Cape Fear Steam Station (15)

ecipi`tion Frequency Data Server http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.huin ?lat--35.6153&...
NOAA Atlas 14, Volume 2, Version 3
i
Y. Location name: Sanford, North Carolina, US" ,
Coordinates: 35.6153, -79.0955
Elevation: 237 ft* yrs
_
'source Google Maps
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T Paaybok, MYekta, and D. Riley
NOAH, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches)'
uratiorr Average recurrence interval (years)
1 �2 10 �25 50 100 200 500 1000-I
__
I 0.420 0A95--'[--0-.574---[ 0.632 0.696 0� 0.781 0.816 0.856 0.885
I 5 -min 0.384-0.461)1(0 453.0.544)1(0.524-0.630) (0.576-0.692) (0.631-0.762)x(0.669-0.810) (0.702-0.854) (0.730 0.893) (0.758-0.937) (0.779-0.970)
Fi
0-min 0.671 0.792 0.919 1.01 7.11 1.18 1.24 129 1.35 1.39
(0.613-0.736) (0.724-0.871) (0.839-1.01)' (0.921-1.11) (1.01-1.22) (1.06-1.29) (1.11-1.36) (1.11 6-1.42) (1.20.1.48) (1.23-1.53)
15 -min 0.838 0.996 116 F 1.28 1.41 1.49 1.57 1.63 1.70 1.75
1(0.766-0.920)110-1.09) (0.91 10-1.09) , (LI 06-1.28) (1.16-1.40) (1.27-1.54) (1.35-1.63) 1 (1.41-1.72) (146-1.79) (1.51-1.86) (1.54-1 92)
30 -min 1.158
1.65 1.85 2.08
1.31.26-1.51) f
2.25
2.40
2.54
2.71
2.83
(1.05-1.26)
( (1.51-1.81) (1.69-2.03) (1.89-2.28)
(2.03-2.46)
(2.16-2.63)
(2.27-2.78)
(2.4D-2.97)
(2.49-311)
60 -min 1.43
(1.31-1.57)
1.73 F 2.12 F 2.41 2.77
(1.58-1.90) (1.93-2.33) (2.20-2.64) (2.52-3.04)
F 3.05
(2.75-3.33)
3 31
(2.97-3.62)
3.56
(3.19-3.90)
3.89
(3.45-4.26)
4.14
(3.644.53)
1.68
2
2.04 2.53 2.80 3.38
3.76
4.13
4.50
4.88
5.36
-hr
(1.53-1.87)
(1.85-2.25) (2.30-2.80) (2.63-3.21) (3.04-3.74)
(3.374.16)
(3.67-4.56)
(3�
(4.36-5.50)
(4.65-5.92)
1.79
3 -hr (1.63-1.98)
2.16 2.69 3.12 3.67
1 (1.97-2.40) (2.45-2.98) (2.82-3.44) (3.31-4.05)
4.11
(3.684.54)
4.56
(4.05-5.03)
5.02
(4.42-5.53)
5.64
(4.91-6.22)
6.14
(5.29-6.77)
22.14
2.59 3.23 3.74 4.43
4.98
5.55
6.14
6.95
7.60
FG -hr
(t" 96-2.36)
F(2.32759 5) (291 5-355) (3.40-4.11) (4.00-4.85)
)
(4.47-5.46)
(4.94-6.07)
(5.41 6.71)
(6.04-7.59)
(6.52-8.31)
12-hr 2.54
(2.32-2.79)
3.07 3.85 4.48 .35
1(2.81-3.38) 1 (3.514.24) (4.074.93) [(41"2-5,86)
6.06
(5.42-6.63)
; 6.80
(6.02-7.42)
7.58
(6.64-8.27)
---
8.68
(747-9.46)
9.57
(8.12-10.4)
2.95
24 -hr (276-3.16)
-
3.56 4.47 5.19 .
(3.3443.82) F(4.18-4.79)()4.84-5.55 (5.73-0.59)
6.93
1 (6.44-7.41)
7.72
1 (7.15-8.26)
8.53
(7.88-9.13)
9.65
(8.87-10.3)
10.5
(9.65-11.3)
2 -day 3.43
(3.20.3.68)
4.145.16 F 5.96 7.04
(3.81 7-4.44) (4.81-5.54) (5.54-6.38) (6.5' 3-7.54)
F 7.88
(7.30.8.46)
F 8.76
(8.09-9.40)
9.66
(8.89-10.4)
10.9
(9.97-11.7)
11.9
(10.8-12.8)
�- 3.64
3 -day (3.39-3.90)
4.37 5.42 6.25 7.37
(4.084.68) (5.05-5.81) (5.81-6.69) (6.83-7.89)
28 6
(7.63-8.84 .
-
9.16
(8.44-9.82)
10.1
(9.28 10 8)
11.4
(10.4-12.2)
12.4 -1
(11.3-13.3)
4 -day 3.84
4.61 5.68 6.54 7.70
I
( 8.62
9.57
10.5
11.9
12.9
(3.584.11)
(4.304.93) (5.30-6.08)(6.0".99) (7.13-8.24)
(7.95-9.23)
(8.80-10 2)
(9.67-11.3)
(10 8--
(11.7-13 9)
4.42
ff 5.27 6.42 7.33 8.58
9.58
10.6
11 6
1 13.1
4 2
[(13'0-;5.2)
7 -day
1(4.144.72)
(4 93-5.63) (6.00-6.85) (6.85-7.82) 1(8.00-9.15)
(8.90-10.2)
(9.81-11.3)
(10.8-12.4)
(12.0-14.0)
10 -da 5.04
y (4.74-5.37)
6.00 7.21 8.16 9.44
(5.64 6.39) (6.77-7.67) (7.66-8.69) (8.83-10,1)
10.5
F(9 .74-11.1)
11.5
(10.7-12.2)
12.b
(11.6 13.3)
13.9
(12.8-14.9)
S.
F(13'8 16.0) I
20 -day 677
(6.31 8-7.19) ,1(7.53-8.48)
7.99 9.44 10.6 12.1
(8.88-10.0) (9.95-11.2) (11.4-12.9)
13.3
I (12.5-14.2)
14.6
(13.6-15.5)
--15.8
(14.7-16.8)
17.5
(16.2-18.6)
18.8
(17.320.0)
8.40
30
9.88 11.5 1 14.4
15.6
I 16.9
18.2
19.8
F--21.1
-day (793-890)
(9.32-10.5) (10.8-12.2) (12.0-13.5) I (13.5-15.3)
(14.7-16.6)
(15.8-18.0)
(17.0-19.3)
(18.4-21.1)
19.622.5)
45 -day 10.7
12.6 14.4 15.8 17.6
18.9
20.3
21.6
23.3
24.6 1
(10.2-11.3)
(11.9-13.2) (13.6-15.1) (14.9-16.6) (16.6-18 5)
I (17.9-20.0)
i (19.1-21.4)
(20.3-22.8)
(21.8-24.7)
(23.0-26.1)
60 -da 12.8
y (12.2-13.5)
14.9 16.9 18.4 20.3
(14.2-15.7) (16.1-17.8) (17.5-19.3) 1 (19.3-21.4)
21.8
1 (20.6-23.0)
23.2
1 (21.9-24.5)
24.6
(23.2-25.9)
26.3
1 (24.B-27.8)
27.7
(26.0-29.3) I
I
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for
a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable mabmum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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PF graphical
of4 9/27/2011 11:49 AM

TABLE OF CONTENTS
STORMWATER MANAGEMENT NARRATIVE
'SOILS INFORMATION
COMPOSITE RUNOFF CURVE NUMBERS
RAINFALL DATA
SITE RUNOFF HYDROGRAPHS
BIO -CELL, DESIGN AND ROUTING
SUPPLEMENTAL DATA
NCDWQ FORMS }
DRAINAGE AREA EXHIBITS
SITE PLAN AND SWM DETAILS
SHEETZ
KING,, NC
STOKES COUNTY, NC
Project # 10-139

ecipitahorj Frequency Data Server http //hdsc nws noxa gov/hdsc/pfds/pfds_printpage html?lat=35 61'53&
PDS -based depth -duration -frequency (DDF) curves
Coordinates 35 6153, -79 0955
30
25
c
5
0
30
25
S
r 20
a -
v
0 15
Gj 10
0
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval(years)
NOAANNWS/OHD)HDSC Created (GMT) Tue Sep 27 15 48 16 2011
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Maps & aerials
of 4
Average recurrence
interval
(years)
— 1
2
— 5
— 10
25
50
100
200
500
1000
Duration
— 5 -min
— 2 -day
— 10 -min
— 3 -day
— 15 -min
— 4 -day
— 30 -min
— ?-day
— 60 -min
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Duration
30
25
S
r 20
a -
v
0 15
Gj 10
0
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval(years)
NOAANNWS/OHD)HDSC Created (GMT) Tue Sep 27 15 48 16 2011
Back to Top
Maps & aerials
of 4
Average recurrence
interval
(years)
— 1
2
— 5
— 10
25
50
100
200
500
1000
Duration
— 5 -min
— 2 -day
— 10 -min
— 3 -day
— 15 -min
— 4 -day
— 30 -min
— ?-day
— 60 -min
— 10 -day
— 2 -hr
— 20 -day
— 3-411
— 30 -day
— "I
— 45 -day,
— 12 -hr
— 60 -day
— 24 -hr
9/27/2011 11'49 AM

-1,
3'AI1VUUVN 1N3W3`:JV'NVIN U-31MMOTS

ecipitat>olo Frequency Data Server
1 arna crala man
http //h6c nws°noaa gov/hdsc/pfds/pfds_printpage html9lat=35 6153&
"' of 9/27/201°l 11 49 AM

`INTRODUCTION
This project is the,construction of an approximately 6,000 square foot Sheetz convenience store
and gas station `in the Northeast•quadrant of the intersection of King Street (;Old U S Highway 52)
and Mountain View Road', within the City Limits of King, NO The site is 2 087 acres Land
disturbance will be limited to the areas of the building / parking area and an off-site bioretention
facility
'The Stdrmwater Management system will receive runoff from all impervious areas of the site plus
the area of the biocell itself (2 27 acres) All off-site runoff will be diverted around `the site and the
bioretention area The existing site is about' 20% impervious cover consisting of a building with
associated asphalt parking areas Runoff from this -,site is not currently being managed for quality
or quantity The proposed stormwater management,system consists of one 6000 square foot
bioretention cell This cell is designed provide quality treatment of runoff,forthe first one inch of
rainfall and to remove 85% of TSS and also provide retention for the peak attenuation of the one
year, 24 hour storm
METHODOLOGY
Existing and proposed hydrologic computations were performed using the Soil Conservation -
Service's Technical Release No 55 (TR -55)' Time of concentration and runoff curve numbers
(CN) were developed by the methodology in TR -55 A time of concentration of 5 minutes was
used in the calculations since the, calculated time of concentrations are unrealistic for small travel
paths which result from this small project site The USDA Soil Conservation Service's website
(Soil Survey) 2 was, used to determine the existing'soil group classifications Soils present on this
site have a hydrologic soils group classification of -'B' The'soil types present on the site and a
brief description are as follows
Soil Name and Map Symbol, Hydrologic Soil Group
CeB2 —Clifford sandy clay loam, 2-8% slopes "B"
FpC2 — Fairview -Poplar Forest complex; 8-15% slopes "B"
The existing site is commercial in nature Open, fair conditions were used to classify pervious
areas in determining the composite runoff Curve Numbers for both the existing and proposed site
The existing site drains to the east to a small tributary of'Muddy Creek The assumed drainage
area for the existing condition is not an actual drainage area for the existing site but rather the
area that matches,the post-development'drainage area in, order to allow for direct comparison of
the pre and post -development water quality conditions All off-site runoff will be diverted around
the bioretention cell
Rainfall data used in the hydrologic analysis for the project was taken from Point Precipitation
Frequency Estimates From NOAA ATLAS 14 4, provided by the NOAA website
Hydrograp'hs follow the SCS Unit Hydrograph Method as outlined in National Engineennng,
Handbook3, (NEH-4) Hydrographs were calculated based on a shape factor of 484; using the
computer modeling system in the software Hydraflow Hydrographs originally produced by
Intellisolve and, now distributed through Autocad`Civil, 3D
Pipe flow from the stormwater management system was calculated under both inlet and outlet
control,'with the lesser ofrthe two,outflows taken as,the control A weir coefficient of 3 0 was used
Storm h,ydrograph routing through the Bioretention system was performed using the Storage
Indication Method as outlined in NEH-4 A brief summary of the routing results are included at the
end of'this narrative Detailed routing calculations are included in the appendices
fj. �