20150402 Ver 1_Application_20150827

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aSo
2
COURTHOUSE DRIVE EXTENSION
STORMWATER CALCULATIONS
Prepared By:
BREC, P.A.
126 Executive Drive
Suite 220
Wilkesboro, NC 28697
NCBELS Firm #C -3448
\��1lilllf / /
�•`` �N CARP
SEAL
035736 -
Prepared For:
Wilkes County Govt.
Room 101
110 North Street
Wilkesboro, NC 28697
21 August 2015
Justin Chur , PE
Principal Engineer
i
A (JG 2 7 20 15
}
Project Site:
Courthouse Drive
Wilkesboro, NC 28697
BREC, P.A. Courthouse Drive Extension I Stormwater Calculations 1

m
I
1.0 General Information
This document contains stormwater calculations for treating post- construction
runoff of an 1187 ft extension of Courthouse Drive in Wilkesboro, NC. Adjacent
property in the amount of 3.34 acres is being deed restricted against future
development to maintain a low density classification of 24% built upon area for
the proposed project. With the deed restriction, no stormwater BMP is required;
however, an oversized plunge pool that will function as a dry detention basin is
being installed to ensure there are no stormwater impacts from the project.
2.0 Methodology
The water quality volume (WQ„) required to be treated from the first flush was
calculated using the Schueler method outlined in the NCDENR Stormwater BMP
Manual. The Schueler method utilizes the following equations:
R„= 0.05 +0.9IA
WQv = 3630RDRvA
Where IA is the impervious fraction of the drainage area, R„ is a runoff coefficient,
RD is the rainfall depth, A is the drainage area, and WQ„ is the runoff volume.
The calculated WQ„ is 2,310 ft3. To route the WQ„ through the dry detention
basin, it is necessary to calculate a modified SCS curve number to avoid
underrepresenting the first flush. The modified curve number is calculated as
follows:
CNm = 1000/ [10 + 5RD + 10WQ„ — 10�/WQV + 1.25WQ„RDI
The modified curve number was used to route the first flush using an SCS 6 hour
balanced storm distribution. The 1 year, 24 hour and 10 year, 24 hour storms
were routed with standard curve numbers and an SCS type II 24 hour storm
distribution.
Routing of the required storms through the sand filters was performed using
Autodesk Storm and Sanitary Analysis (SSA) 2014.
3.0 Results
Based on guidance from Chapter 4 of the NCDOT Stormwater Best Management
Practices Toolbox, discharge from the detention basin is released over the rim of
the basin as opposed to having a dedicated outlet structure. This allows the
discharge to maintain sheet flow as well as exit from the top of the basin to
BREC, FA Courthouse Drive Extension I Stormwater Calculations 2

promote settling of solids. Also, a conservative estimate of 0.25— ,- of soil
infiltration was assumed within the basin.
The basin has sufficient capacity to retain the first 1" rainfall with no direct
discharge. Drawdown will be accomplished by infiltration and evapotranspiration.
The 1 year, 24 hour and 10 year, 24 hour storms were also routed. Pre- and
post- construction discharge rates are both negligible for the 1 year, 24 hour
storm at 0.03 L! and 0.27 L!, respectively.
S S
Model outputs from SSA are included in the Appendix for verification.
BREC, P.A Courthouse Drive Extension I Stormwater Calculations 3

Appendix
BREC, P.A Courthouse Drive Extension I Stormwater Calculations

First Flush Routing
BREC, PA. Courthouse Drive Extension I Stormwater Calculations

Project Description
File Name
BMP_ROUTING SPF
Project Options
Flow Units
CFS
Elevation Type
Elevation
Hydrology Method
SCS TR -55
Time of Concentration (TOC) Method
User - Defined
Link Routing Method
Hydrodynamic
Enable Overflow Ponding at Nodes
YES
Skip Steady State Analysis Time Periods
YES
Analysis Options
Start Analysis On
Jul 09, 2015
00 00 00
End Analysis On
Jul 12, 2015
00 00 00
Start Reporting On
Jul 09, 2015
00 00 00
Antecedent Dry Days
0
days
Runoff (Dry Weather) Time Step
001 0000
days hh mm ss
Runoff (Wet Weather) Time Step
0 00 05 00
days hh mm ss
Reporting Time Step
0 00 05 00
days hh mm ss
Routing Time Step
30
seconds
Number of Elements
Qty
Rain Gages
1
Subbasins
1
Nodes
3
Junctions
1
Outfalls
1
Flow Diversions
0
Inlets
0
Storage Nodes
1
Links
2
Channels
0
Pipes
1
Pumps
0
Onfices
0
Weirs
1
Outlets
0
Pollutants
0
Land Uses
0
Rainfall Details
SN Rain Gage Data Data Source Rainfall Rain State County Return Rainfall Rainfall
ID Source ID Type Units Period Depth Distribution
(years) (inches)
1 WILKESBORO Time Series 11NCH- FIRST -FLUSH Cumulative inches 000

Subbasin Summary
SN Subbasin Area Weighted
Total Total
Total
Peak
Time of
ID Curve Rainfall Runoff
Runoff Runoff
Concentration
Number
Volume
(act
(in) (in)
(ac -in)
(cfs)
(days hh mm ss)
1 ROAD - SURFACE 067 9957
1 00 095
0 64
1 08
0 000506

Node Summary
SN Element Element
ID Type
1 BASIN- TOTAL - OUTLET Junction
2 SITE - OUTFALL Outfall
3 BASIN Storage Node
Invert Ground /Rim
Initial Surcharge Ponded Peak Max HGL
Max
Min
Elevation
(Max)
Water
Elevation
Area Inflow Elevation Surcharge
Freeboard
000
Elevation
Elevation
Attained
Depth
Attained
Attained
(ft)
(ft)
(ft)
(ft)
(ft') (cfs) T1
(ft)
(ft)
100275
100700
100275
000
000 000 100275
000
425
100250
000 100250
100425
100800
100425
000 1 08 100654
Time of Total Total Time
Peak Flooded
Flooded
Flooding Volume
Occurrence
(days hh mm) (ac -in)
(min)
0 0000 000
000
000 000

Link Summary
SN Element Element From To (Outlet)
ID Type (Inlet) Node
Node
1 OUTLET -LINK Pipe BASIN - TOTAL- OUTLET SITE - OUTFALL
2 EMERGENCY - OVERFLOW Weir BASIN BASIN - TOTAL- OUTLET
Length Inlet Outlet Average Diameter or Manning's Peak Design Flow Peak Flow/ Peak Flow Peak Flow Peak Flow Total Time
Invert Invert Slope Height Roughness Flow Capaoty Design Flow Velocity Depth Depth/ Surcharged
Elevation Elevation Ratio Total Depth
Ratio
(fl) (fl) (fl) N (in) (cfs) A) (fUsec) (ft) (min)
1000 100275 100250 25000 15 000 00120 000 1106 000 000 000 000 000
100425 100275 000

��
ao

Subbasin Hydrology
Subbasin: ROAD - SURFACE
Input Data
Area (ac)
Weighted Curve Number
Rain Gage ID
Composite Curve Number
Soil /Surface Description
Composite Area & Weighted CN
Subbasin Runoff Results
Total Rainfall (in)
Total Runoff (in)
Peak Runoff (cfs)
Weighted Curve Number
Time of Concentration (days hh mm ss)
067
9957
WILKESBORO
Area Soil Curve
(acresl Group Number
067 - 9957
067 9957
1 00
095
1 08
9957
0 00 05 00

Subbasin . ROAD - SURFACE
17
164
15-
14-
13-1
12 -!
1 1 1-
i
t I
09 -I
I
m
� 08-f - --
� I
0 07
06 -1 -
04 -i - ---
I
03 -f --
02 -I - --
0 5
Rainfall Intensity Graph
i
j
I Ili
10 15 20 25 30 35 40
Time (hrs)
Runoff Hydrograph
I
I i
I E
45 50 55 60 65 70
1 Z
i
095-
i
Ds
_
0 85 -
I
075-
j
07-
j
i
{
-- 06-
I
I
055-
05
045
I
{
04
i
03
_-- ______ --
___ --
02-:
I
i I
i
015--—
0 1 -
I
006- -
-) - - - —
f-- - - ---- - - -- - --
} - - - - - -- ---
j�
i -- -- -- - - -i ; --
fi -—
I
i
0
5 10 15
20 25 30
35 40 45 50 55 60 65 70
Time (hrs)

Junction Input
SN Element
ID
1 BASIN - TOTAL - OUTLET
Invert Ground /Rim Ground /Rim
Initial Initial Surcharge Surcharge Ponded Minimum
Elevation
(Max)
(Max)
Water Water
Elevation
Depth
Area
Pipe
Elevation
Offset
Elevation Depth
Cover
in
(ft)
(ft)
(ft) (ft)
(ft)
T)
(ft ')
Qn)
100275
100700
425
100275 000
000
-100700
000
000

Junction Results
SN Element Peak
Peak Max HGL Max HGL
Max
Min Average HGL Average HGL
Time of
Time of Total Total Time
ID Inflow
Lateral Elevation
Depth Surcharge Freeboard
Elevation
Depth
Max HGL
Peak Flooded
Flooded
Inflow Attained
Attained
Depth
Attained
Attained
Attained
Occurrence
Flooding Volume
Attained
Occurrence
(cfs)
(cfs) (ft)
(ft)
(ft)
(ft)
(ft)
(ft) (days hh mm) (days hh mm) (ac -in)
(min)
1 BASIN - TOTAL - OUTLET 0 00
000 100275
000
000
425
100275
000
0 0000
0 0000 000
000

Pipe Input
SN Element Length
Inlet Inlet
Outlet Outlet Total Average Pipe
Pipe
Pipe
ID
Invert Invert
Invert Invert Drop
Slope Shape
Diameter or
Width
Elevation Offset
Elevation Offset
Height
(ft)
(ft) (ft)
(ft) (ft) (ft)
N
(n)
(in)
1 OUTLET -LINK 1000
100275 000
100250 000 025
2 5000 CIRCULAR
15 000
15 000
Manning's Entrance Exit/Bend Additional Initial Flap No of
Roughness Losses Losses Losses Flow Gate Barrels
(cfs)
00120 05000 05000 0 0000 0 00 No

Pipe Results
SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow
Peak Flow Total Time Froude Reported
ID Flow Peak Flow Capacity Design Flow
Velocity Time
Depth
Depth/ Surcharged Number Condition
Occurrence Ratio
Total Depth
Ratio
(cfs) (days hh mm) (cfs)
(ft/sec) (min)
(ft)
(min)
1 OUTLET -LINK 000 0 0000 11 06 000
000
000
000 000 Calculated

Storage Nodes
Storage Node: BASIN
Input Data
Invert Elevation (ft)
100425
Max (Rim) Elevation (ft)
100800
Max (Rim) Offset (ft)
375
Initial Water Elevation (ft)
100425
Initial Water Depth (ft)
000
Ponded Area (ft')
000
Evaporation Loss
000
I nfi Itration /Exfi Itration
Exfiltration Rate (in /hr) 02500
Storage Area Volume Curves
Storage Curve BASIN - CONTOURS
Stage
Storage
Storage
Area
Volume
(ft)
jw)
(fts)
0
736
0 000
075
902
61425
1 75
1144
163725
275
1411
291475
375
1703
4471 75

Storage Area Volume Curves
^ mm tom 1,50 2,000 2,50" 3,00 3,50 4�000 4�500
2 ' - ' ---------'-------i-----'--------«
. . . . . .
� . . f ---'--.-----'�. ------------------------------------ �.9
- � -� -- —u
� �—_------_--'�---__�------�_-----1�
.
. . � . .
� -- -----.-----'�-----�-------------�a
'' . � . �
' � ---�---------- �----------- �---------- �-----'�-----'^m
----------------- � � -------------------------- .
. _--_-----_------_4
. . � �
i-----'�-----�-----' -----�----- -----'^�
—. � . . . . �
1.2-,: . '�-----'�----- ------�---_—�—_--------_-��
� . . . . .
1.1 --'------'�-----I-----'I-----I-----'-------m
. . . . . � �
�-- T ----�_----'�—____------'-_----.—__--'._—__—` ,
uo ----------------- � � ' � —o�
------r-----r----' -----' -----r----- -----
�u u"
� � —�-----�-----'�-----1-----'�-----�-----�-----'
� . . �
ur' ------ --- -----' ----- ------r----'�-----r-----ur
� . . � . . . ------------------------ .
ua ---�-----.-----'�-----�-----'�----- uo
� ' ! !
us ----------- ------ .
u« ' . . � � �� . . . ' -----' r. ' ----'��� . ' ------ ----- —� � . ------. � � -----�� —
-----. � �
------
- 0.4
o3 -- '-----�. --_—___---' ' ' ' 0.3 v� --'�-----' � �-----' I - ' � ' -----'-"a
"^� ---' L �-----'------� ' --'m ----- . � -----
«—' ----------- r—'---- '� ------- i �'--'.'---'--! �''- ''---''�i
----- . -- ' '�—� '' o
750 800 $50 900 950 1.0001,050 1,100 1,150 1,200 1,2501,300 1.350 1,400 1,450 1,500 1.550 1,600 1,650 1,700
Storage Area (ftj
— Storage Area — Storage Volume I

Storage Node : BASIN (continued)
Outflow Weirs
SN Element Weir Flap Crest Crest Length Weir Total Discharge
ID Type Gate Elevation Offset Height Coefficient
CM (ft) (ft) (ft)
1 EMERGENCY - OVERFLOW Rectangular No 100790 365 6000 010 333
Output Summary Results
Peak Inflow (cfs)
1 08
Peak Lateral Inflow (cfs)
1 08
Peak Outflow (cfs)
000
Peak Exfiltration Flow Rate (cfm)
045
Max HGL Elevation Attained (ft)
100654
Max HGL Depth Attained (ft)
229
Average HGL Elevation Attained (ft)
100580
Average HGL Depth Attained (ft)
1 55
Time of Max HGL Occurrence (days hh mm)
0 01 16
Total Exfiltration Volume (1000 -ft3)
1 645
Total Flooded Volume (ac -in)
0
Total Time Flooded (min)
0
Total Retention Time (sec)
000

1 year, 24 hour Routing
BREC, P.A Courthouse Drive Extension I Stormwater Calculations

Project Description
File Name BMP_ROUTING SPF
Project Options
Flow Units
CFS
Elevation Type
Elevation
Hydrology Method
SCS TR -55
Time of Concentration (TOC) Method
User - Defined
Link Routing Method
Hydrodynamic
Enable Overflow Ponding at Nodes
YES
Skip Steady State Analysis Time Periods
YES
Analysis Options
Start Analysis On
Jul 09, 2015
00 00 00
End Analysis On
Jul 12, 2015
00 00 00
Start Reporting On
Jul 09, 2015
00 00 00
Antecedent Dry Days
0
days
Runoff (Dry Weather) Time Step
001 0000
days hh mm ss
Runoff (Wet Weather) Time Step
0 00 05 00
days hh mm ss
Reporting Time Step
0 00 05 00
days hh mm ss
Routing Time Step
30
seconds
Number of Elements
Qty
Rain Gages
1
Subbasins
1
Nodes
3
Junctions
1
Ouffalls
1
Flow Diversions
0
Inlets
0
Storage Nodes
1
Links
2
Channels
0
Pipes
1
Pumps
0
Onfices
0
Weirs
1
Outlets
0
Pollutants
0
Land Uses
0
Rainfall Details
SN Rain Gage Data Data Source
Rainfall
Rain State County Return Rainfall Rainfall
ID Source ID
Type
Units Period Depth Distribution
(years) (inches)
1 WILKESBORO Time Series 1YR -24HR
Cumulative
inches North Carolina Wilkes (North) 1 2 96 SCS Type II 24 -hr

Subbasin Summary
SN Subbasin Area Weighted Total
Total
Total
Peak
Time of
ID Curve Rainfall Runoff
Runoff
Runoff
Concentration
Number
Volume
(ac) (in)
Qn)
(ac -in)
(cfs)
(days hh mm ss)
1 ROAD - SURFACE 0 67 9800 296
273
1 83
258
0 00 05 00

Node Summary
SN Element Element
ID Type
1 BASIN - TOTAL - OUTLET Junction
2 SITE - OUTFALL Outfall
3 BASIN Storage Node
Invert Ground /Rim
Initial Surcharge Ponded
Peak Max HGL
Max
Min
Elevation
(Max)
Water
Elevation
Area
Inflow Elevation Surcharge Freeboard
Elevation
Elevation
Attained
Depth
Attained
Attained
L8)
(ft)
Lft)
(ft)
w)
(cfs) (ft)
(ft)
(ft)
100275
100700
100275
000
000
027 100291
000
409
100250
027 100264
100425
100800
100425
000
258 100791
Time of Total Total Time
Peak Flooded
Flooded
Flooding Volume
Occurrence
(days hh mm) (ac -in)
(min)
0 0000 000
000
000 000

Link Summary
SN Element Element From To (Outlet)
ID Type (Inlet) Node
Node
1 OUTLET -LINK Pipe BASIN - TOTAL- OUTLET SITE - OUTFALL
2 EMERGENCY - OVERFLOW Weir BASIN BASIN - TOTAL- OUTLET
Length Inlet Outlet Average Diameter or Manning's Peak Design Flow Peak Flow/ Peak Flow Peak Flow Peak Flow Total Time
Invert Invert Slope Height Roughness Flow Capacaty Design Flow Velocity Depth Depth/ Surcharged
Elevation Elevation Ratio Total Depth
Ratio
(ft) A (a) N (m) (cis) (cfs) (f /sec) (fl) (min)
1000 100275 100250 25000 15 000 00120 027 1106 002 330 015 012 000
100425 100275 027

Repoded
Conddion
Calculated

Subbasin Hydrology
Subbasin: ROAD - SURFACE
Input Data
Area (ac) 067
Weighted Curve Number 9800
Rain Gage ID WILKESBORO
Composite Curve Number
Area Soil Curve
Soil /Surface Description (acresl Group Number
067 - 9800
Composite Area & Weighted CN 067 9800
Subbasin Runoff Results
Total Rainfall (in) 296
Total Runoff (in) 273
Peak Runoff (cfs) 258
Weighted Curve Number 9800
Time of Concentration (days hh mm ss) 0 00 05 00

Subbasin: ROAD-SURFACE
4, - 'f ---
ae� |
{ /
as �
� _ __ _-
34 |
32 |
. ` |
Rainfall Intensity Graph
-
/ | /
� / -- -- | / ---- '----
aa� - --
26-/ ------ -----_---------� ----- '
z*'
u' ' -----�---'
� | i
� 1o�' ' |
Ia'| � |
14 / ! |
08-i | | | |
oa
o^'!
02-! � ---------------------
n o /0 15 20 26 30 35 40 m 50 55 60 66 70
Time (hrs)
Runoff Hva,pemph
ur
ze
zs
u4
----
22-
z�
19 (
18 `
1r !
� 1s
� 12 -
}
�
--
--
��'------�----
U '
os'
oo
or
""' -_ | / |
0 | ! - -------|---�1 - -------�--'
� � !
»4
oa
oz' | `-
o1
o ----s � m 15 20 . 2� | 3b [ --- 35 � � | | � � � ' ! � | r�
Time (hrs)
----� -- �
� (
!

Junction Input
SN Element
ID
1 BASIN - TOTAL - OUTLET
Invert Ground /Rim Ground /Rim
Initial Initial Surcharge Surcharge Ponded Minimum
Elevation
(Max)
(Max)
Water Water
Elevation
Depth
Area
Pipe
Elevation
Offset
Elevation Depth
Cover
(ft1
(ft)
(ft)
(ft) (ff)
(ft)
(ft)
(ft')
Qn)
100275
100700
425
100275 000
000
-100700
000
000

Junction Results
SN Element Peak
Peak Max HGL Max HGL
Max
Min Average HGL Average HGL
Time of
Time of Total Total Time
ID Inflow
Lateral Elevation
Depth Surcharge Freeboard
Elevation
Depth
Max HGL
Peak Flooded
Flooded
Inflow Attained
Attained
Depth
Attained
Attained
Attained
Occurrence
Flooding Volume
Attained
Occurrence
(cfs)
(cfs) (ft)
(ft)
(ft)
(ft)
(ft)
(ft) (days hh mm)
(days hh mm) (ac -in)
(min)
1 BASIN- TOTAL - OUTLET 0 27
000 100291
016
000
409
100276
001
0 1227
0 0000 000
000

Pipe Input
SN Element Length
Inlet Inlet
Outlet Outlet Total Average Pipe
Pipe
Pipe Manning's Entrance Exit/Bend Additional Initial Flap No of
ID
Invert Invert
Invert Invert Drop
Slope Shape
Diameter or
Width Roughness Losses
Losses Losses Flow Gate Barrels
Elevation Offset
Elevation Offset
Height
(ft)
(ft) (ft)
(ft) (ft) (ft)
N
(in)
(n)
(cfs)
1 OUTLET -LINK 1000
100275 000
100250 000 025
2 5000 CIRCULAR
15 000
15 000 00120 05000
05000 00000 000 No 1

Pipe Results
SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow
Peak Flow Total Time Froude Reported
ID Flow Peak Flow
Capacity Design Flow
Velocity Time
Depth
Depth/ Surcharged Number Condition
Occurrence
Ratio
Total Depth
Ratio
(cfs) (days hh mm)
(cfs)
(ftlsec) (min)
(ft)
(min)
1 OUTLET -LINK 027 0 1225
11 06 002
330 005
015
012 000 Calculated

Storage Nodes
Storage Node : BASIN
Input Data
Invert Elevation (ft)
100425
Max (Rim) Elevation (ft)
100800
Max (Rim) Offset (ft)
375
Initial Water Elevation (ft)
100425
Initial Water Depth (ft)
000
Ponded Area (ft2)
000
Evaporation Loss
000
I nfiltration /Exfiltration
Exfiltration Rate (in /hr) 02500
Storage Area Volume Curves
Storage Curve BASIN - CONTOURS
Stage
Storage
Storage
Area
Volume
(ft)
eft')
(ft)
0
736
0 000
075
902
61425
1 75
1144
163725
275
1411
291475
375
1703
4471 75

Storage Area Volume Curves
Ston. ge Volume (ft)
^ am 1,0" ,,5^ �°� ,�" ,�o +o� �p�
3.r o
:� + + 'zo
3.5 -^ ` ^ ^ '3.5
----'- 3.4
zo -� - � � ------------ 3.3
. � � . . � . . �
x� --------'zz
� � � . . . . . �
xx| -------- ----------
3-: -----�-----''x
. . . � . . .
2.9 -`------�------'a»
zu-� ' ' ' ' -------------------------------- �
. . . . . � .
x� ' ' ' ' --------- ------------------------
sa-� ' ' ' ' -----�-----' -----'e�
. . . . . . . . .
ss ' . ----_'� ' . ' ----_' '
'
� r ------ _.5
2.4 ----------- ------------- � � --- ----- '�- - a^
2.3 . ---------------------------------------------
za- ^ . ------r----'r--- I r
----- 2.2
2.1 . - ----_' -----'��
x-
. . . . . . ---. . -----'. �- �
---'
�
1.9 � . � � '^ � . '
^� o
�
� i + � ----'i-----'�----- -----�-----'�u
. � � � �
1�-r - -r----'.-----' ----- -----' -----��
� . � � .
1-6 7� � _ ------------------------------------------------- . � �
. . � � � .
�a�� + ---�----- -----' ----'�-----'�-----'1�
� .
^4 ----------------------------------��
. . � � � � � �
^o � � ^�
-� � � '.-_---'.-----�------�_-__-�----_'�--_--'
v� � � -�------r-------------------------------------------------------- -'��
-� . � � .
. --'�-----'.-----�-_---'�---_-.--_--'�-----'��
-� � . . . . . �
� -_-- -----' ----- _----' ----- ----------- ----------- 1
uo-� ' ' ' � � ' � oo
_' �
~~ i' - '�-----.-----'.----'�------�-----.-----'�-----'�"°
0.8 -'------�-----' ----- -----' ----- ------ ----------- �uo
0.7 ' ' --'�----- -----'�----- -----' -----�-----'�-----'-ur
0.6 i ---'�' � -----�� ' . ----'� �. -----�. ---'-. ' � -----�� '
-----^� ��
-----'-ua
us - 'L ----------------------- ----------- ----------- ------------ 0.5
0.4 ' ------------ -- --- -----------' -----------'�-----�u*
. � �
0.3 � + � � ------------------------ ux
_� -'.-----.-----.__--_-...__-__�-_-__�_---_-
uu� �r � L � ---.'
�uo j
^x - �-----' �----------- -----^! -----'- ^----- I ! ' ' ^�x
v_� ' �f'-----�� � '��'-- -`�- -'--7- -�---'- 0
750 800 $50 900 950 1.000 1.050 1.100 1.150 1,2001.2501.3001.350 1,400 1,450 1.500 1,550 1.6001.650,,700
Storage Area (ftj-
|- -cnomyeAreo --- Storage Volume U

Storage Node : BASIN (continued)
Outflow Weirs
SN Element Weir Flap Crest Crest Length Weir Total Discharge
ID Type Gate Elevation Offset Height Coefficient
(ft) (ft) (ft) (ft)
1 EMERGENCY - OVERFLOW Rectangular No 100790 365 6000 010 333
Output Summary Results
Peak Inflow (cfs)
258
Peak Lateral Inflow (cfs)
258
Peak Outflow (cfs)
027
Peak Exfiltration Flow Rate (cfm)
058
Max HGL Elevation Attained (ft)
100791
Max HGL Depth Attained (ft)
366
Average HGL Elevation Attained (ft)
100703
Average HGL Depth Attained (ft)
278
Time of Max HGL Occurrence (days hh mm)
0 1225
Total Exfiltration Volume (1000 -ft')
2 127
Total Flooded Volume (ac -in)
0
Total Time Flooded (min)
0
Total Retention Time (sec)
000

10 year, 24 hour Routing
BREC, P.A. Courthouse Drive Extension I Stormwater Calculations

Project Description
File Name BMP_ROUTING SPF
Project Options
Flow Units
CFS
Elevation Type
Elevation
Hydrology Method
SCS TR -55
Time of Concentration (TOC) Method
User - Defined
Link Routing Method
Hydrodynamic
Enable Overflow Ponding at Nodes
YES
Skip Steady State Analysis Time Periods
YES
Analysis Options
Start Analysis On
Jul 09, 2015
00 00 00
End Analysis On
Jul 12, 2015
00 00 00
Start Reporting On
Jul 09, 2015
00 00 00
Antecedent Dry Days
0
days
Runoff (Dry Weather) Time Step
001 0000
days hh mm ss
Runoff (Wet Weather) Time Step
0 00 05 00
days hh mm ss
Reporting Time Step
0 00 05 00
days hh mm ss
Routing Time Step
30
seconds
Number of Elements
Rainfall Details
SN Rain Gage Data Data Source Rainfall Rain State County Return Rainfall Rainfall
ID Source ID Type Units Period Depth Distribution
(years) (inches)
1 WILKESBORO Time Series 10YR -24HR Cumulative inches North Carolina Wilkes (North) 10 533 SCS Type II 24 -hr
Qty
Rain Gages
1
Subbasins
1
Nodes
3
Junctions
1
Outfalls
1
Flow Diversions
0
Inlets
0
Storage Nodes
1
Links
2
Channels
0
Pipes
1
Pumps
0
Orifices
0
Weirs
1
Outlets
0
Pollutants
0
Land Uses
0
Rainfall Details
SN Rain Gage Data Data Source Rainfall Rain State County Return Rainfall Rainfall
ID Source ID Type Units Period Depth Distribution
(years) (inches)
1 WILKESBORO Time Series 10YR -24HR Cumulative inches North Carolina Wilkes (North) 10 533 SCS Type II 24 -hr

Subbasin Summary
SN Subbasin Area Weighted
Total
Total
Total
Peak
Time of
ID Curve Rainfall Runoff
Runoff Runoff
Concentration
Number
Volume
(ac)
(n)
(in)
(ac -in)
(cfs)
(days hh mm ss)
1 ROAD - SURFACE 067 9800
533
509
341
470
0 00 05 00

Node Summary
SN Element Element
ID Type
1 BASIN - TOTAL - OUTLET Junction
2 SITE - OUTFALL Outfall
3 BASIN Storage Node
Invert Ground /Rim
Initial Surcharge Ponded Peak Max HGL
Max
Min
Elevation
(Max)
Water
Elevation
Area Inflow Elevation Surcharge Freeboard
0 11 55 002
Elevation
Elevation
Attained
Depth
Attained
Attained
(ft)
(ft)
(ft)
(ft)
(ft') (cfs) (ft)
(ft)
(ft)
100275
100700
100275
000
000 462 100700
000
000
100250
5917 100375
100425
100800
100425
000 470 100798
Time of Total Total Time
Peak Flooded
Flooded
Flooding Volume
Occurrence
(days hh mm) (ac -in)
(min)
0 11 55 002
1 00
000 000

Link Summary
SN Element Element From To (Outlet)
ID Type (Inlet) Node
Node
1 OUTLET -LINK Pipe BASIN - TOTAL- OUTLET SITE- OUTFALL
2 EMERGENCY - OVERFLOW Weir BASIN BASIN - TOTAL- OUTLET
Length Inlet Outlet Average Diameter or Manning's Peak Design Flow Peak Flow/ Peak Flow Peak flow Peak Flow Total Time
Invert Invert Slope Height Roughness Flow Capacity Design Flow Velocity Depth Depth/ Surcharged
Elevation Elevation Ratio Total Depth
Ratio
(fl) (ft) (ft) N (in) (cfs) (cfs) (ft/sec) (ft) (min)
1000 100275 100250 25000 15 000 00120 5917 1106 5 35 4821 073 100 100
100425 100275 462

Repoded
Condton
SURCHARGED

Subbasin Hydrology
Subbasin : ROAD - SURFACE
Input Data
Area (ac) 067
Weighted Curve Number 9800
Rain Gage ID WILKESBORO
Composite Curve Number
Area Soil Curve
Soil /Surface Description (acres) Group Number
067 - 9800
Composite Area & Weighted CN 067 9800
Subbasm Runoff Results
Total Rainfall (in)
533
Total Runoff (in)
509
Peak Runoff (cfs)
470
Weighted Curve Number
9800
Time of Concentration (days hh mm ss)
0 00 05 00

Subbasin . ROAD - SURFACE
Rainfall Intensity Graph
7C ,
7 i
I
65- _-
6
i
t
45 �
L
c 4_' i
35-1 - --- - ---- - -- -- —
I
25
2;
1 -I
0 5 —r
0 5 10 15
i
i
3
3
20 25 30 35 40 45 50
Time (hrs)
Runoff Hydrograph
55 60 65 70
48
46
'.
I
44-
42 - - - -- -
- - -- - --
+
- - - -- --
4
38
I
;
36-
!
J
I
l
32-
1-
—
+
3-
281 _ _
F _
22
i
I
2_
- - --- - ----- - - - - --
3
14
i
12-
i
i
- - -- -- - - -
-- - - -- -- - -- -- - - -- --- - -- -
06
1- -- - - - --
-- — —
0 4
-
-- - -- - --
0
5
10 15
20 25 30 35 40
45 50 55 60 65 70
Time (hrs)

Junction Input
SN Element Invert Ground /Rim Ground /Rim
Initial Initial Surcharge Surcharge Ponded Minimum
ID Elevation
(Max)
(Max)
Water Water
Elevation
Depth Area
Pipe
Elevation
Offset
Elevation Depth
Cover
(ft)
(ft)
(ft)
(ft) (ft)
(ft)
(ft) (ft')
(in)
1 BASIN - TOTAL - OUTLET 100275
100700
425
100275 000
000
-100700 000
000

Junction Results
SN Element Peak Peak Max HGL Max HGL Max Min Average HGL Average HGL
ID Inflow Lateral Elevation Depth Surcharge Freeboard Elevation Depth
Inflow Attained Attained Depth Attained Attained Attained
Attained
(cfs) (cfs) (ft) (ft) (ft) (ft) (ft) (ft)
1 BASIN - TOTAL - OUTLET 462 000 100700 425 000 000 100286 Oil
Time of
Time of Total Total Time
Max HGL
Peak Flooded Flooded
Occurrence
Flooding Volume
Occurrence
(days hh mm)
(days hh mm) (ac -in) (min)
0 11 55
0 11 55 002 1 00

Pipe Input
SN Element Length
Inlet inlet
Outlet Outlet Total Average Pipe
Pipe
Pipe
ID
Invert Invert
Invert Invert Drop
Slope Shape
Diameter or
Width
Elevation Offset
Elevation Offset
Height
(ff)
(ft) (ft)
(ft) (ft) (ft)
S %)
(in)
(in)
1 OUTLET -LINK 1000
100275 000
100250 000 025
2 5000 CIRCULAR
15 000
15 000
Manning's Entrance Exit/Bend Additional Initial Flap No of
Roughness Losses Losses Losses Flow Gate Barrels
(cfs)
00120 05000 05000 0 0000 0 00 No

Pipe Results
SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow
Peak Flow Total Time Froude Reported
ID Flow Peak Flow
Capacity Design Flow
Velocity Time
Depth
Depth/ Surcharged Number Condition
Occurrence
Ratio
Total Depth
Ratio
(cfs) (days hh mm)
(cfs)
(f /sec) (min)
(ft)
(min)
1 OUTLET -LINK 5917 0 11 55
11 06 535
4821 000
073
1 00 1 00 SURCHARGED

Storage Nodes
Storage Node : BASIN
Input Data
Invert Elevation (ft)
100425
Max (Rim) Elevation (ft)
100800
Max (Rim) Offset (ft)
375
Initial Water Elevation (ft)
100425
Initial Water Depth (ft)
000
Ponded Area (ft')
000
Evaporation Loss
000
Infiltration /Exfiltration
Exfiltration Rate (in /hr) 02500
Storage Area Volume Curves
Storage Curve BASIN - CONTOURS
Stage
Storage
Storage
Area
Volume
(ft)
iftl)
eft')
0
736
0 000
075
902
61425
1 75
1144
163725
275
1411
291475
375
1703
4471 75

Storage Area Volume Curves
" mm 1,000 1,5" »�o �wv ,^" �w" �o� �s�
/ .
lL
--'4------------------------------ 2
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u
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�r
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-. � �
i ' � ���
. � � � .
� --'.-----+----- -----�----- ----------- :-1.5
. .
1.4 -----------------_---------------_^«
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i ��
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v� ' -�-----'�-----�------�-----�-----'�------���
. . . � � . . .
1.1-: . --' -----'.-----�-----' -_---�----_'�----_-�1�
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. . . . . . . .
uo ' ' ----'�-----'�-----�-----'�-----�-----'�-----'�o�
� � � . . � � . �
0u '�
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o7 ' --' '-----' ----- -----'' ' ' Ao
-------, --'�' --� . . �-----�--_--�_-----
ao-� ---�-----�-----'�-----�-----'�-----�-----^------�a
. �
o.5 -i � . ---� � �-��� ��. �----.- �� � --. � --�. . .
-----'
-----'
�oy
u* - ' L ' - , - '.- -� 'r----- �4
0.3 - ---_----�-----�___--------- � ' � � � u3
0.2 --- --'T------------------------ . -----' - ' +----- ------' 0.2 ox-- Jx '------�--_-- � � -� � '� � � -� ' ��
o ------- � ---''�--�--'�''� _ �-�_��'_'-___�'''�'__��-�--'---i-� o
750 800 850 900 950 1.000 1,050 1,100 1,150 1,200 1,250 1.300 1.350 1,400 1,450 1,500 1,550 1,600 1,650 1,TOO
Storage Area ("
| - -'sooraueAmu - -suomonvolumn U

Storage Node : BASIN (continued)
Outflow Weirs
SN Element Weir Flap Crest Crest Length Weir Total Discharge
ID Type Gate Elevation Offset Height Coefficient
R (ft) (ft) (ff)
1 EMERGENCY - OVERFLOW Rectangular No 100790 365 6000 010 333
Output Summary Results
Peak Inflow (cfs)
470
Peak Lateral Inflow (cfs)
470
Peak Outflow (cfs)
462
Peak Exfiltration Flow Rate (cfm)
059
Max HGL Elevation Attained (ft)
100798
Max HGL Depth Attained (ff)
373
Average HGL Elevation Attained (ft)
100724
Average HGL Depth Attained (ft)
299
Time of Max HGL Occurrence (days hh mm)
0 1200
Total Exfiftration Volume (1000 -ft3)
2 168
Total Flooded Volume (ac -in)
0
Total Time Flooded (min)
0
Total Retention Time (sec)
000