — I — — — I — — —I — — T — — T — — 7 — — — — — — —I — —
2 Ru'b6ff 136pthT2.247.
tc=5.0 m i n
-- - -- -- - -- --T-- - -- -------CAI=7�-
1 I I I I I I I I I I I I I I I I I I I I I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 34
Summary for Subcatchment EWS_B1: (new Subcat)
Runoff = 8.84 cfs @ 11.96 hrs, Volume= 0.407 af, Depth= 3.10"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-Year Rainfall=4.94"
Area (sf) CN Description
490
98
PAVEMENT
2,942
98
SIDEWALK
36,968
98
BUILDING
28,322
61
GRASS
68,722
83
Weighted Average
28,322
41.21 % Pervious Area
40,400
58.79% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
8
7
6
5
o
LL
3
--------
2
--------
Subcatchment EWS_B1: (new Subcat)
Hydrograph
1 L L ■Runoff
----------J--1--i--L--'L-----''- Run, off='8.04 cf$-
�Type II 24-hr
50,Ydae R'aiffail1=4.94'
-
6661 o rea'= 15
-----'-- --4 -- --Run-offVolum+e=*.-407-aif-
-- --! -!-*--r--'r-- --! TC?5.'0-rni--
ON=83
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 35
Summary for Subcatchment PWS_A1: (new Subcat)
Runoff = 5.88 cfs @ 11.96 hrs, Volume= 0.280 af, Depth= 3.62"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-Year Rainfall=4.94"
Area (so
CN
Description
27,808
98
PAVEMENT
1,777
98
SIDEWALK
10,849
61
GRASS
0
98
BUILDING
40,434 88 Weighted Average
10,849 26.83% Pervious Area
29,585 73.17% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment PWS_A1: (new Subcat)
Hydrograph
I I I I I I I I I I I I I I I I I ■ RunoH
9 cfs
Runoff=',5.08'Icf$
-----';-- -- -- --'I --' ---Tylpe'if�24--hr-
50,Ydar` R'aiiifaill=4.194"
--_I I I I I
ulno rea=40,
Runoff Volumle�0.1280 aif
--------I-- 1 -- ----T -- t -- F--I--------+--+-- F----- I --- I--
RunOff D6pT th3..'82;..
T—
—T——T——T--T——I_—— I ---I— T— Tc=5016, i-P
ON=88
L
----T--T--T--T--T T --T --T
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 36
Summary for Subcatchment PWS_B1: (new Subcat)
Runoff = 8.84 cfs @ 11.96 hrs, Volume= 0.407 af, Depth= 3.10"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-Year Rainfall=4.94"
Area (sf) CN Description
490
98
PAVEMENT
2,942
98
SIDEWALK
36,968
98
BUILDING
28,322
61
GRASS
68,722
83
Weighted Average
28,322
41.21 % Pervious Area
40,400
58.79% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
8
7
6
5
o
LL
3
--------
2
--------
Subcatchment PWS_B1: (new Subcat)
Hydrograph
1 L L ■Runoff
----------J--1--i--L--'L-----''- Run, off='8.04 cf$-
�Type II 24-hr
50,Ydae R'aiffail1=4.94'
-
6661 o rea'= 15
-----'-- --4 -- --Run-offVolum+e=*.-407-aif-
-- --! -!-*--r--'r-- --! TC?5.'0-rni--
ON=83
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 37
Summary for Reach 1T02: (new Reach)
[52] Hint: Inlet/Outlet conditions not evaluated
[62] Hint: Exceeded Reach 2TO3 OUTLET depth by 0.13' @ 12.07 hrs
[79] Warning: Submerged Pond BMPA Primary device # 1 INLET by 0.99'
Inflow Area = 2.506 ac, 64.11 % Impervious, Inflow Depth = 3.29" for 50-Year event
Inflow = 13.92 cfs @ 11.98 hrs, Volume= 0.686 of
Outflow = 13.90 cfs @ 11.98 hrs, Volume= 0.686 af, Atten= 0%, Lag= 0.1 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.99 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 2.77 fps, Avg. Travel Time= 0.3 min
Peak Storage= 65 cf @ 11.98 hrs
Average Depth at Peak Storage= 0.99'
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 28.38 cfs
24.0" Round Pipe
n= 0.011
Length= 41.7' Slope= 0.0113 '/'
Inlet Invert= 2,192.00', Outlet Invert= 2,191.53'
0

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 38
Reach 1 T02: (new Reach)
Hydrograph
■ Inflow
15
�i
- - - - -i 13.92
---i_--- - - -- ----i_--i_--�i-- i-_�i�i _/Ji__ �i��i
�OUtf�OW
cfs
��
13.90cfs
ry�F
� � _ -In{I0w Areai=-L,5W—gicr
r r
14
1
--1---1--1--L-
--I--L-- ----J--1--L--1--J----r-ap#IQw�'E.$CfiS-
13
---------i -
----i --r---------r---------li0#[W- 1
�[.30LIirS
12
11-
Avg-F1",-De-prt -=P
10
------- ----
-----------------------------M-ax'Ver fps
w 9
--�--r--�--r-
--,--r--r--I--r'--�--r--I--�--,--r--r--I--r'--r-�4.D,�
$
-
d i e
RoanPp
3
c
LL
--,-------,--
-
-------,- -,-----,--,- -,- -,-------,- -,-------- --
- - - - - - - ---
�
n=0.01A
----------
----+----li------1--Ir-1------Ir--li----+--r--r-
--r----r--r-
01
--r--r--r--r-r--r--r--r-r--r--/ram--r--i- r 4--r r
4
- - -1--L-
-1--L----1--J--1--L--1--J--1--�+ �� s� -
ty $.3$ ifs
3
2
---------r-
-------r---------r---------r--i-----i--r --r --i--
1
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 39
Summary for Reach 2TO3: (new Reach)
[52] Hint: Inlet/Outlet conditions not evaluated
Inflow Area = 1.578 ac, 58.79% Impervious, Inflow Depth = 3.10" for 50-Year event
Inflow = 8.84 cfs @ 11.96 hrs, Volume= 0.407 of
Outflow = 8.81 cfs @ 11.97 hrs, Volume= 0.407 af, Atten= 0%, Lag= 0.5 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Max. Velocity= 7.14 fps, Min. Travel Time= 0.3 min
Avg. Velocity = 2.19 fps, Avg. Travel Time= 0.9 min
Peak Storage= 145 cf @ 11.96 hrs
Average Depth at Peak Storage= 0.99'
Bank -Full Depth= 1.50' Flow Area= 1.8 sf, Capacity= 11.44 cfs
18.0" Round Pipe
n= 0.011
Length= 117.7' Slope= 0.0085 7'
Inlet Invert= 2,193.00', Outlet Invert= 2,192.00'
0
8
6
- --
--I-
y
I I
I I
vI
I
I I
5
------
-r - -Ir
0
LL
4
3
2
- --
I I
---
I I
1
Reach 2TO3: (new Reach)
Hydrograph
I I I I I I I I I I I I I I I I I ■Inflow
-- -----I-- -- -- --I-- -- -----I-- -- -----I-- -- -- ❑ Outflow
Inflow AreA=t.578 aic
--
Inflow=8.84 cfs
----- - - - I ------- - -- I -- --------_'Outfloriv=8:81-cfs-
--An. Flow Dopt'Ih=p.99'
Maxi Vel=�.14 fps
-- -----I-- -- -- --I----L--1--- 1--+---------18.0it
n=d.011
---------------------------i--i
7.7
-- ---II-- -- ---I _SIB=A00na'-
Caoacity;=11.44 cfs
I I II II II II II II II II II II II II II II II
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM
Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 40
Summary for Pond 1 P: (new Pond)
[57] Hint: Peaked at 2,205.10' (Flood elevation advised)
Inflow Area = 1.578 ac, 58.79% Impervious, Inflow Depth = 3.10" for 50-Year event
Inflow = 8.84 cfs @ 11.96 hrs, Volume= 0.407 of
Outflow = 8.84 cfs @ 11.96 hrs, Volume= 0.407 af, Atten= 0%, Lag= 0.0 min
Primary = 8.84 cfs @ 11.96 hrs, Volume= 0.407 of
Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Peak Elev= 2,205.10' @ 11.96 hrs
Device Routing Invert Outlet Devices
#1 Primary 2,204.00' 48.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Primary OutFlow Max=8.84 cfs @ 11.96 hrs HW=2,205.10' (Free Discharge)
L1=0rifice/Grate (Orifice Controls 8.84 cfs @ 4.42 fps)
9
a.a
--II--!
-T--T-
--III--III--
--III--
6-
--III--T--
li--
-
wIIIII
IL
3 5-
4
3
2
---J--1--L
1
Pond 1 P: (new Pond)
Hydrograph
❑ Inflow
-L-- L - -I-- -- -- -----I-- -- --I-- -- -- -----I-- -- ❑Primary
-T--! --III-- --! - -!-llllnflowl Are-011-157r8_IlAc -
--T--! --III- --! --! --III---III--
-- - --III---II-- -- --III---III--Primia y:T8I34_ 8--
01 _I14�1
--T--�--II--�--T--�--II---II--+--�--II--�--T--I�--II---II--T--
--+--r----L--+--r-------7--r----L--+--r-------+--
- 1 - - L - - - - L - - 1 - - L - - - - J - - L - - L L - - - - - - + - - IL - - - - J - - 1
L2 - -
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 41
Summary for Pond BMPA: (new Pond)
Inflow Area = 0.928 ac, 73.17% Impervious, Inflow Depth = 3.62" for 50-Year event
Inflow = 5.88 cfs @ 11.96 hrs, Volume= 0.280 of
Outflow = 5.27 cfs @ 11.99 hrs, Volume= 0.279 af, Atten= 10%, Lag= 2.0 min
Primary = 5.27 cfs @ 11.99 hrs, Volume= 0.279 of
Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Peak Elev= 2,198.84' @ 11.99 hrs Surf.Area= 3,047 sf Storage= 2,424 cf
Plug -Flow detention time= 26.5 min calculated for 0.279 of (100% of inflow)
Center -of -Mass det. time= 24.4 min ( 818.4 - 794.0 )
Volume Invert
Avail.Storage Storage Description
#1 2,198.00'
6,243 cf Custom Stage Data (Prismatic) Listed below (Recalc)
#2 2,195.00'
96 cf 4.00'W x 4.00'L x 6.00'H Prismatoid
6,339 cf Total Available Storage
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft) (cubic -feet) (cubic -feet)
2,198.00
2,592 0 0
2,199.00
3,114 2,853 2,853
2,200.00
3,666 3,390 6,243
Device Routing
Invert Outlet Devices
#1 Primary
2,192.00' 24.0" Round Culvert
L= 41.7' Box, 00 wingwalls, square crown edge, Ke= 0.700
Inlet / Outlet Invert= 2,192.00' / 2,191.53' S= 0.0113'/' Cc= 0.900
n= 0.011, Flow Area= 3.14 sf
#2 Primary
2,198.50' 10.0' long x 6.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#3 Device 1
2,197.50' 4.0" Vert. Orifice/Grate C= 0.490
Primary OutFlow Max=5.26 cfs @ 11.99 hrs HW=2,198.84' (Free Discharge)
1=Culvert (Passes 0.37 cfs of 32.25 cfs potential flow)
L3=Orifice/Grate (Orifice Controls 0.37 cfs @ 4.26 fps)
2=Broad-Crested Rectangular Weir (Weir Controls 4.89 cfs @ 1.44 fps)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 42
6
----T--T--
5.2
5-
4-
2 3
LL
--I--T--T--T-
2
1
I I
I
I
Pond BMPA: (new Pond)
Hydrograph
❑ Inflow
-+--+----+--+--+-------+--+----+--+-- -----+-- ❑Primary
I'Infllow',Are�=0.928 'ac
I I I I I I I I I l�nf�oinr 15.8 I I
-
-T-- -- T--T--I - - -
I---
- - - - - - --Prima ryT&27_ tfq- -
Peak IIE lev=1,198.84
-- --I ---- -- -- -- Sfprag— -424, ct-
--T--T----T--T--T-------T--T----T--T--T-------T--
1LI__ I1LII__ 1__ LIJ__ 1__ LII__ 1_
I I I I I I I I I I I I I I I I I
I%////////////////�ii�����iiiiiiiiii�I//////////////////////////////////////////////%

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 43
Summary for Link ELp: (new Link)
Inflow Area = 2.506 ac, 64.11 % Impervious, Inflow Depth = 3.29" for 50-Year event
Inflow = 13.90 cfs @ 11.98 hrs, Volume= 0.686 of
Primary = 13.90 cfs @ 11.98 hrs, Volume= 0.686 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Link ELp: (new Link)
Hydrograph
C Inflow
15
14
'll
------ --1
I
y 13.90cfs
13.90cfs ----------------------II----------II----iII------�I-- ❑ Primary
y 11 � iJy
�f low Areal .5-�c�I'�c_
13
Inf-13�.9Q-Of$�
12
--'-- -- --!-
-- --!--' --'I-- --!--' --'I--
I�I
10
I I I I
I I I I I I I I I I I I I I I I I
9
w
tl
8
i
--I--�--rt--r-
--J--1--L-
--�--r--Ir--li--�--r--Ir--Ir-�--7--r--li---li--rt--r--Ir--li--
--�--L--1---1--J--1--L--1--J--1--L--1---�--1--L--L--�--
c 7
LL
� I
I I I I-
I
-- �--r---� I I I --I---I---I---I--I---I---I---I--I---I---I--
6
i
rJ
4
--I--�--�--r-
--�--r--Ir--li--�--r--Ir--li--7--7--r--Ir--li--7--r--Ir--li--
3
--1--J--1--L-
-�--L--1---1--J--1--L--1--J--1--L--1---�--1--L--L--�--
1
0
0 2
4 6 8 10 12
14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

NORTH BUNCOMBE STORM SYSTEM Type 1124-hr 50-Year Rainfall=4.94"
Prepared by Brooks Engineering Associates, PA Printed 7/11/2019
HydroCADO 10.00-14 s/n 08975 © 2015 HydroCAD Software Solutions LLC Page 44
Summary for Link ELx: (new Link)
Inflow Area = 2.506 ac, 49.11 % Impervious, Inflow Depth = 2.78" for 50-Year event
Inflow = 12.71 cfs @ 11.96 hrs, Volume= 0.580 of
Primary = 12.71 cfs @ 11.96 hrs, Volume= 0.580 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs
Link ELx: (new Link)
Hydrograph
14 I 12.71 cfs I I I I I I 17��///1���I j�I��� I I I� I I I AM I jI ❑ Primary
13-----i-- i— 12.71 cfs -- --il --il-------T—�11 1ViYY Ili iQ�2 1 -a�/
12 'I
-1--J--1--'- -1--L--1---1--J--1--L--1--J--1--L--1---1--1--L--'--'--
I 0W-- --
10------- ---- ----------li---li--li---li---IRrhliatry--42I. I-Cf�-
w $ ---------II - ----II --II-----I--II --II---------II---------II --II --I--
-J--1--'--1--L--1---1-- ----L--1--J-----
--1L11--1--L--'--'--
3 7 I I I I I I I I I I I
0
lLL 6----+--+--r- --+--r--r----+--+--r--r-+--+--r-------+--r--r--I--
5-
4
3 --I-- -- --r- ----r--r--I----r--r--r-r--+--r-----I----r--r--I--
2---------i ----i --i-----i--i --i---------i---------i --i --i--
1
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)