SW8950317_HISTORICAL FILE_20170720

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW8 qs 0311
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
L� HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
2U 11 0 1 20
YYYYMMDD

Casmer, Jo
From:
Casmer, Jo
Sent:
Tuesday, May 23, 2017 8:59 AM
To:
Newsom, David
Subject:
Onslow Memorial Hospital; Stormwater Permit SW8 950317
The Wilmington Regional Office of the Division of Energy. Mineral, and Land Resources (Stormwater Section)
accepted the Stormwater Permit Application and $505.00 fee on May 22, 2017. The project has been assigned to
Kelly Johnson and you will be notified if additional information is needed. Please be advised that no construction
activities may commence until the Stormwater Permit is issued.
The application did not reflect an email address for the applicant so we ask you please provide this status to them.
Jo Casmer
Administrative Assistant for DEMLR/Stormwater Section
North Carolina Department of Environmental Quality
Department of Environmental Assistance & Customer Service
910 796-7336 office
910 350-2004 fax
lo.casmer(o)ncdenr.gov
127 Cardinal Drive Extension
Wilmington, NC 28405
-,Nlothing . . .
v + _
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
1

/ 1 Completeness Review Checklist (S i7
Project Name: }�� y���- j st t; c �e Received Date:
Project Location: 00Y'� U c cam, h` — _ r)' 1 > fh,,, ik&ccepted Date:
Rule(s) 1:12008 Coastal 1:11995 Coastal Phase II (WiRO) Universal �1988 Coastal
Type of Permit: New or Mod or PR Existing Permit # (Mod or PR): q5n 3 ( nPE Cert on File?
Density: H or LD Type: Commercial or Residential �NCG:
%: OK?) Stream Class: E]SA Map �Off site to SW8
Subdivided?: Subdivision or Single Lot nORW Map nExempt
Paperwork Emailed Engineer on:
Supplement(s) (1 original per BMP) BMP Type(s):
�&M with correct/original signatures (1 original per BMP except LS/VFS and swoles)
pplication with correct/original signatures OS—ee'd
nCorp or LLC: Sig. Auth. per SoS or letter Email Address: Design Engineer
$505 (within 6mo) Email Address: Owner
Soils Report with SHWT rl'"S�J �°� � ❑ Note weaver: �
alculations (signed/sealed) 4 I
�
MNo obvious errors �eC�.Q
Density includes common areas, etc
Deed Restrictions, if subdivided:
Signed & Notarized
5� -- VY-k-� c zc i -7.
Plans
02 Sets
Nub
tails (roads, cul-de-sacs, curbs, sidewalks, BMPs, Buildings, et
�� `� ✓
Grading
Wetlands: Delineated
or No Wetlands
OV icinity Map
[26yout (
imen ' ns) � � �` �° f
6r J J—
Legend
�DA Maps
Project Boundaries
J L`-d
Infiltration
Wet Pond
Offsite
Soils Report >
J'
Soils Report
�PE Cert for Master Lot #:
SHWT:
SHWT:
Deed Rest for Master ED Lot # Matches Master
Bottom:
PP:
BUA Permitted (Master):
sf
Visited.
BUA Proposed (Offsite):
sf
Additional Information:
Permitted
Proposed:
Proposed: Proposed:
BUA (sf)
DA (sf)
PP (el)
SHWT (el)
Depth (ft)
SA (sf)

JOHN L. PIERCE & ASSOCIATES, P.A.
LAND SURVEYING — LAND PLANNING — MAPPING
P.O. 13OX 1685
JACKSONVILLE, NC 28541
OFFICE: [phone] FAX: [phone]
E-MAIL, bettvbnjll2m.com
OrbrianiCa 1pno.com
TO: Ms. Georgette Scott -State Stormwater
Program Supervisor
N.C. Department of Environment and Natural
. Resources —Division of Energy. Mineral & Land
Resources/Land Quality Section
127 Cardinal Drive Extension
Wilmington, NC 28405
Letter of Transmittal
DATE:
Mav 18, 2017
ATTENTION:
Georgette Scott
Re:
Onslow Memorial lion ital-SW8950317
COPIES DATE NUMBER DESCRIPTION
2 Original signed & notarized "Page 6 of 6" of the Stormwater
application to accompany previously submitted application dated
4/24/17
@,Y 9 ZO
SIGNED: Betty Bullock b a
�L

Scott, Georgette
From: Scott, Georgette
Sent: Wednesday, May 17, 2017 3:20 PM
To: 'David Newsom'
Subject: RE: Onslow Memorial Hospital (Wet Pond 1 Retrofit) SW8 950317
Importance: High
David,
Have not received the notarized signatures for this project. I will have to return next week if I don't get
this. Can you tell be the status?
Georgette Scott
State Stormwater Program Supervisor
Department of Environmental Quality
Office [phone]
Fax [phone]
Georgette. Scott(cD ncdenr. g ov
127 Cardinal Drive Ext
Wilmington, NC 28405
Nothing Compares
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third padres.
From: Scott, Georgette
Sent: Tuesday, May 02, 2017 2:12 PM
To: 'David Newsom' <[e-mail]>
Subject: RE: Onslow Memorial Hospital (Wet Pond 1 Retrofit) SW8 950317
']'hanks!
Georgette Scott
State Stormwater Program Supervisor
Department of Environmental Quality
Office [phone]
Fax [phone]
Georgette.Scottno ncdenr qov
127 Cardinal Drive Ext.
Wilmington, NC 28405
(Nothing Compares, -
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third patties.

Scott, Georgette
From: Scott, Georgette
Sent: Monday, May 01, 2017 3:52 PM
To: David Newsom
Cc: Betty Bullock ([e-mail])
Subject: Onslow Memorial Hospital (Wet Pond 1 Retrofit) SW8 950317
David,
Looked through the application. Before I accept 1 need the original notarized signature (on page 6 of the
application) of David Cotton, Interim County Manger that authorizes Daniel Walker to submit this change to
the permitted pond.
Please make sure you send me the original signature and a copy for the application.
Thank you
Georgette Scott
State Stormwater Program Supervisor
Department of Environmental Quality
Office [phone]
Fax [phone]
Georg.ette.Scott(a)ncdenrgov
127 Cardinal Drive Ext
Wilmington, NC 28405
Nothing Compares,_
�i C' -
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

JOHN L. PIERCE & ASSOCIATES, P.A.
LAND SURVEYING — LAND PLANNING — MAPPING
P.O. BOX 1685
JACKSONVILLE. NC 28541
OFFICE:[phone] FAX: [phone]
E-MAIL:bett bajlpnc.com
Or brian'iou ilpnacom
TO: Mr. Steven Puse
N.C. Department of Environment and Natural
. Resources —Division of Energy, Mineral & Land
Resources/Land Quality Section
127 Cardinal Drive Extension
Wilmington. NC 28405
Letter of Transmittal
DATE
April 24. 2017
ATTENTION
Mr Steven Pusev
Re:
Onslow Memorial Hos nal-SW8950317
COPIES DATE NUMBER DESCRIPTION
2 Sets of plans
2 Stormwater applications with calculations for pond modification
I Check in the amount of $505.00
2 Narrative
1 Copy of Deed of Record
SIGNED: Betty Bullock by: E) OIMA kIPJ.

Stormwater Treatment Narrative
Parking -ER & Surgical Pavilion — Onslow Memorial Hospital
(Wet Pond No. 1 Retrofit)
Onslow County owns a 44.92 acres tract located on Western Blvd within the city limits of
Jacksonville, NC. In 2012, DWQ issued SW8 950317 Mod 2 to Onslow Memorial
Hospital. That permit required the Permittee to apply for a future "modification to
expand the wet detention pond (Pond No. 1)". That expansion "will need to be designed
to handle 295,594 (pre 1988 + newer) square feet of BUA, plus any future BUA"
requirements.,
Existing Wet Pond No. 1 is located in the northwestern section of the site as shown on the
attached Construction Drawings. This project will retrofit (enlarge) that existing pond to
accommodate the above specified 295,594 sf BUA, plus an allowance for 14,742 sf of
future unspecified BUA.
The project site is located in the White Oak River basin. The site is relatively flat (0.6%-
1.5% slopes).
This pond enlargement has been designed to meet the Coastal Stormwater Rules, and
according to current BMP Manual Specifications. The stormwater pond has been
designed with a connected forebay and main pond. Runoff generated from new
impervious surfaces on site will be diverted to the forebay via inlets and underground
storm drain pipes. Treated Stormwater will exit the main pond via the outlet
structure/18" outlet pipe and underground storm drain pipes and into a nearby swale.

Crystal Coast Engineering, PA
205-3 Ward Road = `t
Swansboro, INC 28584 18
910-325-0006 L:
Business License: C-2553 '; q!'FV t7AE` i
Design Calculations
Stormwater Treatment Facilities
for
Onslow Memorial Hospital - Wet Pond No. 1 Retrofit
located in
Onslow County
1. PROJECT DESCRIPTION
Pond enlargement to bring Permittee into compliance with SW Permit SW8 950317 Mod 2.
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
Off -site
Sub -Total
FUTURE (unspecified)
FUTURE(reserved)
Total
Total Area Drainage to Pond:
Percent Impervious =
EK9t9
Proposed
84,329
0
0
0
182,504
0
23,383
0
0
0
5,378
0
295,594
0
Total
84,329 SF
0 SF
182,504 SF
23,383 SF
0
5,378
295,594 SF
0 14 742 14,742 SF
0 0 0
295,594 14,742 310,336 SF
0.522 or 52.2 %
594,158 SF
ECE1VG
Apo 2 5 2017
b. Compute Pond Surface Area gy.
Using Surface Area toto— Drainage eArea Ratio Chart for 90% TSS Removal (copy attached) and
assuming foot pond depth:
SA/DA = 3.68 % (interpolated - Select from Highlighted Cell in SA/DA)
Therefore:
Surface Area = SA/DA x Drainage Area
= 21,856 SF say 21 859 SF
must be> 21,856 SF
1A

c. Compute Minimum Pond Dimensions
Assume rectangular shape with 3:1 Length (L) to Width (W) Ratio:
Min Length = 256.06 feet
Min Width = 85.35 feet
Site conditions, however, dictate irregular shaped pond:
Hydr. Length F 260.0 feet
so, Hydr. Width (a% 84.1 feet (avg)
Actual L/W = 3.1 (irregular shape)
3. DETERMINE REQUIRED STORAGE VOLUME
Design Rainfall Depth =1 1.5 inches
Using Schuler "Simple Method":
Rv = 0.05 + 0.009(I) where I = percent impervious
Rv = 0.520 in/in
Control Volume = Design Rainfall x Rv x Drainage Area
Control Volume = 38,626 CF
4. DETERMINE REQUIRED STORAGE DEPTH
Assume: 3:1 side slopes
solving for depth (d) by trial & error:
d = 1 64
5. 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 3-1/2 day period:
D = (Q / 0.026 (h) 5).5
Where: Q = (Control Volume / 3.5 days x 86,400 sec/day)
= 0.131 cfs
Solving for D:
h=D/3
= 0.55
D = 2.61 Use 2.50 " pipe
say 11110W—M-2-21 CF
Must be > 38,626 SF

Actual Drawdown with actual drawdown pipe diameter (using orifice equation):
Q= 0.120 cfs
Draw Down Period = 3.72 days OK , < 5 0
6. SELECT OUTLET STRUCTURE SIZE
Size outlet structure such that depth of Q10 flow < or + to 1.5 Feet
Using Rational Formula (Q=CIA) where:
Cimper = 0.9
Cpery = 0.2
Ccum = 0.57
110 = 7.16 in/hr
A = 13.64 ac
Q10 = 55 24 cfs
Using Francis Formula (Q=3.OLH1'5) to solve for L such that H = 1.5 Feet
Min L = 10.023 Linear Feet
Use 12 Linear Foot Weir
Use 13 Square Precast Structure
7. DETERMINE Q10 STAGE
Q10 = 55.24 cfs
From Routing Analysis, H10 = 2.63
8. DETERMINE Q100 STAGE (ELEV. OF EMERGENCY SPILLWAY)
Using Rational Formula (Q=CIA) where:
Cimper = 0.9
Cpery = 0.2
Ccum = 0.57
1100 = 9.50 in/hr
A= 13.64 ac
Q100 = 73.29 cfs
From Routing Analysis, H100 = 3.15
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 = (Q/(Cw x L))ti'
where: Q = Q100 73.29 cfs
Cw = 3.0
Length = 30 feet
H = 0.87 feet
10. FOREBAY SIZING
Compute Actual Pond Volumes (using average end method):
Avg
Incr. Incr.
Cum.
Main Bay Volume :
Elevation Area SF
Area SF
Depth (FT) Vol (CF)
Vol (CF)
Pond Bottom
22.00 3,273
Bottom Veg Shelf
31.50 13,479
8,376
9.50 79,572
79,572
Normal Pond
32.00 16,693
15,086
0.50 7,543
87,115
Main Bay Volume = 87,115 CF
Forebay Volume 7 Elevation Area SF Area SF Depth (FT) Vol (CF) Vol (CF)
Pond Bottom 24.00 361
Normal Pond 32.001 5.166 2,764 8.00 22,108 22,108
Forebay Volume = 22,108 CF
Total Pond Volume = 109,223 CF
Total Pond Area = 21,859 SF
Forebay Volume equates to 20.2 % of Total Volume
Must be > 18% and < 22%
Average Pond Depth = 5.00 feet
Compare to assumed Depth 5.00 feet
Temp. Storage Volume Elevation Area SF Area SF Depth FT Vol (CF) Vol CF
Normal Pond 32.00 21,859
Temp. Pond Level 33.64 ' 26,3381 24,099 1.64 39,522 39,522
Temporary Level should be 33.64 or greater
Temp. Pool Volume = 39,522 CF
11. SUMMARY
Pond Elevations:
Top Berm (minimum)
Relative Actual
15.66 36.02
�j

100-Yr. Storm
10-Yr. Storm
Temporary Storage
Permanent Pool
Pond Bottom
12. WET DETENTION BASIN SUPPLEMENT
Site Characteristics 594,158sf
Drainage Area 310,336 sf
Impervious Area 522 %
% Impervious 1.5 in
Design Rainfall Depth
Storage Volume
Min. Volume Required 38,626 cf
Volume Provided 39,522 cf
Peak Flow Calculations
1-yr. 24 hour rainfall depth
3.65
in
Rational C, predevelopment
0.15
Rational C, post development
0.57
Rainfall Intensity 1 yr 24 hr
0.15 in/hr
Pre Dev Q1(24 hour)
0.31 cfs
Post Dev Q1 (24 hour)
1.17 cfs
Pre/Post Flow Control
0.86 cfs
Basin Elevations
H= 0 87
H100 = 3 15
H10 = 2.63
Storage depth = 1.64
pond depth = 1000
Basin Bottom Elevation
21.00 feet (Elev)
Sediment Cleanout Elevation
22.00 feet (Elev)
Permanent Pool Elevation
32.00 feet (Elev)
Temporary Pool Elevation
33.64 feet (Elev)
Volume and Surface Area Calculations
SA/DA ratio
3.68
Surface Area Required
21,856 sf
Surface Area Provided
21,859 sf
Permanent Pool Volume
109,223 cf
Average Depth
5.00 feet
Forebay Volume
22,108 cf
Forebay % of Total Volume
20.2 %
Temporary pool Area
26,338 sf
14.79 35.15 (emerg. weir elev)
14.27 34.63
11.64 33.64 (primary weir elev)
10.00 32.00 (invert out elev)
0 22.00
�j

Drawdown Calculations
Drawdown Time
3.72 days
Discharge Rate
0.120 cfs
Pre Dev Q1(24 hour)
0.31 cfs
Post Dev 01 (24 hour)
0.12 cfs
Additional Information
Diameter of orifice
2.50 in
Design TSS Removal
90 %
Basin Side Slopes
3 ;1
Vegetated Shelf Slope
10 :1
Vegetated Shelf Width
10 ft
Length to Width Ratio
3 ;1
Trash Rack?
Yes
Freeboard Provided?
Yes
Vegetated Filter Provided?
No
Recorded Easement?
Yes
Captures all Runoff?
Yes
Drain Mechanism
Pump
Y6

Simplified Routing Procedure - 10
Year Storm
=
1 8
Crystal Coast Engineering P
Project:
Onslow Memorial Hospital
-Pond 1 Enlargement
- •'.
h• . �.� :'b��;'
205-3 Ward Road
Swansboro, NC 28584
Date:
14115/2017
�1'
910-325-0006
Business License:
C-25531�minutes
Increment
�
(Must be <
30
minutes)
Orifice Weir
Pump
Total
Total
Time
Time
Inflow(cfs)
Inflow
Stored Volume
Stage
Water Surface
Outflow Outflow
Outflow
Outflow
Outflow
min
da s
cfs
cif
cj)f
u
Elevation
cfs) (cfs)
(cfs)
(Cfs
cif
0
0.0
0.00
0.00
0
0.00
32.00
0.00
0.00
0.00
0.00
0
1
0.0
0.15
8.79
9
0.00
32.00
0.00
0.00
0.00
0.00
0
2
0.0
0.58
35.07
44
0.00
32.00
0.01
0.00
0.00
0.01
1
3
0.0
1.31
78.55
122
0.01
32.01
0.01
0.00
0.00
0.01
1
4
0.0
2.31
138.78
259
0.02
32.02
0.02
0.00
0.00
0.02
1
5
0.0
3.59
215.12
473
0.03
32.03
0.03
0.00
0.00
0.03
2
6
0.0
5.11
306.76
778
0.04
32.04
0.03
0.00
0.00
0.03
2
7
0.0
6.88
412.72
1189
0.07
32.07
0.04
0.00
0.00
0.04
3
8
0.0
8.86
531.88
1718
0.09
32.09
0.05
0.00
0.00
0.05
3
9
0.0
11.05
662.98
2378
0.12
32.12
0.06
0.00
0.00
0.06
3
10
0.0
13.41
804.63
3180
0.16
32.16
0.07
0.00
0.00
0.07
4
11
0.0
15.92
955.32
4131
0.21
32.21
007
0.00
000
0.07
4
12
0.0
18.56
1113.46
5240
0.26
32.26
0.08
0.00
0.00
0.08
5
13
0.0
21.29
1277.36
6512
0.31
32.31
0.09
0.00
0.00
0.09
5
14
0.0
24.09
1445.30
7952
0.37
32.37
0.10
0.00
0.00
0.10
6
15
0.0
26.92
1615.48
9562
0.44
32.44
0.11
0.00
0.00
011
7
16
0.0
29.77
1786.11
11341
0.52
32.52
0.12
0.00
0.00
0.12
7
17
0.0
32.59
1955.36
13289
0.60
32.60
0.13
0.00
0.00
0.13
8
18
0.0
35.36
2121.46
15403
0.68
32.68
0.14
0.00
0.00
0.14
8
19
0.0
38.04
2282.63
17678
0.78
32.78
0.14
0.00
0.00
0.14
9
20
0.0
40.62
2437.16
20106
0.87
32.87
0.15
0.00
0.00
0.15
9
21
0.0
43.06
2583.42
22680
0.97
32.97
0.16
0.00
0.00
0.16
10
22
0.0
45.33
2719.86
25391
1.08
33.08
0.17
0.00
0.00
0.17
10
23
0.0
47.42
2845.02
28225
1.19
33.19
0.18
0.00
0.00
0.18
11
24
0.0
49.29
2957.58
31172
1.30
33.30
0.19
0.00
0.00
0.19
11
25
0.0
50.94
3056.34
34217
1.42
33.42
0.20
0.00
0.00
0.20
12
26
0.0
52.34
3140.27
37346
1.53
33.53
0.20
0.00
0.00
0.20
12

27
0.0
53.47
3208.46
40542
1.65
33.65
0.21
0.06
0.00
0.27
16
28
0.0
54.34
3260.19
43786
1.77
33.77
0.22
1.76
0.00
1.98
119
29
0.0
54.92
3294.92
46962
1.89
33.89
0.23
4.52
0.00
4.75
285
30
0.0
5520
3312.28
49990
2.00
34.00
0.23
7.83
0.00
8.06
484
31
0.0
55.20
3312.08
52818
2.10
34.10
0.24
11.40
0.00
11.64
698
32
0.0
54.91
3294.32
55414
2.20
34.20
0.24
15.04
0.00
15.28
917
33
0.0
54.32
3259.20
57756
2.28
34.28
0.25
18.58
0.00
18.83
1130
34
0.0
53.45
3207.08
59834
2.36
34..36
0.25
21.91
0.00
22.16
1330
35
0.0
52.31
3138.52
61642
2.42
34.42
0.26
24.95
0.00
25.20
1512
36
0.0
50.90
3054.24
63184
2.48
34.48
0.26
27.63
0.00
27.89
1673
37
0.0
49.25
2955.15
64466
2.52
34.52
0.26
29.93
0.00
30.19
1811
38
0.0
47.37
2842.29
65497
2.56
34.56
0.26
31.81
0.00
32.08
1925
39
0.0
45.42
2725.23
66298
2.59
34.59
0.26
33.30
0.00
33.57
2014.
40
00
43.52
2611.43
66895
2.61
34.61
0.27
34.43
0.00
34.69
2082
41
0.0
41.71
2502.38
67316
2.63
34.63
0.27
35.23
0.00
35.49
2130
42
0.0
39.96
2397.88
67584
2.64
34.64
0.27
35.74
0.00
36.01
2160
43
00
38.30
2297.75
67721
2.64
34.64
0.27
36.00
0.00
36.27
2176
44
0.0
36.70
2201.80
67747
2.64
34.64
0.27
36.05
0.00
36.32
2179
45
0.0
35.16
2109.85
67678
2.64
34.64
0.27
35.92
0.00
36.19
2171
46
0.0
33.70
2021.74
67528
2.63
34.63
0.27
35.63
0.00
35.90
2154
47
0.0
32.29
1937.32
67312
2.63
34.63
0.27
35.22
0.00
35.49
2129
48
00
30.94
1856.42
67039
2.62
34.62
0.27
34.70
0.00
34.97
2098
49
0.0
29.65
1778.89
66720
2.60
34.60
0.26
34.10
0.00
34.36
2062
50
0.0
28.41
1704.61
66363
2.59
34.59
0.26
33.43
0.00
33.69
2021
51
0.0
27.22
1633.43
65975
2.58
34.58
0.26
32.70
0.00
32.96
1978
52
0.0
26.09
1565.22
65562
2.56
34.56
0.26
31.93
0.00
32.20
1932
53
0.0
25.00
1499.85
65130
2.55
34.55
0.26
31.14
0.00
31.40
1884
54
0.0
23.95
1437.22
64683
2.53
34.53
0.26
30.32
0.00
30.58
1835
55
0.0
22.95
1377.20
64226
2.52
34.52
0.26
29.49
0.00
29.75
1785
56
0.0
21.99
1319.69
63760
2.50
34.50
0.26
28.66
0.00
28.91
1735
57
0.0
21.08
1264.58
63290
2.48
34.48
0.26
27.82
0.00
28.08
1685
58
0.0
20.20
1211.78
62817
2.47
34.47
0.26
26.98
0.00
27.24
1635
59
0.0
19.35
1161.17
62344
2.45
34.45
0.26
26.16
0.00
26.41
1585
60
0.0
18.54
1112.68
61872
2.43
34.43
0.26
25.34
0.00
25.60
1536
61
0.0
17.77
1066.22
61402
2.41
34.41
0.25
24.54
0.00
24.79
1487
62
0.0
17.03
1021.69
60936
2.40
34.40
0.25
23.75
0.00
24.00
1440
63
0.0
16.32
979.03
60475
2.38
34.38
0.25
22.97
0.00
23.23
1394
v/

64
0.0
15.64
938.15
60020
2.36
34.36
0.25
22.22
0.00
22.47
1348
65
0.0
14.98
898.97
59570
235
34.35
0.25
21.48
0.00
21.73
1304
66
0.0
14.36
861.43
59128
2.33
34.33
0.25
20.76
0.00
21.01
1261
67
0.0
13.76
825.46
58693
2.32
34.32
0.25
20.06
0.00
20.31
1219
68
0.0
13.18
790.99
58265
2.30
34.30
0.25
19.38
0.00
19.63
1178
69
0.0
12.63
757.96
57846
2.29
34.29
0.25
18.72
0.00
18.97
1138
70
0.0
12.11
726.30
57434
2.27
34.27
0.25
18.08
0.00
18.33
1100
71
0.0
11.60
695.97
57030
2.26
34.26
0.25
17.46
0.00
17.70
1062
72
0.1
11.12
666.91
56635
2.24
34.24
0.25
16.85
0.00
17.10
1026
73
0.1
10.65
639.06
56248
2.23
34.23
0.24
16.27
0.00
16.52
991
74
0.1
10.21
612.37
55869
2.22
34.22
0.24
15.71
0.00
15.95
957
75
0.1
9.78
586.80
55499
2.20
34.20
0.24
15.16
0.00
15.41
924
76
0.1
9.37
562.30
55137
2.19
34.19
0.24
14.64
0.00
14.88
893
77
0.1
8.98
538.82
54783
2.18
34.18
0.24
14.13
0.00
14.37
862
78
0.1
8.61
516.32
54437
2.16
34.16
0.24
13.63
0.00
13.87
832
79
0.1
8.25
494.75
54100
2.15
34.15
0.24
13.16
0.00
13.40
804
80
0.1
7.90
474.09
53770
2.14
34.14
0.24
12.70
0.00
12.94
776
81
0.1
7.57
454.30
53448
2.13
34.13
0.24
12.26
0.00
12.49
750
82
0.1
7.26
435.33
53133
2.12
34.12
0.24
11.83
0.00
12.07
724
83
0.1
6.95
417.15
52827
2.10
34.10
0.24
11.41
0.00
11.65
699
84
0.1
6.66
399.73
52527
2.09
34.09
0.24
11.02
0.00
11.25
675
85
0.1
6.38
383.03
52235
2.08
34.08
0.24
10.63
0.00
10.87
652
86
0.1
6.12
367.04
51950
2.07
34.07
0.24
10.26
0.00
10.50
630
87
0.1
5.86
351.71
51672
2.06
34.06
0.24
9.90
0.00
10.14
608
88
0.1
5.62
337.02
51400
2.05
34.05
0.24
9.56
0.00
9.79
588
89
0.1
5.38
322.95
51136
2.04
34.04
0.23
9.23
0.00
9.46
568
90
0.1
5.16
309.46
50878
2.03
34.03
0.23
8.91
0.00
9.14
548
91
0.1
4.94
296.54
50626
2.02
34.02
0.23
8.60
0.00
8.83
530
92
0.1
4.74
284.16
50380
2.02
34.02
0.23
8.30
0.00
8.53
512
93
0.1
4.54
272.29
50141
2.01
34.01
0.23
8.01
0.00
8.24
495
94
0.1
4.35
260.92
49907
2.00
34.00
0.23
7.73
0.00
7.96
478
95
0.1
4.17
250.03
49679
1.99
33.99
0.23
7.46
0.00
7.70
462
96
0.1
3.99
239.58
49457
1.98
33.98
0.23
7.21
0.00
7.44
446
97
0.1
3.83
229.58
49240
1.97
33.97
0.23
6.96
0.00
7.19
431
98
0.1
3.67
219.99
49029
1.97
33.97
0.23
6.72
0.00
6.95
417
99
0.1
3.51
210.81
48823
1.96
33.96
0.23
6.49
0.00
6.72
403
100
0.1
3.37
202.00
48622
1.95
33.95
0.23
6.26
0.00
6.49
390

101
0.1
3.23
193.57
48426
1.94
33.94
0.23
6.05
0.00
6.28
377
102
0.1
3.09
185.48
48235
1.94
33.94
0.23
5.84
0.00
6.07
364
103
0.1
2.96
177.74
48048
1.93
33.93
0.23
5.64
0.00
5.87
352
104
0.1
2.84
170.32
47866
1.92
33.92
0.23
5.45
0.00
5.68
341
105
0.1
2.72
163.20
47689
1.92
33.92
0.23
5.26
0.00
5.49
329
106
0.1
2.61
15639
47516
1.91
33.91
0.23
5.08
0.00
5.31
319
107
0.1
2.50
149.86
47347
1.90
33.90
0.23
4.91
0.00
5.14
308
108
0.1
2.39
143.60
47183
1.90
33.90
0.23
4.74
0.00
4.97
298
109
0.1
2.29
137.60
47022
1.89
33.89
0.23
4.58
0.00
4.81
288
110
0.1
2.20
131.86
46866
1.89
33.89
0.23
4.43
0.00
4.65
279
111
0.1
2.11
126.35
46713
1.88
33.88
0.23
4.28
0.00
4.50
270
112
0.1
2.02
121.07
46564
1.88
33.88
0.22
4.13
0.00
4.36
261
113
0.1
1.93
116.02
46418
1.87
33.87
0.22
3.99
0.00
4.22
253
114
0.1
1.85
111.17
46277
1.87
33.87
0.22
3.86
0.00
4.08
245
115
0.1
1.78
106.53
46138
1.86
33.86
0.22
3.73
0.00
3.95
237
116
0.1
1.70
102.08
46003
1.86
33.86
0.22
3.60
0.00
3.83
230
117
0.1
1.63
97.82
45871
1.85
33.85
0.22
3.48
0.00
3.71
222
118
0.1
1.56
93.74
45743
1.85
33.85
0.22
3.37
0.00
3.59
215
119
0.1
1.50
89.82
45617
1.84
33.84
0.22
3.25
0.00
3.48
209
120
0.1
1.43
86.07
45495
1.84
33.84
0.22
3.14
0.00
3.37
202

50.00
1 11
N
30.00
3
0
20.00
10.00
1 11
1 11 21 31 41 51 61 71 81 91 101 111 121
Time (minutes)
—Inflow
—Outflow

Simplified Routing Procedure - 100 Year Storm
=
^r
Crystal Coast
Engineering, R
-
205-3 Ward Road
Project:
Onslow Memorial Hospital
-Pond 1 Enlargement
T
`
Swansboro, NC 28584
Date
I4/15/2017
�G 'N
i'lf�;agn,�
910-325-0006
Business License:
C-2553
Increment
r--minutes
(Must be<
47minutes)
Orifice
Weir
Pump
Total
Total
Time
Time
Inflow(cfs)
Inflow
Stored Volume
Stage
Water Surface
Outflow
Outflow
Outflow
Outflow
Outflow
min
da s
cfs
cuf
cj__)f
L)
Elevation
cfs)
(cfs)
(cfs)
(Cfs
cuf
0
0.0
0.00
0.00
0
0.00
32.00
0.00
0.00
0.00
0.00
0
1
0.0
0.08
4.89
5
0.00
32.00
0.00
0.00
0.00
0.00
0
2
0.0
0.33
19.52
24
0.00
32.00
0.01
0.00
0.00
0.01
0
3
0.0
0.73
43.85
68
0.00
32.00
0.01
0.00
0.00
0.01
1
4
0.0
1.30
77.75
145
0.01
32.01
0.02
0.00
0.00
0.02
1
5
0.0
2.02
121.07
265
0.02
32.02
0.02
0.00
0.00
0.02
1
6
0.0
2.89
173.63
437
0.03
32.03
0.03
0.00
0.00
0.03
2
7
0.0
3.92
235.19
671
0.04
32.04
0.03
0.00
0.00
0.03
2
8
00
5.09
305.48
974
0.06
32.06
0.04
0.00
0.00
0.04
2
9
0.0
6.40
384.19
1356
0.07
32.07
0.04
0.00
0.00
0.04
3
10
0.0
7.85
470.95
1824
0.10
32.10
0.05
0.00
0.00
0.05
3
11
0.0
9.42
565.40
2387
0.12
32.12
0.06
0.00
0.00
0.06
3
12
0.0
11.12
667.11
3050
0.16
32.16
0.06
0.00
0.00
0.06
4
13
0.0
12.93
775.62
3822
0.19
32.19
0.07
0.00
0.00
0.07
4
14
0.0
14.84
890.46
4708
0.23
32.23
0.08
0.00
0.00
0.08
5
15
0.0
16.85
1011.12
5715
0.28
32.28
0.09
0.00
0.00
0.09
5
16
0.0
18.95
1137.05
6846
0.33
32.33
0.09
0.00
0.00
0.09
6
17
0.0
21.13
1267.70
8109
0.38
32.38
0.10
0.00
0.00
0.10
6
18
0.0
23.37
1402.49
9505
0.44
32.44
0.11
0.00
0.00
0.11
7
19
0.0
25.68
1540.82
11039
0.50
32.50
0.12
0.00
0.00
0.12
7
20
0.0
28.03
1682.07
12714
0.57
32.57
0.12
0.00
0.00
0.12
7
21
0.0
30.43
1825.62
14532
0.65
32.65
0.13
0.00
0.00
0.13
8
22
0.0
32.85
1970.83
16495
0.73
32.73
0.14
0.00
0.00
0.14
8
23
0.0
35.28
2117.05
18604
0.81
32.81
0.15
0.00
0.00
0.15
9
24
0.0
37.73
2263.63
20859
0.90
32.90
0.16
0.00
0.00
0.16
9
25
0.0
40.17
2409.93
23259
1.00
33.00
0.16
0.00
0.00
0.16
10
26
0.0
42.59
2555.29
25805
1.10
33.10
0.17
0.00
0.00
0.17
10

27
0.0
44.98
2699.06
28494
1.20
33.20
0.18
0.00
0.00
0.18
11
28
0.0
47.34
2840.61
31323
1.31
33.31
0.19
0.00
0.00
0.19
11
29
0.0
49.66
2979.31
34291
1.42
33.42
0.20
0.00
0.00
0.20
12
30
0.0
51.91
3114.53
37394
1.54
33.54
0.20
0.00
0.00
0.20
12
31
0.0
54.09
3245.69
40628
1.66
33.66
0.21
0.08
0.00
0.29
17
32
0.0
56.20
3372.20
43983
1.78
33.78
0.22
1.91
0.00
2.13
128
33
0.0
58.22
3493.49
47348
1.90
33.90
0.23
4.91
0.00
5.14
308
34
0.0
60.15
3609.02
50649
2.03
34.03
0.23
8.62
0.00
8.86
531
35
0.0
6197
3718.29
53836
2.14
34.14
0.24
12.79
0.00
13.03
782
36
0.0
63.68
3820.81
56875
2.25
34.25
0.25
17.22
0.00
17.47
1048
37
0.0
65.27
3916.11
59743
2.35
34.35
0.25
21.76
0.00
22.01
1321
38
0.0
66.73
4003.79
62426
2.45
3445
0.26
26.30
0.00
26.56
1593
39
0.0
68.06
4083.44
64916
2.54
34.54
0.26
30.75
0.00
31.01
1860
40
0.0
69.25
4154.71
67210
2.62
34.62
0.27
35.03
0.00
35.29
2118
41
0.0
70.29
4217.30
69310
2.70
34.70
0.27
39.09
0.00
39.36
2362
42
0.0
71 18
4270.91
71219
2.76
34.76
0.27
4291
0.00
43.18
2591
43
0.0
71.92
4315.31
72944
2.83
34.83
0.28
46.45
0.00
46.72
2803
44
0.0
72.51
4350.30
74491
2.88
34.88
0.28
49.69
0.00
49.97
2998
45
0.0
72.93
4375.73
75868
2.93
34.93
0.28
52.64
0.00
52.92
3175
46
0.0
73.19
4391.49
77085
2.97
34.97
0.28
55.28
0.00
55.56
3334
47
0.0
73.29
4397.50
78149
3.01
35.01
0.28
57.62
0.00
57.91
3475
48
0.0
73.23
4393.74
79068
3.04
35.04
0.29
59.67
0.00
59.96
3598
49
0.0
73.00
4380.23
79850
3.07
35.07
0.29
61.44
0.00
61.72
3703
50
0.0
72.62
4357.02
80504
3.09
35.09
0.29
62.92
0.00
63.21
3792
51
0.0
72.07
4324.21
81036
3.11
35.11
0.29
64.13
0.00
64.42
3865
52
0.0
71.37
4281.96
81453
3.12
35.12
0.29
65.09
0.00
65.38
3923
53
0.0
70.51
4230.46
81760
3.13
35.13
0.29
65.80
0.00
66.09
3965
54
0.0
69.50
4169.92
81965
3.14
35.14
0.29
66.27
0.00
66.56
3994
55
0.0
68.34
4100.62
82072
3.15
35.15
0.29
66.52
0.00
66.81
4009
56
0.0
67.05
4022.87
82086
3.15
35.15
0.29
66.55
0.00
66.84
4011
57
0.0
65.62
3937.01
82012
3.14
35.14
0.29
66.38
0.00
66.67
4000
58
0.0
64.06
3843.43
81856
3.14
35.14
0.29
66.02
0.00
66.31
3979
59
0.0
62.41
3744.72
81622
3.13
35.13
0.29
65.48
0.00
65.77
3946
60
0.0
60.71
3642.76
81318
3.12
35.12
0.29
64.78
0.00
65.07
3904
61
0.0
5906
3543.59
80958
3.11
35.11
0.29
63.95
0.00
64.24
3855
62
0.0
57.45
3447.11
80550
3.09
35.09
0.29
63.02
0.00
63.31
3799
63
0.0
55.89
3353.26
80105
3.08
35.08
0.29
62.01
0.00
62.30
3738

64
0.0
54.37
3261.97
79629
3.06
35.06
0.29
60.93
0.00
61.22
3673
65
0.0
52.89
3173.16
79129
3.04
35.04
0.29
59.81
0.00
60.10
3606
66
0.0
51.45
3086.77
78610
3.02
35.02
0.29
58.65
0.00
58.93
3536
67
0.0
50.05
3002.73
78076
3.01
35.01
0.28
57.46
0.00
57.75
3465
68
0.0
48.68
2920.98
77532
2.99
34.99
0.28
56.26
0.00
56.55
3393
69
0.0
47.36
2841.45
76981
2.97
34.97
0.28
55.05
0.00
55.34
3320
70
0.0
46.07
2764.09
76425
2.95
34.95
0.28
53.84
0.00
54.12
3247
71
0.0
44.81
2688.84
75866
2.93
34.93
0.28
52.63
0.00
52.91
3175
72
0.1
43.59
2615.63
75307
2.91
34.91
0.28
51.43
0.00
51.71
3103
73
0.1
42.41
2544.42
74749
2.89
34.89
028
50.24
0.00
50.52
3031
74
0.1
41.25
2475.15
74193
2.87
34.87
0.28
49.06
0.00
49.34
2960
75
0.1
40.13
2407.76
73641
2.85
34.85
0.28
47.90
0.00
48.18
2891
76
0.1
39.04
2342.21
73092
2.83
34.83
0.28
46.75
0.00
47.03
2822
77
0.1
37.97
2278.44
72549
2.81
34.81
0.28
45.63
0.00
45.90
2754
78
0.1
36.94
2216.41
72011
2.79
34.79
0.27
44.52
0.00
44.80
2688
79
0.1
35.93
2156.07
71479
2.77
34.77
0.27
43.44
0.00
43.71
2623
80
0.1
34.96
2097.37
70954
2.75
34.75
0.27
42.37
0.00
42.64
2559
81
0.1
34.00
2040.26
70436
2.74
34.74
027
41.33
0.00
41.60
2496
82
0.1
33.08
1984.72
69925
2.72
34.72
0.27
40.31
0.00
40.58
2435
83
0.1
32.18
1930.68
69420
2.70
34.70
0.27
39.31
0.00
39.58
2375
84
0.1
31.30
1878.12
68924
2.68
34.68
0.27
38.34
0.00
38.60
2316
85
0.1
30.45
1826.98
68435
2.67
34.67
0.27
37.38
0.00
37.65
2259
86
0.1
29.62
1777.24
67953
2.65
34.65
0.27
36.45
0.00
36.72
2203
87
0.1
28.81
1728.86
67479
2.63
34.63
0.27
35.54
0.00
35.81
2148
88
0.1
28.03
1681.79
67012
2.61
34.61
0.27
34.65
0.00
34.92
2095
89
0.1
27.27
1636.00
66553
2.60
34.60
0.26
33.78
0.00
34.05
2043
90
0.1
26.52
1591.46
66102
2.58
34.58
0.26
32.94
0.00
33.20
1992
91
0.1
25.80
1548.13
65658
2.57
34.57
0.26
32.11
0.00
32.37
1942
92
0.1
25.10
1505.98
65221
2.55
34.55
0.26
31.31
0.00
31.57
1894
93
0.1
24.42
1464.98
64792
2.54
34.54
0.26
30.52
0.00
30.78
1847
94
0.1
23.75
1425.10
64371
2.52
34.52
0.26
29.75
0.00
30.01
1801
95
0.1
23.10
1386.30
63956
2.51
34.51
0.26
29.01
0.00
29.27
1756
96
0.1
22.48
1348.55
63549
2.49
34.49
0.26
28.28
0.00
28.54
1712
97
0.1
2186
1311.84
63148
2.48
34.48
0.26
27.57
0.00
27.83
1670
98
0.1
21.27
1276.12
62755
2.46
34.46
0.26
26.88
0.00
27.13
1628
99
0.1
20.69
1241.38
62368
2.45
34.45
0.26
26.20
0.00
26.46
1587
100
0.1
20.13
1207.58
61988
2.44
34.44
0.26
25.54
0.00
25.80
1548

101
0.1
19.58
1174.71
61615
2.42
34.42
0.26
24.90
0.00
25.16
1509
102
0.1
19.05
1142.72
61249
2.41
34.41
0.25
24.28
0.00
24.53
1472
103
0.1
18.53
1111.61
60888
2.40
34.40
0.25
23.67
0.00
23.92
1435
104
0.1
18.02
1081.35
60534
2.38
34.38
0.25
23.07
0.00
23.33
1400
105
0.1
17.53
1051.91
60187
2.37
34.37
0.25
22.49
0.00
22.75
1365
106
0.1
17.05
1023.27
59845
2.36
34.36
0.25
21.93
0.00
22.18
1331
107
0.1
16.59
995.41
59510
2.35
34.35
0.25
21.38
0.00
21.63
1298
108
0.1
16.14
968.31
59180
2.33
34.33
0.25
20.84
0.00
21.09
1266
109
0.1
15.70
941.95
58857
2.32
34.32
0.25
20.32
0.00
20.57
1234
110
0.1
15.27
916.30
58539
2.31
34.31
0.25
19.81
0.00
20.06
1204
111
0.1
14.86
891.35
58226
2.30
34.30
0.25
19.32
0.00
19.57
1174
112
0.1
14.45
867.09
57919
2.29
34.29
0.25
18.83
0.00
19.08
1145
113
0.1
14.06
843.48
57618
2.28
34.28
0.25
18.36
0.00
18.61
1117
114
0.1
13.68
820.52
57322
2.27
34.27
0.25
17.90
0.00
18.15
1089
115
0.1
13.30
798.18
57031
2.26
34.26
0.25
17.46
0.00
1770
1062
116
0.1
12.94
776.45
56745
2.25
34.25
0.25
17.02
0.00
17.27
1036
117
0.1
12.59
755.31
56464
2.24
34.24
0.25
16.60
0.00
16.84
1011
118
0.1
12.25
734.74
56188
2.23
34.23
0.24
16.18
0.00
16.43
986
119
0.1
11.91
714.74
55918
2.22
34.22
0.24
15.78
0.00
16.02
961
120
0.1
11.59
695.28
55651
2.21
34.21
0.24
15.39
0.00
15.63
938

80 00
70.00
60.00
50.00
3
40.00
0
30.00
20.00
10.00
0.00
—Inflow
—Outflow
1 11 21 31 41 51 61 71 81 91 101 111 121
Time (minutes)
5/

Crystal Coast. Engineering, PA
205-3 Ward Road
Swansboro, NC 28584 18 'Z
910-325-0006
Business License: C-2553 sa'Fv tP.IE
Design Calculations '• K. fat ;:
Stormwater _for Treatment Facilities
Onslow Memorial Hospital, We . u _ , �,y ..._
l..
t Pond No. 1 Retrofit
located in
Onslow County
1. PROJECT DESCRIPTION
Pond enlargement to bring Permittee into compliance with SW Permit SW8 950317 Mod 2.
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
Off -site
Sub -Total
FUTURE (unspecified)
FUTURE(reserved)
Total
Total Area Drainage to Pond:
Percent Impervious =
295,594 0
0 0
295,594 14,742
0.522 or 52.2 %
b. Compute Pond Surface Area
Using Surface Area to Drainsg'e Area Ratio Chart for 90% TSS Removal (copy attached) and
assuming ,X;5 foot pond depth:
SA/DA = 3.68 % (interpolated - Select from Highlighted Cell in SA/DA)
Therefore:
Surface Area = SA/DA x Drainage Area
= 21,856 SF
say
must be >
Total
84,329 SF
0 SF
182,504 SF
23,383 SF
0
5,378
295,594 SF
14,742 SF
0
310,336 SF
„" 594;958 SF
SF
21,856 SF

c. Compute Minimum Pond Dimensions
Assume rectangular shape with 3:1 Length (L) to Width (W) Ratio:
Min Length = 256.06 feet
Min Width = 85.35 feet
" "Site`conditiohs,'h6wever,"di6t6t6 irre ular"§haped;pond:
9,...
Hyde. Leridt6"=feet
so, Hydr. Width (a� 84.1 feet (avg)
Actual L/W = 3.1 (irregular shape)
3. DETERMINE REQUIRED STORAGE VOLUME
Design Rainfall Depth = ; _ 3i1�5 inches
Using Schuler "Simple Method":
Rv = 0.05 + 0.009(I) where I = percent impervious
Rv = 0.520 in/in
Control Volume = Design Rainfall x Rv x Drainage Area
Control Volume = 38,626 CF
4. DETERMINE REQUIRED STORAGE DEPTH
Assume: 3:1 side slopes
solving for depth (d) by trial & error:
d= 1.64
5. 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 3-1/2 day period:
D = (Q / 0.026 (h) s).5
Where: Q = (Control Volume / 3.5 days x 86,400 sec/day)
0.131 cfs
Solving for D:
h=D/3
= 0.55
D = 2.61 Use " pipe
say ggjgNwuE
Must be >
CF
38,626 SF

Actual Drawdown with actual drawdown pipe diameter (using orifice equation):
Q= 0.120 cfs
Draw Down Period = 3!7 days OK, < 5.0
6:-SEL•ECT OUTLET STRUCTURE�SIZE ---,.•_....................... .... _. .._,..._ .._ . ,_
Size outlet structure such that depth of Q10 flow < or + to �"`1?5?"; Feet
Using Rational Formula (Q=CIA) where:
Cimper
Cpery =0 2
Ccum = 0.57
110 = 7ri:16 in/hr
A = 13.64 ac
Q10 = 55.24 cfs
Using Francis Formula (Q=3.OLH") to solve for L such that H =
Min L = 10.023 Linear Feet
Use .512 Linear Foot Weir
Use 13 Square Precast Structure
7. DETERMINE Q10 STAGE
Q10 = 55.24 cfs
From Routing Analysis, H10 =
8. DETERMINE Q100 STAGE (ELEV. OF EMERGENCY SPILLWAY)
Using Rational Formula (Q=CIA) where:
Cimper =
0.9
Cpery =
0.2
Ccum =
0.57
1100 = in/hr
A =
13.64 ac
Q100 = 73.29 cfs
From Routing Analysis, H100 =
9. DETERMINE Q100 STAGE OVER EMERGENCY SPILLWAY (TOP BERM ELEV.)
1.5
Feet

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 = (Q/(Cw x L))213
where: Q = Q100 73.29 cfs
Cw = 3.0
Length = 30 feet
H = 0.87 feet
10. FOREBAY SIZING
Compute Actual Pond Volumes (using average end method):
Avg
Main Bay Volume :
Elevation Area SF
Area SF
Pond Bottom
2M!M—O 3127,3'
Bottom Veg Shelf
31:.50 , 13 9
8,376
Normal Pond
, . 32°OQ _1.6,693
15,086
Main Bay Volume =
87,115 CF
Forebay Volume:
Elevation Area SF
Area SF
Pond Bottom
x ; ' r 2100
36
Normal Pond
32.00
- : 5,1,66
2,764
Forebay Volume =
22,108 CF
Total Pond Volume =
109,223 CF
Total Pond Area =
21,859 SF
Incr.
Depth FT
9.50
0.50
Depth (FT)
8.00
Forebay Volume equates to 7 °% of Total Volume
Must be > 18% and < 22%
Average Pond Depth = 5.00 feet
Compare to assumed Depth feet
Temp. Storage Volume: Elevation Area SF Area SF Depth FT
NormalPond 32.00 21,859
Temp. Pond Level . W 3°6:4'' . 26;338 24,099 1.64
Temporary Level should be 33.64 or greater
Temp. Pool Volume = 39,522 CF
11. SUMMARY
Pond Elevations:
Top Berm (minimum)
Relative Actual
15.66 36.02
Incr.
Cum.
Vol (CF)
Vol CF
79,572
79,572
7,543
87,115
Vol (CF) Vol (CF)
22,108 22,108
Vol (CF) Vol CF
39,522 39,522

H= 0.87
100-Yr. Storm
14.79
35.15 (emerg. weir elev)
H100= 3.15
10-Yr. Storm
14.27
34.63
H10 = 2.63
Temporary Storage
11.64
33.64 (primary weir elev)
storage depth = 1.64
Permanent Pool
_.
,....
iieptti'= 10'00
10.00
32.00 (invert out elev)
Pond Bottom
pon.d
0
22.00 w
12. WET DETENTION BASIN SUPPLEMENT
Site Characteristics
594,158 sf
Drainage Area
310,336 sf
Impervious Area
52:2 %
% °Impervious
1.5 in
Design Rainfall Depth
Storage Volume
Min. Volume Required
38,626 cf
Volume Provided
39,522 cf
Peak Flow Calculations
1-yr, 24 hour rainfall depth
,3Rin
Rational C, predevelopment
om5
Rational C, post development
0.57
Rainfall Intensity 1 yr 24 hr
0.15 in/hr
Pre Dev Q1(24 hour)
0.31 cfs
Post Dev Q1 (24 hour)
1.17 cfs
Pre/Post Flow Control
0.86 cfs
Basin Elevations
Basin Bottom Elevation 21.00 feet (Elev)
Sediment Cleanout Elevation 22.00 feet (Elev)
Permanent Pool Elevation 32.00 feet (Elev)
Temporary Pool Elevation 33.64 feet (Elev)
Volume and Surface Area Calculations
SA/DA ratio
3.68
Surface Area Required
21,856 sf
Surface Area Provided
21,859 sf
Permanent Pool Volume
109,223 cf
Average Depth
5.00 feet
Forebay Volume
22,108 cf
Forebay % of Total Volume
20.2 %
Temporary pool Area
26,338 sf
�j

Drawdown Calculations
Drawdown Time
3.72 days
Discharge Rate
0.120 cfs
Pre Dev Q1(24 hour)
0.31 cfs
Post Dev Q1 (24 hour)
0.12 cfs
Additional Information
Diameter of orifice
2.50 in
-^Desigh`TSS`ReinoVal" ""
"' "90,%"
81' in Bide Slopes
3 ;1
Vegetated'SFi'elf'Slope
j p"; j
Vegetated Shelf Width
10 ft
Length'to Width Ratio
3 ;1
Trash Rack?
Yes
Freeboard Provided?
Yes
Vegetated Filter Provided?
No
Recorded Easement?
Yes
Captures all Runoff?
Yes
Drain Mechanism
Pump
6

is L
Simplified Routing Procedure,- 10 Year Storm
I
=
lc 8
Crystal Coast'Engineering J
Project:
Onslow1Memorial1Hos
"italVRond 19Enl�rgement
'
`• n- :CA ;'
205-3 Ward (toad-
swansboio,
Date:
G9/u1'5/201k7
. ,
n) ;.•r .O
;q� ' h ,.`'
, NC 25584
910.325-0006
p�I
rC. N�-�i'�
/�/^�
Businessilcenw
C-2553
Increment,
.�i1 minutes
(Must be <
30
minutes)
Time
Time
Inflow(cfs)'
Inflow
Stored Volume
Stage
Water Surface
Orifice Weir
Outflow Outflow
Pump
Outflow '
Total
Total
min
da s
cfs
cuf
LCD
L2
Elevation
cfs) (cfs)
,Outflow
(cfs
Outflow
LCfl
0
0.0
0.00
0.00
0
0.00
32.00
0.00
0.00
0.00
0.00
0
1
0.0
0.15
8.79
9
0.00
32.00
0.00
0.00
0.00
0.00
0
2
0.0
0.58
35.07
44
0.00
32.00
0.01
0.00
0.00`
0.01
1
3
0.0
1.31
78.55
122
0.01
32.01
0.01
0.00
t0.00
0.01
1
4
0.0
2.31
138.78
259
0.02
32.02
0.02
0.00
0.00
0.02
1
5
0.0
3.59
215.12
473
0.03
32.03
0.03
0.00
'0.00,
0.03
2
6
0.0
5.11
306.76
778
0.04
32.04
0.03
0.00
0.00
0.03
2
7
0.0
6.88
412.72
1189
0.07
32.07
0.04
0.00
0.00
0.04
3
8
0.0
6.86
531.88
1718
0.09
32.09
0.05
0.00
0.0Q-,
0.05
3
9
0.0
11.05
662.98
2378
0.12
32.12
0.06
0.00
�0.00_
a06
3
10
0.0
13'.41
804.63
3180
0.16
32.16
0.07
0.00
0.00`.
0:07
4
11
0.0
15.92
955.32
4131
0.21
32.21
0.07
0.00
.0.00`
0.07
4
12
0.0
18.56
1113.46
5240
0.26
32.26
0.08
0.00
.
000,
0.08
5
13
0.0
21.29
1277.36
6512
0.31
32.31
0.09
0.00
:0:00'€
0.09
5
14
0.0
24`.09
1445.30
7952
0.37
32.37
0.10
0.00
'0.00i
0.10
6
15
0.0
26.92
1615.48
9562
0.44
32.44
0.11
0.00
0.00;
0.11
7
16
0.0
26.77
1786.11
11341
0.52
32.52
0.12
0.00
0.001
0.12
7
17
0.0
32:59
1955.36
13289
0.60
32.60
0.13
0.00
.0.00
0.13
8
18
0.0
35.36
2121.46
15403
0.68
32.68
0.14
0.00
0.60f.
0.14
8
19
0.0
38:04
2282.63
17678
0.78
32.78
0.14
0.00
'0.00!
0.14
9
20
0.0
40:62
2437.16
20106
0.87
32.87
0.15
0.00
0.00
0.15
9
21
0.0
43.06
2583.42
22680
0.97
32.97
0.16
0.00
`O.00f
0.16
10
22
0.0
45.33
2719.86
25391
1.08
33.08
0.17
0.00
0.60
0.17
10
23
0.0
47,42
2845.02
28225
1.19
33.19
0.18
0.00
:0.dol
0.18
11
24
0.0
49.29
2957.58
31172
1.30
33.30
0.19
0.00
:0.00
0.19
11
25
0.0
5094
3056.34
34217
1.42
33.42
0.20
0.00
'0.001
0.20
12
26
0.0
52'34
3140.27
37346
1.53
33.53
0.20
0.00
0.0,
0.20
12

27
0.0
53.47
3208.46
40542
1.65
33.65
0.21
0.06
0.00
28
0.0
54.34
3260.19
43786
1.77
33.77
0.22
1.76
0.00
0.27
16
29
0.0
54.92
3294.92
46962
1.89
33.89
0.23
4.52
0.00
1.98
119
30
0.0
55.20
3312.28
49990
2.00
34.00
0.23
7.83
0.00
4.75
285
31
0.0
55.20
3312.08
52818
2.10
34.10
0.24
11.40
0.00
8.06
11.64
484
698
32
0.0
54.91'
3294.32
55414
2.20
34.20
0.24
15.04
0.00
15.28
917
33
0.0
54.32
3259.20
57756
2.28
34.28
0.25
18.58
0.00
18.83
1130
34
0.0
53.45
3207.08
59834
2.36
34.36
0.25
21.91
0.00
22.16
1330
35
0.0
5201
3138.52
61642
2.42
34.42
0.26
24.95
0.00
25.20
1512
36
37
0.0
50.90
3054.24
63184
2.48
34.48
0.26
27.63
10.00
27.89
1673
38
0.0
46.25
2955.15
64466
2.52
34.52
0.26
29.93
0.00
30.19
1811
0.0
47.37
2842.29
65497
2.56
34.56
0.26
31.81
0.00
32.08
1925
39
0.0
45.42
2725.23
66298
2.59
34.59
0.26
33.30
0.00
33.57
2014.
40
0.0
43.52
2611.43
66895
2.61
34.61
0.27
34.43
, O.OQ
34.69
2082
41
0.0
41.71
2502.38
67316
2.63
34.63
0.27
35.23
0.00
35.49
2130
42
0.0
39.9&
2397.88
67584
2.64
34.64
0.27
35.74
0.00
36.01
2160
43
0.0
36.30
2297.75
67721
2.64
34.64
0.27
36.00
0.00
36.27
2176
44
0.0
36.70
2201.80
67747
2.64
34.64
0.27
36.05
0.00'
36.32
2179
45
0.0
35.16'
2109.85
67678
2.64
34.64
0.27
35.92
t0.00
36.19
2171
46
0.0
33.70
2021.74
67528
2.63
34.63
0.27
35.63
0.00.
35.90
2154
47
0.0
32.29
1937.32
67312
2.63
34.63
0.27
35.22
0.00
35.49
2129
48
0.0
30.94•
1856.42
67039
2.62
34.62
0.27
34.70
0.00
34.97
2098
49
0.0
29.65
1778.89
66720
2.60
34.60
0.26
34.10
:0.00.
34.36
2062
50
0.0
28.41
1704.61
66363
2.59
34.59
0.26
33.43
'O.M -
33.69
2021
51
0.0
27.22
1633.43
65975
2.58
34.58
0.26
32.70
'0.00
32:96
1978
52
0.0
26.09
1565.22
65562
2.56
34.56
0.26
31.93
0.00`
32.20
1932
53
0.0
25.00
1499.85
65130
2.55
34.55
0.26
31.14
0.00F.
31.40
1884
54
0.0
23.95
1437.22
64683
2.53
34.53
0.26
30.32
O.6Oj
30.58
1835
55
0.0
22.95
1377.20
64226
2.52
34.52
0.26
29.49
0.00f
29.75
1785
56
0.0
21 99
1319.69
63760
2.50
34.50
0.26
28.66
�0.00;
28.91
1735
57
0.0
21.08
1264.58
63290
2.48
34.48
0.26
27.82
�0.00t
28'08
1685
58
0.0
20.20
1211.78
62817
2.47
34.47
0.26
26.98
O.00i.
27.24
1635
59
0.0
19.35
1161.17
62344
2.45
34.45
0.26
26.16
10.00'" _
26.41
1585
60
0.0
18:54
1112.68
61872
2.43
34.43
0.26
25.34
0.00
25.60
1536
61
0.0
17.77
1066.22
61402
2.41
34.41
0.25
24.54
0.001
24.79
1487
62
0.0
1T.03
1021.69
60936
2.40
34.40
0.25
23.75
;0.001 ':
24.00
1440
63
0.0
16.32
.979.03
60475
2.38
34.38
0.25
22.97
0.00i
23.23
1394

64
0.0
15.64
938.15
60020
2.36
34.36
0.25
22.22
65
0.0
14:98
898.97
59570
2.35
34.35
0.25
21.48
66
0.0
14136
861.43
59128
2.33
34.33
0.25
20.76
67
0.0
13 76
825.46
68693
2.32
34.32
0.25
20.06
68
0.0
13.18
790.99
58265
2.30
34.30
0.25
19.38
69
0.0
1263
757.96
57846
2.29
34.29
0.25
18.72
70
0.0
12.11
726.30
57434
2.27
34.27
0.25
18.08
71
0.0
11E60
695.97
57030
2.26
34.26
0.25
17.46
72
0.1
11:12
666.91
56635
2.24
34.24
0.25
16.85
73
0.1
1065
639.06
56248
2.23
34.23
0.24
16.27
74
0.1
10:21
612.37
55869
2.22
34.22
0.24
15.71
75
0.1
9'78
586.80
55499
2.20
34.20
0.24
15.16
76
0.1
937
562.30
55137
2.19
34.19
0.24
14.64
77
0.1
898
538.82
54783
2.18
34.18
0.24
14.13
78
0.1
8`.61
516.32
54437
2.16
34.16
0.24
13.63
79
0.1
8?25
494.75
54100
2.15
34.15
0.24
13.16
80
0.1
T90
474.09
53770
2.14
34.14
0.24
12.70
81
0.1
T57
454.30
53448
2.13
34.13
0.24
12.26
82
0.1
726
435.33
53133
2.12
34.12
0.24
11.83
83
0.1
6.95
417.15
52827
2.10
34.10
0.24
11.41
84
0.1
6.66
399.73
52527
2.09
34.09
0.24
11.02
85
0.1
638
383.03
52235
2.08
34.08
0.24
10.63
86
0.1
6?12
367.04
51950
2.07
34.07
0.24
10.26
87
0.1
5'86
351.71
51672
2.06
34.06
0.24
9.90
88
0.1
5:62
337.02
51400
2.05
34.05
0.24
9.56
89
0.1
5:38
322.95
51136
2.04
34.04
0.23
9.23
90
0.1
5:16
309.46
50878
2.03
34.03
0.23
8.91
91
0.1
4:94
296.54
50626
2.02
34.02
0.23
8.60
92
0.1
04
284.16
50380
2.02
34.02
0.23
8.30
93
0.1
4554
272.29
50141
2.01
34.01
0.23
8.01
94
0.1
4435
260.92
49907
2.00
34.00
0.23
7.73
95
0.1
4A 7
250.03
49679
1.99
33.99
0.23
7.46
96
0.1
3,99
239.58
49457
1.98
33.98
0.23
7.21
97
0.1
3:83
229.58
49240
1.97
33.97
0.23
6.96
98
0.1
367
219.99
49029
1.97
33.97
0.23
6.72
99
0.1
3°51
210.81
48823
1.96
33.96
0.23
6.49
100
0.1
337
202.00
48622
1.95
33.95
0.23
6.26
0.001
O.00§
O.=
0.00;
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O.00j
0.00
0.00!
0.00
0.00,
0.00
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0.00?
0.00
0.00;
;0.00
0.00
0.00'i
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0.00
0.001
0.003
22.47
21.73
21.01
20.31
19.63
18:97
18.33
17.70
17.10
16.52
15.95
15:41
14.88
14.37
13.87
13.40
12.94
12:49
12.07
11.65
11.25
10:87
10:50
10.14
9.79
9.46
9.14
8:83
8.53
8.24
7.96
7.70
7.44
7.19
6.95
6.72
6.49
1348
1304
1261
1219
1178
1138
1100
1062
1026
991
957
924
893
862
832
804
776
750
724
699
675
652
630
608
588
568
548
530
512
495
478
462
446
431
417
403 _
390

101
0.1
123
193.57
48426
1.94
33.94
0.23
6.05
0.00z
6.28
377
102
103
0.1
3Y09
196
185.48
48235
1.94
33.94
0.23
5.84
.0.001
6.07
364
0.1
177.74
48048
1.93
33.93
0.23
5.64
0.001
5.87
352
104
0.1
2F84
170.32
47866
1.92
33.92
0.23
5.45
;0.00f
5.68
341
105
0.1
2'72
163.20
47689
1.92
33.92
0.23
5.26
0.00l
5.49
329
106
0.1
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156.39
47516
1.91
33.91
0.23
5.08
0.00!
5.31
319
107
0.1
2'50
149.86
47347
1.90
33.90
0.23
4.91
0.00i
5.14
308
108
0.1
2:39
143.60
47183
1.90
33.90
0.23
4.74
0.00i
4.97
298
109
0.1
Z29
137.60
47022
1.89
33.89
0.23
4.58
'0.00,
4.81
288
110
0.1
2120
131.86
46866
1.89
33.89
0.23
4.43
O.00ti
4.65
279
111
0.1
2`11
126.35
46713
1.88
33.88
0.23
4.28
9.00i
4.50
270
112
0.1
2`02
121.07
46564
1.88
33.88
0.22
4.13
0.001
4.36
261
113
0.1
1:93
116.02
46418
1.87
33.87
0.22
3.99
;O.6w
4.22
253
114
0.1
1l85
111.17
46277
1.87
33.87
0.22
3.86
0.00
4.08
245
115
0.1
138
106.53
46138
1.86
33.86
0.22
3.73
0.00
3.95
237
116
0.1
1 i70
102.08
46003
1.86
33.86
0.22
3.60
0.00 -
3.83
230
117
0.1
1:63
97.82
45871
1.85
33.85
0.22
3.48
0.00
3.71
222
118
0.1
1?56
93.74
45743
1.85
33.85
0.22
3.37
'0.00�
3.59
215
119
0.1
V50
89.82
45617
1.84
33.84
0.22
3.25
0.00'
3.48
209
120
0.1
1'43
86.07
45495
1.84
33.84
0.22
3.14
'o.dof
3.37
202

i �-
�. � ��

Simplified Routing Procedure:- 100 Year Storm
Project:
Date:
Increment
Time
min
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Time
da s
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Onslow,Memor,iallHospitagG,Pond11,14Enl rgement
aniq c innittS'"cs'a`
d t `b1 minutes (Must be < 47 minutes)
Inflow(cfs)
cfs
0.00
0.08
6.33
0.73
1.30
2.02
2.89
3.92
5.09
6.40
7.85
9.42
11.12
12.93
14.84
16.85
18.95
21.13
23.37
25.68
28.03
30.43
32.85
35.28
37.73
40.17
42.59=
Inflow
im
0.00
4.89
19.52
43.85
77.75
121.07
173.63
235.19
305.48
384.19
470.95
565.40
667.11
775.62
890.46
1011.12
1137.05
1267.70
1402.49
1540.82
1682.07
1825.62
1970.83
2117.05
2263.63
2409.93
2555.29
Stored Volume
0
5
24
68
145
265
437
671
974
1356
1824
2387
3050
3822
4708
5715
6846
8109
9505
11039
12714
14532
16495
18604
20859
23259
25805
Stage
u
0.00
0.00
0.00
0.00
0.01
0.02
0.03
0.04
0.06
0.07
0.10
0.12
0.16
0.19
0.23
0.28
0.33
0.38
0.44
0.50
0.57
0.65
0.73
0.81
0.90
1.00
1.10
Water Surface
Elevation
32.00
32.00
32.00
32.00
32.01
32.02
32.03
32.04
32.06
32.07
32.10
32.12
32.16
32.19
32.23
32.28
32.33
32.38
32.44
32.50
32.57
32.65
32.73
32.81
32.90
33.00
33.10
IN
Orifice
Outflow
cfs
0.00
0.00
0.01
0.01
0.02
0.02
0.03
0.03
0.04
0.04
0.05
0.06
0.06
0.07
0.08
0.09
0.09
0.10
0.11
0.12
0.12
0.13
0.14
0.15
0.16
0.16
0.17
Weir
Outflow
cfs
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00,
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Crustal Coast Engineerina:.P,
205-3 Ward Road
Swansboro, NC;28584
910-325-0006 '
Business License: C-2563
Pump
Total
Total
Outflow=
;Outflow
Outflow
cfs
cfs
Sc1
aw"
0.00
0
,0.00?
0.00
0
0.00:
0.01
0
0.001
0.01
1
0.00_
0.02
1
0.00
0.02
1
am
0.03
2
£0.00'
0.03
2
10.00i,
0.04
2
;0.00;
0.04
3
0.00.
0.05
3
0.00
0.06
3
-0.60t
0,06
4
0.00e
0.07
4
0.001
0.08
5
0.0W
0.09
5
0.00
0.09
6
0.00,
0.10
6
0.00
0.11
7
A.00
0.12
7
0.W
0.12
7
0.001
0.13
8
0.00�
0.14
8
0.00}
0.15
9
0.60 i
0.16
9
0.00?
0.16
10
0.00t
0.17
10
s

27
0.0
4498
2699.06
28494
1.20
33.20
0.18
0.00
0.00 {
0.18
11
28
0.0
47:34
,2840.61
31323
1.31
33.31
0.19
0.00
0.00
0.19
11
29
0.0
49166
34291
1.42
33.42
0.20
0.00
0.00
0.20
12
30
0.0
5V91
.2979.31
3114.53
37394
1.54
33.54
0.20
0.00
0.001 _
0.20
12
31
0.0
54t09.
3245.69
40628
1.66
33.66
0.21
0.08
0.010
0.29
17
32
0.0
5620
3372.20
43983
1.78
33.78
0.22
1.91
Q.00 i
2.13
128
33
0.0
5&22
3493.49
47348
1.90
33.90
0.23
4.91
6.00 Y
5.14
308
34
0.0
6015
3609.02
50649
2.03
34.03
0.23
8.62
0.00€
8:86
531
35
0.0
6197
3718.29
53836
2.14
34.14
0.24
12.79
0.00!
13.03
782 .
36
0.0
6368
3820.81
56875
2.25
34.25
0.25
17.22
0.001,
17.47
1048 .
37
0.0
6527
3916.11
59743
2.35
34.35
0.25
21.76
0.00 k'
22.01
1321
38
0.0
W73
4003.79
62426
2.45
34.45
0.26
26.30
0.00x.
26:56
1593
39
0.0
6806
4083.44
64916
2.54
34.54
0.26
30.75
O.W
31.01
1860
40
0.0
69�25
4154.71
67210
2.62
34.62
0.27
35.03
0.00'
35.29
2118 .
41
0.0
70r29
4217.30
69310
2.70
34.70
0.27
39.09
0.001
39.36
2362
42
0.0
7118
4270.91
71219
2.76
34.76
0.27
42.91
0.00 1143:18
2591
43
0.0
71M
4315.31
72944
2.83
34.83
0.28
46.45
O.W
46:72
2803
44
0.0
72:'51
4350.30
74491
2.88
34.88
0.28
49.69
0.60J' _
49.97
2998
45
0.0
72.93
4375.73
75868
2.93
34.93
0.28
52.64
'O.00- _
52:92
3175
46
0.0
7319
4391.49
77085
2.97
34.97
0.28
55.28
'O.00t
55.56
3334
47
0.0
7329
4397.50
78149
3.01
35.01
0.28
57.62
0.00f -
5T91
3475
48
0.0
73i23
4393.74
79068
3.04
35.04
0.29
59.67
O.004
59.96
3598
49
0.0
731:00
4380.23
79850
3.07
35.07
0.29
61.44
O.W
61.72
3703
50
0.0
72:62
4357.02
80504
3.09
35.09
0.29
62.92
0.00f
63.21
3792
51
0.0
72.07
4324.21
81036
3.11
35.11
0.29
64.13
0.00
64:42
3865
52
0.0
71`37
4281.96
81453
3.12
35.12
0.29
65.09
'0.00i -
65:38
3923
53
0.0
70:51
4230.46
81760
3.13
35.13
.0.29
65.80
;0.0M
66709
3965
54
0.0
64.50
4169.92
81965
3.14
35.14
0.29
66.27
O.6Oi
66:56
3994
55
0.0
6834
4100.62
82072
3.15
35.15
0.29
66.52
i0.Q0r
66:81
4009
56
0.0
67c05
4022.87
82086
3.15
35.15
0.29
66.55
{O.00P
66.84
4011
57
0.0
65!62
' 3937.01
82012
3.14
35.14
0.29
66.38
10.001 _
66 67
4000
58
0.0
6406
3843.43
81856
3.14
35.14
0.29
66.02
0.00
66.31
3979
59
0.0
62'.41
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%4:

Stormwater Treatment Narrative
Parking -ER & Surgical Pavilion — Onslow Memorial Hospital
(Wet Pond No. 1 Retrofit)
.........w.....r....n.....i....l......ern.a.l.d..v.4......x.ix.r`Yar...nv...i...-dw.�..:Y-..r.wLrml4.u....vr46..-..e......: i.vY_.................. ....... .....n....nY..itiM
Onslow County owns a 44:92acrestract located,on We stem -Blvd •within -the city -limits of
Jacksonville, NC., In-2012, DWQ issued°SW8-9503,17-Mod 2,to Onslow�Memorial
Hospital. That permit required the Permittee to apply for a future "modification to
expand the wet detention pond (Pond No. 1)". That expansion "will need to be designed
to handle 295,594 (pre 1988 + newer) square feet of BUA, plus any future BUA"
requirements.,
Existing Wet Pond No. 1 is located in the northwestern section of the site as shown on the
attached Construction Drawings. This project will retrofit (enlarge) that existing pond to
accommodate the above specified 295,594 sf BUA, plus an allowance for 14,742 sf of
future unspecified BUA.
The project site is located in the White Oak River basin. The site is relatively flat (0.6%-
1.5% slopes).
This pond enlargement has been designed to meet the Coastal Stormwater Rules, and
according to current BMP Manual Specifications. The stormwater pond has been
designed with a connected forebay and main pond. Runoff generated from new
impervious surfaces on site will be diverted to the forebay via inlets and underground
storm drain pipes. Treated Stormwater will exit the main pond via the outlet
structure/18" outlet pipe and underground storm drain pipes and into a nearby swale.
M

Stormwater Treatment Narrative
Parking -ER & Surgical Pavilion — Onslow Memorial Hospital
(Wet Pond No. 1 Retrofit)
Onslow County owns a 44.92 acres tract located on Western Blvd within the city limits of
Jacksonville, NC. In 2012, DWQ issued SW8 950317 Mod 2 to Onslow Memorial
Hospital. That permit required the Permittee to apply for a future "modification to
expand the wet detention pond (Pond No. 1)". That expansion "will need to be designed
to handle 295,594 (pre 1988 + newer) square feet of BUA, plus any future BUA"
requirements.,
Existing Wet Pond No. 1 is located in the northwestern section of the site as shown on the
attached Construction Drawings. This project will retrofit (enlarge) that existing pond to
accommodate the above specified 295,594 sf BUA, plus an allowance for 14,742 sf of
future unspecified BUA.
The project site is located in the White Oak River basin. The site is relatively flat (0.6%-
1.5% slopes).
This pond enlargement has been designed to meet the Coastal Stormwater Rules, and
according to current BMP Manual Specifications. The stormwater pond has been
designed with a connected forebay and main pond. Runoff generated from new
impervious surfaces on site will be diverted to the forebay via inlets and underground
storm drain pipes. Treated Stormwater will exit the main pond via'the outlet
structure/18" outlet pipe and underground storm drain pipes and into a nearby swale.

9t5c:> 317
Scott, Georgette
From: Pusey, Steven
Sent: Friday, November 13, 2015 10.16 AM
To: Scott, Georgette
Subject: FW: Onslow Memorial Hospital
FYI,
Steve
Environmental Engineer
Division of Energy, Mineral and Land Resources — State Stormwater Program
Department of Environmental Quality
910 796 7215 office
910 796 7335 direct
Steven. ousey(a)ncdenr.gov
127 Cardinal Drive Ext.
Wilmington, NC 28405
:,' -,:.,-^Nothing Compares:,,
Ernail correspondence to and from this address is subject to the
North Carolina Public Records tat-✓ and may be disclosed to third parties.
`� h� �' Before printing this email, please consider your budget and the environment.
From: David Newsom [mailto:[e-mail]
Sent: Monday, August 24, 2015 10:35 AM
To: Pusey, Steven <[e-mail]>
Subject: RE: Onslow Memorial Hospital
I will have to make some inquiries into this.....
Not sure at moment what, if anything, they have done ...... and/or what they future plans may be.
Let me make some calls.... Back to you soon.
From: Pusey, Steven [mailto:steven.puseyCcbncdenr.gov]
Sent: Monday, August 24, 2015 10:33 AM
To: David Newsom
Subject: Onslow Memorial Hospital
Importance: High
Dave
I am following up on permit SW8 950317 for the Modification to ER Parking & the Surgical Services Pavilion at
Onslow Memorial Hospital. This permit was a temporary approval pending a modification to expand the wet

detention pond in the high density pocket in order to handle the actual BUA plus future expansion. The pond
was going to be redesigned to handle more BUA in this modification. We gave them a one year extension
which ended on July 2, 2015.
Can you please contact them and provide an update ASAP.
Thanks,
Steve
crt� c. -P
Environmental Engineer
Land Quality Section
Wilmington Regional Office
NC DENR, Division of Energy, Mineral and Land Resources
127 Cardinal Drive Ext.
Wilmington, NC 28405
Phone:[phone]
Fax: [phone],
Website: w%vw.ncdem.Vov
E-Mail: Steven. puseyawncdenr.gov
Before printing this email, please consider your budget and the environment.
Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed to third
parties unless the content is exempt by statute or other regulation.

Crustal Coast Engineering, PA
205-3 Ward Road
Swan§boro, N.C. 28584 .
Tel [phone] Fax: [phone] '
Email: crystalwasteng@bizec mcom• '
October 26, 2015
Mr. Steve G. Pusey
DENR — DEMLR
127 Cardinal Drive Extension
Wilmington, N.C. 28405
Re: Stormwater Project No. SW8 950317
Onslow Memorial Hospital
Onslow County
Dear Mr. Pusey
ECEWEI
OCT 282015
BY:
In response to your email of August 24, 2015, we did indeed once again make
contact with Onslow Memorial Hospital (Mr. Michael Holdren) with regard to the
status of future building projects. You will recall that the April 5, 2012 Permit
Modification issued by your office was a "temporary approval" contingent upon
expansion of an existing wet detention pond (DA1) "to handle pre-1988 + newer)"
BUA. The previous extension granted by your office ended on July 2, 2015.
You may recall, the hospital previously had plans to construct a "proposed expansion
project' ("courtyard area between original "main" building and the more recently
constructed ER & Surgical Pavilion) and intended to construct the required "pond
expansion" at that time. Mr. Holdren now indicates that, due to various reasons
(including budgetary constraints), that building expansion project is no longer
proposed. Mr. Holdren is now attempting to include the cost of the required pond
expansion into other proposed capital projects. However, the budgeting and
scheduling of those projects is uncertain at this particular time. Over the coming 12
months, Mr. Holdren anticipates more clarity with regard to these future capital
projects.
That being the case, we would request that your office grant the Permittee a
temporary extension of 24 months. It is hoped that these budgetary and scheduling
issues can be resolved during that period, and we can then provide your office a
more "concrete" assessment of the timeline for expansion of the existing pond.

• Page 2
October 26, 2015
We are hopeful that this response addresses all concerns. Should you have
questions or additional concerns, please feel free to contact me.
Yours
DaNkl-l< Newsom, PE
CRYSTAL COAST ENGIN