SW8020206_COMPLIANCE_20020815

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW�
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
COMPLIANCE EVALUATION INSPECTION
DOC DATE
_t!
YYYYMMDD

DETENTION POND ANALYSIS FILE NAME: G:IDATAIWPDATAIWQSIPOND1020206.WK1
PROJECT #: SW8 020206 REVIEWER: L. Lewis
PROJECT NAME: Coastal Equipment DATE: 15-Aug-02
Receiving Stream: UT New River Class: C NSW
Drainage Basin: White Oak Index No. 19-(1)
Site Area 2.44 acres
Drainage Area 4fi10;7 Off square feet Area in AcreE 2.44 acres
IMPERVIOUS AREAS
Building
Parking
SW
TOTAL
SURFACE AREA CALCULATION
% IMPERVIOUS 59.02%
Des. Depth 5
TSS: 90
Rational C
30000.00 square feet
31160.00 square feet
1460.00 square feet
square feet
square feet
square feet
62620 0>,': square feet
Rational Cc= 0.08
SAIDA Ratio 4.22%
Req. SA 4479 sf
Prov. SA 15ti0: sf
VOLUME CALCULATION * place a "1" in the box if Rational is used
Rational ?*
Des. Storm
.;:;1.,06inches
Rv=
0.58
Bottom
36.65 msl
Perm. Pool
E'.1 65: msl
...........
Design Pool
42.69 msl
Design SA
5558 sf
Req. Volume
139 cf
Prov. Volume
: ;:5230: cf
ORIFICE CALCULATION
Avg. Head =
Flow Q2, cfs
Flow Q5, cfs
No. of Orifices
Diameter, inches
Drawdown =
IG-ROT457TIVA
Perm. Pool Volume= 12760
Req. Forebay Volume= 2552
Provided Volume= 2620.00
Percent= 205flfo.
SA @ _
Elevation=
COMMENTS
Surface Area , Volume and Orifice are within Design Guideline,
1.26 my
0.50 my
0.79 my
0.019 cfs
in x in

i 6
RECEIVED Design Calculations
Stormwater Treatment Facilities
FEB 0 5 2002 for
DWQ Coastal Equipment
S(� Q ZU ZUCo located off
PROD 0 Western Boulevard - Jacksonville, N.C.
I
1. PROJECT DESCRIPTION
The project consist of an office building 1 warehouse and associated sitework on a 2.44 acre tract located
between Western Boulevard & Williamsburg Parkway in Jacksonville, N.C. Proposed construction will include
a new building, parking lot and sidewalks.
2. COMPUTE POND AREA REQUIRED
a. Compute Percent Impervious:
Impervious Areas:
On -Site Buildings
On -Site Streets
On -Site Parking
On -Site Sidewalks
Other On -Site
Total
Total Area Drainage to Pond:
Percent Impervious =
b. Compute Pond Surface Area
0 62,620
Total
30,000 SF
0 SF
31,160 SF
1,460 SF
0 SF
62,620 SF
F-nnQ6�ft1;$ SF
0.590 or 59.0 %
Using Surface Area to Drainage Area Ratio Chart for 90% TSS Removal (copy attached) and
assuming ��'�' w�3' foot pond depth:
SAIDA r,,M4 2 % (interpolated)
Therefore:
Surface Area = SAIDA x Drainage Area
4,477 SF say SF
c. Compute Minimum Pond Dimensions

x
r is {•. , r'.;
Y
2i

If
Assume rectangular shape with 3:1 Length (L) to Width (W) Ratio:
Length = 116.19 feet
Width = 38.73 feet
3. DETERMINE VOLUME TO BE CONTROLLED FROM 1" STORM
Using Schuler "Simple Method":
Rv = 0.05 + 0.009(1) where I = percent impervious
Rv = 0.581 in/in
Control Volume = Design Rainfall x Rv x Drainage Area
Control Volume = 5,139 CF say CF
4. DETERMINE REQUIRED STORAGE DEPTH
Assume: 3:1 side slopes
solving for depth (d) by (trail and error)
d = 1.04
S. DETERMINE ORIFICE SIZE
Control Volume must be drawn down over a 2 day - 5 day period.
Using orifice equation, solve for Diameter (D) that results in 3-112 day period:
D = (Q 10.026 (h).5).5
Where: Q = (Control Volume 1 3.5 days x 86,400 seclday)
0.017 cfs
h= d12
= 0.52
Solving for D:
D = 0.96 Use 1.00 " pipe
Actual Drawdown with actual drawdown pipe diameter (using orifice equation):
Q= 0.019 cfs
Draw Down Period = 3.21 days OK, < 5.0

S
' L'
. a i .
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' � A y�
i,, a . ... 'S_ . i� � - '�! 1. �e ... 1 `j :�.!. .- �!� . '� ' .<`, +_ _ � I
r
r •l. .1
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r

6. SELECT OUTLET STRUCTURE DIAMETER
Size outlet structure such that depth of Q10 flow <1.0 feet:
Using Rational Formula (Q=CIA) where:
Cimper E f9
Cpery °t1 Al+;I
Ccum = 0.70
110 = f.. inmr
k .
A = 2.44 ac
Q 10 = 9.42 cis
Assuming 112 circumference is used as weir and using
Francis Formula (Q=3.33LH''6) to solve for L such that H = 1.Q.
L = 2.83 Feet
Use 24 inch diameter outlet structure
7. DETERMINE Q10 STAGE
Q 10 = 9.42 cfs
Using Francis Formula (Q=3.33LH'-s) solve for H:
H 10 = 0.93 feet
8. DETERMINE Q100 STAGE (ELEV. OF EMERGENCY SPILLWAY)
Using Rational Formula Ccum = 0.70
1100 = s;°n $t inmr
.;w.
A = 2.44 ac
Q100 = 13.70 cfs
Using Francis Formula (Q=3.33LH'*5) solve for H:
H 100 = 1.20 feet
9. DETERMINE Q100 STAGE OVER EMERGENCY SPILLWAY (TOP BERM ELEV.)
Assume primary spillway blocked (i.e., emergency spillway to accommodate Q100)
Emergency spillway shall be a broad crested earthern weir designed to pass 100 year storm.
Using broad crested weir equation H = (QICw x L)213

f •/ v "1 r i
'A'wFl F..�� 1,. r .`?�• YiR Lrr.� . .r .. wr
.. � w�.7p ,��Y 1. .f'.. ..I1.• ,
- l r

r
where: Q = Q100 13.70 cfs
Cw = 3.0
Length - #-{r°€{{} feet
H = 0.59 feet
10. FOREBAY SIZING
Size forebay to include approx. 20% of total volume:
Approx. Total Volume = 13,131 CF (using average end method)
Desired Forebay Volume = 2,626 CF
✓¢7wrhEr' ?7WU108 = 1.6ZO a {c.4tn9 avo,raJo � e.�/meThmr�}
11. SUMMARY
Pond Dimensions:
Length = 116.19
Width = 38.73
Pond Elevations:
Top Berm (minimum)
H= 0.59
100-Yr. Flood
H100 = 1.20
10-Yr. Flood
N10 = 0.93
1-inch Storage
storage depth = 1.04
Permanent Pool
Pond depth = 5
Pond Bottom
Relative
Actual
7.83
44.48
7.24
43.89 (emergency weir eleva`,iovl1
6.97
43.62
6.04
42.69 (primary weir elevation'
5.00
41.65 (invert out elevation)
0.,_<+

r

where: Q = Q100 13.70 cfs
Cw = 3.0
Length .<y<;r>:.x,#ya";feet
R = 0.59 feet
FQRESAY SIZING �� ��5ur1�5 TdEGij,V�•-UC.�'`�?�
Size forebay to include approx. 20% of total volume:
Approx. Total Volume = 13 131 CF (using average end method)
Desired Forebay Volume = 2,626 CF
11. SUMMARY
Pond Dimensions:
Length =
Width =
Pond Elevations:
Top Berm (minimum)
100-Yr, Flood
10-Yr. Flood
RECEIVED
JUN 2 7 2002
116.19 OWQ
38.73 PROJ 4 5wy 0 ZGZDC4
H= 0.59
H100 = 1.20
H10 = 0.93
1-inch Storage
storage depth = 1.04
Permanent Pool
pond depth = 5
Pond Bottom
r
F,�T'��.yt `,/ �/Z//`rG._,7-'i� .'.'Lz.==Jim'`-•�,%TZ;�
.0
0, y, -7
1 Z ti,
p Z--
I
Relative Actual
7.83 . 44.48
7.24 43.89 (emergency weir eleva
6.97 43.62
6.04 42.69 (primary weir elevation
5.00 41.65 (invert out elevation)
MOW
t
1013 off`'
?'� Pcr

RECEIVED
Trial & Error Calculation of Required Storage Depth APR 2 2 2002
DWQ PROD # 5w-FG Zd��/_�
d Al
A2
VOLUME
0
4500
4,500.00
0
0.01 0
0.01
4500
4,509.30
45.04649
0.01 0
0,02
4500
4, 518.60
90.18605
0.01 0
0.03
4500
4,527.92
135.4188
0.01 0
0.04
4500
4,537.24
180.7448
0.01 0
0.05
4500
4,546.57
226.1641
0.01 0
0.06
4500
4,555.90
271.677
0.01 0
0,07
4500
4,565.24
317.2835
0,01 0
0.08
4500
4,574.59
362.9837
0.01 0
0.09
4500
4,583.95
408.7777
0.01 0
0.1
4500
4,593.31
454.6656
0.01 0
0.11
4500
4,602.68
500.6475
0.01 0
0.12
4500
4,612.06
546.7236
0.01 0
0.13
4500
4.621.45
592.894
0.01 0
0.14
4500
4,630.84
639.1586
0.01 0
0,15
4500
4,640.24
685,5178
0.01 0
0.16
4500
4,649.64
731.9715
0.01 0
0.17
4500
4,659.06
778.5199
0.01 0
0.18
4500
4,668.48
825.1631
0.01 0
0.19
4500
4,677.91
871.9012
0.01 0
0.2
4500
4,687.34
918,7343
0.01 0
021
4500
4,696.79
965,6625
0.01 0
0.22
4500
4,706.24
1012.686
0.01 0
0.23
4500
4,715.69
1059.805
0.01 0
0.24
4500
4,725.16
1107.019
0.01 0
0.25
4500
4,734.63
1154.329
0.01 0
0.26
4500
4,744.11
1201.734
0.01 0
0.27
4500
4,753.59
1249.235
0.01 0
0.28
4500
4,763.09
1296, 832
0.01 0
0.29
4500
4,772.59
1344.525
0.01 0
0.3
4500
4,782.09
1392.314
0.01 0
0.31
4500
4.791.61
1440.199
0.01 0
0.32
4500
4,801.13
1488.181
0.01 0
0.33
4500
4,810.66
1536.259
0.01 0
0.34
4500
4,820.20
1584.433
0.01 0
0.35
4500
4,829.74
1632.705
0.01 0
0,36
4500
4,839.29
1681.072
0.01 0

It
0.37
4500
4, 848.85
1729.537
0.01 0
0,38
4500
4,858.41
1773.099
0.01 0
0.39
4500
4,867.99
1826.757
0.01 0
0.4
4500
4,877.57
1875.513
0.01 0
0.41
4500
4, 887.15
1924.366
0.01 0
0.42
4500
4,896,75
1973.317
0.01 0
0.43
4500
4,906.35
2022.365
0.01 0
0.44
4500
4,915.96
2071.51
0.01 0
0.45
4500
4.925.57
2120.754
0.01 0
0.46
4500
4,935.19
2170.095
0.01 0
0.47
4500
4,944.82
2219, 534
0.01 0
0.48
4500
4,95446
2269.071
0.01 0
0.49
4500
4,964.11
2318.706
0.01 0
0.5
4500
4,973,76
2368.44
0.01 0
0.51
4500
4,983.42
2418.271
0.01 0
0.52
4500
4,99308
2468.202
0.01 0
0.53
4500
5,002.76
2518.23
0.01 0
0.54
4500
5,012.44
2568.358
0.01 0
0.55
4500
5,022.12
2618.584
0.01 0
0.56
4500
5,031.82
2668.909
0.01 0
0.57
4500
5,041.52
2719.333
0.01 0
0.58
4500
, 5, 051.23
2769.857
0.01 0
0.59
4500
5, 060.95
2820.479
0.01 0
0.6
4500
5,070.67
2871.201
0.01 0
0.61
4500
5,080.40
2922.022
0.01 0
0.62
4500
5,090.14
2972.943
0.01 0
0.63
4500
5,099.88
3023.963
0.01 0
0.64
4500
5,109.64
3075.083
0.01 0
0.65
4500
5,119.40
3126.304
0.01 0
0.66
4500
5,129.16
3177.624
0.01 0
0.67
4500
5,138.94
3229.044
0.01 0
0.68
4500
5,148.72
3280.564
0.01 0
0.69
4500
5,158.51
3332.184
0.01 0
0.7
4500
5,168.30
3383.905
0.01 0
0.71
4500
5,178,10
3435.727
0.01 0
0.72
4500
5.187.91
3487.649
0.01 0
0.73
4500
5,197.73
3539.672
0.01 0
0.74
4500
5,207,56
3591.796
0,01 0
0.75
4500
5,217.39
3644.02
0.01 0
0.76
4500
5,227.23
3696.346
0.01. 0
0.77
4500
5,237.07
3748.773
0.01 0
0.78
4500
5,246.92
3801.301
0.01 0
0.79
4500
5,256.79
3853.93
0.01 0
0.8
4500
5,266.65
3906.661
0.01 0
0.81
4500
5,276.53
3959.494
0,01 0
0.82
4500
5,286.41
4012.428
0.01 0
0.83
4500
5,296.30
4065.464
0.01 0
0.34
4500
5,306.20
4118.602
0.01 0
0.85
4500
5,316.10
4171.842
0.01 0
0.86
4500
5,326.01
4225.184
0.01 0

0.87
4500
5,335.93
4278.628
0.01
0
0.88
4500
5,345.85
4332.175
0.01
0
0.89
4500
5,355.78
4385.824
0.01
0
0.9
4500
5,365.72
4439.576
0.01
0
0.91
4500
5,375.67
4493.43
0.01
0
0.92
4500
5,385.63
4547.388
0.01
0
0.93
4500
5,395,59
4601.448
0.01
0
0.94
4500
5,405.55
4655.611
0.01
0
0.95
4500
5,415.53
4709.877
0.01
0
0.96
4500
5,425.51
4764.246
0.01
0
0.97
4500
5,435.50
4818, 719
0.01
0
0.98
4500
5,445.50
4873.295
0.01
0
0.99
4500
5,455.50
4927.975
0.01
0
1
4500
5,465.52
4982.758
0.01
0
1.01
4500
5,475.53
5037.645
0.01
0
1.02
4500
5,485.56
5092.636
0.01
0
1.03
4500
5,495,59
5147.731
0.01
0
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505,63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202,93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505,63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5, 505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202,93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505,63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505.63
5202,93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04
1.04
4500
5,505,63
5202.93
0
1.04
1.04
4500
5,505.63
5202,93
0
1.04
1.04
4500
5,505.63
5202.93
0
1.04